Java example source code file (FileChannelImpl.java)
The FileChannelImpl.java Java example source code/*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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* published by the Free Software Foundation. Oracle designates this
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*
* 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).
*
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* 2 along with this work; if not, write to the Free Software Foundation,
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package sun.nio.ch;
import java.io.FileDescriptor;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.MappedByteBuffer;
import java.nio.channels.*;
import java.util.ArrayList;
import java.util.List;
import java.security.AccessController;
import sun.misc.Cleaner;
import sun.security.action.GetPropertyAction;
public class FileChannelImpl
extends FileChannel
{
// Memory allocation size for mapping buffers
private static final long allocationGranularity;
// Used to make native read and write calls
private final FileDispatcher nd;
// File descriptor
private final FileDescriptor fd;
// File access mode (immutable)
private final boolean writable;
private final boolean readable;
private final boolean append;
// Required to prevent finalization of creating stream (immutable)
private final Object parent;
// Thread-safe set of IDs of native threads, for signalling
private final NativeThreadSet threads = new NativeThreadSet(2);
// Lock for operations involving position and size
private final Object positionLock = new Object();
private FileChannelImpl(FileDescriptor fd, boolean readable,
boolean writable, boolean append, Object parent)
{
this.fd = fd;
this.readable = readable;
this.writable = writable;
this.append = append;
this.parent = parent;
this.nd = new FileDispatcherImpl(append);
}
// Used by FileInputStream.getChannel() and RandomAccessFile.getChannel()
public static FileChannel open(FileDescriptor fd,
boolean readable, boolean writable,
Object parent)
{
return new FileChannelImpl(fd, readable, writable, false, parent);
}
// Used by FileOutputStream.getChannel
public static FileChannel open(FileDescriptor fd,
boolean readable, boolean writable,
boolean append, Object parent)
{
return new FileChannelImpl(fd, readable, writable, append, parent);
}
private void ensureOpen() throws IOException {
if (!isOpen())
throw new ClosedChannelException();
}
// -- Standard channel operations --
protected void implCloseChannel() throws IOException {
// Release and invalidate any locks that we still hold
if (fileLockTable != null) {
for (FileLock fl: fileLockTable.removeAll()) {
synchronized (fl) {
if (fl.isValid()) {
nd.release(fd, fl.position(), fl.size());
((FileLockImpl)fl).invalidate();
}
}
}
}
nd.preClose(fd);
threads.signalAndWait();
if (parent != null) {
// Close the fd via the parent stream's close method. The parent
// will reinvoke our close method, which is defined in the
// superclass AbstractInterruptibleChannel, but the isOpen logic in
// that method will prevent this method from being reinvoked.
//
((java.io.Closeable)parent).close();
} else {
nd.close(fd);
}
}
public int read(ByteBuffer dst) throws IOException {
ensureOpen();
if (!readable)
throw new NonReadableChannelException();
synchronized (positionLock) {
int n = 0;
int ti = -1;
try {
begin();
ti = threads.add();
if (!isOpen())
return 0;
do {
n = IOUtil.read(fd, dst, -1, nd);
} while ((n == IOStatus.INTERRUPTED) && isOpen());
return IOStatus.normalize(n);
} finally {
threads.remove(ti);
end(n > 0);
assert IOStatus.check(n);
}
}
}
public long read(ByteBuffer[] dsts, int offset, int length)
throws IOException
{
if ((offset < 0) || (length < 0) || (offset > dsts.length - length))
throw new IndexOutOfBoundsException();
ensureOpen();
if (!readable)
throw new NonReadableChannelException();
synchronized (positionLock) {
long n = 0;
int ti = -1;
try {
begin();
ti = threads.add();
if (!isOpen())
return 0;
do {
n = IOUtil.read(fd, dsts, offset, length, nd);
} while ((n == IOStatus.INTERRUPTED) && isOpen());
return IOStatus.normalize(n);
} finally {
threads.remove(ti);
end(n > 0);
assert IOStatus.check(n);
}
}
}
