mirror of git://gcc.gnu.org/git/gcc.git
614 lines
25 KiB
Java
614 lines
25 KiB
Java
/*
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* Written by Doug Lea with assistance from members of JCP JSR-166
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* Expert Group and released to the public domain, as explained at
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* http://creativecommons.org/licenses/publicdomain
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*/
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package java.util.concurrent;
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import java.util.*;
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/**
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* A {@link Deque} that additionally supports blocking operations that wait
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* for the deque to become non-empty when retrieving an element, and wait for
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* space to become available in the deque when storing an element.
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*
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* <p><tt>BlockingDeque</tt> methods come in four forms, with different ways
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* of handling operations that cannot be satisfied immediately, but may be
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* satisfied at some point in the future:
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* one throws an exception, the second returns a special value (either
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* <tt>null</tt> or <tt>false</tt>, depending on the operation), the third
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* blocks the current thread indefinitely until the operation can succeed,
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* and the fourth blocks for only a given maximum time limit before giving
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* up. These methods are summarized in the following table:
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*
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* <p>
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* <table BORDER CELLPADDING=3 CELLSPACING=1>
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* <tr>
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* <td ALIGN=CENTER COLSPAN = 5> <b>First Element (Head)</b></td>
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* </tr>
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* <tr>
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* <td></td>
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* <td ALIGN=CENTER><em>Throws exception</em></td>
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* <td ALIGN=CENTER><em>Special value</em></td>
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* <td ALIGN=CENTER><em>Blocks</em></td>
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* <td ALIGN=CENTER><em>Times out</em></td>
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* </tr>
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* <tr>
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* <td><b>Insert</b></td>
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* <td>{@link #addFirst addFirst(e)}</td>
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* <td>{@link #offerFirst(Object) offerFirst(e)}</td>
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* <td>{@link #putFirst putFirst(e)}</td>
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* <td>{@link #offerFirst(Object, long, TimeUnit) offerFirst(e, time, unit)}</td>
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* </tr>
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* <tr>
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* <td><b>Remove</b></td>
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* <td>{@link #removeFirst removeFirst()}</td>
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* <td>{@link #pollFirst pollFirst()}</td>
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* <td>{@link #takeFirst takeFirst()}</td>
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* <td>{@link #pollFirst(long, TimeUnit) pollFirst(time, unit)}</td>
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* </tr>
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* <tr>
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* <td><b>Examine</b></td>
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* <td>{@link #getFirst getFirst()}</td>
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* <td>{@link #peekFirst peekFirst()}</td>
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* <td><em>not applicable</em></td>
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* <td><em>not applicable</em></td>
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* </tr>
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* <tr>
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* <td ALIGN=CENTER COLSPAN = 5> <b>Last Element (Tail)</b></td>
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* </tr>
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* <tr>
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* <td></td>
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* <td ALIGN=CENTER><em>Throws exception</em></td>
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* <td ALIGN=CENTER><em>Special value</em></td>
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* <td ALIGN=CENTER><em>Blocks</em></td>
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* <td ALIGN=CENTER><em>Times out</em></td>
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* </tr>
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* <tr>
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* <td><b>Insert</b></td>
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* <td>{@link #addLast addLast(e)}</td>
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* <td>{@link #offerLast(Object) offerLast(e)}</td>
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* <td>{@link #putLast putLast(e)}</td>
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* <td>{@link #offerLast(Object, long, TimeUnit) offerLast(e, time, unit)}</td>
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* </tr>
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* <tr>
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* <td><b>Remove</b></td>
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* <td>{@link #removeLast() removeLast()}</td>
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* <td>{@link #pollLast() pollLast()}</td>
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* <td>{@link #takeLast takeLast()}</td>
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* <td>{@link #pollLast(long, TimeUnit) pollLast(time, unit)}</td>
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* </tr>
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* <tr>
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* <td><b>Examine</b></td>
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* <td>{@link #getLast getLast()}</td>
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* <td>{@link #peekLast peekLast()}</td>
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* <td><em>not applicable</em></td>
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* <td><em>not applicable</em></td>
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* </tr>
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* </table>
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*
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* <p>Like any {@link BlockingQueue}, a <tt>BlockingDeque</tt> is thread safe,
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* does not permit null elements, and may (or may not) be
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* capacity-constrained.
