io.atlassian.util.concurrent

Class BooleanLatch

java.lang.Object

io.atlassian.util.concurrent.BooleanLatch

All Implemented Interfaces:

Awaitable, ReusableLatch

@ThreadSafe
public class BooleanLatch
extends Object
implements ReusableLatch

A BooleanLatch is a reusable latch that resets after it is released and waited on. It depends on a boolean condition of being released or not and becomes unreleased when one thread successfully awaits it. It is useful for rally like release-wait-release coordination, and as a replacement to waiting on a Condition (it should be faster as the write thread does not need to acquire a lock in order to signal.

This latch is suitable for SRSW coordination. MRSW is supported but has the same semantics as Condition.signal(), that is to say that Condition.signalAll() is not supported and if there are multiple waiters then the particular thread that is released is arbitrary.

Constructor Summary

Constructors

Constructor and Description
BooleanLatch()

Method Summary

Modifier and Type	Method and Description
void	await() Await for the condition to become true.
boolean	await(long timeout, TimeUnit unit) Await for the specified time for the condition to become true.
void	release() Release the latch, releasing one or more threads that are waiting on it.

Methods inherited from class java.lang.Object

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

Constructor Detail

BooleanLatch

public BooleanLatch()

Method Detail

release

public final void release()

Release the latch, releasing one or more threads that are waiting on it. Releases at most one waiting thread. If the current state is released then nothing happens.

Specified by:

release in interface ReusableLatch

await

public final void await()
                 throws InterruptedException

Await for the condition to become true. Causes the current thread to wait until the latch has been released, unless the thread is interrupted.

If the latch has already been released then this method returns immediately.

If the latch is not released then the current thread becomes disabled for thread scheduling purposes and lies dormant until one of two things happen:

• The latch is released by another thread invoking the release() method; or
• Some other thread interrupts the current thread.

If the current thread:

• has its interrupted status set on entry to this method; or
• is interrupted while waiting,

then InterruptedException is thrown and the current thread's interrupted status is cleared.

Specified by:

await in interface Awaitable

Throws:

InterruptedException - if the current thread is interrupted while waiting

await

public final boolean await(long timeout,
                           TimeUnit unit)
                    throws InterruptedException

Await for the specified time for the condition to become true. Causes the current thread to wait until the latch has been released, unless the thread is interrupted, or the specified waiting time elapses.

If the latch has already been released then this method returns immediately with return value true.

If the latch is unreleased then the current thread becomes disabled for thread scheduling purposes and lies dormant until one of three things happen:

• The latch is released by another thread invoking the release() method; or
• Some other thread interrupts the current thread; or
• The specified waiting time elapses.

If latch is released by another thread then the method returns with the value true.

If the current thread:

• has its interrupted status set on entry to this method; or
• is interrupted while waiting,

then InterruptedException is thrown and the current thread's interrupted status is cleared.

If the specified waiting time elapses then the value false is returned. If the time is less than or equal to zero, the method will not wait at all.

Specified by:

await in interface Awaitable

Parameters:

timeout - the amount to wait.

unit - the unit to wait in.

Returns:

true if the condition became true within the time limit, false otherwise.

Throws:

InterruptedException