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My first initial commit with all of mine experimental changes.

Dmitry Kabak (userdima committed 13 years ago

Commit d37b88d1 parent 3f5b46618352 files · +2598093 −-8690Browse files

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1+/*
2+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3+ *
4+ * This code is free software; you can redistribute it and/or modify it
5+ * under the terms of the GNU General Public License version 2 only, as
6+ * published by the Free Software Foundation. Oracle designates this
7+ * particular file as subject to the "Classpath" exception as provided
8+ * by Oracle in the LICENSE file that accompanied this code.
9+ *
10+ * This code is distributed in the hope that it will be useful, but WITHOUT
11+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13+ * version 2 for more details (a copy is included in the LICENSE file that
14+ * accompanied this code).
15+ *
16+ * You should have received a copy of the GNU General Public License version
17+ * 2 along with this work; if not, write to the Free Software Foundation,
18+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19+ *
20+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21+ * or visit www.oracle.com if you need additional information or have any
22+ * questions.
23+ */
24+
25+/*
26+ * This file is available under and governed by the GNU General Public
27+ * License version 2 only, as published by the Free Software Foundation.
28+ * However, the following notice accompanied the original version of this
29+ * file:
30+ *
31+ * Written by Doug Lea with assistance from members of JCP JSR-166
32+ * Expert Group and released to the public domain, as explained at
33+ * http://creativecommons.org/publicdomain/zero/1.0/
34+ */
35+
36+package java.util.concurrent;
37+
38+import java.util.Collection;
39+import java.util.Queue;
40+
41+/**
42+ * A {@link java.util.Queue} that additionally supports operations
43+ * that wait for the queue to become non-empty when retrieving an
44+ * element, and wait for space to become available in the queue when
45+ * storing an element.
46+ *
47+ * <p><tt>BlockingQueue</tt> methods come in four forms, with different ways
48+ * of handling operations that cannot be satisfied immediately, but may be
49+ * satisfied at some point in the future:
50+ * one throws an exception, the second returns a special value (either
51+ * <tt>null</tt> or <tt>false</tt>, depending on the operation), the third
52+ * blocks the current thread indefinitely until the operation can succeed,
53+ * and the fourth blocks for only a given maximum time limit before giving
54+ * up. These methods are summarized in the following table:
55+ *
56+ * <p>
57+ * <table BORDER CELLPADDING=3 CELLSPACING=1>
58+ * <tr>
59+ * <td></td>
60+ * <td ALIGN=CENTER><em>Throws exception</em></td>
61+ * <td ALIGN=CENTER><em>Special value</em></td>
62+ * <td ALIGN=CENTER><em>Blocks</em></td>
63+ * <td ALIGN=CENTER><em>Times out</em></td>
64+ * </tr>
65+ * <tr>
66+ * <td><b>Insert</b></td>
67+ * <td>{@link #add add(e)}</td>
68+ * <td>{@link #offer offer(e)}</td>
69+ * <td>{@link #put put(e)}</td>
70+ * <td>{@link #offer(Object, long, TimeUnit) offer(e, time, unit)}</td>
71+ * </tr>
72+ * <tr>
73+ * <td><b>Remove</b></td>
74+ * <td>{@link #remove remove()}</td>
75+ * <td>{@link #poll poll()}</td>
76+ * <td>{@link #take take()}</td>
77+ * <td>{@link #poll(long, TimeUnit) poll(time, unit)}</td>
78+ * </tr>
79+ * <tr>
80+ * <td><b>Examine</b></td>
81+ * <td>{@link #element element()}</td>
82+ * <td>{@link #peek peek()}</td>
83+ * <td><em>not applicable</em></td>
84+ * <td><em>not applicable</em></td>
85+ * </tr>
86+ * </table>
87+ *
88+ * <p>A <tt>BlockingQueue</tt> does not accept <tt>null</tt> elements.
89+ * Implementations throw <tt>NullPointerException</tt> on attempts
90+ * to <tt>add</tt>, <tt>put</tt> or <tt>offer</tt> a <tt>null</tt>. A
91+ * <tt>null</tt> is used as a sentinel value to indicate failure of
92+ * <tt>poll</tt> operations.
