org.apache.http.impl.conn.tsccm.WaitingThread Maven / Gradle / Ivy
/*
* ====================================================================
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
*
* This class implements throw away objects. It is instantiated whenever
* a thread needs to wait. Instances are not re-used, except if the
* waiting thread experiences a spurious wake up and continues to wait.
*
*
* All methods assume external synchronization on the condition
* passed to the constructor.
* Instances of this class do not synchronize access!
*
*
* @since 4.0
*
* @deprecated (4.2) do not use
*/
@Deprecated
public class WaitingThread {
/** The condition on which the thread is waiting. */
private final Condition cond;
/** The route specific pool on which the thread is waiting. */
//@@@ replace with generic pool interface
private final RouteSpecificPool pool;
/** The thread that is waiting for an entry. */
private Thread waiter;
/** True if this was interrupted. */
private boolean aborted;
/**
* Creates a new entry for a waiting thread.
*
* @param cond the condition for which to wait
* @param pool the pool on which the thread will be waiting,
* or {@code null}
*/
public WaitingThread(final Condition cond, final RouteSpecificPool pool) {
Args.notNull(cond, "Condition");
this.cond = cond;
this.pool = pool;
}
/**
* Obtains the condition.
*
* @return the condition on which to wait, never {@code null}
*/
public final Condition getCondition() {
// not synchronized
return this.cond;
}
/**
* Obtains the pool, if there is one.
*
* @return the pool on which a thread is or was waiting,
* or {@code null}
*/
public final RouteSpecificPool getPool() {
// not synchronized
return this.pool;
}
/**
* Obtains the thread, if there is one.
*
* @return the thread which is waiting, or {@code null}
*/
public final Thread getThread() {
// not synchronized
return this.waiter;
}
/**
* Blocks the calling thread.
* This method returns when the thread is notified or interrupted,
* if a timeout occurrs, or if there is a spurious wakeup.
*
* This method assumes external synchronization.
*
*
* @param deadline when to time out, or {@code null} for no timeout
*
* @return {@code true} if the condition was satisfied,
* {@code false} in case of a timeout.
* Typically, a call to {@link #wakeup} is used to indicate
* that the condition was satisfied. Since the condition is
* accessible outside, this cannot be guaranteed though.
*
* @throws InterruptedException if the waiting thread was interrupted
*
* @see #wakeup
*/
public boolean await(final Date deadline)
throws InterruptedException {
// This is only a sanity check. We cannot synchronize here,
// the lock would not be released on calling cond.await() below.
if (this.waiter != null) {
throw new IllegalStateException
("A thread is already waiting on this object." +
"\ncaller: " + Thread.currentThread() +
"\nwaiter: " + this.waiter);
}
if (aborted) {
throw new InterruptedException("Operation interrupted");
}
this.waiter = Thread.currentThread();
boolean success = false;
try {
if (deadline != null) {
success = this.cond.awaitUntil(deadline);
} else {
this.cond.await();
success = true;
}
if (aborted) {
throw new InterruptedException("Operation interrupted");
}
} finally {
this.waiter = null;
}
return success;
} // await
/**
* Wakes up the waiting thread.
*
* This method assumes external synchronization.
*
*/
public void wakeup() {
// If external synchronization and pooling works properly,
// this cannot happen. Just a sanity check.
if (this.waiter == null) {
throw new IllegalStateException
("Nobody waiting on this object.");
}
// One condition might be shared by several WaitingThread instances.
// It probably isn't, but just in case: wake all, not just one.
this.cond.signalAll();
}
public void interrupt() {
aborted = true;
this.cond.signalAll();
}
} // class WaitingThread