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*
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* <p>A <tt>BlockingDeque</tt> implementation may be used directly as a FIFO
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* <tt>BlockingQueue</tt>. The methods inherited from the
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* <tt>BlockingQueue</tt> interface are precisely equivalent to
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* <tt>BlockingDeque</tt> methods as indicated in the following table:
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*
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* <p>
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* <table BORDER CELLPADDING=3 CELLSPACING=1>
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* <tr>
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* <td ALIGN=CENTER> <b><tt>BlockingQueue</tt> Method</b></td>
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* <td ALIGN=CENTER> <b>Equivalent <tt>BlockingDeque</tt> Method</b></td>
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* </tr>
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* <tr>
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* <td ALIGN=CENTER COLSPAN = 2> <b>Insert</b></td>
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* </tr>
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* <tr>
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* <td>{@link #add(Object) add(e)}</td>
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* <td>{@link #addLast(Object) addLast(e)}</td>
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* </tr>
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* <tr>
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* <td>{@link #offer(Object) offer(e)}</td>
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* <td>{@link #offerLast(Object) offerLast(e)}</td>
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* </tr>
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* <tr>
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* <td>{@link #put(Object) put(e)}</td>
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* <td>{@link #putLast(Object) putLast(e)}</td>
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* </tr>
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* <tr>
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* <td>{@link #offer(Object, long, TimeUnit) offer(e, time, unit)}</td>
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* <td>{@link #offerLast(Object, long, TimeUnit) offerLast(e, time, unit)}</td>
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* </tr>
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* <tr>
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* <td ALIGN=CENTER COLSPAN = 2> <b>Remove</b></td>
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* </tr>
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* <tr>
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* <td>{@link #remove() remove()}</td>
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* <td>{@link #removeFirst() removeFirst()}</td>
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* </tr>
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* <tr>
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* <td>{@link #poll() poll()}</td>
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* <td>{@link #pollFirst() pollFirst()}</td>
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* </tr>
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* <tr>
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* <td>{@link #take() take()}</td>
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* <td>{@link #takeFirst() takeFirst()}</td>
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* </tr>
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* <tr>
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* <td>{@link #poll(long, TimeUnit) poll(time, unit)}</td>
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* <td>{@link #pollFirst(long, TimeUnit) pollFirst(time, unit)}</td>
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* </tr>
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* <tr>
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* <td ALIGN=CENTER COLSPAN = 2> <b>Examine</b></td>
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* </tr>
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* <tr>
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* <td>{@link #element() element()}</td>
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* <td>{@link #getFirst() getFirst()}</td>
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* </tr>
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* <tr>
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* <td>{@link #peek() peek()}</td>
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* <td>{@link #peekFirst() peekFirst()}</td>
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* </tr>
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* </table>
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*
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* <p>Memory consistency effects: As with other concurrent
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* collections, actions in a thread prior to placing an object into a
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* {@code BlockingDeque}
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* <a href="package-summary.html#MemoryVisibility"><i>happen-before</i></a>
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* actions subsequent to the access or removal of that element from
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* the {@code BlockingDeque} in another thread.
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*
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* <p>This interface is a member of the
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* <a href="{@docRoot}/../technotes/guides/collections/index.html">
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* Java Collections Framework</a>.
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*
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* @since 1.6
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* @author Doug Lea
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* @param <E> the type of elements held in this collection
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*/
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public interface BlockingDeque<E> extends BlockingQueue<E>, Deque<E> {
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/*
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* We have "diamond" multiple interface inheritance here, and that
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* introduces ambiguities. Methods might end up with different
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* specs depending on the branch chosen by javadoc. Thus a lot of
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* methods specs here are copied from superinterfaces.