93+ *
94+ * <p>A <tt>BlockingQueue</tt> may be capacity bounded. At any given
95+ * time it may have a <tt>remainingCapacity</tt> beyond which no
96+ * additional elements can be <tt>put</tt> without blocking.
97+ * A <tt>BlockingQueue</tt> without any intrinsic capacity constraints always
98+ * reports a remaining capacity of <tt>Integer.MAX_VALUE</tt>.
99+ *
100+ * <p> <tt>BlockingQueue</tt> implementations are designed to be used
101+ * primarily for producer-consumer queues, but additionally support
102+ * the {@link java.util.Collection} interface. So, for example, it is
103+ * possible to remove an arbitrary element from a queue using
104+ * <tt>remove(x)</tt>. However, such operations are in general
105+ * <em>not</em> performed very efficiently, and are intended for only
106+ * occasional use, such as when a queued message is cancelled.
107+ *
108+ * <p> <tt>BlockingQueue</tt> implementations are thread-safe. All
109+ * queuing methods achieve their effects atomically using internal
110+ * locks or other forms of concurrency control. However, the
111+ * <em>bulk</em> Collection operations <tt>addAll</tt>,
112+ * <tt>containsAll</tt>, <tt>retainAll</tt> and <tt>removeAll</tt> are
113+ * <em>not</em> necessarily performed atomically unless specified
114+ * otherwise in an implementation. So it is possible, for example, for
115+ * <tt>addAll(c)</tt> to fail (throwing an exception) after adding
116+ * only some of the elements in <tt>c</tt>.
117+ *
118+ * <p>A <tt>BlockingQueue</tt> does <em>not</em> intrinsically support
119+ * any kind of &quot;close&quot; or &quot;shutdown&quot; operation to
120+ * indicate that no more items will be added. The needs and usage of
121+ * such features tend to be implementation-dependent. For example, a
122+ * common tactic is for producers to insert special
123+ * <em>end-of-stream</em> or <em>poison</em> objects, that are
124+ * interpreted accordingly when taken by consumers.
125+ *
126+ * <p>
127+ * Usage example, based on a typical producer-consumer scenario.
128+ * Note that a <tt>BlockingQueue</tt> can safely be used with multiple
129+ * producers and multiple consumers.
130+ * <pre>
131+ * class Producer implements Runnable {
132+ * private final BlockingQueue queue;
133+ * Producer(BlockingQueue q) { queue = q; }
134+ * public void run() {
135+ * try {
136+ * while (true) { queue.put(produce()); }
137+ * } catch (InterruptedException ex) { ... handle ...}
138+ * }
139+ * Object produce() { ... }
140+ * }
141+ *
142+ * class Consumer implements Runnable {
143+ * private final BlockingQueue queue;
144+ * Consumer(BlockingQueue q) { queue = q; }
145+ * public void run() {
146+ * try {
147+ * while (true) { consume(queue.take()); }
148+ * } catch (InterruptedException ex) { ... handle ...}
149+ * }
150+ * void consume(Object x) { ... }
151+ * }
152+ *
153+ * class Setup {
154+ * void main() {
155+ * BlockingQueue q = new SomeQueueImplementation();
156+ * Producer p = new Producer(q);
157+ * Consumer c1 = new Consumer(q);
158+ * Consumer c2 = new Consumer(q);
159+ * new Thread(p).start();
160+ * new Thread(c1).start();
161+ * new Thread(c2).start();
162+ * }
163+ * }
164+ * </pre>
165+ *
166+ * <p>Memory consistency effects: As with other concurrent
167+ * collections, actions in a thread prior to placing an object into a
168+ * {@code BlockingQueue}
169+ * <a href="package-summary.html#MemoryVisibility"><i>happen-before</i></a>
170+ * actions subsequent to the access or removal of that element from
171+ * the {@code BlockingQueue} in another thread.
172+ *
173+ * <p>This interface is a member of the
174+ * <a href="{@docRoot}/../technotes/guides/collections/index.html">
175+ * Java Collections Framework</a>.
176+ *
177+ * @since 1.5
178+ * @author Doug Lea
179+ * @param <E> the type of elements held in this collection
180+ */
181+public interface BlockingQueue<E> extends Queue<E> {
182+ /**
183+ * Inserts the specified element into this queue if it is possible to do
184+ * so immediately without violating capacity restrictions, returning
185+ * <tt>true</tt> upon success and throwing an
186+ * <tt>IllegalStateException</tt> if no space is currently available.
