001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    
018    package org.apache.commons.pool.impl;
019    
020    import java.util.ArrayList;
021    import java.util.Collection;
022    import java.util.HashMap;
023    import java.util.Iterator;
024    import java.util.LinkedList;
025    import java.util.List;
026    import java.util.Map;
027    import java.util.NoSuchElementException;
028    import java.util.Set;
029    import java.util.TreeMap;
030    import java.util.TimerTask;
031    
032    import org.apache.commons.pool.BaseKeyedObjectPool;
033    import org.apache.commons.pool.KeyedObjectPool;
034    import org.apache.commons.pool.KeyedPoolableObjectFactory;
035    
036    /**
037     * A configurable <code>KeyedObjectPool</code> implementation.
038     * <p>
039     * When coupled with the appropriate {@link KeyedPoolableObjectFactory},
040     * <code>GenericKeyedObjectPool</code> provides robust pooling functionality for
041     * keyed objects. A <code>GenericKeyedObjectPool</code> can be viewed as a map
042     * of pools, keyed on the (unique) key values provided to the
043     * {@link #preparePool preparePool}, {@link #addObject addObject} or
044     * {@link #borrowObject borrowObject} methods. Each time a new key value is
045     * provided to one of these methods, a new pool is created under the given key
046     * to be managed by the containing <code>GenericKeyedObjectPool.</code>
047     * </p>
048     * <p>A <code>GenericKeyedObjectPool</code> provides a number of configurable
049     * parameters:</p>
050     * <ul>
051     *  <li>
052     *    {@link #setMaxActive maxActive} controls the maximum number of objects
053     *    (per key) that can allocated by the pool (checked out to client threads,
054     *    or idle in the pool) at one time.  When non-positive, there is no limit
055     *    to the number of objects per key. When {@link #setMaxActive maxActive} is
056     *    reached, the keyed pool is said to be exhausted.  The default setting for
057     *    this parameter is 8.
058     *  </li>
059     *  <li>
060     *    {@link #setMaxTotal maxTotal} sets a global limit on the number of objects
061     *    that can be in circulation (active or idle) within the combined set of
062     *    pools.  When non-positive, there is no limit to the total number of
063     *    objects in circulation. When {@link #setMaxTotal maxTotal} is exceeded,
064     *    all keyed pools are exhausted. When <code>maxTotal</code> is set to a
065     *    positive value and {@link #borrowObject borrowObject} is invoked
066     *    when at the limit with no idle instances available, an attempt is made to
067     *    create room by clearing the oldest 15% of the elements from the keyed
068     *    pools. The default setting for this parameter is -1 (no limit).
069     *  </li>
070     *  <li>
071     *    {@link #setMaxIdle maxIdle} controls the maximum number of objects that can
072     *    sit idle in the pool (per key) at any time.  When negative, there
073     *    is no limit to the number of objects that may be idle per key. The
074     *    default setting for this parameter is 8.
075     *  </li>
076     *  <li>
077     *    {@link #setWhenExhaustedAction whenExhaustedAction} specifies the
078     *    behavior of the {@link #borrowObject borrowObject} method when a keyed
079     *    pool is exhausted:
080     *    <ul>
081     *    <li>
082     *      When {@link #setWhenExhaustedAction whenExhaustedAction} is
083     *      {@link #WHEN_EXHAUSTED_FAIL}, {@link #borrowObject borrowObject} will throw
084     *      a {@link NoSuchElementException}
085     *    </li>
086     *    <li>
087     *      When {@link #setWhenExhaustedAction whenExhaustedAction} is
088     *      {@link #WHEN_EXHAUSTED_GROW}, {@link #borrowObject borrowObject} will create a new
089     *      object and return it (essentially making {@link #setMaxActive maxActive}
090     *      meaningless.)
091     *    </li>
092     *    <li>
093     *      When {@link #setWhenExhaustedAction whenExhaustedAction}
094     *      is {@link #WHEN_EXHAUSTED_BLOCK}, {@link #borrowObject borrowObject} will block
095     *      (invoke {@link Object#wait() wait} until a new or idle object is available.
096     *      If a positive {@link #setMaxWait maxWait}
097     *      value is supplied, the {@link #borrowObject borrowObject} will block for at
098     *      most that many milliseconds, after which a {@link NoSuchElementException}
099     *      will be thrown.  If {@link #setMaxWait maxWait} is non-positive,
100     *      the {@link #borrowObject borrowObject} method will block indefinitely.
101     *    </li>
102     *    </ul>
103     *    The default <code>whenExhaustedAction</code> setting is
104     *    {@link #WHEN_EXHAUSTED_BLOCK}.
105     *  </li>
106     *  <li>
107     *    When {@link #setTestOnBorrow testOnBorrow} is set, the pool will
108     *    attempt to validate each object before it is returned from the
109     *    {@link #borrowObject borrowObject} method. (Using the provided factory's
110     *    {@link KeyedPoolableObjectFactory#validateObject validateObject} method.)
111     *    Objects that fail to validate will be dropped from the pool, and a
112     *    different object will be borrowed. The default setting for this parameter
113     *    is <code>false.</code>
114     *  </li>
115     *  <li>
116     *    When {@link #setTestOnReturn testOnReturn} is set, the pool will
117     *    attempt to validate each object before it is returned to the pool in the
118     *    {@link #returnObject returnObject} method. (Using the provided factory's
119     *    {@link KeyedPoolableObjectFactory#validateObject validateObject}
120     *    method.)  Objects that fail to validate will be dropped from the pool.
121     *    The default setting for this parameter is <code>false.</code>
122     *  </li>
123     * </ul>
124     * <p>
125     * Optionally, one may configure the pool to examine and possibly evict objects
126     * as they sit idle in the pool and to ensure that a minimum number of idle
127     * objects is maintained for each key. This is performed by an
128     * "idle object eviction" thread, which runs asynchronously. Caution should be
129     * used when configuring this optional feature. Eviction runs require an
130     * exclusive synchronization lock on the pool, so if they run too frequently
131     * and / or incur excessive latency when creating, destroying or validating
132     * object instances, performance issues may result.  The idle object eviction
133     * thread may be configured using the following attributes:
134     * <ul>
135     *  <li>
136     *   {@link #setTimeBetweenEvictionRunsMillis timeBetweenEvictionRunsMillis}
137     *   indicates how long the eviction thread should sleep before "runs" of examining
138     *   idle objects.  When non-positive, no eviction thread will be launched. The
139     *   default setting for this parameter is -1 (i.e., by default, idle object
140     *   eviction is disabled).
141     *  </li>
142     *  <li>
143     *   {@link #setMinEvictableIdleTimeMillis minEvictableIdleTimeMillis}
144     *   specifies the minimum amount of time that an object may sit idle in the
145     *   pool before it is eligible for eviction due to idle time.  When
146     *   non-positive, no object will be dropped from the pool due to idle time
147     *   alone.  This setting has no effect unless
148     *   <code>timeBetweenEvictionRunsMillis > 0.</code>  The default setting
149     *   for this parameter is 30 minutes.
150     *  </li>
151     *  <li>
152     *   {@link #setTestWhileIdle testWhileIdle} indicates whether or not idle
153     *   objects should be validated using the factory's
154     *   {@link KeyedPoolableObjectFactory#validateObject validateObject} method
155     *   during idle object eviction runs.  Objects that fail to validate will be
156     *   dropped from the pool. This setting has no effect unless
157     *   <code>timeBetweenEvictionRunsMillis > 0.</code>  The default setting
158     *   for this parameter is <code>false.</code>
159     *  </li>
160     *  <li>
161     *    {@link #setMinIdle minIdle} sets a target value for the minimum number of
162     *    idle objects (per key) that should always be available. If this parameter
163     *    is set to a positive number and
164     *    <code>timeBetweenEvictionRunsMillis > 0,</code> each time the idle object
165     *    eviction thread runs, it will try to create enough idle instances so that
166     *    there will be <code>minIdle</code> idle instances available under each
167     *    key. This parameter is also used by {@link #preparePool preparePool}
168     *    if <code>true</code> is provided as that method's
169     *    <code>populateImmediately</code> parameter. The default setting for this
170     *    parameter is 0.
171     *  </li>
172     * </ul>
173     * <p>
174     * The pools can be configured to behave as LIFO queues with respect to idle
175     * objects - always returning the most recently used object from the pool,
176     * or as FIFO queues, where borrowObject always returns the oldest object
177     * in the idle object pool.
178     * <ul>
179     *  <li>
180     *   {@link #setLifo <i>Lifo</i>}
181     *   determines whether or not the pools return idle objects in
182     *   last-in-first-out order. The default setting for this parameter is
183     *   <code>true.</code>
184     *  </li>
185     * </ul>
186     * <p>
187     * GenericKeyedObjectPool is not usable without a {@link KeyedPoolableObjectFactory}.  A
188     * non-<code>null</code> factory must be provided either as a constructor argument
189     * or via a call to {@link #setFactory setFactory} before the pool is used.
190     * </p>
191     * <p>
192     * Implementation note: To prevent possible deadlocks, care has been taken to
193     * ensure that no call to a factory method will occur within a synchronization
194     * block. See POOL-125 and DBCP-44 for more information.
195     * </p>
196     * @see GenericObjectPool
197     * @author Rodney Waldhoff
198     * @author Dirk Verbeeck
199     * @author Sandy McArthur
200     * @version $Revision: 812938 $ $Date: 2009-09-09 09:09:26 -0400 (Wed, 09 Sep 2009) $
201     * @since Pool 1.0
202     */
203    public class GenericKeyedObjectPool extends BaseKeyedObjectPool implements KeyedObjectPool {
204    
205        //--- public constants -------------------------------------------
206    
207        /**
208         * A "when exhausted action" type indicating that when the pool is
209         * exhausted (i.e., the maximum number of active objects has
210         * been reached), the {@link #borrowObject}
211         * method should fail, throwing a {@link NoSuchElementException}.
212         * @see #WHEN_EXHAUSTED_BLOCK
213         * @see #WHEN_EXHAUSTED_GROW
214         * @see #setWhenExhaustedAction
215         */
216        public static final byte WHEN_EXHAUSTED_FAIL   = 0;
217    
218        /**
219         * A "when exhausted action" type indicating that when the pool
220         * is exhausted (i.e., the maximum number
221         * of active objects has been reached), the {@link #borrowObject}
222         * method should block until a new object is available, or the
223         * {@link #getMaxWait maximum wait time} has been reached.
224         * @see #WHEN_EXHAUSTED_FAIL
225         * @see #WHEN_EXHAUSTED_GROW
226         * @see #setMaxWait
227         * @see #getMaxWait
228         * @see #setWhenExhaustedAction
229         */
230        public static final byte WHEN_EXHAUSTED_BLOCK  = 1;
231    
232        /**
233         * A "when exhausted action" type indicating that when the pool is
234         * exhausted (i.e., the maximum number
235         * of active objects has been reached), the {@link #borrowObject}
236         * method should simply create a new object anyway.
237         * @see #WHEN_EXHAUSTED_FAIL
238         * @see #WHEN_EXHAUSTED_GROW
239         * @see #setWhenExhaustedAction
240         */
241        public static final byte WHEN_EXHAUSTED_GROW   = 2;
242    
243        /**
244         * The default cap on the number of idle instances (per key) in the pool.
245         * @see #getMaxIdle
246         * @see #setMaxIdle
247         */
248        public static final int DEFAULT_MAX_IDLE  = 8;
249    
250        /**
251         * The default cap on the total number of active instances (per key)
252         * from the pool.
253         * @see #getMaxActive
254         * @see #setMaxActive
255         */
256        public static final int DEFAULT_MAX_ACTIVE  = 8;
257    
258        /**
259         * The default cap on the the overall maximum number of objects that can
260         * exist at one time.
261         * @see #getMaxTotal
262         * @see #setMaxTotal
263         */
264        public static final int DEFAULT_MAX_TOTAL  = -1;
265    
266        /**
267         * The default "when exhausted action" for the pool.
268         * @see #WHEN_EXHAUSTED_BLOCK
269         * @see #WHEN_EXHAUSTED_FAIL
270         * @see #WHEN_EXHAUSTED_GROW
271         * @see #setWhenExhaustedAction
272         */
273        public static final byte DEFAULT_WHEN_EXHAUSTED_ACTION = WHEN_EXHAUSTED_BLOCK;
274    
275        /**
276         * The default maximum amount of time (in milliseconds) the
277         * {@link #borrowObject} method should block before throwing
278         * an exception when the pool is exhausted and the
279         * {@link #getWhenExhaustedAction "when exhausted" action} is
280         * {@link #WHEN_EXHAUSTED_BLOCK}.
281         * @see #getMaxWait
282         * @see #setMaxWait
283         */
284        public static final long DEFAULT_MAX_WAIT = -1L;
285    
286        /**
287         * The default "test on borrow" value.
288         * @see #getTestOnBorrow
289         * @see #setTestOnBorrow
290         */
291        public static final boolean DEFAULT_TEST_ON_BORROW = false;
292    
293        /**
294         * The default "test on return" value.
295         * @see #getTestOnReturn
296         * @see #setTestOnReturn
297         */
298        public static final boolean DEFAULT_TEST_ON_RETURN = false;
299    
300        /**
301         * The default "test while idle" value.
302         * @see #getTestWhileIdle
303         * @see #setTestWhileIdle
304         * @see #getTimeBetweenEvictionRunsMillis
305         * @see #setTimeBetweenEvictionRunsMillis
306         */
307        public static final boolean DEFAULT_TEST_WHILE_IDLE = false;
308    
309        /**
310         * The default "time between eviction runs" value.
