--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/nio/channels/AsynchronousChannelGroup.java Sun Feb 15 12:25:54 2009 +0000
@@ -0,0 +1,344 @@
+/*
+ * Copyright 2007-2009 Sun Microsystems, Inc. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation. Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+package java.nio.channels;
+
+import java.nio.channels.spi.AsynchronousChannelProvider;
+import java.io.IOException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * A grouping of asynchronous channels for the purpose of resource sharing.
+ *
+ * <p> An asynchronous channel group encapsulates the mechanics required to
+ * handle the completion of I/O operations initiated by {@link AsynchronousChannel
+ * asynchronous channels} that are bound to the group. A group has an associated
+ * thread pool to which tasks are submitted to handle I/O events and dispatch to
+ * {@link CompletionHandler completion-handlers} that consume the result of
+ * asynchronous operations performed on channels in the group. In addition to
+ * handling I/O events, the pooled threads may also execute other tasks required
+ * to support the execution of asynchronous I/O operations.
+ *
+ * <p> An asynchronous channel group is created by invoking the {@link
+ * #withFixedThreadPool withFixedThreadPool} or {@link #withCachedThreadPool
+ * withCachedThreadPool} methods defined here. Channels are bound to a group by
+ * specifying the group when constructing the channel. The associated thread
+ * pool is <em>owned</em> by the group; termination of the group results in the
+ * shutdown of the associated thread pool.
+ *
+ * <p> In addition to groups created explicitly, the Java virtual machine
+ * maintains a system-wide <em>default group</em> that is constructed
+ * automatically. Asynchronous channels that do not specify a group at
+ * construction time are bound to the default group. The default group has an
+ * associated thread pool that creates new threads as needed. The default group
+ * may be configured by means of system properties defined in the table below.
+ * Where the {@link java.util.concurrent.ThreadFactory ThreadFactory} for the
+ * default group is not configured then the pooled threads of the default group
+ * are {@link Thread#isDaemon daemon} threads.
+ *
+ * <table border>
+ * <tr>
+ * <th>System property</th>
+ * <th>Description</th>
+ * </tr>
+ * <tr>
+ * <tr>
+ * <td> {@code java.nio.channels.DefaultThreadPool.threadFactory} </td>
+ * <td> The value of this property is taken to be the fully-qualified name
+ * of a concrete {@link java.util.concurrent.ThreadFactory ThreadFactory}
+ * class. The class is loaded using the system class loader and instantiated.
+ * The factory's {@link java.util.concurrent.ThreadFactory#newThread
+ * newThread} method is invoked to create each thread for the default
+ * group's thread pool. If the process to load and instantiate the value
+ * of the property fails then an unspecified error is thrown during the
+ * construction of the default group. </td>
+ * </tr>
+ * <tr>
+ * <td> {@code java.nio.channels.DefaultThreadPool.initialSize} </td>
+ * <td> The value of the {@code initialSize} parameter for the default
+ * group (see {@link #withCachedThreadPool withCachedThreadPool}).
+ * The value of the property is taken to be the {@code String}
+ * representation of an {@code Integer} that is the initial size parameter.
+ * If the value cannot be parsed as an {@code Integer} it causes an
+ * unspecified error to be thrown during the construction of the default
+ * group. </td>
+ * </tr>
+ * </table>
+ *
+ * <a name="threading"><h4>Threading</h4></a>
+ *
+ * <p> The completion handler for an I/O operation initiated on a channel bound
+ * to a group is guaranteed to be invoked by one of the pooled threads in the
+ * group. This ensures that the completion handler is run by a thread with the
+ * expected <em>identity</em>.
+ *
+ * <p> Where an I/O operation completes immediately, and the initiating thread
+ * is one of the pooled threads in the group then the completion handler may
+ * be invoked directly by the initiating thread. To avoid stack overflow, an
+ * implementation may impose a limit as to the number of activations on the
+ * thread stack. Some I/O operations may prohibit invoking the completion
+ * handler directly by the initiating thread (see {@link
+ * AsynchronousServerSocketChannel#accept(Object,CompletionHandler) accept}).