187+ * When using a capacity-restricted queue, it is generally preferable to
188+ * use {@link #offer(Object) offer}.
189+ *
190+ * @param e the element to add
191+ * @return <tt>true</tt> (as specified by {@link Collection#add})
192+ * @throws IllegalStateException if the element cannot be added at this
193+ * time due to capacity restrictions
194+ * @throws ClassCastException if the class of the specified element
195+ * prevents it from being added to this queue
196+ * @throws NullPointerException if the specified element is null
197+ * @throws IllegalArgumentException if some property of the specified
198+ * element prevents it from being added to this queue
199+ */
200+ boolean add(E e);
201+
202+ /**
203+ * Inserts the specified element into this queue if it is possible to do
204+ * so immediately without violating capacity restrictions, returning
205+ * <tt>true</tt> upon success and <tt>false</tt> if no space is currently
206+ * available. When using a capacity-restricted queue, this method is
207+ * generally preferable to {@link #add}, which can fail to insert an
208+ * element only by throwing an exception.
209+ *
210+ * @param e the element to add
211+ * @return <tt>true</tt> if the element was added to this queue, else
212+ * <tt>false</tt>
213+ * @throws ClassCastException if the class of the specified element
214+ * prevents it from being added to this queue
215+ * @throws NullPointerException if the specified element is null
216+ * @throws IllegalArgumentException if some property of the specified
217+ * element prevents it from being added to this queue
218+ */
219+ boolean offer(E e);
220+
221+ /**
222+ * Inserts the specified element into this queue, waiting if necessary
223+ * for space to become available.
224+ *
225+ * @param e the element to add
226+ * @throws InterruptedException if interrupted while waiting
227+ * @throws ClassCastException if the class of the specified element
228+ * prevents it from being added to this queue
229+ * @throws NullPointerException if the specified element is null
230+ * @throws IllegalArgumentException if some property of the specified
231+ * element prevents it from being added to this queue
232+ */
233+ void put(E e) throws InterruptedException;
234+
235+ /**
236+ * Inserts the specified element into this queue, waiting up to the
237+ * specified wait time if necessary for space to become available.
238+ *
239+ * @param e the element to add
240+ * @param timeout how long to wait before giving up, in units of
241+ * <tt>unit</tt>
242+ * @param unit a <tt>TimeUnit</tt> determining how to interpret the
243+ * <tt>timeout</tt> parameter
244+ * @return <tt>true</tt> if successful, or <tt>false</tt> if
245+ * the specified waiting time elapses before space is available
246+ * @throws InterruptedException if interrupted while waiting
247+ * @throws ClassCastException if the class of the specified element
248+ * prevents it from being added to this queue
249+ * @throws NullPointerException if the specified element is null
250+ * @throws IllegalArgumentException if some property of the specified
251+ * element prevents it from being added to this queue
252+ */
253+ boolean offer(E e, long timeout, TimeUnit unit)
254+ throws InterruptedException;
255+
256+ /**
257+ * Retrieves and removes the head of this queue, waiting if necessary
258+ * until an element becomes available.
259+ *
260+ * @return the head of this queue
261+ * @throws InterruptedException if interrupted while waiting
262+ */
263+ E take() throws InterruptedException;
264+
265+ /**
266+ * Retrieves and removes the head of this queue, waiting up to the
267+ * specified wait time if necessary for an element to become available.
268+ *
269+ * @param timeout how long to wait before giving up, in units of
270+ * <tt>unit</tt>
271+ * @param unit a <tt>TimeUnit</tt> determining how to interpret the
272+ * <tt>timeout</tt> parameter
273+ * @return the head of this queue, or <tt>null</tt> if the
274+ * specified waiting time elapses before an element is available
275+ * @throws InterruptedException if interrupted while waiting
276+ */
277+ E poll(long timeout, TimeUnit unit)
278+ throws InterruptedException;
279+
280+ /**
281+ * Returns the number of additional elements that this queue can ideally
282+ * (in the absence of memory or resource constraints) accept without
283+ * blocking, or <tt>Integer.MAX_VALUE</tt> if there is no intrinsic
284+ * limit.