311         * @see #getTimeBetweenEvictionRunsMillis
312         * @see #setTimeBetweenEvictionRunsMillis
313         */
314        public static final long DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS = -1L;
315    
316        /**
317         * The default number of objects to examine per run in the
318         * idle object evictor.
319         * @see #getNumTestsPerEvictionRun
320         * @see #setNumTestsPerEvictionRun
321         * @see #getTimeBetweenEvictionRunsMillis
322         * @see #setTimeBetweenEvictionRunsMillis
323         */
324        public static final int DEFAULT_NUM_TESTS_PER_EVICTION_RUN = 3;
325    
326        /**
327         * The default value for {@link #getMinEvictableIdleTimeMillis}.
328         * @see #getMinEvictableIdleTimeMillis
329         * @see #setMinEvictableIdleTimeMillis
330         */
331        public static final long DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS = 1000L * 60L * 30L;
332    
333        /**
334         * The default minimum level of idle objects in the pool.
335         * @since Pool 1.3
336         * @see #setMinIdle
337         * @see #getMinIdle
338         */
339        public static final int DEFAULT_MIN_IDLE = 0;
340    
341        /**
342         * The default LIFO status. True means that borrowObject returns the
343         * most recently used ("last in") idle object in a pool (if there are
344         * idle instances available).  False means that pools behave as FIFO
345         * queues - objects are taken from idle object pools in the order that
346         * they are returned.
347         * @see #setLifo
348         */
349        public static final boolean DEFAULT_LIFO = true;
350    
351        //--- constructors -----------------------------------------------
352    
353        /**
354         * Create a new <code>GenericKeyedObjectPool</code> with no factory.
355         *
356         * @see #GenericKeyedObjectPool(KeyedPoolableObjectFactory)
357         * @see #setFactory(KeyedPoolableObjectFactory)
358         */
359        public GenericKeyedObjectPool() {
360            this(null, DEFAULT_MAX_ACTIVE, DEFAULT_WHEN_EXHAUSTED_ACTION, DEFAULT_MAX_WAIT, DEFAULT_MAX_IDLE, 
361                    DEFAULT_TEST_ON_BORROW, DEFAULT_TEST_ON_RETURN, DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS,
362                    DEFAULT_NUM_TESTS_PER_EVICTION_RUN, DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS, DEFAULT_TEST_WHILE_IDLE);
363        }
364    
365        /**
366         * Create a new <code>GenericKeyedObjectPool</code> using the specified values.
367         * @param factory the <code>KeyedPoolableObjectFactory</code> to use to create, validate, and destroy
368         * objects if not <code>null</code>
369         */
370        public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory) {
371            this(factory, DEFAULT_MAX_ACTIVE, DEFAULT_WHEN_EXHAUSTED_ACTION, DEFAULT_MAX_WAIT, DEFAULT_MAX_IDLE,
372                    DEFAULT_TEST_ON_BORROW, DEFAULT_TEST_ON_RETURN, DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS,
373                    DEFAULT_NUM_TESTS_PER_EVICTION_RUN, DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS, DEFAULT_TEST_WHILE_IDLE);
374        }
375    
376        /**
377         * Create a new <code>GenericKeyedObjectPool</code> using the specified values.
378         * @param factory the <code>KeyedPoolableObjectFactory</code> to use to create, validate, and destroy objects
379         * if not <code>null</code>
380         * @param config a non-<code>null</code> {@link GenericKeyedObjectPool.Config} describing the configuration
381         */
382        public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, GenericKeyedObjectPool.Config config) {
383            this(factory, config.maxActive, config.whenExhaustedAction, config.maxWait, config.maxIdle, config.maxTotal,
384                    config.minIdle, config.testOnBorrow, config.testOnReturn, config.timeBetweenEvictionRunsMillis,
385                    config.numTestsPerEvictionRun, config.minEvictableIdleTimeMillis, config.testWhileIdle, config.lifo);
386        }
387    
388        /**
389         * Create a new <code>GenericKeyedObjectPool</code> using the specified values.
390         * @param factory the <code>KeyedPoolableObjectFactory</code> to use to create, validate, and destroy objects
391         * if not <code>null</code>
392         * @param maxActive the maximum number of objects that can be borrowed from me at one time (see {@link #setMaxActive})
393         */
394        public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive) {
395            this(factory,maxActive, DEFAULT_WHEN_EXHAUSTED_ACTION, DEFAULT_MAX_WAIT, DEFAULT_MAX_IDLE,
396                    DEFAULT_TEST_ON_BORROW, DEFAULT_TEST_ON_RETURN, DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS, 
397                    DEFAULT_NUM_TESTS_PER_EVICTION_RUN, DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS, DEFAULT_TEST_WHILE_IDLE);
398        }
399    
400        /**
401         * Create a new <code>GenericKeyedObjectPool</code> using the specified values.
402         * @param factory the <code>KeyedPoolableObjectFactory</code> to use to create, validate, and destroy objects
403         * if not <code>null</code>
404         * @param maxActive the maximum number of objects that can be borrowed from me at one time (see {@link #setMaxActive})
405         * @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #setWhenExhaustedAction})
406         * @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted and
407         *  <code>whenExhaustedAction</code> is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #setMaxWait})
408         */
409        public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction,
410                long maxWait) {
411            this(factory, maxActive, whenExhaustedAction, maxWait, DEFAULT_MAX_IDLE, DEFAULT_TEST_ON_BORROW,
412                    DEFAULT_TEST_ON_RETURN, DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS, DEFAULT_NUM_TESTS_PER_EVICTION_RUN,
413                    DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS, DEFAULT_TEST_WHILE_IDLE);
414        }
415    
416        /**
417         * Create a new <code>GenericKeyedObjectPool</code> using the specified values.
418         * @param factory the <code>KeyedPoolableObjectFactory</code> to use to create, validate, and destroy objects
419         * if not <code>null</code>
420         * @param maxActive the maximum number of objects that can be borrowed from me at one time (see {@link #setMaxActive})
421         * @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted and
422         * <code>whenExhaustedAction</code> is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #setMaxWait})
423         * @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #setWhenExhaustedAction})
424         * @param testOnBorrow whether or not to validate objects before they are returned by the {@link #borrowObject}
425         * method (see {@link #setTestOnBorrow})
426         * @param testOnReturn whether or not to validate objects after they are returned to the {@link #returnObject}
427         * method (see {@link #setTestOnReturn})
428         */
429        public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction,
430                long maxWait, boolean testOnBorrow, boolean testOnReturn) {
431            this(factory, maxActive, whenExhaustedAction, maxWait, DEFAULT_MAX_IDLE,testOnBorrow,testOnReturn,
432                    DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS, DEFAULT_NUM_TESTS_PER_EVICTION_RUN,
433                    DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS, DEFAULT_TEST_WHILE_IDLE);
434        }
435    
436        /**
437         * Create a new <code>GenericKeyedObjectPool</code> using the specified values.
438         * @param factory the <code>KeyedPoolableObjectFactory</code> to use to create, validate, and destroy objects
439         * if not <code>null</code>
440         * @param maxActive the maximum number of objects that can be borrowed from me at one time
441         * (see {@link #setMaxActive})
442         * @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #setWhenExhaustedAction})
443         * @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted and
444         * <code>whenExhaustedAction</code> is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #setMaxWait})
445         * @param maxIdle the maximum number of idle objects in my pool (see {@link #setMaxIdle})
446         */
447        public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction,
448                long maxWait, int maxIdle) {
449            this(factory, maxActive, whenExhaustedAction, maxWait, maxIdle, DEFAULT_TEST_ON_BORROW, DEFAULT_TEST_ON_RETURN,
450                    DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS, DEFAULT_NUM_TESTS_PER_EVICTION_RUN,
451                    DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS, DEFAULT_TEST_WHILE_IDLE);
452        }
453    
454        /**
455         * Create a new <code>GenericKeyedObjectPool</code> using the specified values.
456         * @param factory the <code>KeyedPoolableObjectFactory</code> to use to create, validate, and destroy objects
457         * if not <code>null</code>
458         * @param maxActive the maximum number of objects that can be borrowed from me at one time
459         * (see {@link #setMaxActive})
460         * @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #setWhenExhaustedAction})
461         * @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted and
462         * <code>whenExhaustedAction</code> is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #getMaxWait})
463         * @param maxIdle the maximum number of idle objects in my pool (see {@link #setMaxIdle})
464         * @param testOnBorrow whether or not to validate objects before they are returned by the {@link #borrowObject}
465         * method (see {@link #setTestOnBorrow})
466         * @param testOnReturn whether or not to validate objects after they are returned to the {@link #returnObject}
467         * method (see {@link #setTestOnReturn})
468         */
469        public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction,
470                long maxWait, int maxIdle, boolean testOnBorrow, boolean testOnReturn) {
471            this(factory, maxActive, whenExhaustedAction, maxWait, maxIdle, testOnBorrow, testOnReturn,
472                    DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS, DEFAULT_NUM_TESTS_PER_EVICTION_RUN,
473                    DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS, DEFAULT_TEST_WHILE_IDLE);
474        }
475    
476        /**
477         * Create a new <code>GenericKeyedObjectPool</code> using the specified values.
478         * @param factory the <code>KeyedPoolableObjectFactory</code> to use to create, validate, and destroy objects
479         * if not <code>null</code>
480         * @param maxActive the maximum number of objects that can be borrowed from me at one time
481         * (see {@link #setMaxActive})
482         * @param whenExhaustedAction the action to take when the pool is exhausted 
483         * (see {@link #setWhenExhaustedAction})
484         * @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted and
485         * <code>whenExhaustedAction</code> is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #setMaxWait})
486         * @param maxIdle the maximum number of idle objects in my pool (see {@link #setMaxIdle})
487         * @param testOnBorrow whether or not to validate objects before they are returned by the {@link #borrowObject}
488         * method (see {@link #setTestOnBorrow})
489         * @param testOnReturn whether or not to validate objects after they are returned to the {@link #returnObject}
490         * method (see {@link #setTestOnReturn})
491         * @param timeBetweenEvictionRunsMillis the amount of time (in milliseconds) to sleep between examining idle
492         * objects for eviction (see {@link #setTimeBetweenEvictionRunsMillis})
493         * @param numTestsPerEvictionRun the number of idle objects to examine per run within the idle object eviction
494         * thread (if any) (see {@link #setNumTestsPerEvictionRun})
495         * @param minEvictableIdleTimeMillis the minimum number of milliseconds an object can sit idle in the pool before
496         * it is eligible for eviction (see {@link #setMinEvictableIdleTimeMillis})
497         * @param testWhileIdle whether or not to validate objects in the idle object eviction thread, if any
498         * (see {@link #setTestWhileIdle})
499         */
500        public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction,
501                long maxWait, int maxIdle, boolean testOnBorrow, boolean testOnReturn, long timeBetweenEvictionRunsMillis,
502                int numTestsPerEvictionRun, long minEvictableIdleTimeMillis, boolean testWhileIdle) {
503            this(factory, maxActive, whenExhaustedAction, maxWait, maxIdle, GenericKeyedObjectPool.DEFAULT_MAX_TOTAL,
504                    testOnBorrow, testOnReturn, timeBetweenEvictionRunsMillis, numTestsPerEvictionRun,
505                    minEvictableIdleTimeMillis, testWhileIdle);
506        }
507    
508        /**
509         * Create a new <code>GenericKeyedObjectPool</code> using the specified values.
510         * @param factory the <code>KeyedPoolableObjectFactory</code> to use to create, validate, and destroy objects
511         * if not <code>null</code>
512         * @param maxActive the maximum number of objects that can be borrowed from me at one time
513         * (see {@link #setMaxActive})
514         * @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #setWhenExhaustedAction})
515         * @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted and
516         * <code>whenExhaustedAction</code> is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #setMaxWait})
517         * @param maxIdle the maximum number of idle objects in my pool (see {@link #setMaxIdle})
518         * @param maxTotal the maximum number of objects that can exists at one time (see {@link #setMaxTotal})
519         * @param testOnBorrow whether or not to validate objects before they are returned by the {@link #borrowObject}
520         * method (see {@link #setTestOnBorrow})
521         * @param testOnReturn whether or not to validate objects after they are returned to the {@link #returnObject}
522         * method (see {@link #setTestOnReturn})
523         * @param timeBetweenEvictionRunsMillis the amount of time (in milliseconds) to sleep between examining idle
524         * objects for eviction (see {@link #setTimeBetweenEvictionRunsMillis})
525         * @param numTestsPerEvictionRun the number of idle objects to examine per run within the idle object eviction
526         * thread (if any) (see {@link #setNumTestsPerEvictionRun})
527         * @param minEvictableIdleTimeMillis the minimum number of milliseconds an object can sit idle in the pool
528         * before it is eligible for eviction (see {@link #setMinEvictableIdleTimeMillis})
529         * @param testWhileIdle whether or not to validate objects in the idle object eviction thread, if any
530         * (see {@link #setTestWhileIdle})
531         */
532        public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction,
533                long maxWait, int maxIdle, int maxTotal, boolean testOnBorrow, boolean testOnReturn,
534                long timeBetweenEvictionRunsMillis, int numTestsPerEvictionRun, long minEvictableIdleTimeMillis,
535                boolean testWhileIdle) {
536            this(factory, maxActive, whenExhaustedAction, maxWait, maxIdle, maxTotal,
537                    GenericKeyedObjectPool.DEFAULT_MIN_IDLE, testOnBorrow, testOnReturn, timeBetweenEvictionRunsMillis,
538                    numTestsPerEvictionRun, minEvictableIdleTimeMillis, testWhileIdle);
539        }
540    
541        /**
542         * Create a new <code>GenericKeyedObjectPool</code> using the specified values.
