Package com.ibm.asyncutil.locks

Class FairAsyncNamedReadWriteLock<T>

java.lang.Object

com.ibm.asyncutil.locks.FairAsyncNamedReadWriteLock<T>

All Implemented Interfaces:

AsyncNamedReadWriteLock<T>

public class FairAsyncNamedReadWriteLock<T>
extends Object
implements AsyncNamedReadWriteLock<T>

An implementation of the AsyncNamedReadWriteLock interface which enforces fair acquisitions (i.e. readers will queue behind waiting writers to prevent writer starvation).

null values are not permitted for use as names.

Constructor Summary

Constructors

Constructor	Description
FairAsyncNamedReadWriteLock()

Method Summary

Modifier and Type	Method	Description
CompletionStage<AsyncReadWriteLock.ReadLockToken>	acquireReadLock(T name)	Acquires the read lock associated with the given name.
CompletionStage<AsyncReadWriteLock.WriteLockToken>	acquireWriteLock(T name)	Exclusively acquires the write lock associated with the given name.
Optional<AsyncReadWriteLock.ReadLockToken>	tryReadLock(T name)	Attempts to acquire the read lock associated with the given name.
Optional<AsyncReadWriteLock.WriteLockToken>	tryWriteLock(T name)	Attempts to acquire the write lock associated with the given name.

Methods inherited from interface com.ibm.asyncutil.locks.AsyncNamedReadWriteLock

create, createFair

Methods inherited from class java.lang.Object

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

Constructor Detail

FairAsyncNamedReadWriteLock

public FairAsyncNamedReadWriteLock()

Method Detail

acquireReadLock

public CompletionStage<AsyncReadWriteLock.ReadLockToken> acquireReadLock(T name)

Description copied from interface: AsyncNamedReadWriteLock

Acquires the read lock associated with the given name. The returned stage will complete when the lock is no longer exclusively held by a writer, and the read lock has been acquired. The stage may already be complete if the write lock for the given name is not currently held.

The AsyncReadWriteLock.ReadLockToken held by the returned stage is used to release the read lock after it has been acquired and the read-lock-protected action has completed.

Specified by:

acquireReadLock in interface AsyncNamedReadWriteLock<T>

Parameters:

name - to acquire read access for

Returns:

A CompletionStage which will complete with a AsyncReadWriteLock.ReadLockToken when the read lock associated with name has been acquired

acquireWriteLock

public CompletionStage<AsyncReadWriteLock.WriteLockToken> acquireWriteLock(T name)

Description copied from interface: AsyncNamedReadWriteLock

Exclusively acquires the write lock associated with the given name. The returned stage will complete when the lock is no longer held by any readers or another writer, and the write lock has been exclusively acquired. The stage may already be complete if no locks for the given name are currently held.

The AsyncReadWriteLock.WriteLockToken held by the returned stage is used to release the write lock after it has been acquired and the write-lock-protected action has completed.

Specified by:

acquireWriteLock in interface AsyncNamedReadWriteLock<T>

Parameters:

name - to acquire exclusive write access for

Returns:

A CompletionStage which will complete with a AsyncReadWriteLock.WriteLockToken when the lock associated with name has been exclusively acquired

tryReadLock

public Optional<AsyncReadWriteLock.ReadLockToken> tryReadLock(T name)

Description copied from interface: AsyncNamedReadWriteLock

Attempts to acquire the read lock associated with the given name. If the associated write lock is not currently held, the returned Optional will hold a ReadLockToken representing this acquisition. Otherwise, the returned Optional will be empty.

The AsyncReadWriteLock.ReadLockToken held by the returned optional is used to release the read lock after it has been acquired and the read-lock-protected action has completed.

Specified by:

tryReadLock in interface AsyncNamedReadWriteLock<T>

Parameters:

name - to acquire read access for

Returns:

An Optional holding a AsyncReadWriteLock.ReadLockToken if the write lock associated with name is not held; otherwise an empty Optional

tryWriteLock

public Optional<AsyncReadWriteLock.WriteLockToken> tryWriteLock(T name)

Description copied from interface: AsyncNamedReadWriteLock

Attempts to acquire the write lock associated with the given name. If the associated write lock or read lock is not currently held, the returned Optional will hold a WriteLockToken representing this acquisition. Otherwise, the returned Optional will be empty.

The AsyncReadWriteLock.WriteLockToken held by the returned optional is used to release the write lock after it has been acquired and the write-lock-protected action has completed.

Specified by:

tryWriteLock in interface AsyncNamedReadWriteLock<T>

Parameters:

name - to acquire exclusive write access for

Returns:

An Optional holding a AsyncReadWriteLock.WriteLockToken if the lock associated with name is not held by a writer or any readers; otherwise an empty Optional