com.bigdata.concurrent

Class AccessSemaphore

java.lang.Object

com.bigdata.concurrent.AccessSemaphore

public class AccessSemaphore
extends Object

The AccessSemaphore implements an idiom of exclusive and shared access.

A typical use-case for exclusive/shared access might be single writer/multiple readers

Since this access mechanism builds on a simple semaphore, it is straightforward to bound the number of shares permitted. By default this is set to MAXINT, but it need not be, and a constructor is provided to define this limit.

It is NOT re-entrant.

Author:

Martyn Cutcher

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	AccessSemaphore.Access
static class	AccessSemaphore.AccessSemaphoreNotReentrantException
class	AccessSemaphore.ExclusiveAccess
class	AccessSemaphore.SharedAccess

Constructor Summary

Constructors

Constructor and Description
AccessSemaphore()
AccessSemaphore(int maxShares)

Method Summary

Methods

Modifier and Type	Method and Description
AccessSemaphore.Access	acquireExclusive()
AccessSemaphore.Access	acquireShared()
AccessSemaphore.Access	tryAcquireExclusive(long timeout, TimeUnit unit)
AccessSemaphore.Access	tryAcquireShared(long timeout, TimeUnit unit)

Methods inherited from class java.lang.Object

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

Constructor Detail

AccessSemaphore

public AccessSemaphore()

AccessSemaphore

public AccessSemaphore(int maxShares)

Method Detail

acquireExclusive

public final AccessSemaphore.Access acquireExclusive()
                                              throws InterruptedException

Throws:

InterruptedException

tryAcquireExclusive

public final AccessSemaphore.Access tryAcquireExclusive(long timeout,
                                         TimeUnit unit)
                                                 throws InterruptedException

Throws:

InterruptedException

acquireShared

public final AccessSemaphore.Access acquireShared()
                                           throws InterruptedException

Throws:

InterruptedException

tryAcquireShared

public final AccessSemaphore.Access tryAcquireShared(long timeout,
                                      TimeUnit unit)
                                              throws InterruptedException

Throws:

InterruptedException