543         * @param factory the <code>KeyedPoolableObjectFactory</code> to use to create, validate, and destroy objects
544         * if not <code>null</code>
545         * @param maxActive the maximum number of objects that can be borrowed at one time (see {@link #setMaxActive})
546         * @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #setWhenExhaustedAction})
547         * @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted and
548         * <code>whenExhaustedAction</code> is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #setMaxWait})
549         * @param maxIdle the maximum number of idle objects in my pool (see {@link #setMaxIdle})
550         * @param maxTotal the maximum number of objects that can exists at one time (see {@link #setMaxTotal})
551         * @param minIdle the minimum number of idle objects to have in the pool at any one time (see {@link #setMinIdle})
552         * @param testOnBorrow whether or not to validate objects before they are returned by the {@link #borrowObject}
553         * method (see {@link #setTestOnBorrow})
554         * @param testOnReturn whether or not to validate objects after they are returned to the {@link #returnObject}
555         * method (see {@link #setTestOnReturn})
556         * @param timeBetweenEvictionRunsMillis the amount of time (in milliseconds) to sleep between examining idle
557         * objects
558         * for eviction (see {@link #setTimeBetweenEvictionRunsMillis})
559         * @param numTestsPerEvictionRun the number of idle objects to examine per run within the idle object eviction
560         * thread (if any) (see {@link #setNumTestsPerEvictionRun})
561         * @param minEvictableIdleTimeMillis the minimum number of milliseconds an object can sit idle in the pool before
562         * it is eligible for eviction (see {@link #setMinEvictableIdleTimeMillis})
563         * @param testWhileIdle whether or not to validate objects in the idle object eviction thread, if any
564         * (see {@link #setTestWhileIdle})
565         * @since Pool 1.3
566         */
567        public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction,
568                long maxWait, int maxIdle, int maxTotal, int minIdle, boolean testOnBorrow, boolean testOnReturn,
569                long timeBetweenEvictionRunsMillis, int numTestsPerEvictionRun, long minEvictableIdleTimeMillis,
570                boolean testWhileIdle) {
571            this(factory, maxActive, whenExhaustedAction, maxWait, maxIdle, maxTotal, minIdle, testOnBorrow, testOnReturn,
572                    timeBetweenEvictionRunsMillis, numTestsPerEvictionRun, minEvictableIdleTimeMillis, testWhileIdle,
573                    DEFAULT_LIFO);
574        }
575    
576        /**
577         * Create a new <code>GenericKeyedObjectPool</code> using the specified values.
578         * @param factory the <code>KeyedPoolableObjectFactory</code> to use to create, validate, and destroy objects
579         * if not <code>null</code>
580         * @param maxActive the maximum number of objects that can be borrowed at one time
581         *  (see {@link #setMaxActive})
582         * @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #setWhenExhaustedAction})
583         * @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted and
584         * <code>whenExhaustedAction</code> is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #setMaxWait})
585         * @param maxIdle the maximum number of idle objects in my pool (see {@link #setMaxIdle})
586         * @param maxTotal the maximum number of objects that can exists at one time (see {@link #setMaxTotal})
587         * @param minIdle the minimum number of idle objects to have in the pool at any one time (see {@link #setMinIdle})
588         * @param testOnBorrow whether or not to validate objects before they are returned by the {@link #borrowObject}
589         * method (see {@link #setTestOnBorrow})
590         * @param testOnReturn whether or not to validate objects after they are returned to the {@link #returnObject}
591         * method (see {@link #setTestOnReturn})
592         * @param timeBetweenEvictionRunsMillis the amount of time (in milliseconds) to sleep between examining idle
593         * objects for eviction (see {@link #setTimeBetweenEvictionRunsMillis})
594         * @param numTestsPerEvictionRun the number of idle objects to examine per run within the idle object eviction
595         * thread (if any) (see {@link #setNumTestsPerEvictionRun})
596         * @param minEvictableIdleTimeMillis the minimum number of milliseconds an object can sit idle in the pool before
597         * it is eligible for eviction (see {@link #setMinEvictableIdleTimeMillis})
598         * @param testWhileIdle whether or not to validate objects in the idle object eviction thread, if any
599         * (see {@link #setTestWhileIdle})
600         * @param lifo whether or not the pools behave as LIFO (last in first out) queues (see {@link #setLifo})
601         * @since Pool 1.4
602         */
603        public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction,
604                long maxWait, int maxIdle, int maxTotal, int minIdle, boolean testOnBorrow, boolean testOnReturn,
605                long timeBetweenEvictionRunsMillis, int numTestsPerEvictionRun, long minEvictableIdleTimeMillis,
606                boolean testWhileIdle, boolean lifo) {
607            _factory = factory;
608            _maxActive = maxActive;
609            _lifo = lifo;
610            switch (whenExhaustedAction) {
611                case WHEN_EXHAUSTED_BLOCK:
612                case WHEN_EXHAUSTED_FAIL:
613                case WHEN_EXHAUSTED_GROW:
614                    _whenExhaustedAction = whenExhaustedAction;
615                    break;
616                default:
617                    throw new IllegalArgumentException("whenExhaustedAction " + whenExhaustedAction + " not recognized.");
618            }
619            _maxWait = maxWait;
620            _maxIdle = maxIdle;
621            _maxTotal = maxTotal;
622            _minIdle = minIdle;
623            _testOnBorrow = testOnBorrow;
624            _testOnReturn = testOnReturn;
625            _timeBetweenEvictionRunsMillis = timeBetweenEvictionRunsMillis;
626            _numTestsPerEvictionRun = numTestsPerEvictionRun;
627            _minEvictableIdleTimeMillis = minEvictableIdleTimeMillis;
628            _testWhileIdle = testWhileIdle;
629    
630            _poolMap = new HashMap();
631            _poolList = new CursorableLinkedList();
632    
633            startEvictor(_timeBetweenEvictionRunsMillis);
634        }
635    
636        //--- public methods ---------------------------------------------
637    
638        //--- configuration methods --------------------------------------
639    
640        /**
641         * Returns the cap on the number of object instances allocated by the pool
642         * (checked out or idle),  per key.
643         * A negative value indicates no limit.
644         *
645         * @return the cap on the number of active instances per key.
646         * @see #setMaxActive
647         */
648        public synchronized int getMaxActive() {
649            return _maxActive;
650        }
651    
652        /**
653         * Sets the cap on the number of object instances managed by the pool per key.
654         * @param maxActive The cap on the number of object instances per key.
655         * Use a negative value for no limit.
656         *
657         * @see #getMaxActive
658         */
659        public synchronized void setMaxActive(int maxActive) {
660            _maxActive = maxActive;
661            allocate();
662        }
663    
664        /**
665         * Returns the overall maximum number of objects (across pools) that can
666         * exist at one time. A negative value indicates no limit.
667         * @return the maximum number of instances in circulation at one time.
668         * @see #setMaxTotal
669         */
670        public synchronized int getMaxTotal() {
671            return _maxTotal;
672        }
673    
674        /**
675         * Sets the cap on the total number of instances from all pools combined.
676         * When <code>maxTotal</code> is set to a
677         * positive value and {@link #borrowObject borrowObject} is invoked
678         * when at the limit with no idle instances available, an attempt is made to
679         * create room by clearing the oldest 15% of the elements from the keyed
680         * pools.
681         *
682         * @param maxTotal The cap on the total number of instances across pools.
683         * Use a negative value for no limit.
684         * @see #getMaxTotal
685         */
686        public synchronized void setMaxTotal(int maxTotal) {
687            _maxTotal = maxTotal;
688            allocate();
689        }
690    
691        /**
692         * Returns the action to take when the {@link #borrowObject} method
693         * is invoked when the pool is exhausted (the maximum number
694         * of "active" objects has been reached).
695         *
696         * @return one of {@link #WHEN_EXHAUSTED_BLOCK},
697         * {@link #WHEN_EXHAUSTED_FAIL} or {@link #WHEN_EXHAUSTED_GROW}
698         * @see #setWhenExhaustedAction
699         */
700        public synchronized byte getWhenExhaustedAction() {
701            return _whenExhaustedAction;
702        }
703    
704        /**
705         * Sets the action to take when the {@link #borrowObject} method
706         * is invoked when the pool is exhausted (the maximum number
707         * of "active" objects has been reached).
708         *
709         * @param whenExhaustedAction the action code, which must be one of
710         *        {@link #WHEN_EXHAUSTED_BLOCK}, {@link #WHEN_EXHAUSTED_FAIL},
711         *        or {@link #WHEN_EXHAUSTED_GROW}
712         * @see #getWhenExhaustedAction
713         */
714        public synchronized void setWhenExhaustedAction(byte whenExhaustedAction) {
715            switch(whenExhaustedAction) {
716                case WHEN_EXHAUSTED_BLOCK:
717                case WHEN_EXHAUSTED_FAIL:
718                case WHEN_EXHAUSTED_GROW:
719                    _whenExhaustedAction = whenExhaustedAction;
720                    allocate();
721                    break;
722                default:
723                    throw new IllegalArgumentException("whenExhaustedAction " + whenExhaustedAction + " not recognized.");
724            }
725        }
726    
727    
728        /**
729         * Returns the maximum amount of time (in milliseconds) the
730         * {@link #borrowObject} method should block before throwing
731         * an exception when the pool is exhausted and the
732         * {@link #setWhenExhaustedAction "when exhausted" action} is
733         * {@link #WHEN_EXHAUSTED_BLOCK}.
734         *
735         * When less than or equal to 0, the {@link #borrowObject} method
736         * may block indefinitely.
737         *
738         * @return the maximum number of milliseconds borrowObject will block.
739         * @see #setMaxWait
740         * @see #setWhenExhaustedAction
741         * @see #WHEN_EXHAUSTED_BLOCK
742         */
743        public synchronized long getMaxWait() {
744            return _maxWait;
745        }
746    
747        /**
748         * Sets the maximum amount of time (in milliseconds) the
749         * {@link #borrowObject} method should block before throwing
750         * an exception when the pool is exhausted and the
751         * {@link #setWhenExhaustedAction "when exhausted" action} is
752         * {@link #WHEN_EXHAUSTED_BLOCK}.
753         *
754         * When less than or equal to 0, the {@link #borrowObject} method
755         * may block indefinitely.
756         *
757         * @param maxWait the maximum number of milliseconds borrowObject will block or negative for indefinitely.
758         * @see #getMaxWait
759         * @see #setWhenExhaustedAction
760         * @see #WHEN_EXHAUSTED_BLOCK
761         */
762        public synchronized void setMaxWait(long maxWait) {
763            _maxWait = maxWait;
764        }
765    
766        /**
767         * Returns the cap on the number of "idle" instances per key.
768         * @return the maximum number of "idle" instances that can be held
769         * in a given keyed pool.
770         * @see #setMaxIdle
771         */
772        public synchronized int getMaxIdle() {
773            return _maxIdle;
774        }
775    
776        /**
777         * Sets the cap on the number of "idle" instances in the pool.
778         * If maxIdle is set too low on heavily loaded systems it is possible you
779         * will see objects being destroyed and almost immediately new objects
780         * being created. This is a result of the active threads momentarily
781         * returning objects faster than they are requesting them them, causing the
782         * number of idle objects to rise above maxIdle. The best value for maxIdle
783         * for heavily loaded system will vary but the default is a good starting
784         * point.
785         * @param maxIdle the maximum number of "idle" instances that can be held
786         * in a given keyed pool. Use a negative value for no limit.
787         * @see #getMaxIdle
788         * @see #DEFAULT_MAX_IDLE
789         */
790        public synchronized void setMaxIdle(int maxIdle) {
791            _maxIdle = maxIdle;
792            allocate();
793        }
794    
795        /**
796         * Sets the minimum number of idle objects to maintain in each of the keyed
797         * pools. This setting has no effect unless
798         * <code>timeBetweenEvictionRunsMillis > 0</code> and attempts to ensure
799         * that each pool has the required minimum number of instances are only
800         * made during idle object eviction runs.
801         * @param poolSize - The minimum size of the each keyed pool
802         * @since Pool 1.3
803         * @see #getMinIdle
804         * @see #setTimeBetweenEvictionRunsMillis
805         */
806        public synchronized void setMinIdle(int poolSize) {
807            _minIdle = poolSize;
808        }
809    
810        /**
811         * Returns the minimum number of idle objects to maintain in each of the keyed
812         * pools. This setting has no effect unless
813         * <code>timeBetweenEvictionRunsMillis > 0</code> and attempts to ensure
814         * that each pool has the required minimum number of instances are only
815         * made during idle object eviction runs.
816         * @return minimum size of the each keyed pool
817         * @since Pool 1.3
818         * @see #setTimeBetweenEvictionRunsMillis
819         */
820        public synchronized int getMinIdle() {
821            return _minIdle;
822        }
823    
824        /**
825         * When <code>true</code>, objects will be
826         * {@link org.apache.commons.pool.PoolableObjectFactory#validateObject validated}
827         * before being returned by the {@link #borrowObject}
828         * method.  If the object fails to validate,
829         * it will be dropped from the pool, and we will attempt
830         * to borrow another.
831         *
832         * @return <code>true</code> if objects are validated before being borrowed.
833         * @see #setTestOnBorrow
834         */
835        public boolean getTestOnBorrow() {
836            return _testOnBorrow;
837        }
838    
839        /**
840         * When <code>true</code>, objects will be
841         * {@link org.apache.commons.pool.PoolableObjectFactory#validateObject validated}
842         * before being returned by the {@link #borrowObject}
843         * method.  If the object fails to validate,
844         * it will be dropped from the pool, and we will attempt
845         * to borrow another.
