/*
* 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);
}
}