condvar.java

来自「SRI international 发布的OAA框架软件」· Java 代码 · 共 151 行

/*
  File: ConditionVariable.java
  Originally written by Doug Lea and released into the public domain.
  This may be used for any purposes whatsoever without acknowledgment.
  Thanks for the assistance and support of Sun Microsystems Labs,
  and everyone contributing, testing, and using this code.
  History:
  Date       Who                What
  11Jun1998  dl               Create public version
 */

package edu.emory.mathcs.backport.java.util.concurrent.locks;

import java.util.*;
import edu.emory.mathcs.backport.java.util.concurrent.*;
import edu.emory.mathcs.backport.java.util.concurrent.helpers.*;

class CondVar implements Condition, java.io.Serializable {

    /** The lock **/
    protected final LockInfo lock;

    /**
     * Create a new CondVar that relies on the given mutual
     * exclusion lock.
     * @param lock A non-reentrant mutual exclusion lock.
     **/

    CondVar(LockInfo lock) {
        this.lock = lock;
    }

    public void awaitUninterruptibly() {
        boolean wasInterrupted = false;
        while (true) {
            try {
                await();
                if (wasInterrupted) {
                    Thread.currentThread().interrupt();
                }
                return;
            }
            catch (InterruptedException e) {
                wasInterrupted = true;
            }
        }
    }

    public void await() throws InterruptedException {
        if (Thread.interrupted())
            throw new InterruptedException();
        try {
            synchronized (this) {
                lock.unlock();
                try {
                    wait();
                }
                catch (InterruptedException ex) {
                    notify();
                    throw ex;
                }
            }
        }
        finally {
            lock.lock();
        }
    }

    public boolean await(long timeout, TimeUnit unit) throws InterruptedException {
        if (Thread.interrupted()) throw new InterruptedException();
        long nanos = unit.toNanos(timeout);
        boolean success = false;
        try {
            synchronized (this) {
                lock.unlock();
                try {
                    if (nanos > 0) {
                        long start = Utils.nanoTime();
                        TimeUnit.NANOSECONDS.timedWait(this, nanos);
                        // DK: due to coarse-grained (millis) clock, it seems
                        // preferable to acknowledge timeout (success == false)
                        // when the equality holds (timing is exact)
                        success = Utils.nanoTime() - start < nanos;
                    }
                }
                catch (InterruptedException ex) {
                    notify();
                    throw ex;
                }
            }
        }
        finally {
            lock.lock();
        }
        return success;
    }

//    public long awaitNanos(long timeout) throws InterruptedException {
//        throw new UnsupportedOperationException();
//    }
//
    public boolean awaitUntil(Date deadline) throws InterruptedException {
        if (deadline == null) throw new NullPointerException();
        long abstime = deadline.getTime();
        if (Thread.interrupted()) throw new InterruptedException();

        boolean success = false;
        try {
            synchronized (this) {
                lock.unlock();
                try {
                    long start = System.currentTimeMillis();
                    long msecs = abstime - start;
                    if (msecs > 0) {
                        wait(msecs);
                        // DK: due to coarse-grained (millis) clock, it seems
                        // preferable to acknowledge timeout (success == false)
                        // when the equality holds (timing is exact)
                        success = System.currentTimeMillis() - start < msecs;
                    }
                }
                catch (InterruptedException ex) {
                    notify();
                    throw ex;
                }
            }
        }
        finally {
            lock.lock();
        }
        return success;
    }

    public synchronized void signal() {
        if (!lock.isHeldByCurrentThread()) {
            throw new IllegalMonitorStateException();
        }
        notify();
    }

    public synchronized void signalAll() {
        if (!lock.isHeldByCurrentThread()) {
            throw new IllegalMonitorStateException();
        }
        notifyAll();
    }

    static interface LockInfo extends Lock {
        boolean isHeldByCurrentThread();
    }
}