846         *
847         * @param testOnBorrow whether object should be validated before being returned by borrowObject.
848         * @see #getTestOnBorrow
849         */
850        public void setTestOnBorrow(boolean testOnBorrow) {
851            _testOnBorrow = testOnBorrow;
852        }
853    
854        /**
855         * When <code>true</code>, objects will be
856         * {@link org.apache.commons.pool.PoolableObjectFactory#validateObject validated}
857         * before being returned to the pool within the
858         * {@link #returnObject}.
859         *
860         * @return <code>true</code> when objects will be validated before being returned.
861         * @see #setTestOnReturn
862         */
863        public boolean getTestOnReturn() {
864            return _testOnReturn;
865        }
866    
867        /**
868         * When <code>true</code>, objects will be
869         * {@link org.apache.commons.pool.PoolableObjectFactory#validateObject validated}
870         * before being returned to the pool within the
871         * {@link #returnObject}.
872         *
873         * @param testOnReturn <code>true</code> so objects will be validated before being returned.
874         * @see #getTestOnReturn
875         */
876        public void setTestOnReturn(boolean testOnReturn) {
877            _testOnReturn = testOnReturn;
878        }
879    
880        /**
881         * Returns the number of milliseconds to sleep between runs of the
882         * idle object evictor thread.
883         * When non-positive, no idle object evictor thread will be
884         * run.
885         *
886         * @return milliseconds to sleep between evictor runs.
887         * @see #setTimeBetweenEvictionRunsMillis
888         */
889        public synchronized long getTimeBetweenEvictionRunsMillis() {
890            return _timeBetweenEvictionRunsMillis;
891        }
892    
893        /**
894         * Sets the number of milliseconds to sleep between runs of the
895         * idle object evictor thread.
896         * When non-positive, no idle object evictor thread will be
897         * run.
898         *
899         * @param timeBetweenEvictionRunsMillis milliseconds to sleep between evictor runs.
900         * @see #getTimeBetweenEvictionRunsMillis
901         */
902        public synchronized void setTimeBetweenEvictionRunsMillis(long timeBetweenEvictionRunsMillis) {
903            _timeBetweenEvictionRunsMillis = timeBetweenEvictionRunsMillis;
904            startEvictor(_timeBetweenEvictionRunsMillis);
905        }
906    
907        /**
908         * Returns the max number of objects to examine during each run of the
909         * idle object evictor thread (if any).
910         *
911         * @return number of objects to examine each eviction run.
912         * @see #setNumTestsPerEvictionRun
913         * @see #setTimeBetweenEvictionRunsMillis
914         */
915        public synchronized int getNumTestsPerEvictionRun() {
916            return _numTestsPerEvictionRun;
917        }
918    
919        /**
920         * Sets the max number of objects to examine during each run of the
921         * idle object evictor thread (if any).
922         * <p>
923         * When a negative value is supplied, 
924         * <code>ceil({@link #getNumIdle()})/abs({@link #getNumTestsPerEvictionRun})</code>
925         * tests will be run.  I.e., when the value is <code>-n</code>, roughly one <code>n</code>th of the
926         * idle objects will be tested per run.  When the value is positive, the number of tests
927         * actually performed in each run will be the minimum of this value and the number of instances
928         * idle in the pools.
929         *
930         * @param numTestsPerEvictionRun number of objects to examine each eviction run.
931         * @see #setNumTestsPerEvictionRun
932         * @see #setTimeBetweenEvictionRunsMillis
933         */
934        public synchronized void setNumTestsPerEvictionRun(int numTestsPerEvictionRun) {
935            _numTestsPerEvictionRun = numTestsPerEvictionRun;
936        }
937    
938        /**
939         * Returns the minimum amount of time an object may sit idle in the pool
940         * before it is eligible for eviction by the idle object evictor
941         * (if any).
942         *
943         * @return minimum amount of time an object may sit idle in the pool before it is eligible for eviction.
944         * @see #setMinEvictableIdleTimeMillis
945         * @see #setTimeBetweenEvictionRunsMillis
946         */
947        public synchronized long getMinEvictableIdleTimeMillis() {
948            return _minEvictableIdleTimeMillis;
949        }
950    
951        /**
952         * Sets the minimum amount of time an object may sit idle in the pool
953         * before it is eligible for eviction by the idle object evictor
954         * (if any).
955         * When non-positive, no objects will be evicted from the pool
956         * due to idle time alone.
957         *
958         * @param minEvictableIdleTimeMillis minimum amount of time an object may sit idle in the pool before
959         * it is eligible for eviction.
960         * @see #getMinEvictableIdleTimeMillis
961         * @see #setTimeBetweenEvictionRunsMillis
962         */
963        public synchronized void setMinEvictableIdleTimeMillis(long minEvictableIdleTimeMillis) {
964            _minEvictableIdleTimeMillis = minEvictableIdleTimeMillis;
965        }
966    
967        /**
968         * When <code>true</code>, objects will be
969         * {@link org.apache.commons.pool.PoolableObjectFactory#validateObject validated}
970         * by the idle object evictor (if any).  If an object
971         * fails to validate, it will be dropped from the pool.
972         *
973         * @return <code>true</code> when objects are validated when borrowed.
974         * @see #setTestWhileIdle
975         * @see #setTimeBetweenEvictionRunsMillis
976         */
977        public synchronized boolean getTestWhileIdle() {
978            return _testWhileIdle;
979        }
980    
981        /**
982         * When <code>true</code>, objects will be
983         * {@link org.apache.commons.pool.PoolableObjectFactory#validateObject validated}
984         * by the idle object evictor (if any).  If an object
985         * fails to validate, it will be dropped from the pool.
986         *
987         * @param testWhileIdle <code>true</code> so objects are validated when borrowed.
988         * @see #getTestWhileIdle
989         * @see #setTimeBetweenEvictionRunsMillis
990         */
991        public synchronized void setTestWhileIdle(boolean testWhileIdle) {
992            _testWhileIdle = testWhileIdle;
993        }
994    
995        /**
996         * Sets the configuration.
997         * @param conf the new configuration to use.
998         * @see GenericKeyedObjectPool.Config
999         */
1000        public synchronized void setConfig(GenericKeyedObjectPool.Config conf) {
1001            setMaxIdle(conf.maxIdle);
1002            setMaxActive(conf.maxActive);
1003            setMaxTotal(conf.maxTotal);
1004            setMinIdle(conf.minIdle);
1005            setMaxWait(conf.maxWait);
1006            setWhenExhaustedAction(conf.whenExhaustedAction);
1007            setTestOnBorrow(conf.testOnBorrow);
1008            setTestOnReturn(conf.testOnReturn);
1009            setTestWhileIdle(conf.testWhileIdle);
1010            setNumTestsPerEvictionRun(conf.numTestsPerEvictionRun);
1011            setMinEvictableIdleTimeMillis(conf.minEvictableIdleTimeMillis);
1012            setTimeBetweenEvictionRunsMillis(conf.timeBetweenEvictionRunsMillis);
1013        }
1014    
1015        /**
1016         * Whether or not the idle object pools act as LIFO queues. True means
1017         * that borrowObject returns the most recently used ("last in") idle object
1018         * in a pool (if there are idle instances available).  False means that
1019         * the pools behave as FIFO queues - objects are taken from idle object
1020         * pools in the order that they are returned.
1021         *
1022         * @return <code>true</code> if the pools are configured to act as LIFO queues
1023         * @since 1.4
1024         */
1025         public synchronized boolean getLifo() {
1026             return _lifo;
1027         }
1028    
1029         /**
1030          * Sets the LIFO property of the pools. True means that borrowObject returns
1031          * the most recently used ("last in") idle object in a pool (if there are
1032          * idle instances available).  False means that the pools behave as FIFO
1033          * queues - objects are taken from idle object pools in the order that
1034          * they are returned.
1035          *
1036          * @param lifo the new value for the lifo property
1037          * @since 1.4
1038          */
1039         public synchronized void setLifo(boolean lifo) {
1040             this._lifo = lifo;
1041         }
1042    
1043        //-- ObjectPool methods ------------------------------------------
1044    
1045        /**
1046         * <p>Borrows an object from the keyed pool associated with the given key.</p>
1047         * 
1048         * <p>If there is an idle instance available in the pool associated with the given key, then
1049         * either the most-recently returned (if {@link #getLifo() lifo} == true) or "oldest" (lifo == false)
1050         * instance sitting idle in the pool will be activated and returned.  If activation fails, or
1051         * {@link #getTestOnBorrow() testOnBorrow} is set to true and validation fails, the instance is destroyed and the
1052         * next available instance is examined.  This continues until either a valid instance is returned or there
1053         * are no more idle instances available.</p>
1054         * 
1055         * <p>If there are no idle instances available in the pool associated with the given key, behavior
1056         * depends on the {@link #getMaxActive() maxActive}, {@link #getMaxTotal() maxTotal}, and (if applicable)
1057         * {@link #getWhenExhaustedAction() whenExhaustedAction} and {@link #getMaxWait() maxWait} properties. If the
1058         * number of instances checked out from the pool under the given key is less than <code>maxActive</code> and
1059         * the total number of instances in circulation (under all keys) is less than <code>maxTotal</code>, a new instance
1060         * is created, activated and (if applicable) validated and returned to the caller.</p>
1061         * 
1062         * <p>If the associated keyed pool is exhausted (no available idle instances and no capacity to create new ones),
1063         * this method will either block ({@link #WHEN_EXHAUSTED_BLOCK}), throw a <code>NoSuchElementException</code>
1064         * ({@link #WHEN_EXHAUSTED_FAIL}), or grow ({@link #WHEN_EXHAUSTED_GROW} - ignoring maxActive, maxTotal properties).
1065         * The length of time that this method will block when <code>whenExhaustedAction == WHEN_EXHAUSTED_BLOCK</code>
1066         * is determined by the {@link #getMaxWait() maxWait} property.</p>
1067         * 
1068         * <p>When the pool is exhausted, multiple calling threads may be simultaneously blocked waiting for instances
1069         * to become available.  As of pool 1.5, a "fairness" algorithm has been implemented to ensure that threads receive
1070         * available instances in request arrival order.</p>
1071         * 
1072         * @param key pool key
1073         * @return object instance from the keyed pool
1074         * @throws NoSuchElementException if a keyed object instance cannot be returned.
1075         */
1076         public Object borrowObject(Object key) throws Exception {
1077            long starttime = System.currentTimeMillis();
1078            Latch latch = new Latch(key);
1079            byte whenExhaustedAction;
1080            long maxWait;
1081            synchronized (this) {
1082                // Get local copy of current config. Can't sync when used later as
1083                // it can result in a deadlock. Has the added advantage that config
1084                // is consistent for entire method execution
1085                whenExhaustedAction = _whenExhaustedAction;
1086                maxWait = _maxWait;
1087    
1088                // Add this request to the queue
1089                _allocationQueue.add(latch);
1090    
1091                // Work the allocation queue, allocating idle instances and
1092                // instance creation permits in request arrival order
1093                allocate();
1094            }
1095    
1096            for(;;) {
1097                synchronized (this) {
1098                    assertOpen();
1099                }
1100                // If no object was allocated
1101                if (null == latch.getPair()) {
1102                    // Check to see if we were allowed to create one
1103                    if (latch.mayCreate()) {
1104                        // allow new object to be created
1105                    } else {
1106                        // the pool is exhausted
1107                        switch(whenExhaustedAction) {
1108                            case WHEN_EXHAUSTED_GROW:
1109                                // allow new object to be created
1110                                synchronized (this) {
1111                                    // Make sure another thread didn't allocate us an object
1112                                    // or permit a new object to be created
1113                                    if (latch.getPair() == null && !latch.mayCreate()) {
1114                                        _allocationQueue.remove(latch);
1115                                        latch.getPool().incrementInternalProcessingCount();
1116                                    }
1117                                }
1118                            break;
1119                            case WHEN_EXHAUSTED_FAIL:
1120                                synchronized (this) {
1121                                    // Make sure allocate hasn't already assigned an object
1122                                    // in a different thread or permitted a new object to be created
1123                                    if (latch.getPair() != null || latch.mayCreate()) {
1124                                        break;
1125                                    }
1126                                    _allocationQueue.remove(latch);
1127                                }
1128                                throw new NoSuchElementException("Pool exhausted");
1129                            case WHEN_EXHAUSTED_BLOCK:
1130                                try {
1131                                    synchronized (latch) {
1132                                        // Before we wait, make sure another thread didn't allocate us an object
1133                                        // or permit a new object to be created
1134                                        if (latch.getPair() == null && !latch.mayCreate()) {
1135                                            if (maxWait <= 0) {
1136                                                latch.wait();
1137                                            } else {
1138                                                // this code may be executed again after a notify then continue cycle
1139                                                // so, need to calculate the amount of time to wait
1140                                                final long elapsed = (System.currentTimeMillis() - starttime);
1141                                                final long waitTime = maxWait - elapsed;
1142                                                if (waitTime > 0)
1143                                                {
1144                                                    latch.wait(waitTime);
1145                                                }
1146                                            }
1147                                        } else {
1148                                            break;
1149                                        }
1150                                    }
1151                                } catch(InterruptedException e) {
1152                                    Thread.currentThread().interrupt();
1153                                    throw e;
1154                                    }
1155                                if (maxWait > 0 && ((System.currentTimeMillis() - starttime) >= maxWait)) {
1156                                    synchronized (this) {
1157                                        // Make sure allocate hasn't already assigned an object
1158                                        // in a different thread or permitted a new object to be created
1159                                        if (latch.getPair() == null && !latch.mayCreate()) {
1160                                            _allocationQueue.remove(latch);
1161                                        } else {
1162                                            break;
1163                                        }
1164                                    }
1165                                    throw new NoSuchElementException("Timeout waiting for idle object");
1166                                } else {
1167                                    continue; // keep looping
1168                                }
1169                            default:
1170                                throw new IllegalArgumentException("whenExhaustedAction " + whenExhaustedAction +
1171                                        " not recognized.");
1172                        }
1173                    }
1174                }
1175    
1176                boolean newlyCreated = false;
1177                if (null == latch.getPair()) {
1178                    try {
1179                        Object obj = _factory.makeObject(key);
1180                        latch.setPair(new ObjectTimestampPair(obj));
1181                        newlyCreated = true;
1182                    } finally {
1183                        if (!newlyCreated) {
1184                            // object cannot be created
1185                            synchronized (this) {
1186                                latch.getPool().decrementInternalProcessingCount();
1187                                // No need to reset latch - about to throw exception
1188                                allocate();
1189                            }
1190                        }
1191                    }
1192                }
1193    
1194                // activate & validate the object
1195                try {
1196                    _factory.activateObject(key, latch.getPair().value);
1197                    if (_testOnBorrow && !_factory.validateObject(key, latch.getPair().value)) {
1198                        throw new Exception("ValidateObject failed");
1199                    }
1200                    synchronized (this) {
1201                        latch.getPool().decrementInternalProcessingCount();
1202                        latch.getPool().incrementActiveCount();
1203                    }
1204                    return latch.getPair().value;
1205                } catch (Throwable e) {
1206                    // object cannot be activated or is invalid
1207                    try {
1208                        _factory.destroyObject(key, latch.getPair().value);
1209                    } catch (Throwable e2) {
1210                        // cannot destroy broken object
1211                    }
1212                    synchronized (this) {
1213                        latch.getPool().decrementInternalProcessingCount();
1214                        latch.reset();
1215                        _allocationQueue.add(0, latch);
1216                        allocate();
1217                    }
1218                    if (newlyCreated) {
1219                        throw new NoSuchElementException(
1220                           "Could not create a validated object, cause: " +
1221                                e.getMessage());
1222                    }
1223                    else {
1224                        continue; // keep looping
1225                    }
1226                }
1227            }
1228        }
1229    
1230        /**
1231         * Allocate available instances to latches in the allocation queue.  Then
1232         * set _mayCreate to true for as many additional latches remaining in queue
1233         * as _maxActive allows for each key.
