Class AbstractReadWriteLockManager

java.lang.Object

org.eclipse.rdf4j.common.concurrent.locks.AbstractReadWriteLockManager

All Implemented Interfaces:

ReadWriteLockManager

Direct Known Subclasses:

ReadPrefReadWriteLockManager, WritePrefReadWriteLockManager

public abstract class AbstractReadWriteLockManager
extends Object
implements ReadWriteLockManager

An abstract base implementation of a read/write-lock manager.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
(package private) static class	AbstractReadWriteLockManager.ReadLock
(package private) static class	AbstractReadWriteLockManager.WriteLock

Field Summary

Fields

Modifier and Type	Field	Description
(package private) final LongAdder	readersLocked
(package private) final LongAdder	readersUnlocked
private final LockMonitoring<AbstractReadWriteLockManager.ReadLock>	readLockMonitoring
(package private) final StampedLock	stampedLock
private final int	tryWriteLockMillis
private final LockMonitoring<AbstractReadWriteLockManager.WriteLock>	writeLockMonitoring
(package private) final int	writePreference	When acquiring a write-lock, the thread will acquire the write-lock and then spin invalid input: '&' yield while waiting for readers to unlock their locks.

Constructor Summary

Constructors

Constructor	Description
AbstractReadWriteLockManager()
AbstractReadWriteLockManager(boolean trackLocks)
AbstractReadWriteLockManager(boolean trackLocks, int waitToCollect)
AbstractReadWriteLockManager(String alias, int waitToCollect, LockDiagnostics... lockDiagnostics)
AbstractReadWriteLockManager(String alias, LockDiagnostics... lockDiagnostics)

Method Summary

Modifier and Type	Method	Description
(package private) AbstractReadWriteLockManager.ReadLock	createReadLockInner()
private AbstractReadWriteLockManager.WriteLock	createWriteLockInner()
Lock	getReadLock()	Gets a read lock.
Lock	getWriteLock()	Gets an exclusive write lock.
(package private) abstract int	getWriterPreference()
boolean	isReaderActive()	Returns false if there are no active read locks, otherwise returns true.
boolean	isWriterActive()	Returns false if there are no active write locks, otherwise returns true.
(package private) void	spinWait()
(package private) void	spinWaitAtReadLock()
Lock	tryReadLock()	Gets a read lock, if available.
private AbstractReadWriteLockManager.ReadLock	tryReadLockInner()
Lock	tryWriteLock()	Gets an exclusive write lock, if available.
private AbstractReadWriteLockManager.WriteLock	tryWriteLockInner()
void	waitForActiveReaders()	Blocks until all read locks have been released.
void	waitForActiveWriter()	Blocks until all write locks have been released.
private long	writeLockInterruptibly()
private void	yieldWait()

Methods inherited from class Object

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

Field Details

readLockMonitoring

private final LockMonitoring<AbstractReadWriteLockManager.ReadLock> readLockMonitoring

writeLockMonitoring

private final LockMonitoring<AbstractReadWriteLockManager.WriteLock> writeLockMonitoring

stampedLock

final StampedLock stampedLock

readersLocked

final LongAdder readersLocked

readersUnlocked

final LongAdder readersUnlocked

tryWriteLockMillis

private final int tryWriteLockMillis

writePreference

final int writePreference

When acquiring a write-lock, the thread will acquire the write-lock and then spin invalid input: '&' yield while waiting for readers to unlock their locks. A deadlock is possible if someone already holding a read-lock acquires another read-lock at the same time that another thread is waiting for a write-lock. To stop this from happening we can set READ_PREFERENCE to a number higher than zero. READ_PREFERENCE of 1 means that the thread acquiring a write-lock will release the write-lock if there are any readers. A READ_PREFERENCE of 100 means that the thread acquiring a write-lock will spin invalid input: '&' yield 100 times before it attempts to release the write-lock.

Constructor Details

AbstractReadWriteLockManager

public AbstractReadWriteLockManager()

AbstractReadWriteLockManager

public AbstractReadWriteLockManager(boolean trackLocks)

AbstractReadWriteLockManager

public AbstractReadWriteLockManager(boolean trackLocks,
 int waitToCollect)

AbstractReadWriteLockManager

public AbstractReadWriteLockManager(String alias,
 LockDiagnostics... lockDiagnostics)

AbstractReadWriteLockManager

public AbstractReadWriteLockManager(String alias,
 int waitToCollect,
 LockDiagnostics... lockDiagnostics)

Method Details

getWriterPreference

abstract int getWriterPreference()

isWriterActive

public boolean isWriterActive()

Returns false if there are no active write locks, otherwise returns true.

Specified by:

isWriterActive in interface ReadWriteLockManager

isReaderActive

public boolean isReaderActive()

Returns false if there are no active read locks, otherwise returns true.

Specified by:

isReaderActive in interface ReadWriteLockManager

waitForActiveWriter

public void waitForActiveWriter()
                         throws InterruptedException

Blocks until all write locks have been released.

Specified by:

waitForActiveWriter in interface ReadWriteLockManager

Throws:

InterruptedException - In case the thread requesting the lock was interrupted.

waitForActiveReaders

public void waitForActiveReaders()
                          throws InterruptedException

Blocks until all read locks have been released.

Specified by:

waitForActiveReaders in interface ReadWriteLockManager

Throws:

InterruptedException - In case the thread requesting the lock was interrupted.

getReadLock

public Lock getReadLock()
                 throws InterruptedException

Gets a read lock. This method blocks until the read lock is available.

Specified by:

getReadLock in interface ReadWriteLockManager

Throws:

InterruptedException - In case the thread requesting the lock was interrupted.

createReadLockInner

AbstractReadWriteLockManager.ReadLock createReadLockInner()
                                                   throws InterruptedException

Throws:

InterruptedException

getWriteLock

public Lock getWriteLock()
                  throws InterruptedException

Gets an exclusive write lock. This method blocks until the write lock is available.

Specified by:

getWriteLock in interface ReadWriteLockManager

Throws:

InterruptedException - In case the thread requesting the lock was interrupted.

createWriteLockInner

private AbstractReadWriteLockManager.WriteLock createWriteLockInner()
                                                             throws InterruptedException

Throws:

InterruptedException

writeLockInterruptibly

private long writeLockInterruptibly()
                             throws InterruptedException

Throws:

InterruptedException

tryReadLock

public Lock tryReadLock()

Gets a read lock, if available. This method will return null if the read lock is not immediately available.

Specified by:

tryReadLock in interface ReadWriteLockManager

tryReadLockInner

private AbstractReadWriteLockManager.ReadLock tryReadLockInner()

tryWriteLock

public Lock tryWriteLock()

Gets an exclusive write lock, if available. This method will return null if the write lock is not immediately available.

Specified by:

tryWriteLock in interface ReadWriteLockManager

tryWriteLockInner

private AbstractReadWriteLockManager.WriteLock tryWriteLockInner()

spinWait

void spinWait()
       throws InterruptedException

Throws:

InterruptedException

spinWaitAtReadLock

void spinWaitAtReadLock()
                 throws InterruptedException

Throws:

InterruptedException

yieldWait

private void yieldWait()
                throws InterruptedException

Throws:

InterruptedException