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Berkeley
DB Java Edition version 1.7.1 |
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java.lang.Objectcom.sleepycat.collections.TransactionRunner
Starts a transaction, calls TransactionWorker.doWork()
,
and handles transaction retry and exceptions. To perform a transaction,
the user implements the TransactionWorker
interface and passes an instance of that class to the run(com.sleepycat.collections.TransactionWorker)
method.
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 | |
static int |
DEFAULT_MAX_RETRIES
The default maximum number of retries. |
Constructor Summary | |
TransactionRunner(Environment env) Creates a transaction runner for a given Berkeley DB environment. |
|
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. |
Method Summary | |
boolean |
getAllowNestedTransactions()
Returns whether nested transactions will be created if run() is
called when a transaction is already active for the current thread. |
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.beginTransaction(com.sleepycat.je.Transaction,
com.sleepycat.je.TransactionConfig) . |
void |
run(TransactionWorker worker)
Calls the TransactionWorker.doWork()
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. |
void |
setMaxRetries(int maxRetries)
Changes the maximum number of retries that will be performed when deadlocks are detected. |
void |
setTransactionConfig(TransactionConfig config)
Changes the transaction configuration used for calling Environment.beginTransaction(com.sleepycat.je.Transaction,
com.sleepycat.je.TransactionConfig) . |
Methods inherited from class java.lang.Object |
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
public static final int DEFAULT_MAX_RETRIES
Constructor Detail |
public TransactionRunner(Environment env)
DEFAULT_MAX_RETRIES
)
and a null (default) TransactionConfig
will be used.
env
- is the environment for running
transactions.
public TransactionRunner(Environment env, int maxRetries, TransactionConfig config)
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.beginTransaction(com.sleepycat.je.Transaction,
com.sleepycat.je.TransactionConfig)
, or null to use the default
configuration. The configuration object is not cloned, and any
modifications to it will impact subsequent transactions.
Method Detail |
public int getMaxRetries()
public void setMaxRetries(int maxRetries)
public boolean getAllowNestedTransactions()
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.
public void setAllowNestedTransactions(boolean allowNestedTxn)
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.
public TransactionConfig getTransactionConfig()
Environment.beginTransaction(com.sleepycat.je.Transaction,
com.sleepycat.je.TransactionConfig)
.
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.
public void setTransactionConfig(TransactionConfig config)
Environment.beginTransaction(com.sleepycat.je.Transaction,
com.sleepycat.je.TransactionConfig)
.
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.
config
- the transaction configuration.
public void run(TransactionWorker worker) throws DatabaseException, Exception
TransactionWorker.doWork()
method and, for transactional environments, may begin and end a
transaction. If the environment given is non-transactional, a
transaction will not be used but the doWork() method will still be
called. See the class description for more information.
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.unwrap(java.lang.Exception)
.
The transaction will have been aborted by this method.
DatabaseException
|
Berkeley
DB Java Edition version 1.7.1 |
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