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org.quartz.impl.jdbcjobstore
Class JTANonClusteredSemaphore

java.lang.Object
  extended by org.quartz.impl.jdbcjobstore.JTANonClusteredSemaphore
All Implemented Interfaces:
Semaphore
public class JTANonClusteredSemaphore
extends Object
implements Semaphore

Provides in memory thread/resource locking that is JTA Transaction aware. It is most appropriate for use when using JobStoreCMT without clustering.

This Semaphore implementation is not Quartz cluster safe.

When a lock is obtained/released but there is no active JTA Transaction, then this Semaphore operates just like SimpleSemaphore.

By default, this class looks for the TransactionManager in JNDI under name "java:TransactionManager". If this is not where your Application Server registers it, you can modify the JNDI lookup location using the "transactionManagerJNDIName" property.

IMPORTANT: This Semaphore implementation is currently experimental. It has been tested a limited amount on JBoss 4.0.3SP1. If you do choose to use it, any feedback would be most appreciated!

See Also:
SimpleSemaphore

Field Summary
static String DEFAULT_TRANSACTION_MANANGER_LOCATION
           
 
Constructor Summary
JTANonClusteredSemaphore()
           
 
Method Summary
protected  org.apache.commons.logging.Log getLog()
           
protected  Transaction getTransaction()
          Helper method to get the current Transaction from the TransactionManager in JNDI.
 boolean isLockOwner(Connection conn, String lockName)
          Determine whether the calling thread owns a lock on the identified resource.
 boolean obtainLock(Connection conn, String lockName)
          Grants a lock on the identified resource to the calling thread (blocking until it is available).
 void releaseLock(Connection conn, String lockName)
          Release the lock on the identified resource if it is held by the calling thread, unless currently in a JTA transaction.
protected  void releaseLock(String lockName, boolean fromSynchronization)
          Release the lock on the identified resource if it is held by the calling thread, unless currently in a JTA transaction.
 boolean requiresConnection()
          This Semaphore implementation does not use the database.
 void setTransactionManagerJNDIName(String transactionManagerJNDIName)
           
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

DEFAULT_TRANSACTION_MANANGER_LOCATION

public static final String DEFAULT_TRANSACTION_MANANGER_LOCATION
See Also:
Constant Field Values
Constructor Detail

JTANonClusteredSemaphore

public JTANonClusteredSemaphore()
Method Detail

getLog

protected org.apache.commons.logging.Log getLog()

setTransactionManagerJNDIName

public void setTransactionManagerJNDIName(String transactionManagerJNDIName)

obtainLock

public boolean obtainLock(Connection conn,
                          String lockName)
                   throws LockException
Grants a lock on the identified resource to the calling thread (blocking until it is available).

Specified by:
obtainLock in interface Semaphore
Parameters:
conn - Database connection used to establish lock. Can be null if Semaphore.requiresConnection() returns false.
Returns:
true if the lock was obtained.
Throws:
LockException

getTransaction

protected Transaction getTransaction()
                              throws LockException
Helper method to get the current Transaction from the TransactionManager in JNDI.

Returns:
The current Transaction, null if not currently in a transaction.
Throws:
LockException

releaseLock

public void releaseLock(Connection conn,
                        String lockName)
                 throws LockException
Release the lock on the identified resource if it is held by the calling thread, unless currently in a JTA transaction.

Specified by:
releaseLock in interface Semaphore
Parameters:
conn - Database connection used to establish lock. Can be null if Semaphore.requiresConnection() returns false.
Throws:
LockException

releaseLock

protected void releaseLock(String lockName,
                           boolean fromSynchronization)
                    throws LockException
Release the lock on the identified resource if it is held by the calling thread, unless currently in a JTA transaction.

Parameters:
fromSynchronization - True if this method is being invoked from Synchronization notified of the enclosing transaction having completed.
Throws:
LockException - Thrown if there was a problem accessing the JTA Transaction. Only relevant if fromSynchronization is false.

isLockOwner

public boolean isLockOwner(Connection conn,
                           String lockName)
Determine whether the calling thread owns a lock on the identified resource.

Specified by:
isLockOwner in interface Semaphore
Parameters:
conn - Database connection used to establish lock. Can be null if Semaphore.requiresConnection() returns false.

requiresConnection

public boolean requiresConnection()
This Semaphore implementation does not use the database.

Specified by:
requiresConnection in interface Semaphore
See Also:
Semaphore.isLockOwner(Connection, String), Semaphore.obtainLock(Connection, String), Semaphore.releaseLock(Connection, String)
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