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*/
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/**
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* Inserts the specified element at the front of this deque if it is
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* possible to do so immediately without violating capacity restrictions,
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* throwing an <tt>IllegalStateException</tt> if no space is currently
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* available. When using a capacity-restricted deque, it is generally
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* preferable to use {@link #offerFirst(Object) offerFirst}.
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*
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* @param e the element to add
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* @throws IllegalStateException {@inheritDoc}
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* @throws ClassCastException {@inheritDoc}
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* @throws NullPointerException if the specified element is null
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* @throws IllegalArgumentException {@inheritDoc}
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*/
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void addFirst(E e);
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/**
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* Inserts the specified element at the end of this deque if it is
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* possible to do so immediately without violating capacity restrictions,
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* throwing an <tt>IllegalStateException</tt> if no space is currently
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* available. When using a capacity-restricted deque, it is generally
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* preferable to use {@link #offerLast(Object) offerLast}.
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*
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* @param e the element to add
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* @throws IllegalStateException {@inheritDoc}
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* @throws ClassCastException {@inheritDoc}
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* @throws NullPointerException if the specified element is null
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* @throws IllegalArgumentException {@inheritDoc}
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*/
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void addLast(E e);
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/**
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* Inserts the specified element at the front of this deque if it is
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* possible to do so immediately without violating capacity restrictions,
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* returning <tt>true</tt> upon success and <tt>false</tt> if no space is
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* currently available.
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* When using a capacity-restricted deque, this method is generally
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* preferable to the {@link #addFirst(Object) addFirst} method, which can
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* fail to insert an element only by throwing an exception.
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*
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* @param e the element to add
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* @throws ClassCastException {@inheritDoc}
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* @throws NullPointerException if the specified element is null
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* @throws IllegalArgumentException {@inheritDoc}
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*/
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boolean offerFirst(E e);
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/**
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* Inserts the specified element at the end of this deque if it is
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* possible to do so immediately without violating capacity restrictions,
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* returning <tt>true</tt> upon success and <tt>false</tt> if no space is
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* currently available.
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* When using a capacity-restricted deque, this method is generally
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* preferable to the {@link #addLast(Object) addLast} method, which can
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* fail to insert an element only by throwing an exception.
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*
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* @param e the element to add
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* @throws ClassCastException {@inheritDoc}
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* @throws NullPointerException if the specified element is null
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* @throws IllegalArgumentException {@inheritDoc}
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*/
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boolean offerLast(E e);
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/**
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* Inserts the specified element at the front of this deque,
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* waiting if necessary for space to become available.
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*
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* @param e the element to add
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* @throws InterruptedException if interrupted while waiting
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* @throws ClassCastException if the class of the specified element
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* prevents it from being added to this deque
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* @throws NullPointerException if the specified element is null
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* @throws IllegalArgumentException if some property of the specified
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* element prevents it from being added to this deque
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*/
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void putFirst(E e) throws InterruptedException;
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/**
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* Inserts the specified element at the end of this deque,
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* waiting if necessary for space to become available.
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*
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* @param e the element to add
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* @throws InterruptedException if interrupted while waiting
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* @throws ClassCastException if the class of the specified element
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* prevents it from being added to this deque
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* @throws NullPointerException if the specified element is null
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* @throws IllegalArgumentException if some property of the specified
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* element prevents it from being added to this deque
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*/
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void putLast(E e) throws InterruptedException;
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/**
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* Inserts the specified element at the front of this deque,
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* waiting up to the specified wait time if necessary for space to
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* become available.
