001// License: GPL. For details, see LICENSE file.
002package org.openstreetmap.josm.io;
003
004import java.awt.image.BufferedImage;
005import java.io.File;
006import java.io.RandomAccessFile;
007import java.math.BigInteger;
008import java.security.MessageDigest;
009import java.util.Iterator;
010import java.util.Set;
011import java.util.TreeMap;
012
013import javax.imageio.ImageIO;
014
015import org.openstreetmap.josm.Main;
016import org.openstreetmap.josm.tools.Utils;
017
018/**
019 * Use this class if you want to cache a lot of files that shouldn't be kept in memory. You can
020 * specify how much data should be stored and after which date the files should be expired.
021 * This works on a last-access basis, so files get deleted after they haven't been used for x days.
022 * You can turn this off by calling setUpdateModTime(false). Files get deleted on a first-in-first-out
023 * basis.
024 * @author xeen
025 *
026 */
027public class CacheFiles {
028    /**
029     * Common expirey dates
030     */
031    final static public int EXPIRE_NEVER = -1;
032    final static public int EXPIRE_DAILY = 60 * 60 * 24;
033    final static public int EXPIRE_WEEKLY = EXPIRE_DAILY * 7;
034    final static public int EXPIRE_MONTHLY = EXPIRE_WEEKLY * 4;
035
036    final private File dir;
037    final private String ident;
038    final private boolean enabled;
039
040    private long expire;  // in seconds
041    private long maxsize; // in megabytes
042    private boolean updateModTime = true;
043
044    // If the cache is full, we don't want to delete just one file
045    private static final int CLEANUP_TRESHOLD = 20;
046    // We don't want to clean after every file-write
047    private static final int CLEANUP_INTERVAL = 5;
048    // Stores how many files have been written
049    private int writes = 0;
050
051    /**
052     * Creates a new cache class. The ident will be used to store the files on disk and to save
053     * expire/space settings. Set plugin state to <code>true</code>.
054     * @param ident cache identifier
055     */
056    public CacheFiles(String ident) {
057        this(ident, true);
058    }
059
060    /**
061     * Creates a new cache class. The ident will be used to store the files on disk and to save
062     * expire/space settings.
063     * @param ident cache identifier
064     * @param isPlugin Whether this is a plugin or not (changes cache path)
065     */
066    public CacheFiles(String ident, boolean isPlugin) {
067        String pref = isPlugin ?
068                Main.pref.getPluginsDirectory().getPath() + File.separator + "cache" :
069                Main.pref.getCacheDirectory().getPath();
070
071        boolean dir_writeable;
072        this.ident = ident;
073        String cacheDir = Main.pref.get("cache." + ident + "." + "path", pref + File.separator + ident + File.separator);
074        this.dir = new File(cacheDir);
075        try {
076            this.dir.mkdirs();
077            dir_writeable = true;
078        } catch(Exception e) {
079            // We have no access to this directory, so don't do anything
080            dir_writeable = false;
081        }
082        this.enabled = dir_writeable;
083        this.expire = Main.pref.getLong("cache." + ident + "." + "expire", EXPIRE_DAILY);
084        if(this.expire < 0) {
085            this.expire = CacheFiles.EXPIRE_NEVER;
086        }
087        this.maxsize = Main.pref.getLong("cache." + ident + "." + "maxsize", 50);
088        if(this.maxsize < 0) {
089            this.maxsize = -1;
090        }
091    }
092
093    /**
094     * Loads the data for the given ident as an byte array. Returns null if data not available.
095     * @param ident cache identifier
096     * @return stored data
097     */
098    public byte[] getData(String ident) {
099        if(!enabled) return null;
100        try {
101            File data = getPath(ident);
102            if(!data.exists())
103                return null;
104
105            if(isExpired(data)) {
106                data.delete();
107                return null;
108            }
109
110            // Update last mod time so we don't expire recently used data
111            if(updateModTime) {
112                data.setLastModified(System.currentTimeMillis());
113            }
114
115            byte[] bytes = new byte[(int) data.length()];
116            new RandomAccessFile(data, "r").readFully(bytes);
117            return bytes;
118        } catch (Exception e) {
119            Main.warn(e);
120        }
121        return null;
122    }
123
124    /**
125     * Writes an byte-array to disk
126     * @param ident cache identifier
127     * @param data data to store
128     */
129    public void saveData(String ident, byte[] data) {
130        if(!enabled) return;
131        try {
132            File f = getPath(ident);
133            if (f.exists()) {
134                f.delete();
135            }
136            // rws also updates the file meta-data, i.e. last mod time
137            RandomAccessFile raf = new RandomAccessFile(f, "rws");
138            try {
139                raf.write(data);
140            } finally {
141                Utils.close(raf);
142            }
143        } catch (Exception e) {
144            Main.warn(e);
145        }
146
147        writes++;
148        checkCleanUp();
149    }
150
151    /**
152     * Loads the data for the given ident as an image. If no image is found, null is returned
153     * @param ident cache identifier
154     * @return BufferedImage or null
155     */
156    public BufferedImage getImg(String ident) {
157        if(!enabled) return null;
158        try {
159            File img = getPath(ident, "png");
160            if(!img.exists())
161                return null;
162
163            if(isExpired(img)) {
164                img.delete();
165                return null;
166            }
167            // Update last mod time so we don't expire recently used images
168            if(updateModTime) {
169                img.setLastModified(System.currentTimeMillis());
170            }
171            return ImageIO.read(img);
172        } catch (Exception e) {
173            Main.warn(e);
174        }
175        return null;
176    }
177
178    /**
179     * Saves a given image and ident to the cache
180     * @param ident cache identifier
181     * @param image imaga data for storage
182     */
183    public void saveImg(String ident, BufferedImage image) {
184        if (!enabled) return;
185        try {
186            ImageIO.write(image, "png", getPath(ident, "png"));
187        } catch (Exception e) {
188            Main.warn(e);
189        }
190
191        writes++;
192        checkCleanUp();
193    }
194
195    /**
196     * Sets the amount of time data is stored before it gets expired
197     * @param amount of time in seconds
198     * @param force will also write it to the preferences
199     */
200    public void setExpire(int amount, boolean force) {
201        String key = "cache." + ident + "." + "expire";
202        if(!Main.pref.get(key).isEmpty() && !force)
203            return;
204
205        this.expire = amount > 0 ? amount : EXPIRE_NEVER;
206        Main.pref.putLong(key, this.expire);
207    }
208
209    /**
210     * Sets the amount of data stored in the cache
211     * @param amount in Megabytes
212     * @param force will also write it to the preferences
213     */
214    public void setMaxSize(int amount, boolean force) {
215        String key = "cache." + ident + "." + "maxsize";
216        if(!Main.pref.get(key).isEmpty() && !force)
217            return;
218
219        this.maxsize = amount > 0 ? amount : -1;
220        Main.pref.putLong(key, this.maxsize);
221    }
222
223    /**
224     * Call this with <code>true</code> to update the last modification time when a file it is read.