1234         */
1235        private void allocate() {
1236            boolean clearOldest = false;
1237    
1238            synchronized (this) {
1239                if (isClosed()) return;
1240                
1241                Iterator allocationQueueIter = _allocationQueue.iterator();
1242                
1243                while (allocationQueueIter.hasNext()) {
1244                    // First use any objects in the pool to clear the queue
1245                    Latch latch = (Latch) allocationQueueIter.next();
1246                    ObjectQueue pool = (ObjectQueue)(_poolMap.get(latch.getkey()));
1247                    if (null == pool) {
1248                        pool = new ObjectQueue();
1249                        _poolMap.put(latch.getkey(), pool);
1250                        _poolList.add(latch.getkey());
1251                    }
1252                    latch.setPool(pool);
1253                    if (!pool.queue.isEmpty()) {
1254                        allocationQueueIter.remove();
1255                        latch.setPair(
1256                                (ObjectTimestampPair) pool.queue.removeFirst());
1257                        pool.incrementInternalProcessingCount();
1258                        _totalIdle--;
1259                        synchronized (latch) {
1260                            latch.notify();
1261                        }
1262                        // Next item in queue
1263                        continue;
1264                    }
1265    
1266                    // If there is a totalMaxActive and we are at the limit then
1267                    // we have to make room
1268                    if ((_maxTotal > 0) &&
1269                            (_totalActive + _totalIdle + _totalInternalProcessing >= _maxTotal)) {
1270                        clearOldest = true;
1271                        break;
1272                    }
1273    
1274                    // Second utilise any spare capacity to create new objects
1275                    if ((_maxActive < 0 || pool.activeCount + pool.internalProcessingCount < _maxActive) &&
1276                            (_maxTotal < 0 || _totalActive + _totalIdle + _totalInternalProcessing < _maxTotal)) {
1277                        // allow new object to be created
1278                        allocationQueueIter.remove();
1279                        latch.setMayCreate(true);
1280                        pool.incrementInternalProcessingCount();
1281                        synchronized (latch) {
1282                            latch.notify();
1283                        }
1284                        // Next item in queue
1285                        continue;
1286                    }
1287    
1288                    // If there is no per-key limit and we reach this point we
1289                    // must have allocated all the objects we possibly can and there
1290                    // is no point looking at the rest of the allocation queue
1291                    if (_maxActive < 0) {
1292                        break;
1293                    }
1294                }
1295            }
1296            
1297            if (clearOldest) {
1298                /* Clear oldest calls factory methods so it must be called from
1299                 * outside the sync block.
1300                 * It also needs to be outside the sync block as it calls
1301                 * allocate(). If called inside the sync block, the call to
1302                 * allocate() would be able to enter the sync block (since the
1303                 * thread already has the lock) which may have unexpected,
1304                 * unpleasant results.
1305                 */
1306                clearOldest();
1307            }
1308        }
1309        
1310        /**
1311         * Clears any objects sitting idle in the pool by removing them from the
1312         * idle instance pool and then invoking the configured 
1313         * {@link KeyedPoolableObjectFactory#destroyObject(Object, Object)} method on
1314         * each idle instance.
1315         *  
1316         * <p> Implementation notes:
1317         * <ul><li>This method does not destroy or effect in any way instances that are
1318         * checked out when it is invoked.</li>
1319         * <li>Invoking this method does not prevent objects being
1320         * returned to the idle instance pool, even during its execution. It locks
1321         * the pool only during instance removal. Additional instances may be returned
1322         * while removed items are being destroyed.</li></ul></p>
1323         */
1324        public void clear() {
1325            Map toDestroy = new HashMap();
1326            synchronized (this) {
1327                for (Iterator it = _poolMap.keySet().iterator(); it.hasNext();) {
1328                    Object key = it.next();
1329                    ObjectQueue pool = (ObjectQueue)_poolMap.get(key);
1330                    // Copy objects to new list so pool.queue can be cleared inside
1331                    // the sync
1332                    List objects = new ArrayList();
1333                    objects.addAll(pool.queue);
1334                    toDestroy.put(key, objects);
1335                    it.remove();
1336                    _poolList.remove(key);
1337                    _totalIdle = _totalIdle - pool.queue.size();
1338                    _totalInternalProcessing =
1339                        _totalInternalProcessing + pool.queue.size();
1340                    pool.queue.clear();
1341                }
1342            }
1343            destroy(toDestroy);
1344        }
1345    
1346        /**
1347         * Clears oldest 15% of objects in pool.  The method sorts the
1348         * objects into a TreeMap and then iterates the first 15% for removal.
1349         * 
1350         * @since Pool 1.3
1351         */
1352        public void clearOldest() {
1353            // Map of objects to destroy my key
1354            final Map toDestroy = new HashMap();
1355    
1356            // build sorted map of idle objects
1357            final Map map = new TreeMap();
1358            synchronized (this) {
1359                for (Iterator keyiter = _poolMap.keySet().iterator(); keyiter.hasNext();) {
1360                    final Object key = keyiter.next();
1361                    final CursorableLinkedList list = ((ObjectQueue)_poolMap.get(key)).queue;
1362                    for (Iterator it = list.iterator(); it.hasNext();) {
1363                        // each item into the map uses the objectimestamppair object
1364                        // as the key.  It then gets sorted based on the timstamp field
1365                        // each value in the map is the parent list it belongs in.
1366                        map.put(it.next(), key);
1367                    }
1368                }
1369    
1370                // Now iterate created map and kill the first 15% plus one to account for zero
1371                Set setPairKeys = map.entrySet();
1372                int itemsToRemove = ((int) (map.size() * 0.15)) + 1;
1373    
1374                Iterator iter = setPairKeys.iterator();
1375                while (iter.hasNext() && itemsToRemove > 0) {
1376                    Map.Entry entry = (Map.Entry) iter.next();
1377                    // kind of backwards on naming.  In the map, each key is the objecttimestamppair
1378                    // because it has the ordering with the timestamp value.  Each value that the
1379                    // key references is the key of the list it belongs to.
1380                    Object key = entry.getValue();
1381                    ObjectTimestampPair pairTimeStamp = (ObjectTimestampPair) entry.getKey();
1382                    final CursorableLinkedList list =
1383                        ((ObjectQueue)(_poolMap.get(key))).queue;
1384                    list.remove(pairTimeStamp);
1385    
1386                    if (toDestroy.containsKey(key)) {
1387                        ((List)toDestroy.get(key)).add(pairTimeStamp);
1388                    } else {
1389                        List listForKey = new ArrayList();
1390                        listForKey.add(pairTimeStamp);
1391                        toDestroy.put(key, listForKey);
1392                    }
1393                    // if that was the last object for that key, drop that pool
1394                    if (list.isEmpty()) {
1395                        _poolMap.remove(key);
1396                        _poolList.remove(key);
1397                    }
1398                    _totalIdle--;
1399                    _totalInternalProcessing++;
1400                    itemsToRemove--;
1401                }
1402    
1403            }
1404            destroy(toDestroy);
1405        }
1406    
1407        /**
1408         * Clears the specified pool, removing all pooled instances corresponding to the given <code>key</code>.
1409         *
1410         * @param key the key to clear
1411         */
1412        public void clear(Object key) {
1413            Map toDestroy = new HashMap();
1414    
1415            final ObjectQueue pool;
1416            synchronized (this) {
1417                pool = (ObjectQueue)(_poolMap.remove(key));
1418                if (pool == null) {
1419                    return;
1420                } else {
1421                    _poolList.remove(key);
1422                }
1423                // Copy objects to new list so pool.queue can be cleared inside
1424                // the sync
1425                List objects = new ArrayList();
1426                objects.addAll(pool.queue);
1427                toDestroy.put(key, objects);
1428                _totalIdle = _totalIdle - pool.queue.size();
1429                _totalInternalProcessing =
1430                    _totalInternalProcessing + pool.queue.size();
1431                pool.queue.clear();
1432            }
1433            destroy(toDestroy);
1434        }
1435    
1436        /**
1437         * Assuming Map<Object,Collection<ObjectTimestampPair>>, destroy all
1438         * ObjectTimestampPair.value
1439         * 
1440         * @param m Map containing keyed pools to clear
1441         */
1442        private void destroy(Map m) {
1443            for (Iterator keys = m.keySet().iterator(); keys.hasNext();) {
1444                Object key = keys.next();
1445                Collection c = (Collection) m.get(key);
1446                for (Iterator it = c.iterator(); it.hasNext();) {
1447                    try {
1448                        _factory.destroyObject(
1449                                key,((ObjectTimestampPair)(it.next())).value);
1450                    } catch(Exception e) {
1451                        // ignore error, keep destroying the rest
1452                    } finally {
1453                        synchronized(this) {
1454                            _totalInternalProcessing--;
1455                            allocate();
1456                        }
1457                    }
1458                }
1459    
1460            }
1461        }
1462    
1463        /**
1464         * Returns the total number of instances current borrowed from this pool but not yet returned.
1465         *
1466         * @return the total number of instances currently borrowed from this pool
1467         */
1468        public synchronized int getNumActive() {
1469            return _totalActive;
1470        }
1471    
1472        /**
1473         * Returns the total number of instances currently idle in this pool.
1474         *
1475         * @return the total number of instances currently idle in this pool
1476         */
1477        public synchronized int getNumIdle() {
1478            return _totalIdle;
1479        }
1480    
1481        /**
1482         * Returns the number of instances currently borrowed from but not yet returned
1483         * to the pool corresponding to the given <code>key</code>.
1484         *
1485         * @param key the key to query
1486         * @return the number of instances corresponding to the given <code>key</code> currently borrowed in this pool
1487         */
1488        public synchronized int getNumActive(Object key) {
1489            final ObjectQueue pool = (ObjectQueue)(_poolMap.get(key));
1490            return pool != null ? pool.activeCount : 0;
1491        }
1492    
1493        /**
1494         * Returns the number of instances corresponding to the given <code>key</code> currently idle in this pool.
1495         *
1496         * @param key the key to query
1497         * @return the number of instances corresponding to the given <code>key</code> currently idle in this pool
1498         */
1499        public synchronized int getNumIdle(Object key) {
1500            final ObjectQueue pool = (ObjectQueue)(_poolMap.get(key));
1501            return pool != null ? pool.queue.size() : 0;
1502        }
1503    
1504        /**
1505         * <p>Returns an object to a keyed pool.</p>
1506         * 
1507         * <p>For the pool to function correctly, the object instance <strong>must</strong> have been borrowed
1508         * from the pool (under the same key) and not yet returned. Repeated <code>returnObject</code> calls on
1509         * the same object/key pair (with no <code>borrowObject</code> calls in between) will result in multiple
1510         * references to the object in the idle instance pool.</p>
1511         * 
1512         * <p>If {@link #getMaxIdle() maxIdle} is set to a positive value and the number of idle instances under the given
1513         * key has reached this value, the returning instance is destroyed.</p>
1514         * 
1515         * <p>If {@link #getTestOnReturn() testOnReturn} == true, the returning instance is validated before being returned
1516         * to the idle instance pool under the given key.  In this case, if validation fails, the instance is destroyed.</p>
1517         * 
1518         * @param key pool key
1519         * @param obj instance to return to the keyed pool
1520         * @throws Exception
1521         */
1522        public void returnObject(Object key, Object obj) throws Exception {
1523            try {
1524                addObjectToPool(key, obj, true);
1525            } catch (Exception e) {
1526                if (_factory != null) {
1527                    try {
1528                        _factory.destroyObject(key, obj);
1529                    } catch (Exception e2) {
1530                        // swallowed
1531                    }
1532                    // TODO: Correctness here depends on control in addObjectToPool.
