/* * Copyright (c) 2008, 2009, Oracle and/or its affiliates. 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.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package sun.nio.ch; import java.nio.ByteBuffer;import java.nio.channels.*;import java.util.concurrent.ExecutorService;import java.util.concurrent.Future;import java.util.concurrent.locks.*;import java.io.FileDescriptor;import java.io.IOException; /** * Base implementation of AsynchronousFileChannel. */ abstract class AsynchronousFileChannelImpl    extends AsynchronousFileChannel{    // close support    protected final ReadWriteLock closeLock = new ReentrantReadWriteLock();    protected volatile boolean closed;     // file descriptor    protected final FileDescriptor fdObj;     // indicates if open for reading/writing    protected final boolean reading;    protected final boolean writing;     // associated Executor    protected final ExecutorService executor;     protected AsynchronousFileChannelImpl(FileDescriptor fdObj,                                          boolean reading,                                          boolean writing,                                          ExecutorService executor)    {        this.fdObj = fdObj;        this.reading = reading;        this.writing = writing;        this.executor = executor;    }     final ExecutorService executor() {        return executor;    }     @Override    public final boolean isOpen() {        return !closed;    }     /**     * Marks the beginning of an I/O operation.     *     * @throws  ClosedChannelException  If channel is closed     */    protected final void begin() throws IOException {        closeLock.readLock().lock();        if (closed)            throw new ClosedChannelException();    }     /**     * Marks the end of an I/O operation.     */    protected final void end() {        closeLock.readLock().unlock();    }     /**     * Marks end of I/O operation     */    protected final void end(boolean completed) throws IOException {        end();        if (!completed && !isOpen())            throw new AsynchronousCloseException();    }     // -- file locking --     abstract <A> Future<FileLock> implLock(long position,                                           long size,                                           boolean shared,                                           A attachment,                                           CompletionHandler<FileLock,? super A> handler);     @Override    public final Future<FileLock> lock(long position,                                       long size,                                       boolean shared)     {        return implLock(position, size, shared, null, null);    }     @Override    public final <A> void lock(long position,                               long size,                               boolean shared,                               A attachment,                               CompletionHandler<FileLock,? super A> handler)    {        if (handler == null)            throw new NullPointerException("'handler' is null");        implLock(position, size, shared, attachment, handler);    }     private volatile FileLockTable fileLockTable;     final void ensureFileLockTableInitialized() throws IOException {        if (fileLockTable == null) {            synchronized (this) {                if (fileLockTable == null) {                    fileLockTable = FileLockTable.newSharedFileLockTable(this, fdObj);                }            }        }    }     final void invalidateAllLocks() throws IOException {        if (fileLockTable != null) {            for (FileLock fl: fileLockTable.removeAll()) {                synchronized (fl) {                    if (fl.isValid()) {                        FileLockImpl fli = (FileLockImpl)fl;                        implRelease(fli);                        fli.invalidate();                    }                }            }        }    }     /**     * Adds region to lock table     */    protected final FileLockImpl addToFileLockTable(long position, long size, boolean shared) {        final FileLockImpl fli;        try {            // like begin() but returns null instead of exception            closeLock.readLock().lock();            if (closed)                return null;             try {                ensureFileLockTableInitialized();            } catch (IOException x) {                // should not happen                throw new AssertionError(x);            }            fli = new FileLockImpl(this, position, size, shared);            // may throw OverlappedFileLockException            fileLockTable.add(fli);        } finally {            end();        }        return fli;    }     protected final void removeFromFileLockTable(FileLockImpl fli) {        fileLockTable.remove(fli);    }     /**     * Releases the given file lock.     */    protected abstract void implRelease(FileLockImpl fli) throws IOException;     /**     * Invoked by FileLockImpl to release the given file lock and remove it     * from the lock table.     */    final void release(FileLockImpl fli) throws IOException {        try {            begin();            implRelease(fli);            removeFromFileLockTable(fli);        } finally {            end();        }    }      // -- reading and writing --     abstract <A> Future<Integer> implRead(ByteBuffer dst,                                         long position,                                         A attachment,                                         CompletionHandler<Integer,? super A> handler);     @Override    public final Future<Integer> read(ByteBuffer dst, long position) {        return implRead(dst, position, null, null);    }     @Override    public final <A> void read(ByteBuffer dst,                               long position,                               A attachment,                               CompletionHandler<Integer,? super A> handler)    {        if (handler == null)            throw new NullPointerException("'handler' is null");        implRead(dst, position, attachment, handler);    }     abstract <A> Future<Integer> implWrite(ByteBuffer src,                                           long position,                                           A attachment,                                           CompletionHandler<Integer,? super A> handler);      @Override    public final Future<Integer> write(ByteBuffer src, long position) {        return implWrite(src, position, null, null);    }     @Override    public final <A> void write(ByteBuffer src,                                long position,                                A attachment,                                CompletionHandler<Integer,? super A> handler)    {        if (handler == null)            throw new NullPointerException("'handler' is null");        implWrite(src, position, attachment, handler);    }}