225     * Call this with <code>false</code> to not update the last modification time when a file is read.
226     * @param to update state
227     */
228    public void setUpdateModTime(boolean to) {
229        updateModTime = to;
230    }
231
232    /**
233     * Checks if a clean up is needed and will do so if necessary
234     */
235    public void checkCleanUp() {
236        if(this.writes > CLEANUP_INTERVAL) {
237            cleanUp();
238        }
239    }
240
241    /**
242     * Performs a default clean up with the set values (deletes oldest files first)
243     */
244    public void cleanUp() {
245        if(!this.enabled || maxsize == -1) return;
246
247        TreeMap<Long, File> modtime = new TreeMap<Long, File>();
248        long dirsize = 0;
249
250        for(File f : dir.listFiles()) {
251            if(isExpired(f)) {
252                f.delete();
253            } else {
254                dirsize += f.length();
255                modtime.put(f.lastModified(), f);
256            }
257        }
258
259        if(dirsize < maxsize*1000*1000) return;
260
261        Set<Long> keySet = modtime.keySet();
262        Iterator<Long> it = keySet.iterator();
263        int i=0;
264        while (it.hasNext()) {
265            i++;
266            modtime.get(it.next()).delete();
267
268            // Delete a couple of files, then check again
269            if(i % CLEANUP_TRESHOLD == 0 && getDirSize() < maxsize)
270                return;
271        }
272        writes = 0;
273    }
274
275    final static public int CLEAN_ALL = 0;
276    final static public int CLEAN_SMALL_FILES = 1;
277    final static public int CLEAN_BY_DATE = 2;
278    /**
279     * Performs a non-default, specified clean up
280     * @param type any of the CLEAN_XX constants.
281     * @param size for CLEAN_SMALL_FILES: deletes all files smaller than (size) bytes
282     */
283    public void customCleanUp(int type, int size) {
284        switch(type) {
285        case CLEAN_ALL:
286            for(File f : dir.listFiles()) {
287                f.delete();
288            }
289            break;
290        case CLEAN_SMALL_FILES:
291            for(File f: dir.listFiles())
292                if(f.length() < size) {
293                    f.delete();
294                }
295            break;
296        case CLEAN_BY_DATE:
297            cleanUp();
298            break;
299        }
300    }
301
302    /**
303     * Calculates the size of the directory
304     * @return long Size of directory in bytes
305     */
306    private long getDirSize() {
307        if(!enabled) return -1;
308        long dirsize = 0;
309
310        for(File f : this.dir.listFiles()) {
311            dirsize += f.length();
312        }
313        return dirsize;
314    }
315
316    /**
317     * Returns a short and unique file name for a given long identifier
318     * @return String short filename
319     */
320    private static String getUniqueFilename(String ident) {
321        try {
322            MessageDigest md = MessageDigest.getInstance("MD5");
323            BigInteger number = new BigInteger(1, md.digest(ident.getBytes()));
324            return number.toString(16);
325        } catch(Exception e) {
326            // Fall back. Remove unsuitable characters and some random ones to shrink down path length.
327            // Limit it to 70 characters, that leaves about 190 for the path on Windows/NTFS
328            ident = ident.replaceAll("[^a-zA-Z0-9]", "");
329            ident = ident.replaceAll("[acegikmoqsuwy]", "");
330            return ident.substring(ident.length() - 70);
331        }
332    }
333
334    /**
335     * Gets file path for ident with customizable file-ending
336     * @param ident cache identifier
337     * @param ending file extension
338     * @return file structure
339     */
340    private File getPath(String ident, String ending) {
341        return new File(dir, getUniqueFilename(ident) + "." + ending);
342    }
343
344    /**
345     * Gets file path for ident
346     * @param ident cache identifier
347     * @return file structure
348     */
349    private File getPath(String ident) {
350        return new File(dir, getUniqueFilename(ident));
351    }
352
353    /**
354     * Checks whether a given file is expired
355     * @param file file description structure
356     * @return expired state
357     */
358    private boolean isExpired(File file) {
359        if(CacheFiles.EXPIRE_NEVER == this.expire)
360            return false;
361        return (file.lastModified() < (System.currentTimeMillis() - expire*1000));
362    }
363}