com.sleepycat.collections
public class TransactionRunner extends Object
A single TransactionRunner instance may be used by any number of threads for any number of transactions.
The behavior of the run() method depends on whether the environment is transactional, whether nested transactions are enabled, and whether a transaction is already active.
In a transactional environment, the rules described above support nested calls to the run() method and guarantee that the outermost call will cause the transaction to be committed or aborted. This is true whether or not nested transactions are supported or enabled. Note that nested transactions are provided as an optimization for improving concurrency but do not change the meaning of the outermost transaction. Nested transactions are not currently supported by the JE product.
Field Summary | |
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static int | DEFAULT_MAX_RETRIES The default maximum number of retries. |
Constructor Summary | |
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TransactionRunner(Environment env)
Creates a transaction runner for a given Berkeley DB environment.
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TransactionRunner(Environment env, int maxRetries, TransactionConfig config)
Creates a transaction runner for a given Berkeley DB environment and
with a given number of maximum retries.
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Method Summary | |
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boolean | getAllowNestedTransactions()
Returns whether nested transactions will be created if
run() is called when a transaction is already active for
the current thread.
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int | getMaxRetries()
Returns the maximum number of retries that will be performed when
deadlocks are detected. |
TransactionConfig | getTransactionConfig()
Returns the transaction configuration used for calling
Environment.
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void | run(TransactionWorker worker)
Calls the TransactionWorker method and, for transactional
environments, may begin and end a transaction. |
void | setAllowNestedTransactions(boolean allowNestedTxn)
Changes whether nested transactions will be created if
run() is called when a transaction is already active for
the current thread.
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void | setMaxRetries(int maxRetries)
Changes the maximum number of retries that will be performed when
deadlocks are detected.
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void | setTransactionConfig(TransactionConfig config)
Changes the transaction configuration used for calling
Environment.
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Parameters: env is the environment for running transactions.
Parameters: env is the environment for running transactions. maxRetries is the maximum number of retries that will be performed when deadlocks are detected. config the transaction configuration used for calling Environment, or null to use the default configuration. The configuration object is not cloned, and any modifications to it will impact subsequent transactions.
run()
is called when a transaction is already active for
the current thread.
By default this property is false.
Note that this method always returns false in the JE product, since nested transactions are not supported by JE.
If this property is null, the default configuration is used. The configuration object is not cloned, and any modifications to it will impact subsequent transactions.
Returns: the transaction configuration.
Throws: DeadlockException when it is thrown by doWork() and the maximum number of retries has occurred. The transaction will have been aborted by this method. Exception when any other exception is thrown by doWork(). The exception will first be unwrapped by calling ExceptionUnwrapper. The transaction will have been aborted by this method.
run()
is called when a transaction is already active for
the current thread.
Calling this method does not impact transactions already running.
Note that true may not be passed to this method in the JE product, since nested transactions are not supported by JE.
If this property is null, the default configuration is used. The configuration object is not cloned, and any modifications to it will impact subsequent transactions.
Parameters: config the transaction configuration.