1533                    // These two methods should be refactored, removing the
1534                    // "behavior flag", decrementNumActive, from addObjectToPool.
1535                    ObjectQueue pool = (ObjectQueue) (_poolMap.get(key));
1536                    if (pool != null) {
1537                        synchronized(this) {
1538                            pool.decrementActiveCount();
1539                            allocate();
1540                        }
1541                    }
1542                }
1543            }
1544        }
1545    
1546        /**
1547         * <p>Adds an object to the keyed pool.</p>
1548         * 
1549         * <p>Validates the object if testOnReturn == true and passivates it before returning it to the pool.
1550         * if validation or passivation fails, or maxIdle is set and there is no room in the pool, the instance
1551         * is destroyed.</p>
1552         * 
1553         * <p>Calls {@link #allocate()} on successful completion</p>
1554         * 
1555         * @param key pool key
1556         * @param obj instance to add to the keyed pool
1557         * @param decrementNumActive whether or not to decrement the active count associated with the keyed pool
1558         * @throws Exception
1559         */
1560        private void addObjectToPool(Object key, Object obj,
1561                boolean decrementNumActive) throws Exception {
1562    
1563            // if we need to validate this object, do so
1564            boolean success = true; // whether or not this object passed validation
1565            if (_testOnReturn && !_factory.validateObject(key, obj)) {
1566                success = false;
1567            } else {
1568                _factory.passivateObject(key, obj);
1569            }
1570    
1571            boolean shouldDestroy = !success;
1572            ObjectQueue pool;
1573    
1574            // Add instance to pool if there is room and it has passed validation
1575            // (if testOnreturn is set)
1576            synchronized (this) {
1577                // grab the pool (list) of objects associated with the given key
1578                pool = (ObjectQueue) (_poolMap.get(key));
1579                // if it doesn't exist, create it
1580                if (null == pool) {
1581                    pool = new ObjectQueue();
1582                    _poolMap.put(key, pool);
1583                    _poolList.add(key);
1584                }
1585                if (isClosed()) {
1586                    shouldDestroy = true;
1587                } else {
1588                    // if there's no space in the pool, flag the object for destruction
1589                    // else if we passivated successfully, return it to the pool
1590                    if (_maxIdle >= 0 && (pool.queue.size() >= _maxIdle)) {
1591                        shouldDestroy = true;
1592                    } else if (success) {
1593                        // borrowObject always takes the first element from the queue,
1594                        // so for LIFO, push on top, FIFO add to end
1595                        if (_lifo) {
1596                            pool.queue.addFirst(new ObjectTimestampPair(obj));
1597                        } else {
1598                            pool.queue.addLast(new ObjectTimestampPair(obj));
1599                        }
1600                        _totalIdle++;
1601                        if (decrementNumActive) {
1602                            pool.decrementActiveCount();
1603                        }
1604                        allocate();
1605                    }
1606                }
1607            }
1608    
1609            // Destroy the instance if necessary
1610            if (shouldDestroy) {
1611                try {
1612                    _factory.destroyObject(key, obj);
1613                } catch(Exception e) {
1614                    // ignored?
1615                }
1616                // Decrement active count *after* destroy if applicable
1617                if (decrementNumActive) {
1618                    synchronized(this) {
1619                        pool.decrementActiveCount();
1620                        allocate();
1621                    }
1622                }
1623            }
1624        }
1625    
1626        /**
1627         * <p>Invalidates the object instance associated with the given key.  Decrements the active count
1628         * associated with the given keyed pool and destroys the instance.</p>
1629         * 
1630         * @param key pool key
1631         * @param obj instance to invalidate
1632         * @throws Exception if an exception occurs destroying the object
1633         */
1634        public void invalidateObject(Object key, Object obj) throws Exception {
1635            try {
1636                _factory.destroyObject(key, obj);
1637            } finally {
1638                synchronized (this) {
1639                    ObjectQueue pool = (ObjectQueue) (_poolMap.get(key));
1640                    if (null == pool) {
1641                        pool = new ObjectQueue();
1642                        _poolMap.put(key, pool);
1643                        _poolList.add(key);
1644                    }
1645                    pool.decrementActiveCount();
1646                    allocate(); // _totalActive has changed
1647                }
1648            }
1649        }
1650    
1651        /**
1652         * Create an object using the {@link KeyedPoolableObjectFactory#makeObject factory},
1653         * passivate it, and then place it in the idle object pool.
1654         * <code>addObject</code> is useful for "pre-loading" a pool with idle objects.
1655         *
1656         * @param key the key a new instance should be added to
1657         * @throws Exception when {@link KeyedPoolableObjectFactory#makeObject} fails.
1658         * @throws IllegalStateException when no {@link #setFactory factory} has been set or after {@link #close} has been
1659         * called on this pool.
1660         */
1661        public void addObject(Object key) throws Exception {
1662            assertOpen();
1663            if (_factory == null) {
1664                throw new IllegalStateException("Cannot add objects without a factory.");
1665            }
1666            Object obj = _factory.makeObject(key);
1667            try {
1668                assertOpen();
1669                addObjectToPool(key, obj, false);
1670            } catch (IllegalStateException ex) { // Pool closed
1671                try {
1672                    _factory.destroyObject(key, obj);
1673                } catch (Exception ex2) {
1674                    // swallow
1675                }
1676                throw ex;
1677            }
1678        }
1679    
1680        /**
1681         * Registers a key for pool control.
1682         *
1683         * If <code>populateImmediately</code> is <code>true</code> and
1684         * <code>minIdle > 0,</code> the pool under the given key will be
1685         * populated immediately with <code>minIdle</code> idle instances.
1686         *
1687         * @param key - The key to register for pool control.
1688         * @param populateImmediately - If this is <code>true</code>, the pool
1689         * will be populated immediately.
1690         * @since Pool 1.3
1691         */
1692        public synchronized void preparePool(Object key, boolean populateImmediately) {
1693            ObjectQueue pool = (ObjectQueue)(_poolMap.get(key));
1694            if (null == pool) {
1695                pool = new ObjectQueue();
1696                _poolMap.put(key,pool);
1697                _poolList.add(key);
1698            }
1699    
1700            if (populateImmediately) {
1701                try {
1702                    // Create the pooled objects
1703                    ensureMinIdle(key);
1704                }
1705                catch (Exception e) {
1706                    //Do nothing
1707                }
1708            }
1709        }
1710    
1711        /**
1712         * Closes the keyed object pool.  Once the pool is closed, {@link #borrowObject(Object)}
1713         * will fail with IllegalStateException, but {@link #returnObject(Object, Object)} and
1714         * {@link #invalidateObject(Object, Object)} will continue to work. This method does not
1715         * {@link #clear()} the pool. The method is idempotent - that is, it is OK to call it on a closed
1716         * pool. 
1717         * 
1718         * @throws Exception
1719         */
1720        public void close() throws Exception {
1721            super.close();
1722            synchronized (this) {
1723                clear();
1724                if (null != _evictionCursor) {
1725                    _evictionCursor.close();
1726                    _evictionCursor = null;
1727                }
1728                if (null != _evictionKeyCursor) {
1729                    _evictionKeyCursor.close();
1730                    _evictionKeyCursor = null;
1731                }
1732                startEvictor(-1L);
1733            }
1734        }
1735    
1736        /**
1737         * <p>Sets the keyed poolable object factory associated with this pool.</p>
1738         * 
1739         * <p>If this method is called when objects are checked out of any of the keyed pools,
1740         * an IllegalStateException is thrown.  Calling this method also has the side effect of
1741         * destroying any idle instances in existing keyed pools.</p>
1742         * 
1743         * @param factory KeyedPoolableObjectFactory to use when creating keyed object pool instances
1744         * @throws IllegalStateException if there are active (checked out) instances associated with this keyed object pool
1745         */
1746        public void setFactory(KeyedPoolableObjectFactory factory) throws IllegalStateException {
1747            Map toDestroy = new HashMap();
1748            synchronized (this) {
1749                assertOpen();
1750                if (0 < getNumActive()) {
1751                    throw new IllegalStateException("Objects are already active");
1752                } else {
1753                    for (Iterator it = _poolMap.keySet().iterator(); it.hasNext();) {
1754                        Object key = it.next();
1755                        ObjectQueue pool = (ObjectQueue)_poolMap.get(key);
1756                        if (pool != null) {
1757                            // Copy objects to new list so pool.queue can be cleared
1758                            // inside the sync
1759                            List objects = new ArrayList();
1760                            objects.addAll(pool.queue);
1761                            toDestroy.put(key, objects);
1762                            it.remove();
1763                            _poolList.remove(key);
1764                            _totalIdle = _totalIdle - pool.queue.size();
1765                            _totalInternalProcessing =
1766                                _totalInternalProcessing + pool.queue.size();
1767                            pool.queue.clear();
1768                        }
1769                    }
1770                    _factory = factory;
1771                }
1772            }
1773            destroy(toDestroy);
1774        }
1775    
1776        /**
1777         * <p>Perform <code>numTests</code> idle object eviction tests, evicting
1778         * examined objects that meet the criteria for eviction. If
1779         * <code>testWhileIdle</code> is true, examined objects are validated
1780         * when visited (and removed if invalid); otherwise only objects that
1781         * have been idle for more than <code>minEvicableIdletimeMillis</code>
1782         * are removed.</p>
1783         *
1784         * <p>Successive activations of this method examine objects in keyed pools
1785         * in sequence, cycling through the keys and examining objects in
1786         * oldest-to-youngest order within the keyed pools.</p>
1787         *
1788         * @throws Exception when there is a problem evicting idle objects.
1789         */
1790        public void evict() throws Exception {
1791            Object key = null;
1792            boolean testWhileIdle;
1793            long minEvictableIdleTimeMillis;
1794    
1795            synchronized (this) {
1796                // Get local copy of current config. Can't sync when used later as
1797                // it can result in a deadlock. Has the added advantage that config
1798                // is consistent for entire method execution
1799                testWhileIdle = _testWhileIdle;
1800                minEvictableIdleTimeMillis = _minEvictableIdleTimeMillis;
1801    
1802                // Initialize key to last key value
1803                if (_evictionKeyCursor != null &&
1804                        _evictionKeyCursor._lastReturned != null) {
1805                    key = _evictionKeyCursor._lastReturned.value();
1806                }
1807            }
1808    
1809            for (int i=0, m=getNumTests(); i<m; i++) {
1810                final ObjectTimestampPair pair;
1811                synchronized (this) {
1812                    // make sure pool map is not empty; otherwise do nothing
1813                    if (_poolMap == null || _poolMap.size() == 0) {
1814                        continue;
1815                    }
1816    
1817                    // if we don't have a key cursor, then create one
1818                    if (null == _evictionKeyCursor) {
1819                        resetEvictionKeyCursor();
1820                        key = null;
1821                    }
1822    
1823                    // if we don't have an object cursor, create one
1824                    if (null == _evictionCursor) {
1825                        // if the _evictionKeyCursor has a next value, use this key
1826                        if (_evictionKeyCursor.hasNext()) {
1827                            key = _evictionKeyCursor.next();
1828                            resetEvictionObjectCursor(key);
1829                        } else {
1830                            // Reset the key cursor and try again
1831                            resetEvictionKeyCursor();
1832                            if (_evictionKeyCursor != null) {
1833                                if (_evictionKeyCursor.hasNext()) {
1834                                    key = _evictionKeyCursor.next();
1835                                    resetEvictionObjectCursor(key);
1836                                }
1837                            }
1838                        }
1839                    }
1840    
1841                    if (_evictionCursor == null) {
1842                        continue; // should never happen; do nothing
1843                    }
1844    
1845                    // If eviction cursor is exhausted, try to move
1846                    // to the next key and reset
1847                    if ((_lifo && !_evictionCursor.hasPrevious()) ||
1848                            (!_lifo && !_evictionCursor.hasNext())) {
1849                        if (_evictionKeyCursor != null) {
1850                            if (_evictionKeyCursor.hasNext()) {
1851                                key = _evictionKeyCursor.next();
1852                                resetEvictionObjectCursor(key);
1853                            } else { // Need to reset Key cursor
1854                                resetEvictionKeyCursor();
1855                                if (_evictionKeyCursor != null) {
1856                                    if (_evictionKeyCursor.hasNext()) {
1857                                        key = _evictionKeyCursor.next();
1858                                        resetEvictionObjectCursor(key);
1859                                    }
1860                                }
1861                            }
1862                        }
1863                    }
1864    
1865                    if ((_lifo && !_evictionCursor.hasPrevious()) ||
1866                            (!_lifo && !_evictionCursor.hasNext())) {
1867                        continue; // reset failed, do nothing
1868                    }
1869    
1870                    // if LIFO and the _evictionCursor has a previous object,
1871                    // or FIFO and _evictionCursor has a next object, test it
1872                    pair = _lifo ?
