--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/nio/channels/AsynchronousChannel.java Sun Feb 15 12:25:54 2009 +0000
@@ -0,0 +1,116 @@
+/*
+ * 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.io.IOException;
+import java.util.concurrent.Future; // javadoc
+
+/**
+ * A channel that supports asynchronous I/O operations. Asynchronous I/O
+ * operations will usually take one of two forms:
+ *
+ * <ol>
+ * <li><pre>{@link Future}<V> <em>operation</em>(<em>...</em>)</pre></li>
+ * <li><pre>Future<V> <em>operation</em>(<em>...</em> A attachment, {@link CompletionHandler}<V,? super A> handler)</pre></li>
+ * </ol>
+ *
+ * where <i>operation</i> is the name of the I/O operation (read or write for
+ * example), <i>V</i> is the result type of the I/O operation, and <i>A</i> is
+ * the type of an object attached to the I/O operation to provide context when
+ * consuming the result. The attachment is important for cases where a
+ * <em>state-less</em> {@code CompletionHandler} is used to consume the result
+ * of many I/O operations.
+ *
+ * <p> In the first form, the methods defined by the {@link Future Future}
+ * interface may be used to check if the operation has completed, wait for its
+ * completion, and to retrieve the result. In the second form, a {@link
+ * CompletionHandler} is invoked to consume the result of the I/O operation when
+ * it completes, fails, or is cancelled.
+ *
+ * <p> A channel that implements this interface is <em>asynchronously
+ * closeable</em>: If an I/O operation is outstanding on the channel and the
+ * channel's {@link #close close} method is invoked, then the I/O operation
+ * fails with the exception {@link AsynchronousCloseException}.
+ *
+ * <p> Asynchronous channels are safe for use by multiple concurrent threads.
+ * Some channel implementations may support concurrent reading and writing, but
+ * may not allow more than one read and one write operation to be outstanding at
+ * any given time.
+ *
+ * <h4>Cancellation</h4>
+ *
+ * <p> The {@code Future} interface defines the {@link Future#cancel cancel}
+ * method to cancel execution of a task.
+ *
+ * <p> Where the {@code cancel} method is invoked with the {@code
+ * mayInterruptIfRunning} parameter set to {@code true} then the I/O operation
+ * may be interrupted by closing the channel. This will cause any other I/O
+ * operations outstanding on the channel to complete with the exception {@link
+ * AsynchronousCloseException}.
+ *
+ * <p> If a {@code CompletionHandler} is specified when initiating an I/O
+ * operation, and the {@code cancel} method is invoked to cancel the I/O
+ * operation before it completes, then the {@code CompletionHandler}'s {@link
+ * CompletionHandler#cancelled cancelled} method is invoked.
+ *
+ * <p> If an implementation of this interface supports a means to cancel I/O
+ * operations, and where cancellation may leave the channel, or the entity to
+ * which it is connected, in an inconsistent state, then the channel is put into
+ * an implementation specific <em>error state</em> that prevents further
+ * attempts to initiate I/O operations on the channel. For example, if a read
+ * operation is cancelled but the implementation cannot guarantee that bytes
+ * have not been read from the channel then it puts the channel into error state
+ * state; further attempts to initiate a {@code read} operation causes an
+ * unspecified runtime exception to be thrown.
+ *
+ * <p> Where the {@code cancel} method is invoked to cancel read or write
+ * operations then it recommended that all buffers used in the I/O operations be
+ * discarded or care taken to ensure that the buffers are not accessed while the
+ * channel remains open.
+ *
+ * @since 1.7
+ */
+
+public interface AsynchronousChannel
+ extends Channel
+{
+ /**
+ * Closes this channel.
+ *
+ * <p> Any outstanding asynchronous operations upon this channel will
+ * complete with the exception {@link AsynchronousCloseException}. After a
+ * channel is closed then further attempts to initiate asynchronous I/O
+ * operations complete immediately with cause {@link ClosedChannelException}.
+ *
+ * <p> This method otherwise behaves exactly as specified by the {@link
+ * Channel} interface.
+ *
+ * @throws IOException
+ * If an I/O error occurs
+ */
+ @Override
+ void close() throws IOException;
+}