Berkeley DB Java Edition
version 1.7.0

com.sleepycat.je
Class Transaction

java.lang.Object
  extended bycom.sleepycat.je.Transaction

public class Transaction
extends Object

The Transaction object is the handle for a transaction. Methods off the transaction handle are used to configure, abort and commit the transaction. Transaction handles are provided to other Berkeley DB methods in order to transactionally protect those operations.

Transaction handles are free-threaded; transactions handles may be used concurrently by multiple threads. Once the Transaction.abort or Transaction.commit methods are called, the handle may not be accessed again, regardless of the success or failure of the method.

To obtain a transaction with default attributes:

    Transaction txn = myEnvironment.beginTransaction(null, null);
To customize the attributes of a transaction:
    TransactionConfig config = new TransactionConfig();
    config.setDirtyRead(true);
    Transaction txn = myEnvironment.beginTransaction(null, config);


Method Summary
 void abort()
          Cause an abnormal termination of the transaction.
 void commit()
          End the transaction.
 void commitNoSync()
          End the transaction, not committing synchronously.
 void commitSync()
          End the transaction, committing synchronously.
 void commitWriteNoSync()
          End the transaction, writing but not flushing the log.
 long getId()
          Return the transaction's unique ID.
 String getName()
          Get the user visible name for the transaction.
 void setLockTimeout(long timeOut)
          Configure the lock request timeout value for the transaction.
 void setName(String name)
          Set the user visible name for the transaction.
 void setTxnTimeout(long timeOut)
          Configure the timeout value for the transaction lifetime.
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Method Detail

getId

public long getId()
           throws DatabaseException
Return the transaction's unique ID.

Returns:
The transaction's unique ID.

Throws:
DatabaseException - if a failure occurs.

abort

public void abort()
           throws DatabaseException
Cause an abnormal termination of the transaction.

The log is played backward, and any necessary undo operations are done. Before Transaction.abort returns, any locks held by the transaction will have been released.

In the case of nested transactions, aborting a parent transaction causes all children (unresolved or not) of the parent transaction to be aborted.

All cursors opened within the transaction must be closed before the transaction is aborted.

After Transaction.abort has been called, regardless of its return, the Transaction handle may not be accessed again.

Throws:
DatabaseException - if a failure occurs.

commit

public void commit()
            throws DatabaseException
End the transaction. If the environment is configured for synchronous commit, the transaction will be committed synchronously to stable storage before the call returns. This means the transaction will exhibit all of the ACID (atomicity, consistency, isolation, and durability) properties.

If the environment is not configured for synchronous commit, the commit will not necessarily have been committed to stable storage before the call returns. This means the transaction will exhibit the ACI (atomicity, consistency, and isolation) properties, but not D (durability); that is, database integrity will be maintained, but it is possible this transaction may be undone during recovery.

All cursors opened within the transaction must be closed before the transaction is committed.

After this method returns the Transaction handle may not be accessed again, regardless of the method's success or failure. If the method encounters an error, the transaction and all child transactions of the transaction will have been aborted when the call returns.

Throws:
DatabaseException - if a failure occurs.

commitSync

public void commitSync()
                throws DatabaseException
End the transaction, committing synchronously. This means the transaction will exhibit all of the ACID (atomicity, consistency, isolation, and durability) properties.

This behavior is the default for database environments unless otherwise configured using the EnvironmentConfig.setTxnNoSync method. This behavior may also be set for a single transaction using the Environment.beginTransaction method. Any value specified to this method overrides both of those settings.

All cursors opened within the transaction must be closed before the transaction is committed.

After this method returns the Transaction handle may not be accessed again, regardless of the method's success or failure. If the method encounters an error, the transaction and all child transactions of the transaction will have been aborted when the call returns.

Throws:
DatabaseException - if a failure occurs.

commitNoSync

public void commitNoSync()
                  throws DatabaseException
End the transaction, not committing synchronously. This means the transaction will exhibit the ACI (atomicity, consistency, and isolation) properties, but not D (durability); that is, database integrity will be maintained, but it is possible this transaction may be undone during recovery.

This behavior may be set for a database environment using the EnvironmentConfig.setTxnNoSync method or for a single transaction using the Environment.beginTransaction method. Any value specified to this method overrides both of those settings.

All cursors opened within the transaction must be closed before the transaction is committed.

After this method returns the Transaction handle may not be accessed again, regardless of the method's success or failure. If the method encounters an error, the transaction and all child transactions of the transaction will have been aborted when the call returns.

Throws:
DatabaseException - if a failure occurs.

commitWriteNoSync

public void commitWriteNoSync()
                       throws DatabaseException
End the transaction, writing but not flushing the log. This means the transaction will exhibit the ACI (atomicity, consistency, and isolation) properties, but not D (durability); that is, database integrity will be maintained, but it is possible this transaction may be undone during recovery in the event that the operating system crashes. This option provides more durability than an asynchronous commit and has less performance cost than a synchronous commit.

This behavior may be set for a database environment using the EnvironmentConfig.setTxnWriteNoSync method or for a single transaction using the Environment.beginTransaction method. Any value specified to this method overrides both of those settings.

All cursors opened within the transaction must be closed before the transaction is committed.

After this method returns the Transaction handle may not be accessed again, regardless of the method's success or failure. If the method encounters an error, the transaction and all child transactions of the transaction will have been aborted when the call returns.

Throws:
DatabaseException - if a failure occurs.

setTxnTimeout

public void setTxnTimeout(long timeOut)
                   throws DatabaseException
Configure the timeout value for the transaction lifetime.

If the transaction runs longer than this time, the transaction may may throw DatabaseException.

Timeouts are checked whenever a thread of control blocks on a lock or when deadlock detection is performed. For this reason, the accuracy of the timeout depends on how often deadlock detection is performed.

Parameters:
timeOut - The timeout value for the transaction lifetime, in microseconds. As the value is an unsigned 32-bit number of microseconds, the maximum timeout is roughly 71 minutes. A value of 0 disables timeouts for the transaction.

This method may be called at any time during the life of the application.

Throws:
DatabaseException - if a failure occurs.

setLockTimeout

public void setLockTimeout(long timeOut)
                    throws DatabaseException
Configure the lock request timeout value for the transaction.

If a lock request cannot be granted in this time, the transaction may throw DatabaseException.

Timeouts are checked whenever a thread of control blocks on a lock or when deadlock detection is performed. For this reason, the accuracy of the timeout depends on how often deadlock detection is performed.

Parameters:
timeOut - The lock request timeout value for the transaction, in microseconds. As the value is an unsigned 32-bit number of microseconds, the maximum timeout is roughly 71 minutes. A value of 0 disables timeouts for the transaction.

This method may be called at any time during the life of the application.

Throws:
DatabaseException - if a failure occurs.

setName

public void setName(String name)
Set the user visible name for the transaction.

Parameters:
name - The user visible name for the transaction.


getName

public String getName()
Get the user visible name for the transaction.

Returns:
The user visible name for the transaction.


Berkeley DB Java Edition
version 1.7.0

Copyright (c) 1996-2004 Sleepycat Software, Inc. - All rights reserved.