public int write(ByteBuffer src) throws IOException {
ensureOpen();
if (!writable)
throw new NonWritableChannelException();
synchronized (positionLock) {
int n = 0;
int ti = -1;
try {
begin();
ti = threads.add();
if (!isOpen())
return 0;
do {
n = IOUtil.write(fd, src, -1, nd);
} while ((n == IOStatus.INTERRUPTED) && isOpen());
return IOStatus.normalize(n);
} finally {
threads.remove(ti);
end(n > 0);
assert IOStatus.check(n);
}
}
}
public long write(ByteBuffer[] srcs, int offset, int length)
throws IOException
{
if ((offset < 0) || (length < 0) || (offset > srcs.length - length))
throw new IndexOutOfBoundsException();
ensureOpen();
if (!writable)
throw new NonWritableChannelException();
synchronized (positionLock) {
long n = 0;
int ti = -1;
try {
begin();
ti = threads.add();
if (!isOpen())
return 0;
do {
n = IOUtil.write(fd, srcs, offset, length, nd);
} while ((n == IOStatus.INTERRUPTED) && isOpen());
return IOStatus.normalize(n);
} finally {
threads.remove(ti);
end(n > 0);
assert IOStatus.check(n);
}
}
}
// -- Other operations --
public long position() throws IOException {
ensureOpen();
synchronized (positionLock) {
long p = -1;
int ti = -1;
try {
begin();
ti = threads.add();
if (!isOpen())
return 0;
do {
// in append-mode then position is advanced to end before writing
p = (append) ? nd.size(fd) : position0(fd, -1);
} while ((p == IOStatus.INTERRUPTED) && isOpen());
return IOStatus.normalize(p);
} finally {
threads.remove(ti);
end(p > -1);
assert IOStatus.check(p);
}
}
}
public FileChannel position(long newPosition) throws IOException {
ensureOpen();
if (newPosition < 0)
throw new IllegalArgumentException();
synchronized (positionLock) {
long p = -1;
int ti = -1;
try {
begin();
ti = threads.add();
if (!isOpen())
return null;
do {
p = position0(fd, newPosition);
} while ((p == IOStatus.INTERRUPTED) && isOpen());
return this;
} finally {
threads.remove(ti);
end(p > -1);
assert IOStatus.check(p);
}
}
}
public long size() throws IOException {
ensureOpen();
synchronized (positionLock) {
long s = -1;
int ti = -1;
try {
begin();
ti = threads.add();
if (!isOpen())
return -1;
do {
s = nd.size(fd);
} while ((s == IOStatus.INTERRUPTED) && isOpen());
return IOStatus.normalize(s);
} finally {
threads.remove(ti);
end(s > -1);
assert IOStatus.check(s);
}
}
}
public FileChannel truncate(long newSize) throws IOException {
ensureOpen();
if (newSize < 0)
throw new IllegalArgumentException("Negative size");
if (!writable)
throw new NonWritableChannelException();
synchronized (positionLock) {
int rv = -1;
long p = -1;
int ti = -1;
try {
begin();
ti = threads.add();
if (!isOpen())
return null;
// get current size
long size;
do {
size = nd.size(fd);
} while ((size == IOStatus.INTERRUPTED) && isOpen());
if (!isOpen())
return null;
// get current position
do {
p = position0(fd, -1);
} while ((p == IOStatus.INTERRUPTED) && isOpen());
if (!isOpen())
return null;
assert p >= 0;
// truncate file if given size is less than the current size
if (newSize < size) {
do {
rv = nd.truncate(fd, newSize);
} while ((rv == IOStatus.INTERRUPTED) && isOpen());
if (!isOpen())
return null;
}
// if position is beyond new size then adjust it
if (p > newSize)
p = newSize;
do {
rv = (int)position0(fd, p);
} while ((rv == IOStatus.INTERRUPTED) && isOpen());
return this;
} finally {
threads.remove(ti);
end(rv > -1);
assert IOStatus.check(rv);
}
}
}
public void force(boolean metaData) throws IOException {
ensureOpen();
int rv = -1;
int ti = -1;
try {
begin();
ti = threads.add();
if (!isOpen())
return;
do {
rv = nd.force(fd, metaData);
} while ((rv == IOStatus.INTERRUPTED) && isOpen());
} finally {
threads.remove(ti);
end(rv > -1);
assert IOStatus.check(rv);
}
}
// Assume at first that the underlying kernel supports sendfile();
// set this to false if we find out later that it doesn't
//
private static volatile boolean transferSupported = true;
// Assume that the underlying kernel sendfile() will work if the target
// fd is a pipe; set this to false if we find out later that it doesn't
//
private static volatile boolean pipeSupported = true;
// Assume that the underlying kernel sendfile() will work if the target
// fd is a file; set this to false if we find out later that it doesn't
