1/*
2 * $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk/module-client/src/main/java/org/apache/http/impl/conn/tsccm/WaitingThread.java $
3 * $Revision: 649217 $
4 * $Date: 2008-04-17 11:32:32 -0700 (Thu, 17 Apr 2008) $
5 *
6 * ====================================================================
7 *
8 *  Licensed to the Apache Software Foundation (ASF) under one or more
9 *  contributor license agreements.  See the NOTICE file distributed with
10 *  this work for additional information regarding copyright ownership.
11 *  The ASF licenses this file to You under the Apache License, Version 2.0
12 *  (the "License"); you may not use this file except in compliance with
13 *  the License.  You may obtain a copy of the License at
14 *
15 *      http://www.apache.org/licenses/LICENSE-2.0
16 *
17 *  Unless required by applicable law or agreed to in writing, software
18 *  distributed under the License is distributed on an "AS IS" BASIS,
19 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
20 *  See the License for the specific language governing permissions and
21 *  limitations under the License.
22 * ====================================================================
23 *
24 * This software consists of voluntary contributions made by many
25 * individuals on behalf of the Apache Software Foundation.  For more
26 * information on the Apache Software Foundation, please see
27 * <http://www.apache.org/>.
28 *
29 */
30
31package org.apache.http.impl.conn.tsccm;
32
33
34import java.util.Date;
35import java.util.concurrent.locks.Condition;
36
37
38/**
39 * Represents a thread waiting for a connection.
40 * This class implements throwaway objects. It is instantiated whenever
41 * a thread needs to wait. Instances are not re-used, except if the
42 * waiting thread experiences a spurious wakeup and continues to wait.
43 * <br/>
44 * All methods assume external synchronization on the condition
45 * passed to the constructor.
46 * Instances of this class do <i>not</i> synchronize access!
47 *
48 * @author <a href="mailto:rolandw at apache.org">Roland Weber</a>
49 *
50 * @deprecated Please use {@link java.net.URL#openConnection} instead.
51 *     Please visit <a href="http://android-developers.blogspot.com/2011/09/androids-http-clients.html">this webpage</a>
52 *     for further details.
53 */
54@Deprecated
55public class WaitingThread {
56
57    /** The condition on which the thread is waiting. */
58    private final Condition cond;
59
60    /** The route specific pool on which the thread is waiting. */
61    //@@@ replace with generic pool interface
62    private final RouteSpecificPool pool;
63
64    /** The thread that is waiting for an entry. */
65    private Thread waiter;
66
67    /** True if this was interrupted. */
68    private boolean aborted;
69
70
71    /**
72     * Creates a new entry for a waiting thread.
73     *
74     * @param cond      the condition for which to wait
75     * @param pool      the pool on which the thread will be waiting,
76     *                  or <code>null</code>
77     */
78    public WaitingThread(Condition cond, RouteSpecificPool pool) {
79
80        if (cond == null) {
81            throw new IllegalArgumentException("Condition must not be null.");
82        }
83
84        this.cond = cond;
85        this.pool = pool;
86    }
87
88
89    /**
90     * Obtains the condition.
91     *
92     * @return  the condition on which to wait, never <code>null</code>
93     */
94    public final Condition getCondition() {
95        // not synchronized
96        return this.cond;
97    }
98
99
100    /**
101     * Obtains the pool, if there is one.
102     *
103     * @return  the pool on which a thread is or was waiting,
104     *          or <code>null</code>
105     */
106    public final RouteSpecificPool getPool() {
107        // not synchronized
108        return this.pool;
109    }
110
111
112    /**
113     * Obtains the thread, if there is one.
114     *
115     * @return  the thread which is waiting, or <code>null</code>
116     */
117    public final Thread getThread() {
118        // not synchronized
119        return this.waiter;
120    }
121
122
123    /**
124     * Blocks the calling thread.
125     * This method returns when the thread is notified or interrupted,
126     * if a timeout occurrs, or if there is a spurious wakeup.
127     * <br/>
128     * This method assumes external synchronization.
129     *
130     * @param deadline  when to time out, or <code>null</code> for no timeout
131     *
132     * @return  <code>true</code> if the condition was satisfied,
133     *          <code>false</code> in case of a timeout.
134     *          Typically, a call to {@link #wakeup} is used to indicate
135     *          that the condition was satisfied. Since the condition is
136     *          accessible outside, this cannot be guaranteed though.
137     *
138     * @throws InterruptedException     if the waiting thread was interrupted
139     *
140     * @see #wakeup
141     */
142    public boolean await(Date deadline)
143        throws InterruptedException {
144
145        // This is only a sanity check. We cannot synchronize here,
146        // the lock would not be released on calling cond.await() below.
147        if (this.waiter != null) {
148            throw new IllegalStateException
149                ("A thread is already waiting on this object." +
150                 "\ncaller: " + Thread.currentThread() +
151                 "\nwaiter: " + this.waiter);
152        }
153
154        if (aborted)
155            throw new InterruptedException("Operation interrupted");
156
157        this.waiter = Thread.currentThread();
158
159        boolean success = false;
160        try {
161            if (deadline != null) {
162                success = this.cond.awaitUntil(deadline);
163            } else {
164                this.cond.await();
165                success = true;
166            }
167            if (aborted)
168                throw new InterruptedException("Operation interrupted");
169        } finally {
170            this.waiter = null;
171        }
172        return success;
173
174    } // await
175
176
177    /**
178     * Wakes up the waiting thread.
179     * <br/>
180     * This method assumes external synchronization.
181     */
182    public void wakeup() {
183
184        // If external synchronization and pooling works properly,
185        // this cannot happen. Just a sanity check.
186        if (this.waiter == null) {
187            throw new IllegalStateException
188                ("Nobody waiting on this object.");
189        }
190
191        // One condition might be shared by several WaitingThread instances.
192        // It probably isn't, but just in case: wake all, not just one.
193        this.cond.signalAll();
194    }
195
196    public void interrupt() {
197        aborted = true;
198        this.cond.signalAll();
199    }
200
201
202} // class WaitingThread
203