1873                            (ObjectTimestampPair) _evictionCursor.previous() :
1874                            (ObjectTimestampPair) _evictionCursor.next();
1875                    _evictionCursor.remove();
1876                    _totalIdle--;
1877                    _totalInternalProcessing++;
1878                }
1879    
1880                boolean removeObject=false;
1881                if ((minEvictableIdleTimeMillis > 0) &&
1882                   (System.currentTimeMillis() - pair.tstamp >
1883                   minEvictableIdleTimeMillis)) {
1884                    removeObject=true;
1885                }
1886                if (testWhileIdle && removeObject == false) {
1887                    boolean active = false;
1888                    try {
1889                        _factory.activateObject(key,pair.value);
1890                        active = true;
1891                    } catch(Exception e) {
1892                        removeObject=true;
1893                    }
1894                    if (active) {
1895                        if (!_factory.validateObject(key,pair.value)) {
1896                            removeObject=true;
1897                        } else {
1898                            try {
1899                                _factory.passivateObject(key,pair.value);
1900                            } catch(Exception e) {
1901                                removeObject=true;
1902                            }
1903                        }
1904                    }
1905                }
1906    
1907                if (removeObject) {
1908                    try {
1909                        _factory.destroyObject(key, pair.value);
1910                    } catch(Exception e) {
1911                        // ignored
1912                    } finally {
1913                        // Do not remove the key from the _poolList or _poolmap,
1914                        // even if the list stored in the _poolMap for this key is
1915                        // empty when minIdle > 0.
1916                        //
1917                        // Otherwise if it was the last object for that key,
1918                        // drop that pool
1919                        if (_minIdle == 0) {
1920                            synchronized (this) {
1921                                ObjectQueue objectQueue =
1922                                    (ObjectQueue)_poolMap.get(key);
1923                                if (objectQueue != null &&
1924                                        objectQueue.queue.isEmpty()) {
1925                                    _poolMap.remove(key);
1926                                    _poolList.remove(key);
1927                                }
1928                            }
1929                        }
1930                    }
1931                }
1932                synchronized (this) {
1933                    if (!removeObject) {
1934                        _evictionCursor.add(pair);
1935                        _totalIdle++;
1936                        if (_lifo) {
1937                            // Skip over the element we just added back
1938                            _evictionCursor.previous();
1939                        }
1940                    }
1941                    _totalInternalProcessing--;
1942                }
1943            }
1944        }
1945    
1946        /**
1947         * Resets the eviction key cursor and closes any
1948         * associated eviction object cursor
1949         */
1950        private void resetEvictionKeyCursor() {
1951            if (_evictionKeyCursor != null) {
1952                _evictionKeyCursor.close();
1953            }
1954            _evictionKeyCursor = _poolList.cursor();
1955            if (null != _evictionCursor) {
1956                _evictionCursor.close();
1957                _evictionCursor = null;
1958            }
1959        }
1960    
1961        /**
1962         * Resets the eviction object cursor for the given key
1963         *
1964         * @param key eviction key
1965         */
1966        private void resetEvictionObjectCursor(Object key) {
1967            if (_evictionCursor != null) {
1968                _evictionCursor.close();
1969            }
1970            if (_poolMap == null) {
1971                return;
1972            }
1973            ObjectQueue pool = (ObjectQueue) (_poolMap.get(key));
1974            if (pool != null) {
1975                CursorableLinkedList queue = pool.queue;
1976                _evictionCursor = queue.cursor(_lifo ? queue.size() : 0);
1977            }
1978        }
1979    
1980        /**
1981         * Iterates through all the known keys and creates any necessary objects to maintain
1982         * the minimum level of pooled objects.
1983         * @see #getMinIdle
1984         * @see #setMinIdle
1985         * @throws Exception If there was an error whilst creating the pooled objects.
1986         */
1987        private void ensureMinIdle() throws Exception {
1988            //Check if should sustain the pool
1989            if (_minIdle > 0) {
1990                Object[] keysCopy;
1991                synchronized(this) {
1992                    // Get the current set of keys
1993                    keysCopy = _poolMap.keySet().toArray();
1994                }
1995    
1996                // Loop through all elements in _poolList
1997                // Find out the total number of max active and max idle for that class
1998                // If the number is less than the minIdle, do creation loop to boost numbers
1999                for (int i=0; i < keysCopy.length; i++) {
2000                    //Get the next key to process
2001                    ensureMinIdle(keysCopy[i]);
2002                }
2003            }
2004        }
2005    
2006        /**
2007         * Re-creates any needed objects to maintain the minimum levels of
2008         * pooled objects for the specified key.
2009         *
2010         * This method uses {@link #calculateDeficit} to calculate the number
2011         * of objects to be created. {@link #calculateDeficit} can be overridden to
2012         * provide a different method of calculating the number of objects to be
2013         * created.
2014         * @param key The key to process
2015         * @throws Exception If there was an error whilst creating the pooled objects
2016         */
2017        private void ensureMinIdle(Object key) throws Exception {
2018            // Calculate current pool objects
2019            ObjectQueue pool;
2020            synchronized(this) {
2021                pool = (ObjectQueue)(_poolMap.get(key));
2022            }
2023            if (pool == null) {
2024                return;
2025            }
2026    
2027            // this method isn't synchronized so the
2028            // calculateDeficit is done at the beginning
2029            // as a loop limit and a second time inside the loop
2030            // to stop when another thread already returned the
2031            // needed objects
2032            int objectDeficit = calculateDeficit(pool, false);
2033    
2034            for (int i = 0; i < objectDeficit && calculateDeficit(pool, true) > 0; i++) {
2035                try {
2036                    addObject(key);
2037                } finally {
2038                    synchronized (this) {
2039                        pool.decrementInternalProcessingCount();
2040                        allocate();
2041                    }
2042                }
2043            }
2044        }
2045    
2046        //--- non-public methods ----------------------------------------
2047    
2048        /**
2049         * Start the eviction thread or service, or when
2050         * <code>delay</code> is non-positive, stop it
2051         * if it is already running.
2052         *
2053         * @param delay milliseconds between evictor runs.
2054         */
2055        protected synchronized void startEvictor(long delay) {
2056            if (null != _evictor) {
2057                EvictionTimer.cancel(_evictor);
2058                _evictor = null;
2059            }
2060            if (delay > 0) {
2061                _evictor = new Evictor();
2062                EvictionTimer.schedule(_evictor, delay, delay);
2063            }
2064        }
2065    
2066        /**
2067         * Returns pool info including {@link #getNumActive()}, {@link #getNumIdle()}
2068         * and currently defined keys.
2069         * 
2070         * @return string containing debug information
2071         */
2072        synchronized String debugInfo() {
2073            StringBuffer buf = new StringBuffer();
2074            buf.append("Active: ").append(getNumActive()).append("\n");
2075            buf.append("Idle: ").append(getNumIdle()).append("\n");
2076            Iterator it = _poolMap.keySet().iterator();
2077            while (it.hasNext()) {
2078                Object key = it.next();
2079                buf.append("\t").append(key).append(" ").append(_poolMap.get(key)).append("\n");
2080            }
2081            return buf.toString();
2082        }
2083    
2084        /** 
2085         * Returns the number of tests to be performed in an Evictor run,
2086         * based on the current values of <code>_numTestsPerEvictionRun</code>
2087         * and <code>_totalIdle</code>.
2088         * 
2089         * @see #setNumTestsPerEvictionRun
2090         * @return the number of tests for the Evictor to run
2091         */
2092        private synchronized int getNumTests() {
2093            if (_numTestsPerEvictionRun >= 0) {
2094                return Math.min(_numTestsPerEvictionRun, _totalIdle);
2095            } else {
2096                return(int)(Math.ceil(_totalIdle/Math.abs((double)_numTestsPerEvictionRun)));
2097            }
2098        }
2099    
2100        /**
2101         * This returns the number of objects to create during the pool
2102         * sustain cycle. This will ensure that the minimum number of idle
2103         * instances is maintained without going past the maxActive value.
2104         * 
2105         * @param pool the ObjectPool to calculate the deficit for
2106         * @param incrementInternal - Should the count of objects currently under
2107         *                            some form of internal processing be
2108         *                            incremented?
2109         * @return The number of objects to be created
2110         */
2111        private synchronized int calculateDeficit(ObjectQueue pool,
2112                boolean incrementInternal) {
2113            int objectDefecit = 0;
2114    
2115            //Calculate no of objects needed to be created, in order to have
2116            //the number of pooled objects < maxActive();
2117            objectDefecit = getMinIdle() - pool.queue.size();
2118            if (getMaxActive() > 0) {
2119                int growLimit = Math.max(0, getMaxActive() - pool.activeCount - pool.queue.size() - pool.internalProcessingCount);
2120                objectDefecit = Math.min(objectDefecit, growLimit);
2121            }
2122    
2123            // Take the maxTotal limit into account
2124            if (getMaxTotal() > 0) {
2125                int growLimit = Math.max(0, getMaxTotal() - getNumActive() - getNumIdle() - _totalInternalProcessing);
2126                objectDefecit = Math.min(objectDefecit, growLimit);
2127            }
2128    
2129            if (incrementInternal && objectDefecit > 0) {
2130                pool.incrementInternalProcessingCount();
2131            }
2132            return objectDefecit;
2133        }
2134    
2135        //--- inner classes ----------------------------------------------
2136    
2137        /**
2138         * A "struct" that keeps additional information about the actual queue of pooled objects.
2139         */
2140        private class ObjectQueue {
2141            /** Number of instances checked out to clients from this queue */
2142            private int activeCount = 0;
2143            
2144            /** Idle instance queue */
2145            private final CursorableLinkedList queue = new CursorableLinkedList();
2146            
2147            /** Number of instances in process of being created */
2148            private int internalProcessingCount = 0;
2149    
2150            /** Increment the active count for this queue */
2151            void incrementActiveCount() {
2152                synchronized (GenericKeyedObjectPool.this) {
2153                    _totalActive++;
2154                }
2155                activeCount++;
2156            }
2157    
2158            /** Decrement the active count for this queue */
2159            void decrementActiveCount() {
2160                synchronized (GenericKeyedObjectPool.this) {
2161                    _totalActive--;
2162                }
2163                if (activeCount > 0) {
2164                    activeCount--;
2165                }
2166            }
2167    
2168            /** Record the fact that one more instance is queued for creation */
2169            void incrementInternalProcessingCount() {
2170                synchronized (GenericKeyedObjectPool.this) {
2171                    _totalInternalProcessing++;
2172                }
2173                internalProcessingCount++;
2174            }
2175    
2176            /** Decrement the number of instances in process of being created */
2177            void decrementInternalProcessingCount() {
2178                synchronized (GenericKeyedObjectPool.this) {
2179                    _totalInternalProcessing--;
2180                }
2181                internalProcessingCount--;
2182            }
2183        }
2184    
2185        /**
2186         * A simple "struct" encapsulating an object instance and a timestamp.
2187         *
2188         * Implements Comparable, objects are sorted from old to new.
2189         *
2190         * This is also used by {@link GenericObjectPool}.
2191         */
2192        static class ObjectTimestampPair implements Comparable {
2193            
2194            /** Object instance */
2195            Object value;
2196            
2197            /** timestamp */
2198            long tstamp;
2199    
2200            /**
2201             * Create a new ObjectTimestampPair using the given object and the current system time.
2202             * @param val object instance
2203             */
2204            ObjectTimestampPair(Object val) {
2205                this(val, System.currentTimeMillis());
2206            }
2207    
2208            /**
2209             * Create a new ObjectTimeStampPair using the given object and timestamp value.
2210             * @param val object instance
2211             * @param time long representation of timestamp
2212             */
2213            ObjectTimestampPair(Object val, long time) {
2214                value = val;
2215                tstamp = time;
2216            }
2217    
2218            /**
2219             * Returns a string representation.
2220             * 
2221             * @return String representing this ObjectTimestampPair
2222             */
2223            public String toString() {
2224                return value + ";" + tstamp;
2225            }
2226    
2227            /**
2228             * Compares this to another object by casting the argument to an
2229             * ObjectTimestampPair.
2230             * 
2231             * @param obj object to cmpare
2232             * @return result of comparison
2233             */
2234            public int compareTo(Object obj) {
2235                return compareTo((ObjectTimestampPair) obj);
2236            }
2237    
2238            /**
2239             * Compares this to another ObjectTimestampPair, using the timestamp as basis for comparison.
2240             * Implementation is consistent with equals.
2241             * 
2242             * @param other object to compare
2243             * @return result of comparison
2244             */
2245            public int compareTo(ObjectTimestampPair other) {
2246                final long tstampdiff = this.tstamp - other.tstamp;
2247                if (tstampdiff == 0) {
2248                    // make sure the natural ordering is consistent with equals
2249                    // see java.lang.Comparable Javadocs
2250                    return System.identityHashCode(this) - System.identityHashCode(other);
2251                } else {
2252                    // handle int overflow
2253                    return (int)Math.min(Math.max(tstampdiff, Integer.MIN_VALUE), Integer.MAX_VALUE);
2254                }
2255            }
2256        }
2257    
2258        /**
2259         * The idle object evictor {@link TimerTask}.
2260         * @see GenericKeyedObjectPool#setTimeBetweenEvictionRunsMillis
2261         */
2262        private class Evictor extends TimerTask {
2263            /**
2264             * Run pool maintenance.  Evict objects qualifying for eviction and then
2265             * invoke {@link GenericKeyedObjectPool#ensureMinIdle()}.
2266             */
2267            public void run() {
2268                //Evict from the pool
2269                try {
2270                    evict();
2271                } catch(Exception e) {
2272                    // ignored
2273                } catch(OutOfMemoryError oome) {
2274                    // Log problem but give evictor thread a chance to continue in
2275                    // case error is recoverable
2276                    oome.printStackTrace(System.err);
2277                }
2278                //Re-create idle instances.