//
private static volatile boolean fileSupported = true;
private long transferToDirectly(long position, int icount,
WritableByteChannel target)
throws IOException
{
if (!transferSupported)
return IOStatus.UNSUPPORTED;
FileDescriptor targetFD = null;
if (target instanceof FileChannelImpl) {
if (!fileSupported)
return IOStatus.UNSUPPORTED_CASE;
targetFD = ((FileChannelImpl)target).fd;
} else if (target instanceof SelChImpl) {
// Direct transfer to pipe causes EINVAL on some configurations
if ((target instanceof SinkChannelImpl) && !pipeSupported)
return IOStatus.UNSUPPORTED_CASE;
targetFD = ((SelChImpl)target).getFD();
}
if (targetFD == null)
return IOStatus.UNSUPPORTED;
int thisFDVal = IOUtil.fdVal(fd);
int targetFDVal = IOUtil.fdVal(targetFD);
if (thisFDVal == targetFDVal) // Not supported on some configurations
return IOStatus.UNSUPPORTED;
long n = -1;
int ti = -1;
try {
begin();
ti = threads.add();
if (!isOpen())
return -1;
do {
n = transferTo0(thisFDVal, position, icount, targetFDVal);
} while ((n == IOStatus.INTERRUPTED) && isOpen());
if (n == IOStatus.UNSUPPORTED_CASE) {
if (target instanceof SinkChannelImpl)
pipeSupported = false;
if (target instanceof FileChannelImpl)
fileSupported = false;
return IOStatus.UNSUPPORTED_CASE;
}
if (n == IOStatus.UNSUPPORTED) {
// Don't bother trying again
transferSupported = false;
return IOStatus.UNSUPPORTED;
}
return IOStatus.normalize(n);
} finally {
threads.remove(ti);
end (n > -1);
}
}
// Maximum size to map when using a mapped buffer
private static final long MAPPED_TRANSFER_SIZE = 8L*1024L*1024L;
private long transferToTrustedChannel(long position, long count,
WritableByteChannel target)
throws IOException
{
boolean isSelChImpl = (target instanceof SelChImpl);
if (!((target instanceof FileChannelImpl) || isSelChImpl))
return IOStatus.UNSUPPORTED;
// Trusted target: Use a mapped buffer
long remaining = count;
while (remaining > 0L) {
long size = Math.min(remaining, MAPPED_TRANSFER_SIZE);
try {
MappedByteBuffer dbb = map(MapMode.READ_ONLY, position, size);
try {
// ## Bug: Closing this channel will not terminate the write
int n = target.write(dbb);
assert n >= 0;
remaining -= n;
if (isSelChImpl) {
// one attempt to write to selectable channel
break;
}
assert n > 0;
position += n;
} finally {
unmap(dbb);
}
} catch (ClosedByInterruptException e) {
// target closed by interrupt as ClosedByInterruptException needs
// to be thrown after closing this channel.
assert !target.isOpen();
try {
close();
} catch (Throwable suppressed) {
e.addSuppressed(suppressed);
}
throw e;
} catch (IOException ioe) {
// Only throw exception if no bytes have been written
if (remaining == count)
throw ioe;
break;
}
}
return count - remaining;
}
private long transferToArbitraryChannel(long position, int icount,
WritableByteChannel target)
throws IOException
{
// Untrusted target: Use a newly-erased buffer
int c = Math.min(icount, TRANSFER_SIZE);
ByteBuffer bb = Util.getTemporaryDirectBuffer(c);
long tw = 0; // Total bytes written
long pos = position;
try {
Util.erase(bb);
while (tw < icount) {
bb.limit(Math.min((int)(icount - tw), TRANSFER_SIZE));
int nr = read(bb, pos);
if (nr <= 0)
break;
bb.flip();
// ## Bug: Will block writing target if this channel
// ## is asynchronously closed
int nw = target.write(bb);
tw += nw;
if (nw != nr)
break;
pos += nw;
bb.clear();
}
return tw;
} catch (IOException x) {
if (tw > 0)
return tw;
throw x;
} finally {
Util.releaseTemporaryDirectBuffer(bb);
}
}
public long transferTo(long position, long count,
WritableByteChannel target)
throws IOException
{
ensureOpen();
if (!target.isOpen())
throw new ClosedChannelException();
if (!readable)
throw new NonReadableChannelException();
if (target instanceof FileChannelImpl &&
!((FileChannelImpl)target).writable)
throw new NonWritableChannelException();
if ((position < 0) || (count < 0))
throw new IllegalArgumentException();
long sz = size();
if (position > sz)
return 0;
int icount = (int)Math.min(count, Integer.MAX_VALUE);
if ((sz - position) < icount)
icount = (int)(sz - position);
long n;
// Attempt a direct transfer, if the kernel supports it
if ((n = transferToDirectly(position, icount, target)) >= 0)
return n;