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*
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* @param e the element to add
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* @param timeout how long to wait before giving up, in units of
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* <tt>unit</tt>
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* @param unit a <tt>TimeUnit</tt> determining how to interpret the
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* <tt>timeout</tt> parameter
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* @return <tt>true</tt> if successful, or <tt>false</tt> if
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* the specified waiting time elapses before space is available
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* @throws InterruptedException if interrupted while waiting
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* @throws ClassCastException if the class of the specified element
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* prevents it from being added to this deque
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* @throws NullPointerException if the specified element is null
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* @throws IllegalArgumentException if some property of the specified
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* element prevents it from being added to this deque
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*/
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boolean offerFirst(E e, long timeout, TimeUnit unit)
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throws InterruptedException;
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/**
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* Inserts the specified element at the end of this deque,
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* waiting up to the specified wait time if necessary for space to
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* become available.
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*
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* @param e the element to add
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* @param timeout how long to wait before giving up, in units of
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* <tt>unit</tt>
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* @param unit a <tt>TimeUnit</tt> determining how to interpret the
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* <tt>timeout</tt> parameter
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* @return <tt>true</tt> if successful, or <tt>false</tt> if
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* the specified waiting time elapses before space is available
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* @throws InterruptedException if interrupted while waiting
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* @throws ClassCastException if the class of the specified element
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* prevents it from being added to this deque
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* @throws NullPointerException if the specified element is null
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* @throws IllegalArgumentException if some property of the specified
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* element prevents it from being added to this deque
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*/
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boolean offerLast(E e, long timeout, TimeUnit unit)
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throws InterruptedException;
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/**
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* Retrieves and removes the first element of this deque, waiting
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* if necessary until an element becomes available.
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*
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* @return the head of this deque
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* @throws InterruptedException if interrupted while waiting
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*/
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E takeFirst() throws InterruptedException;
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/**
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* Retrieves and removes the last element of this deque, waiting
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* if necessary until an element becomes available.
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*
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* @return the tail of this deque
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* @throws InterruptedException if interrupted while waiting
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*/
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E takeLast() throws InterruptedException;
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/**
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* Retrieves and removes the first element of this deque, waiting
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* up to the specified wait time if necessary for an element to
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* become available.
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*
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* @param timeout how long to wait before giving up, in units of
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* <tt>unit</tt>
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* @param unit a <tt>TimeUnit</tt> determining how to interpret the
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* <tt>timeout</tt> parameter
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* @return the head of this deque, or <tt>null</tt> if the specified
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* waiting time elapses before an element is available
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* @throws InterruptedException if interrupted while waiting
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*/
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E pollFirst(long timeout, TimeUnit unit)
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throws InterruptedException;
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/**
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* Retrieves and removes the last element of this deque, waiting
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* up to the specified wait time if necessary for an element to
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* become available.
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*
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* @param timeout how long to wait before giving up, in units of
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* <tt>unit</tt>
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* @param unit a <tt>TimeUnit</tt> determining how to interpret the
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* <tt>timeout</tt> parameter
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* @return the tail of this deque, or <tt>null</tt> if the specified
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* waiting time elapses before an element is available
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* @throws InterruptedException if interrupted while waiting
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*/
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E pollLast(long timeout, TimeUnit unit)
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throws InterruptedException;
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/**
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* Removes the first occurrence of the specified element from this deque.
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* If the deque does not contain the element, it is unchanged.
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* More formally, removes the first element <tt>e</tt> such that
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* <tt>o.equals(e)</tt> (if such an element exists).
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* Returns <tt>true</tt> if this deque contained the specified element
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* (or equivalently, if this deque changed as a result of the call).
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*
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* @param o element to be removed from this deque, if present
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* @return <tt>true</tt> if an element was removed as a result of this call
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* @throws ClassCastException if the class of the specified element
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* is incompatible with this deque (optional)
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* @throws NullPointerException if the specified element is null (optional)
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*/
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boolean removeFirstOccurrence(Object o);
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/**
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* Removes the last occurrence of the specified element from this deque.
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* If the deque does not contain the element, it is unchanged.
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* More formally, removes the last element <tt>e</tt> such that
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* <tt>o.equals(e)</tt> (if such an element exists).
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* Returns <tt>true</tt> if this deque contained the specified element
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* (or equivalently, if this deque changed as a result of the call).
