6781363: New I/O: Update socket-channel API to jsr203/nio2-b99
4313887: New I/O: Improved filesystem interface
4607272: New I/O: Support asynchronous I/O
Reviewed-by: sherman, chegar
/*
* 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.ByteBuffer;
import java.util.concurrent.Future;
/**
* An asynchronous channel that can read and write bytes.
*
* <p> Some channels may not allow more than one read or write to be outstanding
* at any given time. If a thread invokes a read method before a previous read
* operation has completed then a {@link ReadPendingException} will be thrown.
* Similarly, if a write method is invoked before a previous write has completed
* then {@link WritePendingException} is thrown. Whether or not other kinds of
* I/O operations may proceed concurrently with a read operation depends upon
* the type of the channel.
*
* <p> Note that {@link java.nio.ByteBuffer ByteBuffers} are not safe for use by
* multiple concurrent threads. When a read or write operation is initiated then
* care must be taken to ensure that the buffer is not accessed until the
* operation completes.
*
* @see Channels#newInputStream(AsynchronousByteChannel)
* @see Channels#newOutputStream(AsynchronousByteChannel)
*
* @since 1.7
*/
public interface AsynchronousByteChannel
extends AsynchronousChannel
{
/**
* Reads a sequence of bytes from this channel into the given buffer.
*
* <p> This method initiates an operation to read a sequence of bytes from
* this channel into the given buffer. The method returns a {@link Future}
* representing the pending result of the operation. The result of the
* operation, obtained by invoking the {@code Future} 's {@link
* Future#get() get} method, is the number of bytes read or {@code -1} if
* all bytes have been read and the channel has reached end-of-stream.
*
* <p> This method initiates a read operation to read up to <i>r</i> bytes
* from the channel, where <i>r</i> is the number of bytes remaining in the
* buffer, that is, {@code dst.remaining()} at the time that the read is
* attempted. Where <i>r</i> is 0, the read operation completes immediately
* with a result of {@code 0} without initiating an I/O operation.
*
* <p> Suppose that a byte sequence of length <i>n</i> is read, where
* <tt>0</tt> <tt><</tt> <i>n</i> <tt><=</tt> <i>r</i>.
* This byte sequence will be transferred into the buffer so that the first
* byte in the sequence is at index <i>p</i> and the last byte is at index
* <i>p</i> <tt>+</tt> <i>n</i> <tt>-</tt> <tt>1</tt>,
* where <i>p</i> is the buffer's position at the moment the read is
* performed. Upon completion the buffer's position will be equal to
* <i>p</i> <tt>+</tt> <i>n</i>; its limit will not have changed.
*
* <p> Buffers are not safe for use by multiple concurrent threads so care
* should be taken to not to access the buffer until the operaton has completed.
*
* <p> This method may be invoked at any time. Some channel types may not
* allow more than one read to be outstanding at any given time. If a thread
* initiates a read operation before a previous read operation has
* completed then a {@link ReadPendingException} will be thrown.
*
* <p> The <tt>handler</tt> parameter is used to specify a {@link
* CompletionHandler}. When the read operation completes the handler's
* {@link CompletionHandler#completed completed} method is executed.
*
*
* @param dst
* The buffer into which bytes are to be transferred
* @param attachment
* The object to attach to the I/O operation; can be {@code null}
* @param handler
* The completion handler object; can be {@code null}
*
* @return A Future representing the result of the operation
*
* @throws IllegalArgumentException
* If the buffer is read-only
* @throws ReadPendingException
* If the channel does not allow more than one read to be outstanding
* and a previous read has not completed
*/
<A> Future<Integer> read(ByteBuffer dst,
A attachment,
CompletionHandler<Integer,? super A> handler);
/**
* Reads a sequence of bytes from this channel into the given buffer.
*
* <p> An invocation of this method of the form <tt>c.read(dst)</tt>
* behaves in exactly the same manner as the invocation
* <blockquote><pre>
* c.read(dst, null, null);</pre></blockquote>
*
* @param dst
* The buffer into which bytes are to be transferred
*
* @return A Future representing the result of the operation
*
* @throws IllegalArgumentException
* If the buffer is read-only
* @throws ReadPendingException
* If the channel does not allow more than one read to be outstanding
* and a previous read has not completed
*/
Future<Integer> read(ByteBuffer dst);
/**
* Writes a sequence of bytes to this channel from the given buffer.
*
* <p> This method initiates an operation to write a sequence of bytes to
* this channel from the given buffer. This method returns a {@link
* Future} representing the pending result of the operation. The result
* of the operation, obtained by invoking the <tt>Future</tt>'s {@link
* Future#get() get} method, is the number of bytes written, possibly zero.
*
* <p> This method initiates a write operation to write up to <i>r</i> bytes
* to the channel, where <i>r</i> is the number of bytes remaining in the
* buffer, that is, {@code src.remaining()} at the moment the write is
* attempted. Where <i>r</i> is 0, the write operation completes immediately
* with a result of {@code 0} without initiating an I/O operation.
*
* <p> Suppose that a byte sequence of length <i>n</i> is written, where
* <tt>0</tt> <tt><</tt> <i>n</i> <tt><=</tt> <i>r</i>.
* This byte sequence will be transferred from the buffer starting at index
* <i>p</i>, where <i>p</i> is the buffer's position at the moment the
* write is performed; the index of the last byte written will be
* <i>p</i> <tt>+</tt> <i>n</i> <tt>-</tt> <tt>1</tt>.
* Upon completion the buffer's position will be equal to
* <i>p</i> <tt>+</tt> <i>n</i>; its limit will not have changed.
*
* <p> Buffers are not safe for use by multiple concurrent threads so care
* should be taken to not to access the buffer until the operaton has completed.
*
* <p> This method may be invoked at any time. Some channel types may not
* allow more than one write to be outstanding at any given time. If a thread
* initiates a write operation before a previous write operation has
* completed then a {@link WritePendingException} will be thrown.
*
* <p> The <tt>handler</tt> parameter is used to specify a {@link
* CompletionHandler}. When the write operation completes the handler's
* {@link CompletionHandler#completed completed} method is executed.
*
* @param src
* The buffer from which bytes are to be retrieved
* @param attachment
* The object to attach to the I/O operation; can be {@code null}
* @param handler
* The completion handler object; can be {@code null}
*
* @return A Future representing the result of the operation
*
* @throws WritePendingException
* If the channel does not allow more than one write to be outstanding
* and a previous write has not completed
*/
<A> Future<Integer> write(ByteBuffer src,
A attachment,
CompletionHandler<Integer,? super A> handler);
/**
* Writes a sequence of bytes to this channel from the given buffer.
*
* <p> An invocation of this method of the form <tt>c.write(src)</tt>
* behaves in exactly the same manner as the invocation
* <blockquote><pre>
* c.write(src, null, null);</pre></blockquote>
*
* @param src
* The buffer from which bytes are to be retrieved
*
* @return A Future representing the result of the operation
*
* @throws WritePendingException
* If the channel does not allow more than one write to be outstanding
* and a previous write has not completed
*/
Future<Integer> write(ByteBuffer src);
}