org.gridgain.grid.cache.datastructures

Interface GridCacheCountDownLatch

All Known Subinterfaces:

GridCacheCountDownLatchEx

All Known Implementing Classes:

GridCacheCountDownLatchImpl

public interface GridCacheCountDownLatch

This interface provides a rich API for working with distributed count down latch.

Functionality

Distributed count down latch provides functionality similar to java.util.CountDownLatch. Note that you cannot remove count down latch having count greater that zero. It should be counted down to zero first.

Creating Distributed Count Down Latch

Instance of cache count down latch can be created by calling the following method: GridCacheDataStructures.countDownLatch(String, int, boolean, boolean).

See Also:

GridCacheDataStructures.countDownLatch(String, int, boolean, boolean), GridCacheDataStructures.removeCountDownLatch(String)

Method Summary

Methods

Modifier and Type	Method and Description
boolean	autoDelete() Gets autoDelete flag.
void	await() Causes the current thread to wait until the latch has counted down to zero, unless current thread is interrupted.
boolean	await(long timeout) 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.
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.
int	count() Gets current count value of the latch.
int	countDown() Decrements the count of the latch, releasing all waiting threads on all nodes if the count reaches zero.
int	countDown(int val) Decreases the count of the latch using passed in value, releasing all waiting threads on all nodes if the count reaches zero.
void	countDownAll() Counts down this latch to zero, releasing all waiting threads on all nodes.
int	initialCount() Gets initial count value of the latch.
String	name() Gets name of the latch.
boolean	removed() Gets removed status of the latch.

Method Detail

name

String name()

Gets name of the latch.

Returns:

Name of the latch.

count

int count()

Gets current count value of the latch.

Returns:

Current count.

initialCount

int initialCount()

Gets initial count value of the latch.

Returns:

Initial count.

autoDelete

boolean autoDelete()

Gets autoDelete flag. If this flag is true latch is removed from cache when it has been counted down to 0.

Returns:

Value of autoDelete flag.

await

void await()
           throws GridException

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

If the current count of the latch 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 on any node; 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 GridInterruptedException is thrown and the current thread's interrupted status is cleared.

Throws:

GridException - If operation failed.

GridInterruptedException - if the current thread is interrupted while waiting

await

boolean await(long timeout)
              throws GridException

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 on any node; 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 GridInterruptedException 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.

Parameters:

timeout - The maximum time to wait in milliseconds.

Returns:

True if the count reached zero and false if the waiting time elapsed before the count reached zero.

Throws:

GridInterruptedException - If the current thread is interrupted while waiting.

GridException - If operation failed.

await

boolean await(long timeout,
            TimeUnit unit)
              throws GridException

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 on any node; 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 GridInterruptedException 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.

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:

GridInterruptedException - If the current thread is interrupted while waiting.

GridException - If operation failed.

countDown

int countDown()
              throws GridException

Decrements the count of the latch, releasing all waiting threads on all nodes 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.

Returns:

Count after decrement.

Throws:

GridException - If operation failed.

countDown

int countDown(int val)
              throws GridException

Decreases the count of the latch using passed in value, releasing all waiting threads on all nodes if the count reaches zero.

If the current count is greater than zero then it is decreased. 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.

Parameters:

val - Value to decrease counter on.

Returns:

Count after decreasing.

Throws:

GridException - If operation failed.

countDownAll

void countDownAll()
                  throws GridException

Counts down this latch to zero, releasing all waiting threads on all nodes.

If the current count equals zero then nothing happens.

Throws:

GridException - If operation failed.

removed

boolean removed()

Gets removed status of the latch.

Returns:

True if latch was removed from cache, false otherwise.