org.exist.storage.lock
Class MultiReadReentrantLock

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

All Implemented Interfaces:

Lock

public class MultiReadReentrantLock

extends java.lang.Object

implements Lock

A reentrant read/write lock, which allows multiple readers to acquire a lock. Waiting writers are preferred. This is an adapted and bug-fixed version of code taken from Apache's Turbine JCS.

Field Summary

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

NO_LOCK, READ_LOCK, WRITE_LOCK

Constructor Summary

MultiReadReentrantLock()
Default constructor.

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.
boolean	isLockedForWrite() Returns true if there are active or pending write locks.
void	release() Release a lock.
void	release(int mode) Release a lock of the specified type.

Methods inherited from class java.lang.Object

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

Constructor Detail

MultiReadReentrantLock

public MultiReadReentrantLock()

Default constructor.

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:

release

public void release()

Description copied from interface: Lock

Release a lock. This method assumes that the lock is a read lock.

Specified by:

release in interface Lock

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 -

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: