org.apache.river.thread

Class ReadersWriter

java.lang.Object

org.apache.river.thread.ReadersWriter

public class ReadersWriter
extends Object

An Object to control the concurrent state. Allows multiple readers or a single writer. Waiting priority writers have priority over waiting regular writers and waiting readers. A single thread cannot hold a lock more than once.

Author:

Sun Microsystems, Inc.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ReadersWriter.ConcurrentLockException InterruptedException transformed to a runtime exception.

Constructor Summary

Constructors

Constructor and Description
ReadersWriter()

Method Summary

Modifier and Type	Method and Description
Condition	newCondition() Condition for use with writeLock()
void	priorityWriteLock() Obtain a priority write lock.
void	readerWait(Object notifier, long time) Release a read lock, wait the given period of time or until notified by notifier, then obtain a read lock again.
void	readLock() Obtain a read lock.
void	readUnlock() Release a read lock.
void	waiterNotify(Object notifier) Wake up any threads waiting on this notifier.
void	writeLock() Obtain a regular write lock.
void	writerWait(Object notifier, long time) Deprecated. use newCondition() and Condition instead
void	writeUnlock() Release a (regular or priority) write lock.

Methods inherited from class java.lang.Object

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

Constructor Detail

ReadersWriter

public ReadersWriter()

Method Detail

newCondition

public Condition newCondition()

Condition for use with writeLock()

Returns:

readLock

public void readLock()

Obtain a read lock. Multiple concurrent readers allowed.

readUnlock

public void readUnlock()

Release a read lock.

writeLock

public void writeLock()

Obtain a regular write lock. Only a single writer allowed at once.

priorityWriteLock

public void priorityWriteLock()

Obtain a priority write lock. Only a single writer allowed at once.

writeUnlock

public void writeUnlock()

Release a (regular or priority) write lock.

readerWait

public void readerWait(Object notifier,
                       long time)

Release a read lock, wait the given period of time or until notified by notifier, then obtain a read lock again. Throws ConcurrentLockException if the thread gets interrupted; in that case, the read lock is still held.

writerWait

@Deprecated
public void writerWait(Object notifier,
                                    long time)

Deprecated. use newCondition() and Condition instead

Release a write lock, wait the given period of time or until notified by notifier, then obtain a regular write lock again. Throws ConcurrentLockException if the thread gets interrupted; in that case, the write lock is still held.

waiterNotify

public void waiterNotify(Object notifier)

Wake up any threads waiting on this notifier. In general, because there is no wakeup-waiting flag, this method must be called from a thread that holds a lock that conflicts with the lock that the waiter was holding. If the waiter calls writerWait, then waiterNotify can be called either under a readLock or a writeLock, but if the waiter calls readerWait, then waiterNotify should only be called under a writeLock.