Package com.oracle.coherence.concurrent

Class RemoteCountDownLatch

java.lang.Object

com.oracle.coherence.concurrent.RemoteCountDownLatch

All Implemented Interfaces:

CountDownLatch

public class RemoteCountDownLatch
extends Object
implements CountDownLatch

A distributed count down latch with the same basic behavior and semantics as the Java CountDownLatch class, but uses the NamedCache to support for synchronization aid that allows one or more threads across multiple cluster members to wait until a set of operations being performed in other threads/members completes.

Since:

21.12

Author:

as, lh 2021.11.16

Constructor Summary

Constructors

Constructor	Description
RemoteCountDownLatch(String sName, int count, NamedMap<String,com.oracle.coherence.concurrent.internal.LatchCounter> latches)	Constructs a RemoteCountDownLatch initialized with the given count.

Method Summary

Modifier and Type	Method	Description
void	await()	Causes the current thread to wait until the latch has counted down to zero, unless the thread is interrupted.
boolean	await(long timeout, TimeUnit unit)	Causes the current thread to wait until the latch has counted down to zero, unless the thread is interrupted, or the specified waiting time elapses.
void	countDown()	Decrements the latch count, releasing all waiting threads if the count reaches zero.
long	getCount()	Returns the current count.
long	getInitialCount()	Returns the initial count of the latch.
protected void	signalLocalThreads()	It is called by the delete event handler to release all waiting threads on the local member if the count reaches zero.
String	toString()	Returns a string identifying this latch, as well as its state.

Methods inherited from class java.lang.Object

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

Constructor Detail

RemoteCountDownLatch

public RemoteCountDownLatch(String sName,
                            int count,
                            NamedMap<String,com.oracle.coherence.concurrent.internal.LatchCounter> latches)

Constructs a RemoteCountDownLatch initialized with the given count.

Parameters:

sName - the name of the latch

count - the number of times countDown() must be invoked before threads can pass through await()

latches - the NamedMap that stores this latch's state

Throws:

IllegalArgumentException - if count is negative

Method Detail

await

public void await()
           throws InterruptedException

Causes the current thread to wait until the latch has counted down to zero, unless the thread is interrupted.

If the current count is zero then this method returns immediately.

If the current count is greater than zero then the current thread becomes disabled for thread scheduling purposes and lies dormant until one of two things happen:

• The count reaches zero due to invocations of the countDown() 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 CountDownLatch

Throws:

InterruptedException - if the current thread is interrupted while waiting

await

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

Causes the current thread to wait until the latch has counted down to zero, unless the thread is interrupted, or the specified waiting time elapses.

If the current count is zero then this method returns immediately with the value true.

If the current count is greater than zero then the current thread becomes disabled for thread scheduling purposes and lies dormant until one of three things happen:

• The count reaches zero due to invocations of the countDown() method; or
• Some other thread interrupts the current thread; or
• The specified waiting time elapses.

If the count reaches zero 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 CountDownLatch

Parameters:

timeout - the maximum time to wait

unit - the time unit of the timeout argument

Returns:

true if the count reached zero and false if the waiting time elapsed before the count reached zero

Throws:

InterruptedException - if the current thread is interrupted while waiting

countDown

public void countDown()

Decrements the latch count, releasing all waiting threads if the count reaches zero.

If the current count is greater than zero then it is decremented. If the new count is zero then all waiting threads are re-enabled for thread scheduling purposes.

If the current count equals zero then nothing happens.

Specified by:

countDown in interface CountDownLatch

getCount

public long getCount()

Returns the current count.

This method is typically used for debugging and testing purposes.

Specified by:

getCount in interface CountDownLatch

Returns:

the current count

getInitialCount

public long getInitialCount()

Returns the initial count of the latch.

Returns:

the initial count

toString

public String toString()

Returns a string identifying this latch, as well as its state.

Overrides:

toString in class Object

Returns:

a string identifying this latch, as well as its state

signalLocalThreads

protected void signalLocalThreads()

It is called by the delete event handler to release all waiting threads on the local member if the count reaches zero. If the current count is greater than zero then nothing happens. It passes 0 for releases argument to indicate no countdown on the latch.