com.hazelcast.util

Class ContextMutexFactory

java.lang.Object

com.hazelcast.util.ContextMutexFactory

public final class ContextMutexFactory
extends Object

Utility class that provides reference-counted mutexes suitable for synchronization in the context of a supplied object. Context objects and their associated mutexes are stored in a Map. Client code is responsible to invoke ContextMutexFactory.Mutex.close() on the obtained Mutex after having synchronized on the mutex; failure to do so, will leave an entry residing in the internal Map which may have adverse effects on the ability to garbage collect the context object and the mutex. The returned ContextMutexFactory.Mutexes implement Closeable, so can be conveniently used in a try-with-resources statement. Typical usage would allow, for example, synchronizing access to a non-thread-safe Map on a per-key basis, to avoid blocking other threads who would perform updates on other entries of the Map.

     class Test {

         private static final ContextMutexFactory mutexFactory = new ContextMutexFactory();
         private Map<String, String> mapToSync = new HashMap<String, String>();

         public void test(String key, String value) {
             // critical section
             ContextMutexFactory.Mutex mutex = mutexFactory.mutexFor(key);
             try {
                 synchronized (mutex) {
                      if (mapToSync.get(key) == null) {
                          mapToSync.put(key, value);
                      }
                 }
             }
             finally {
                 mutex.close();
             }
         }
     }
 

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	ContextMutexFactory.Mutex Reference counted mutex, which will remove itself from the mutexMap when it is no longer referenced.

Constructor Summary

Constructors

Constructor and Description
ContextMutexFactory()

Method Summary

Methods

Modifier and Type	Method and Description
ContextMutexFactory.Mutex	mutexFor(Object mutexKey)

Methods inherited from class java.lang.Object

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

Constructor Detail

ContextMutexFactory

public ContextMutexFactory()

Method Detail

mutexFor

public ContextMutexFactory.Mutex mutexFor(Object mutexKey)