Module com.aoapps.concurrent

Package com.aoapps.concurrent

Class KeyedConcurrencyReducer<K,R>

java.lang.Object

com.aoapps.concurrent.KeyedConcurrencyReducer<K,R>

Direct Known Subclasses:

ConcurrencyLimiter

public class KeyedConcurrencyReducer<K,R>
extends Object

Limits the concurrency to a resource identified by any arbitrary key object. When a second thread tries to access the same resource as a previous thread, it will share the results that are obtained by the previous thread.

Constructor Summary

Constructors

Constructor	Description
KeyedConcurrencyReducer()

Method Summary

Modifier and Type	Method	Description
R	executeSerialized(K key, Callable<? extends R> callable)	Executes a callable at most once for the given key.

Methods inherited from class java.lang.Object

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

Constructor Detail

KeyedConcurrencyReducer

public KeyedConcurrencyReducer()

Method Detail

executeSerialized

public R executeSerialized(K key,
                           Callable<? extends R> callable)
                    throws InterruptedException,
                           ExecutionException

Executes a callable at most once for the given key. If a callable is in the process of being executed by a different thread (determined by key, not the callable instance), the current thread will wait and use the results obtained by the other thread.

Consider the following scenario:

1. Thread A invokes MySQL: "CHECK TABLE example FAST QUICK"
2. Thread B invokes MySQL: "CHECK TABLE example FAST QUICK" before Thread A has finished
3. Thread B wait for results determined by Thread A
4. Thread A completes, passes results to Thread B
5. Threads A and B both return the results obtained only by Thread A

Throws:

InterruptedException

ExecutionException