2279                try {
2280                    ensureMinIdle();
2281                } catch (Exception e) {
2282                    // ignored
2283                }
2284            }
2285        }
2286    
2287        /**
2288         * A simple "struct" encapsulating the
2289         * configuration information for a <code>GenericKeyedObjectPool</code>.
2290         * @see GenericKeyedObjectPool#GenericKeyedObjectPool(KeyedPoolableObjectFactory,GenericKeyedObjectPool.Config)
2291         * @see GenericKeyedObjectPool#setConfig
2292         */
2293        public static class Config {
2294            /**
2295             * @see GenericKeyedObjectPool#setMaxIdle
2296             */
2297            public int maxIdle = GenericKeyedObjectPool.DEFAULT_MAX_IDLE;
2298            /**
2299             * @see GenericKeyedObjectPool#setMaxActive
2300             */
2301            public int maxActive = GenericKeyedObjectPool.DEFAULT_MAX_ACTIVE;
2302            /**
2303             * @see GenericKeyedObjectPool#setMaxTotal
2304             */
2305            public int maxTotal = GenericKeyedObjectPool.DEFAULT_MAX_TOTAL;
2306            /**
2307             * @see GenericKeyedObjectPool#setMinIdle
2308             */
2309            public int minIdle = GenericKeyedObjectPool.DEFAULT_MIN_IDLE;
2310            /**
2311             * @see GenericKeyedObjectPool#setMaxWait
2312             */
2313            public long maxWait = GenericKeyedObjectPool.DEFAULT_MAX_WAIT;
2314            /**
2315             * @see GenericKeyedObjectPool#setWhenExhaustedAction
2316             */
2317            public byte whenExhaustedAction = GenericKeyedObjectPool.DEFAULT_WHEN_EXHAUSTED_ACTION;
2318            /**
2319             * @see GenericKeyedObjectPool#setTestOnBorrow
2320             */
2321            public boolean testOnBorrow = GenericKeyedObjectPool.DEFAULT_TEST_ON_BORROW;
2322            /**
2323             * @see GenericKeyedObjectPool#setTestOnReturn
2324             */
2325            public boolean testOnReturn = GenericKeyedObjectPool.DEFAULT_TEST_ON_RETURN;
2326            /**
2327             * @see GenericKeyedObjectPool#setTestWhileIdle
2328             */
2329            public boolean testWhileIdle = GenericKeyedObjectPool.DEFAULT_TEST_WHILE_IDLE;
2330            /**
2331             * @see GenericKeyedObjectPool#setTimeBetweenEvictionRunsMillis
2332             */
2333            public long timeBetweenEvictionRunsMillis = GenericKeyedObjectPool.DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS;
2334            /**
2335             * @see GenericKeyedObjectPool#setNumTestsPerEvictionRun
2336             */
2337            public int numTestsPerEvictionRun =  GenericKeyedObjectPool.DEFAULT_NUM_TESTS_PER_EVICTION_RUN;
2338            /**
2339             * @see GenericKeyedObjectPool#setMinEvictableIdleTimeMillis
2340             */
2341            public long minEvictableIdleTimeMillis = GenericKeyedObjectPool.DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS;
2342            /**
2343             * @see GenericKeyedObjectPool#setLifo
2344             */
2345            public boolean lifo = GenericKeyedObjectPool.DEFAULT_LIFO;
2346        }
2347    
2348        /**
2349         * Latch used to control allocation order of objects to threads to ensure
2350         * fairness. That is, for each key, objects are allocated to threads in the order
2351         * that threads request objects.
2352         * 
2353         * @since 1.5
2354         */
2355        private static final class Latch {
2356            
2357            /** key of associated pool */
2358            private final Object _key;
2359            
2360            /** keyed pool associated with this latch */
2361            private ObjectQueue _pool;
2362            
2363            /** holds an ObjectTimestampPair when this latch has been allocated an instance */
2364            private ObjectTimestampPair _pair;
2365            
2366            /** indicates that this latch can create an instance */
2367            private boolean _mayCreate = false;
2368    
2369            /**
2370             * Create a latch with the given key
2371             * @param key key of the pool associated with this latch
2372             */
2373            private Latch(Object key) {
2374                _key = key;
2375            }
2376    
2377            /**
2378             * Retuns the key of the associated pool
2379             * @return associated pool key
2380             */
2381            private synchronized Object getkey() {
2382                return _key;
2383            }
2384    
2385            /**
2386             * Returns the pool associated with this latch
2387             * @return pool
2388             */
2389            private synchronized ObjectQueue getPool() {
2390                return _pool;
2391            }
2392            
2393            /**
2394             * Sets the pool associated with this latch
2395             * @param pool the pool
2396             */
2397            private synchronized void setPool(ObjectQueue pool) {
2398                _pool = pool;
2399            }
2400    
2401            /**
2402             * Gets the ObjectTimestampPair allocated to this latch.
2403             * Returns null if this latch does not have an instance allocated to it. 
2404             * @return the associated ObjectTimestampPair
2405             */
2406            private synchronized ObjectTimestampPair getPair() {
2407                return _pair;
2408            }
2409            
2410            /**
2411             * Allocate an ObjectTimestampPair to this latch.
2412             * @param pair ObjectTimestampPair on this latch
2413             */
2414            private synchronized void setPair(ObjectTimestampPair pair) {
2415                _pair = pair;
2416            }
2417    
2418            /**
2419             * Whether or not this latch can create an instance
2420             * @return true if this latch has an instance creation permit
2421             */
2422            private synchronized boolean mayCreate() {
2423                return _mayCreate;
2424            }
2425            
2426            /**
2427             * Sets the mayCreate property
2428             * 
2429             * @param mayCreate true means this latch can create an instance
2430             */
2431            private synchronized void setMayCreate(boolean mayCreate) {
2432                _mayCreate = mayCreate;
2433            }
2434    
2435            /**
2436             * Reset the latch data. Used when an allocation fails and the latch
2437             * needs to be re-added to the queue.
2438             */
2439            private synchronized void reset() {
2440                _pair = null;
2441                _mayCreate = false;
2442            }
2443        }
2444    
2445        //--- protected attributes ---------------------------------------
2446    
2447        /**
2448         * The cap on the number of idle instances in the pool.
2449         * @see #setMaxIdle
2450         * @see #getMaxIdle
2451         */
2452        private int _maxIdle = DEFAULT_MAX_IDLE;
2453    
2454        /**
2455         * The minimum no of idle objects to keep in the pool.
2456         * @see #setMinIdle
2457         * @see #getMinIdle
2458         */
2459        private int _minIdle = DEFAULT_MIN_IDLE;
2460    
2461        /**
2462         * The cap on the number of active instances from the pool.
2463         * @see #setMaxActive
2464         * @see #getMaxActive
2465         */
2466        private int _maxActive = DEFAULT_MAX_ACTIVE;
2467    
2468        /**
2469         * The cap on the total number of instances from the pool if non-positive.
2470         * @see #setMaxTotal
2471         * @see #getMaxTotal
2472         */
2473        private int _maxTotal = DEFAULT_MAX_TOTAL;
2474    
2475        /**
2476         * The maximum amount of time (in millis) the
2477         * {@link #borrowObject} method should block before throwing
2478         * an exception when the pool is exhausted and the
2479         * {@link #getWhenExhaustedAction "when exhausted" action} is
2480         * {@link #WHEN_EXHAUSTED_BLOCK}.
2481         *
2482         * When less than or equal to 0, the {@link #borrowObject} method
2483         * may block indefinitely.
2484         *
2485         * @see #setMaxWait
2486         * @see #getMaxWait
2487         * @see #WHEN_EXHAUSTED_BLOCK
2488         * @see #setWhenExhaustedAction
2489         * @see #getWhenExhaustedAction
2490         */
2491        private long _maxWait = DEFAULT_MAX_WAIT;
2492    
2493        /**
2494         * The action to take when the {@link #borrowObject} method
2495         * is invoked when the pool is exhausted (the maximum number
2496         * of "active" objects has been reached).
2497         *
2498         * @see #WHEN_EXHAUSTED_BLOCK
2499         * @see #WHEN_EXHAUSTED_FAIL
2500         * @see #WHEN_EXHAUSTED_GROW
2501         * @see #DEFAULT_WHEN_EXHAUSTED_ACTION
2502         * @see #setWhenExhaustedAction
2503         * @see #getWhenExhaustedAction
2504         */
2505        private byte _whenExhaustedAction = DEFAULT_WHEN_EXHAUSTED_ACTION;
2506    
2507        /**
2508         * When <code>true</code>, objects will be
2509         * {@link org.apache.commons.pool.PoolableObjectFactory#validateObject validated}
2510         * before being returned by the {@link #borrowObject}
2511         * method.  If the object fails to validate,
2512         * it will be dropped from the pool, and we will attempt
2513         * to borrow another.
2514         *
2515         * @see #setTestOnBorrow
2516         * @see #getTestOnBorrow
2517         */
2518        private volatile boolean _testOnBorrow = DEFAULT_TEST_ON_BORROW;
2519    
2520        /**
2521         * When <code>true</code>, objects will be
2522         * {@link org.apache.commons.pool.PoolableObjectFactory#validateObject validated}
2523         * before being returned to the pool within the
2524         * {@link #returnObject}.
2525         *
2526         * @see #getTestOnReturn
2527         * @see #setTestOnReturn
2528         */
2529        private volatile boolean _testOnReturn = DEFAULT_TEST_ON_RETURN;
2530    
2531        /**
2532         * When <code>true</code>, objects will be
2533         * {@link org.apache.commons.pool.PoolableObjectFactory#validateObject validated}
2534         * by the idle object evictor (if any).  If an object
2535         * fails to validate, it will be dropped from the pool.
2536         *
2537         * @see #setTestWhileIdle
2538         * @see #getTestWhileIdle
2539         * @see #getTimeBetweenEvictionRunsMillis
2540         * @see #setTimeBetweenEvictionRunsMillis
2541         */
2542        private boolean _testWhileIdle = DEFAULT_TEST_WHILE_IDLE;
2543    
2544        /**
2545         * The number of milliseconds to sleep between runs of the
2546         * idle object evictor thread.
2547         * When non-positive, no idle object evictor thread will be
2548         * run.
2549         *
2550         * @see #setTimeBetweenEvictionRunsMillis
2551         * @see #getTimeBetweenEvictionRunsMillis
2552         */
2553        private long _timeBetweenEvictionRunsMillis = DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS;
2554    
2555        /**
2556         * The number of objects to examine during each run of the
2557         * idle object evictor thread (if any).
2558         * <p>
2559         * When a negative value is supplied, <code>ceil({@link #getNumIdle})/abs({@link #getNumTestsPerEvictionRun})</code>
2560         * tests will be run.  I.e., when the value is <code>-n</code>, roughly one <code>n</code>th of the
2561         * idle objects will be tested per run.
2562         *
2563         * @see #setNumTestsPerEvictionRun
2564         * @see #getNumTestsPerEvictionRun
2565         * @see #getTimeBetweenEvictionRunsMillis
2566         * @see #setTimeBetweenEvictionRunsMillis
2567         */
2568        private int _numTestsPerEvictionRun =  DEFAULT_NUM_TESTS_PER_EVICTION_RUN;
2569    
2570        /**
2571         * The minimum amount of time an object may sit idle in the pool
2572         * before it is eligible for eviction by the idle object evictor
2573         * (if any).
2574         * When non-positive, no objects will be evicted from the pool
2575         * due to idle time alone.
2576         *
2577         * @see #setMinEvictableIdleTimeMillis
2578         * @see #getMinEvictableIdleTimeMillis
2579         * @see #getTimeBetweenEvictionRunsMillis
2580         * @see #setTimeBetweenEvictionRunsMillis
2581         */
2582        private long _minEvictableIdleTimeMillis = DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS;
2583    
2584        /** My hash of pools (ObjectQueue). */
2585        private Map _poolMap = null;
2586    
2587        /** The total number of active instances. */
2588        private int _totalActive = 0;
2589    
2590        /** The total number of idle instances. */
2591        private int _totalIdle = 0;
2592    
2593        /**
2594         * The number of objects subject to some form of internal processing
2595         * (usually creation or destruction) that should be included in the total
2596         * number of objects but are neither active nor idle.
2597         */
2598        private int _totalInternalProcessing = 0;
2599    
2600        /** My {@link KeyedPoolableObjectFactory}. */
2601        private KeyedPoolableObjectFactory _factory = null;
2602    
2603        /**
2604         * My idle object eviction {@link TimerTask}, if any.
2605         */
2606        private Evictor _evictor = null;
2607    
2608        /**
2609         * A cursorable list of my pools.
2610         * @see GenericKeyedObjectPool.Evictor#run
2611         */
2612        private CursorableLinkedList _poolList = null;
2613    
2614        /** Eviction cursor (over instances within-key) */
2615        private CursorableLinkedList.Cursor _evictionCursor = null;
2616        
2617        /** Eviction cursor (over keys) */
2618        private CursorableLinkedList.Cursor _evictionKeyCursor = null;
2619    
2620        /** Whether or not the pools behave as LIFO queues (last in first out) */
2621        private boolean _lifo = DEFAULT_LIFO;
2622    
2623        /**
2624         * Used to track the order in which threads call {@link #borrowObject()} so
2625         * that objects can be allocated in the order in which the threads requested
2626         * them.
2627         */
2628        private LinkedList _allocationQueue = new LinkedList();
2629    
2630    }