WriterPreferenceReadWriteLock

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org.ematgine.utils.concurrent
Class WriterPreferenceReadWriteLock

java.lang.Object
  org.ematgine.utils.concurrent.WriterPreferenceReadWriteLock

All Implemented Interfaces:: ReadWriteLock

Direct Known Subclasses:: ReaderPreferenceReadWriteLock, ReentrantWriterPreferenceReadWriteLock

public class WriterPreferenceReadWriteLock
extends java.lang.Object
implements ReadWriteLock

A ReadWriteLock that prefers waiting writers over waiting readers when there is contention. This class is adapted from the versions described in CPJ, improving on the ones there a bit by segregating reader and writer wait queues, which is typically more efficient.

The locks are NOT reentrant. In particular, even though it may appear to usually work OK, a thread holding a read lock should not attempt to re-acquire it. Doing so risks lockouts when there are also waiting writers.

[ Introduction to this package. ]

Nested Class Summary

protected class WriterPreferenceReadWriteLock.ReaderLock


protected class WriterPreferenceReadWriteLock.Signaller
          Reader and Writer requests are maintained in two different wait sets, by two different objects.

protected class WriterPreferenceReadWriteLock.WriterLock


Field Summary

protected long activeReaders_


protected java.lang.Thread activeWriter_


protected WriterPreferenceReadWriteLock.ReaderLock readerLock_


protected long waitingReaders_


protected long waitingWriters_


protected WriterPreferenceReadWriteLock.WriterLock writerLock_


Constructor Summary

WriterPreferenceReadWriteLock()


Method Summary

protected boolean allowReader()
          Override this method to change to reader preference

protected void cancelledWaitingReader()


protected void cancelledWaitingWriter()


protected WriterPreferenceReadWriteLock.Signaller endRead()
          Called upon termination of a read.

protected WriterPreferenceReadWriteLock.Signaller endWrite()
          Called upon termination of a write.

Sync readLock()
          get the readLock

protected boolean startRead()


protected boolean startReadFromNewReader()


protected boolean startReadFromWaitingReader()


protected boolean startWrite()


protected boolean startWriteFromNewWriter()


protected boolean startWriteFromWaitingWriter()


Sync writeLock()
          get the writeLock

Methods inherited from class java.lang.Object

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

Field Detail

activeReaders_

protected long activeReaders_

activeWriter_

protected java.lang.Thread activeWriter_

waitingReaders_

protected long waitingReaders_

waitingWriters_

protected long waitingWriters_

readerLock_

protected final WriterPreferenceReadWriteLock.ReaderLock readerLock_

writerLock_

protected final WriterPreferenceReadWriteLock.WriterLock writerLock_

Constructor Detail