com.sleepycat.je.latch
Class Java5SharedLatchImpl

java.lang.Object
  java.util.concurrent.locks.ReentrantReadWriteLock
      com.sleepycat.je.latch.Java5SharedLatchImpl

All Implemented Interfaces:

SharedLatch, Serializable, ReadWriteLock

 class Java5SharedLatchImpl
extends ReentrantReadWriteLock
implements SharedLatch

Java5SharedLatchImpl provides an implementation of the SharedLatch interface. By using a wrapper class we can avoid link errors when we run in Java 1.4 JVMs. LatchSupport will only reference this class if it knows that the ReentrantReadWriteLock class is available at runtime through Class.forName(). LatchSupport only references this class through the SharedLatch interface and only constructs this using Class.forName("Java5LatchImpl").newInstance();

Nested Class Summary

Nested classes/interfaces inherited from class java.util.concurrent.locks.ReentrantReadWriteLock

ReentrantReadWriteLock.ReadLock, ReentrantReadWriteLock.WriteLock

Constructor Summary

Java5SharedLatchImpl()

Method Summary

void	acquireExclusive() Acquire a latch for exclusive/write access.
boolean	acquireExclusiveNoWait() Probe a latch for exclusive access, but don't block if it's not available.
void	acquireShared() Acquire a latch for shared/read access.
boolean	isOwner() Return true if this thread is an owner, reader, or write.
void	release() Release an exclusive or shared latch.
void	releaseIfOwner() Release the latch.
void	setExclusiveOnly(boolean exclusiveOnly) Indicate whether this latch can only be set exclusively (not shared).
void	setName(String name) Set the latch name, used for latches in objects instantiated from the log.
boolean	setNoteLatch(boolean noteLatch) If noteLatch is true, then track latch usage in the latchTable.

Methods inherited from class java.util.concurrent.locks.ReentrantReadWriteLock

getOwner, getQueuedReaderThreads, getQueuedThreads, getQueuedWriterThreads, getQueueLength, getReadHoldCount, getReadLockCount, getWaitingThreads, getWaitQueueLength, getWriteHoldCount, hasQueuedThread, hasQueuedThreads, hasWaiters, isFair, isWriteLocked, isWriteLockedByCurrentThread, readLock, toString, writeLock

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface com.sleepycat.je.latch.SharedLatch

isWriteLockedByCurrentThread

Constructor Detail

Java5SharedLatchImpl

Java5SharedLatchImpl()

Method Detail

setExclusiveOnly

public void setExclusiveOnly(boolean exclusiveOnly)

Description copied from interface: SharedLatch

Indicate whether this latch can only be set exclusively (not shared). Used for BIN latches that are Shared, but should only be latched exclusively.

Specified by:

setExclusiveOnly in interface SharedLatch

setName

public void setName(String name)

Set the latch name, used for latches in objects instantiated from the log.

Specified by:

setName in interface SharedLatch

setNoteLatch

public boolean setNoteLatch(boolean noteLatch)

If noteLatch is true, then track latch usage in the latchTable. Always return true so this can be called as an assert.

Specified by:

setNoteLatch in interface SharedLatch

acquireExclusive

public void acquireExclusive()
                      throws DatabaseException

Acquire a latch for exclusive/write access. Wait for the latch if some other thread is holding it. If there are threads waiting for access, they will be granted the latch on a FIFO basis if fair latches are set. When the method returns, the latch is held for exclusive access.

Specified by:

acquireExclusive in interface SharedLatch

Throws:

LatchException - if the latch is already held by the current thread for exclusive access.

DatabaseException

acquireExclusiveNoWait

public boolean acquireExclusiveNoWait()
                               throws DatabaseException

Description copied from interface: SharedLatch

Probe a latch for exclusive access, but don't block if it's not available.

Specified by:

acquireExclusiveNoWait in interface SharedLatch

Returns:

true if the latch was acquired, false if it is not available.

Throws:

LatchException - if the latch is already held by the calling thread.

DatabaseException

acquireShared

public void acquireShared()
                   throws DatabaseException

Acquire a latch for shared/read access.

Specified by:

acquireShared in interface SharedLatch

Throws:

RunRecoveryException - if an InterruptedException exception occurs.

DatabaseException

isOwner

public boolean isOwner()

Description copied from interface: SharedLatch

Return true if this thread is an owner, reader, or write.

Specified by:

isOwner in interface SharedLatch

release

public void release()
             throws LatchNotHeldException

Release an exclusive or shared latch. If there are other thread(s) waiting for the latch, they are woken up and granted the latch.

Specified by:

release in interface SharedLatch

Throws:

LatchNotHeldException

releaseIfOwner

public void releaseIfOwner()
                    throws LatchNotHeldException

Description copied from interface: SharedLatch

Release the latch. If there are other thread(s) waiting for the latch, one is woken up and granted the latch. If the latch was not owned by the caller, just return.

Specified by:

releaseIfOwner in interface SharedLatch

Throws:

LatchNotHeldException