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*
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* @param o element to be removed from this deque, if present
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* @return <tt>true</tt> if an element was removed as a result of this call
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* @throws ClassCastException if the class of the specified element
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* is incompatible with this deque (optional)
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* @throws NullPointerException if the specified element is null (optional)
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*/
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boolean removeLastOccurrence(Object o);
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// *** BlockingQueue methods ***
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/**
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* Inserts the specified element into the queue represented by this deque
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* (in other words, at the tail of this deque) if it is possible to do so
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* immediately without violating capacity restrictions, returning
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* <tt>true</tt> upon success and throwing an
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* <tt>IllegalStateException</tt> if no space is currently available.
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* When using a capacity-restricted deque, it is generally preferable to
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* use {@link #offer(Object) offer}.
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*
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* <p>This method is equivalent to {@link #addLast(Object) addLast}.
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*
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* @param e the element to add
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* @throws IllegalStateException {@inheritDoc}
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* @throws ClassCastException if the class of the specified element
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* prevents it from being added to this deque
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* @throws NullPointerException if the specified element is null
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* @throws IllegalArgumentException if some property of the specified
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* element prevents it from being added to this deque
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*/
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boolean add(E e);
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/**
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* Inserts the specified element into the queue represented by this deque
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* (in other words, at the tail of this deque) if it is possible to do so
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* immediately without violating capacity restrictions, returning
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* <tt>true</tt> upon success and <tt>false</tt> if no space is currently
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* available. When using a capacity-restricted deque, this method is
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* generally preferable to the {@link #add} method, which can fail to
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* insert an element only by throwing an exception.
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*
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* <p>This method is equivalent to {@link #offerLast(Object) offerLast}.
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*
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* @param e the element to add
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* @throws ClassCastException if the class of the specified element
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* prevents it from being added to this deque
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* @throws NullPointerException if the specified element is null
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* @throws IllegalArgumentException if some property of the specified
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* element prevents it from being added to this deque
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*/
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boolean offer(E e);
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/**
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* Inserts the specified element into the queue represented by this deque
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* (in other words, at the tail of this deque), waiting if necessary for
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* space to become available.
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*
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* <p>This method is equivalent to {@link #putLast(Object) putLast}.
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*
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* @param e the element to add
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* @throws InterruptedException {@inheritDoc}
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* @throws ClassCastException if the class of the specified element
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* prevents it from being added to this deque
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* @throws NullPointerException if the specified element is null
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* @throws IllegalArgumentException if some property of the specified
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* element prevents it from being added to this deque
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*/
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void put(E e) throws InterruptedException;
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/**
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* Inserts the specified element into the queue represented by this deque
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* (in other words, at the tail of this deque), waiting up to the
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* specified wait time if necessary for space to become available.
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*
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* <p>This method is equivalent to
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* {@link #offerLast(Object,long,TimeUnit) offerLast}.
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*
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* @param e the element to add
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* @return <tt>true</tt> if the element was added to this deque, else
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* <tt>false</tt>
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* @throws InterruptedException {@inheritDoc}
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* @throws ClassCastException if the class of the specified element
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* prevents it from being added to this deque
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* @throws NullPointerException if the specified element is null
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* @throws IllegalArgumentException if some property of the specified
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* element prevents it from being added to this deque
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*/
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boolean offer(E e, long timeout, TimeUnit unit)
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throws InterruptedException;
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/**
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* Retrieves and removes the head of the queue represented by this deque
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* (in other words, the first element of this deque).
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* This method differs from {@link #poll poll} only in that it
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* throws an exception if this deque is empty.
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*
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* <p>This method is equivalent to {@link #removeFirst() removeFirst}.
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*
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* @return the head of the queue represented by this deque
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* @throws NoSuchElementException if this deque is empty
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*/
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E remove();
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/**
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* Retrieves and removes the head of the queue represented by this deque
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* (in other words, the first element of this deque), or returns
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* <tt>null</tt> if this deque is empty.
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*
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* <p>This method is equivalent to {@link #pollFirst()}.