+ *
+ * <a name="shutdown"><h4>Shutdown and Termination</h4></a>
+ *
+ * <p> The {@link #shutdown() shutdown} method is used to initiate an <em>orderly
+ * shutdown</em> of a group. An orderly shutdown marks the group as shutdown;
+ * further attempts to construct a channel that binds to the group will throw
+ * {@link ShutdownChannelGroupException}. Whether or not a group is shutdown can
+ * be tested using the {@link #isShutdown() isShutdown} method. Once shutdown,
+ * the group <em>terminates</em> when all asynchronous channels that are bound to
+ * the group are closed, all actively executing completion handlers have run to
+ * completion, and resources used by the group are released. No attempt is made
+ * to stop or interrupt threads that are executing completion handlers. The
+ * {@link #isTerminated() isTerminated} method is used to test if the group has
+ * terminated, and the {@link #awaitTermination awaitTermination} method can be
+ * used to block until the group has terminated.
+ *
+ * <p> The {@link #shutdownNow() shutdownNow} method can be used to initiate a
+ * <em>forceful shutdown</em> of the group. In addition to the actions performed
+ * by an orderly shutdown, the {@code shutdownNow} method closes all open channels
+ * in the group as if by invoking the {@link AsynchronousChannel#close close}
+ * method.
+ *
+ * @since 1.7
+ *
+ * @see AsynchronousSocketChannel#open(AsynchronousChannelGroup)
+ * @see AsynchronousServerSocketChannel#open(AsynchronousChannelGroup)
+ */
+
+public abstract class AsynchronousChannelGroup {
+ private final AsynchronousChannelProvider provider;
+
+ /**
+ * Initialize a new instance of this class.
+ *
+ * @param provider
+ * The asynchronous channel provider for this group
+ */
+ protected AsynchronousChannelGroup(AsynchronousChannelProvider provider) {
+ this.provider = provider;
+ }
+
+ /**
+ * Returns the provider that created this channel group.
+ *
+ * @return The provider that created this channel group
+ */
+ public final AsynchronousChannelProvider provider() {
+ return provider;
+ }
+
+ /**
+ * Creates an asynchronous channel group with a fixed thread pool.
+ *
+ * <p> The resulting asynchronous channel group reuses a fixed number of
+ * threads. At any point, at most {@code nThreads} threads will be active
+ * processing tasks that are submitted to handle I/O events and dispatch
+ * completion results for operations initiated on asynchronous channels in
+ * the group.
+ *
+ * <p> The group is created by invoking the {@link
+ * AsynchronousChannelProvider#openAsynchronousChannelGroup(int,ThreadFactory)
+ * openAsynchronousChannelGroup(int,ThreadFactory)} method of the system-wide
+ * default {@link AsynchronousChannelProvider} object.
+ *
+ * @param nThreads
+ * The number of threads in the pool
+ * @param threadFactory
+ * The factory to use when creating new threads
+ *
+ * @return A new asynchronous channel group
+ *
+ * @throws IllegalArgumentException
+ * If {@code nThreads <= 0}
+ * @throws IOException
+ * If an I/O error occurs
+ */
+ public static AsynchronousChannelGroup withFixedThreadPool(int nThreads,
+ ThreadFactory threadFactory)
+ throws IOException
+ {
+ return AsynchronousChannelProvider.provider()
+ .openAsynchronousChannelGroup(nThreads, threadFactory);
+ }
+
+ /**
+ * Creates an asynchronous channel group with a given thread pool that
+ * creates new threads as needed.
+ *
+ * <p> The {@code executor} parameter is an {@code ExecutorService} that
+ * creates new threads as needed to execute tasks that are submitted to
+ * handle I/O events and dispatch completion results for operations initiated
+ * on asynchronous channels in the group. It may reuse previously constructed
+ * threads when they are available.
+ *
+ * <p> The {@code initialSize} parameter may be used by the implementation
+ * as a <em>hint</em> as to the initial number of tasks it may submit. For
+ * example, it may be used to indictae the initial number of threads that
+ * wait on I/O events.
+ *
+ * <p> The executor is intended to be used exclusively by the resulting
+ * asynchronous channel group. Termination of the group results in the
+ * orderly {@link ExecutorService#shutdown shutdown} of the executor
+ * service. Shutting down the executor service by other means results in
+ * unspecified behavior.
+ *
+ * <p> The group is created by invoking the {@link
+ * AsynchronousChannelProvider#openAsynchronousChannelGroup(ExecutorService,int)
+ * openAsynchronousChannelGroup(ExecutorService,int)} method of the system-wide
+ * default {@link AsynchronousChannelProvider} object.
