EDU.oswego.cs.dl.util.concurrent

Class PrioritySemaphore

java.lang.Object

EDU.oswego.cs.dl.util.concurrent.Semaphore

EDU.oswego.cs.dl.util.concurrent.QueuedSemaphore

EDU.oswego.cs.dl.util.concurrent.PrioritySemaphore

All Implemented Interfaces:

Sync

public class PrioritySemaphore
extends QueuedSemaphore

A Semaphore that grants requests to threads with higher Thread priority rather than lower priority when there is contention. Ordering of requests with the same priority is approximately FIFO. Priorities are based on Thread.getPriority. Changing the priority of an already-waiting thread does NOT change its ordering. This class also does not specially deal with priority inversion -- when a new high-priority thread enters while a low-priority thread is currently running, their priorities are not artificially manipulated.

[ Introduction to this package. ]

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	PrioritySemaphore.PriorityWaitQueue

Nested classes/interfaces inherited from class EDU.oswego.cs.dl.util.concurrent.QueuedSemaphore

QueuedSemaphore.WaitQueue

Field Summary

Fields inherited from class EDU.oswego.cs.dl.util.concurrent.QueuedSemaphore

wq_

Fields inherited from class EDU.oswego.cs.dl.util.concurrent.Semaphore

permits_

Fields inherited from interface EDU.oswego.cs.dl.util.concurrent.Sync

ONE_CENTURY, ONE_DAY, ONE_HOUR, ONE_MINUTE, ONE_SECOND, ONE_WEEK, ONE_YEAR

Constructor Summary

Constructors

Constructor and Description
PrioritySemaphore(long initialPermits) Create a Semaphore with the given initial number of permits.

Method Summary

Methods inherited from class EDU.oswego.cs.dl.util.concurrent.QueuedSemaphore

acquire, attempt, getSignallee, precheck, recheck, release, release

Methods inherited from class EDU.oswego.cs.dl.util.concurrent.Semaphore

permits

Methods inherited from class java.lang.Object

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

Constructor Detail

PrioritySemaphore

public PrioritySemaphore(long initialPermits)

Create a Semaphore with the given initial number of permits. Using a seed of one makes the semaphore act as a mutual exclusion lock. Negative seeds are also allowed, in which case no acquires will proceed until the number of releases has pushed the number of permits past 0.