org.exist.storage.lock
Class ReentrantReadWriteLock

java.lang.Object
  org.exist.storage.lock.ReentrantReadWriteLock

All Implemented Interfaces:

Lock

public class ReentrantReadWriteLock

extends java.lang.Object

implements Lock

A lock with the same semantics as builtin Java synchronized locks: Once a thread has a lock, it can re-obtain it any number of times without blocking. The lock is made available to other threads when as many releases as acquires have occurred. The lock has a timeout: a read lock will be released if the timeout is reached.

Field Summary

protected long	holds_
protected java.lang.String	id_
protected int	mode_
protected java.lang.Thread	owner_

Fields inherited from interface org.exist.storage.lock.Lock

NO_LOCK, READ_LOCK, WRITE_LOCK

Constructor Summary

ReentrantReadWriteLock(java.lang.String id)

Method Summary

boolean	acquire() Acquire a lock for read.
boolean	acquire(int mode) Acquire a lock for read or write.
boolean	attempt(int mode) Attempt to acquire a lock for read or write.
long	holds() Return the number of unreleased acquires performed by the current thread.
boolean	isLockedForWrite() Returns true if there are active or pending write locks.
void	release() Release the lock.
void	release(int mode) Release a lock of the specified type.
void	release(long n) Release the lock N times.

Methods inherited from class java.lang.Object

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

Field Detail

id_

protected java.lang.String id_

owner_

protected java.lang.Thread owner_

holds_

protected long holds_

mode_

protected int mode_

Constructor Detail

ReentrantReadWriteLock

public ReentrantReadWriteLock(java.lang.String id)

Method Detail

acquire

public boolean acquire()
                throws LockException

Description copied from interface: Lock

Acquire a lock for read.

Specified by:

acquire in interface Lock

Returns:

Throws:

LockException

acquire

public boolean acquire(int mode)
                throws LockException

Description copied from interface: Lock

Acquire a lock for read or write. mode is one of Lock.READ_LOCK or Lock.WRITE_LOCK.

Specified by:

acquire in interface Lock

Parameters:

mode -

Returns:

Throws:

LockException

attempt

public boolean attempt(int mode)

Description copied from interface: Lock

Attempt to acquire a lock for read or write. This method will fail immediately if the lock cannot be acquired.

Specified by:

attempt in interface Lock

Parameters:

mode -

Returns:

isLockedForWrite

public boolean isLockedForWrite()

Description copied from interface: Lock

Returns true if there are active or pending write locks.

Specified by:

isLockedForWrite in interface Lock

Returns:

release

public void release(int mode)

Description copied from interface: Lock

Release a lock of the specified type.

Specified by:

release in interface Lock

Parameters:

mode -

release

public void release()

Release the lock.

Specified by:

release in interface Lock

Throws:

java.lang.Error - thrown if not current owner of lock

release

public void release(long n)

Release the lock N times. release(n) is equivalent in effect to:

   for (int i = 0; i < n; ++i) release();
 

Throws:

java.lang.Error - thrown if not current owner of lock or has fewer than N holds on the lock

holds

public long holds()

Return the number of unreleased acquires performed by the current thread. Returns zero if current thread does not hold lock.