+ *
+ * @param executor
+ * The thread pool for the resulting group
+ * @param initialSize
+ * A value {@code >=0} or a negative value for implementation
+ * specific default
+ *
+ * @return A new asynchronous channel group
+ *
+ * @throws IOException
+ * If an I/O error occurs
+ *
+ * @see java.util.concurrent.Executors#newCachedThreadPool
+ */
+ public static AsynchronousChannelGroup withCachedThreadPool(ExecutorService executor,
+ int initialSize)
+ throws IOException
+ {
+ return AsynchronousChannelProvider.provider()
+ .openAsynchronousChannelGroup(executor, initialSize);
+ }
+
+ /**
+ * Creates an asynchronous channel group with a given thread pool.
+ *
+ * <p> The {@code executor} parameter is an {@code ExecutorService} that
+ * executes tasks submitted to dispatch completion results for operations
+ * initiated on asynchronous channels in the group.
+ *
+ * <p> Care should be taken when configuring the executor service. It
+ * should support <em>direct handoff</em> or <em>unbounded queuing</em> of
+ * submitted tasks, and the thread that invokes the {@link
+ * ExecutorService#execute execute} method should never invoke the task
+ * directly. An implementation may mandate additional constraints.
+ *
+ * <p> The executor is intended to be used exclusively by the resulting
+ * asynchronous channel group. Termination of the group results in the
+ * orderly {@link ExecutorService#shutdown shutdown} of the executor
+ * service. Shutting down the executor service by other means results in
+ * unspecified behavior.
+ *
+ * <p> The group is created by invoking the {@link
+ * AsynchronousChannelProvider#openAsynchronousChannelGroup(ExecutorService,int)
+ * openAsynchronousChannelGroup(ExecutorService,int)} method of the system-wide
+ * default {@link AsynchronousChannelProvider} object with an {@code
+ * initialSize} of {@code 0}.
+ *
+ * @param executor
+ * The thread pool for the resulting group
+ *
+ * @return A new asynchronous channel group
+ *
+ * @throws IOException
+ * If an I/O error occurs
+ */
+ public static AsynchronousChannelGroup withThreadPool(ExecutorService executor)
+ throws IOException
+ {
+ return AsynchronousChannelProvider.provider()
+ .openAsynchronousChannelGroup(executor, 0);
+ }
+
+ /**
+ * Tells whether or not this asynchronous channel group is shutdown.
+ *
+ * @return {@code true} if this asynchronous channel group is shutdown or
+ * has been marked for shutdown.
+ */
+ public abstract boolean isShutdown();
+
+ /**
+ * Tells whether or not this group has terminated.
+ *
+ * <p> Where this method returns {@code true}, then the associated thread
+ * pool has also {@link ExecutorService#isTerminated terminated}.
+ *
+ * @return {@code true} if this group has terminated
+ */
+ public abstract boolean isTerminated();
+
+ /**
+ * Initiates an orderly shutdown of the group.
+ *
+ * <p> This method marks the group as shutdown. Further attempts to construct
+ * channel that binds to this group will throw {@link ShutdownChannelGroupException}.
+ * The group terminates when all asynchronous channels in the group are
+ * closed, all actively executing completion handlers have run to completion,
+ * and all resources have been released. This method has no effect if the
+ * group is already shutdown.
+ */
+ public abstract void shutdown();
+
+ /**
+ * Shuts down the group and closes all open channels in the group.
+ *
+ * <p> In addition to the actions performed by the {@link #shutdown() shutdown}
+ * method, this method invokes the {@link AsynchronousChannel#close close}
+ * method on all open channels in the group. This method does not attempt to
+ * stop or interrupt threads that are executing completion handlers. The
+ * group terminates when all actively executing completion handlers have run
+ * to completion and all resources have been released. This method may be
+ * invoked at any time. If some other thread has already invoked it, then
+ * another invocation will block until the first invocation is complete,
+ * after which it will return without effect.
+ *
+ * @throws IOException
+ * If an I/O error occurs
+ */
+ public abstract void shutdownNow() throws IOException;
+
+ /**
+ * Awaits termination of the group.
+
+ * <p> This method blocks until the group has terminated, or the timeout
+ * occurs, or the current thread is interrupted, whichever happens first.
+ *
+ * @param timeout
+ * The maximum time to wait, or zero or less to not wait
+ * @param unit
+ * The time unit of the timeout argument
+ *
+ * @return {@code true} if the group has terminated; {@code false} if the
+ * timeout elapsed before termination
+ *
+ * @throws InterruptedException
+ * If interrupted while waiting
+ */
+ public abstract boolean awaitTermination(long timeout, TimeUnit unit)
+ throws InterruptedException;
+}