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*
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* @return the head of this deque, or <tt>null</tt> if this deque is empty
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*/
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E poll();
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/**
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* Retrieves and removes the head of the queue represented by this deque
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* (in other words, the first element of this deque), waiting if
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* necessary until an element becomes available.
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*
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* <p>This method is equivalent to {@link #takeFirst() takeFirst}.
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*
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* @return the head of this deque
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* @throws InterruptedException if interrupted while waiting
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*/
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E take() throws InterruptedException;
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/**
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* Retrieves and removes the head of the queue represented by this deque
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* (in other words, the first element of this deque), waiting up to the
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* specified wait time if necessary for an element to become available.
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*
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* <p>This method is equivalent to
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* {@link #pollFirst(long,TimeUnit) pollFirst}.
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*
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* @return the head of this deque, or <tt>null</tt> if the
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* specified waiting time elapses before an element is available
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* @throws InterruptedException if interrupted while waiting
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*/
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E poll(long timeout, TimeUnit unit)
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throws InterruptedException;
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/**
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* Retrieves, but does not remove, the head of the queue represented by
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* this deque (in other words, the first element of this deque).
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* This method differs from {@link #peek peek} only in that it throws an
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* exception if this deque is empty.
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*
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* <p>This method is equivalent to {@link #getFirst() getFirst}.
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*
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* @return the head of this deque
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* @throws NoSuchElementException if this deque is empty
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*/
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E element();
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/**
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* Retrieves, but does not remove, the head of the queue represented by
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* this deque (in other words, the first element of this deque), or
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* returns <tt>null</tt> if this deque is empty.
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*
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* <p>This method is equivalent to {@link #peekFirst() peekFirst}.
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*
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* @return the head of this deque, or <tt>null</tt> if this deque is empty
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*/
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E peek();
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/**
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* Removes the first occurrence of the specified element from this deque.
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* If the deque does not contain the element, it is unchanged.
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* More formally, removes the first element <tt>e</tt> such that
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* <tt>o.equals(e)</tt> (if such an element exists).
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* Returns <tt>true</tt> if this deque contained the specified element
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* (or equivalently, if this deque changed as a result of the call).
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*
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* <p>This method is equivalent to
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* {@link #removeFirstOccurrence(Object) removeFirstOccurrence}.
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*
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* @param o element to be removed from this deque, if present
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* @return <tt>true</tt> if this deque changed as a result of the call
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* @throws ClassCastException if the class of the specified element
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* is incompatible with this deque (optional)
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* @throws NullPointerException if the specified element is null (optional)
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*/
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boolean remove(Object o);
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/**
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* Returns <tt>true</tt> if this deque contains the specified element.
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* More formally, returns <tt>true</tt> if and only if this deque contains
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* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>.
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*
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* @param o object to be checked for containment in this deque
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* @return <tt>true</tt> if this deque contains the specified element
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* @throws ClassCastException if the class of the specified element
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* is incompatible with this deque (optional)
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* @throws NullPointerException if the specified element is null (optional)
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*/
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public boolean contains(Object o);
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/**
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* Returns the number of elements in this deque.
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*
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* @return the number of elements in this deque
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*/
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public int size();
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/**
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* Returns an iterator over the elements in this deque in proper sequence.
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* The elements will be returned in order from first (head) to last (tail).
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*
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* @return an iterator over the elements in this deque in proper sequence
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*/
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Iterator<E> iterator();
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// *** Stack methods ***
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/**
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* Pushes an element onto the stack represented by this deque. In other
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* words, inserts the element at the front of this deque unless it would
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* violate capacity restrictions.
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*
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* <p>This method is equivalent to {@link #addFirst(Object) addFirst}.
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*
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* @throws IllegalStateException {@inheritDoc}
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* @throws ClassCastException {@inheritDoc}
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* @throws NullPointerException if the specified element is null
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* @throws IllegalArgumentException {@inheritDoc}
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*/
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void push(E e);
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}
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