Package org.apache.ignite.internal.util

Class GridCountDownCallback

java.lang.Object

org.apache.ignite.internal.util.GridCountDownCallback

public class GridCountDownCallback
extends Object

Allows to execute callback when a set of operations will be completed. Also has an execution counter, which allows to block callback execution in case if it is below given threshold. By default, threshold is 0 and nothing blocks callback execution.

Sample usage::

     GridCountDownCallback countDownCb = new GridCountDownCallback(
         n,                     //internal counter is initiated with n
         () -> doSomething()    //callback
     );

     //each call of countDown() decrements internal counter
     //doSomething() will be executed after counter reaches 0
     for (int i = 0; i < n; i++)
         new Thread(() -> countDownCb.countDown()).start();
 

Usage with execution threshold::

     GridCountDownCallback countDownCb = new GridCountDownCallback(
         n,                     //internal counter is initiated with n
         () -> doSomething(),   //callback
         n/2                    //execution threshold is initiated with n/2
     );

     //a half of calls of countDown() increase execution counter, so it reaches threshold and callback executes.
     //doSomething() will be executed after n threads will perform countDown()
     for (int i = 0; i < n; i++)
         new Thread(() -> countDownCb.countDown(n % 2 == 0)).start();
 

Constructor Summary

Constructors

Constructor	Description
GridCountDownCallback(int initCnt, Runnable cb)	Constructor.
GridCountDownCallback(int initCnt, Runnable cb, int executionThreshold)	Constructor.

Method Summary

Modifier and Type	Method	Description
void	countDown()	Decrements the internal counter.
void	countDown(boolean doIncreaseExecutionCounter)	Decrements the internal counter.

Methods inherited from class java.lang.Object

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

Constructor Detail

GridCountDownCallback

public GridCountDownCallback(int initCnt,
                             Runnable cb,
                             int executionThreshold)

Constructor.

Parameters:

initCnt - count of invocations of countDown(boolean).

cb - callback which will be executed after initialCount invocations of countDown(boolean).

executionThreshold - minimal count of really performed operations to execute callback.

GridCountDownCallback

public GridCountDownCallback(int initCnt,
                             Runnable cb)

Constructor. Execution threshold is set to 0.

Parameters:

initCnt - count of invocations of countDown(boolean).

cb - callback which will be executed after initialCount invocations of countDown(boolean).

Method Detail

countDown

public void countDown(boolean doIncreaseExecutionCounter)

Decrements the internal counter. If counter becomes 0, callback will be executed.

Parameters:

doIncreaseExecutionCounter - whether to increase execution counter

countDown

public void countDown()

Decrements the internal counter. If counter becomes 0, callback will be executed.