285+ *
286+ * <p>Note that you <em>cannot</em> always tell if an attempt to insert
287+ * an element will succeed by inspecting <tt>remainingCapacity</tt>
288+ * because it may be the case that another thread is about to
289+ * insert or remove an element.
290+ *
291+ * @return the remaining capacity
292+ */
293+ int remainingCapacity();
294+
295+ /**
296+ * Removes a single instance of the specified element from this queue,
297+ * if it is present. More formally, removes an element <tt>e</tt> such
298+ * that <tt>o.equals(e)</tt>, if this queue contains one or more such
299+ * elements.
300+ * Returns <tt>true</tt> if this queue contained the specified element
301+ * (or equivalently, if this queue changed as a result of the call).
302+ *
303+ * @param o element to be removed from this queue, if present
304+ * @return <tt>true</tt> if this queue changed as a result of the call
305+ * @throws ClassCastException if the class of the specified element
306+ * is incompatible with this queue
307+ * (<a href="../Collection.html#optional-restrictions">optional</a>)
308+ * @throws NullPointerException if the specified element is null
309+ * (<a href="../Collection.html#optional-restrictions">optional</a>)
310+ */
311+ boolean remove(Object o);
312+
313+ /**
314+ * Returns <tt>true</tt> if this queue contains the specified element.
315+ * More formally, returns <tt>true</tt> if and only if this queue contains
316+ * at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>.
317+ *
318+ * @param o object to be checked for containment in this queue
319+ * @return <tt>true</tt> if this queue contains the specified element
320+ * @throws ClassCastException if the class of the specified element
321+ * is incompatible with this queue
322+ * (<a href="../Collection.html#optional-restrictions">optional</a>)
323+ * @throws NullPointerException if the specified element is null
324+ * (<a href="../Collection.html#optional-restrictions">optional</a>)
325+ */
326+ public boolean contains(Object o);
327+
328+ /**
329+ * Removes all available elements from this queue and adds them
330+ * to the given collection. This operation may be more
331+ * efficient than repeatedly polling this queue. A failure
332+ * encountered while attempting to add elements to
333+ * collection <tt>c</tt> may result in elements being in neither,
334+ * either or both collections when the associated exception is
335+ * thrown. Attempts to drain a queue to itself result in
336+ * <tt>IllegalArgumentException</tt>. Further, the behavior of
337+ * this operation is undefined if the specified collection is
338+ * modified while the operation is in progress.
339+ *
340+ * @param c the collection to transfer elements into
341+ * @return the number of elements transferred
342+ * @throws UnsupportedOperationException if addition of elements
343+ * is not supported by the specified collection
344+ * @throws ClassCastException if the class of an element of this queue
345+ * prevents it from being added to the specified collection
346+ * @throws NullPointerException if the specified collection is null
347+ * @throws IllegalArgumentException if the specified collection is this
348+ * queue, or some property of an element of this queue prevents
349+ * it from being added to the specified collection
350+ */
351+ int drainTo(Collection<? super E> c);
352+
353+ /**
354+ * Removes at most the given number of available elements from
355+ * this queue and adds them to the given collection. A failure
356+ * encountered while attempting to add elements to
357+ * collection <tt>c</tt> may result in elements being in neither,
358+ * either or both collections when the associated exception is
359+ * thrown. Attempts to drain a queue to itself result in
360+ * <tt>IllegalArgumentException</tt>. Further, the behavior of
361+ * this operation is undefined if the specified collection is
362+ * modified while the operation is in progress.
363+ *
364+ * @param c the collection to transfer elements into
365+ * @param maxElements the maximum number of elements to transfer
366+ * @return the number of elements transferred
367+ * @throws UnsupportedOperationException if addition of elements
368+ * is not supported by the specified collection
369+ * @throws ClassCastException if the class of an element of this queue
370+ * prevents it from being added to the specified collection
371+ * @throws NullPointerException if the specified collection is null
372+ * @throws IllegalArgumentException if the specified collection is this
373+ * queue, or some property of an element of this queue prevents
374+ * it from being added to the specified collection
375+ */
376+ int drainTo(Collection<? super E> c, int maxElements);
377+}