// Attempt a mapped transfer, but only to trusted channel types
if ((n = transferToTrustedChannel(position, icount, target)) >= 0)
return n;
// Slow path for untrusted targets
return transferToArbitraryChannel(position, icount, target);
}
private long transferFromFileChannel(FileChannelImpl src,
long position, long count)
throws IOException
{
if (!src.readable)
throw new NonReadableChannelException();
synchronized (src.positionLock) {
long pos = src.position();
long max = Math.min(count, src.size() - pos);
long remaining = max;
long p = pos;
while (remaining > 0L) {
long size = Math.min(remaining, MAPPED_TRANSFER_SIZE);
// ## Bug: Closing this channel will not terminate the write
MappedByteBuffer bb = src.map(MapMode.READ_ONLY, p, size);
try {
long n = write(bb, position);
assert n > 0;
p += n;
position += n;
remaining -= n;
} catch (IOException ioe) {
// Only throw exception if no bytes have been written
if (remaining == max)
throw ioe;
break;
} finally {
unmap(bb);
}
}
long nwritten = max - remaining;
src.position(pos + nwritten);
return nwritten;
}
}
private static final int TRANSFER_SIZE = 8192;
private long transferFromArbitraryChannel(ReadableByteChannel src,
long position, long count)
throws IOException
{
// Untrusted target: Use a newly-erased buffer
int c = (int)Math.min(count, TRANSFER_SIZE);
ByteBuffer bb = Util.getTemporaryDirectBuffer(c);
long tw = 0; // Total bytes written
long pos = position;
try {
Util.erase(bb);
while (tw < count) {
bb.limit((int)Math.min((count - tw), (long)TRANSFER_SIZE));
// ## Bug: Will block reading src if this channel
// ## is asynchronously closed
int nr = src.read(bb);
if (nr <= 0)
break;
bb.flip();
int nw = write(bb, pos);
tw += nw;
if (nw != nr)
break;
pos += nw;
bb.clear();
}
return tw;
} catch (IOException x) {
if (tw > 0)
return tw;
throw x;
} finally {
Util.releaseTemporaryDirectBuffer(bb);
}
}
public long transferFrom(ReadableByteChannel src,
long position, long count)
throws IOException
{
ensureOpen();
if (!src.isOpen())
throw new ClosedChannelException();
if (!writable)
throw new NonWritableChannelException();
if ((position < 0) || (count < 0))
throw new IllegalArgumentException();
if (position > size())
return 0;
if (src instanceof FileChannelImpl)
return transferFromFileChannel((FileChannelImpl)src,
position, count);
return transferFromArbitraryChannel(src, position, count);
}
public int read(ByteBuffer dst, long position) throws IOException {
if (dst == null)
throw new NullPointerException();
if (position < 0)
throw new IllegalArgumentException("Negative position");
if (!readable)
throw new NonReadableChannelException();
ensureOpen();
if (nd.needsPositionLock()) {
synchronized (positionLock) {
return readInternal(dst, position);
}
} else {
return readInternal(dst, position);
}
}
private int readInternal(ByteBuffer dst, long position) throws IOException {
assert !nd.needsPositionLock() || Thread.holdsLock(positionLock);
int n = 0;
int ti = -1;
try {
begin();
ti = threads.add();
if (!isOpen())
return -1;
do {
n = IOUtil.read(fd, dst, position, nd);
} while ((n == IOStatus.INTERRUPTED) && isOpen());
return IOStatus.normalize(n);
} finally {
threads.remove(ti);
end(n > 0);
assert IOStatus.check(n);
}
}
public int write(ByteBuffer src, long position) throws IOException {
if (src == null)
throw new NullPointerException();
if (position < 0)
throw new IllegalArgumentException("Negative position");
if (!writable)
throw new NonWritableChannelException();
ensureOpen();
if (nd.needsPositionLock()) {
synchronized (positionLock) {
return writeInternal(src, position);
}
} else {
return writeInternal(src, position);
}
}
private int writeInternal(ByteBuffer src, long position) throws IOException {
assert !nd.needsPositionLock() || Thread.holdsLock(positionLock);
int n = 0;
int ti = -1;
try {
begin();
ti = threads.add();
if (!isOpen())
return -1;
do {
n = IOUtil.write(fd, src, position, nd);
} while ((n == IOStatus.INTERRUPTED) && isOpen());
return IOStatus.normalize(n);
} finally {
threads.remove(ti);
end(n > 0);
assert IOStatus.check(n);
}
}
// -- Memory-mapped buffers --
private static class Unmapper
implements Runnable
{
// may be required to close file
private static final NativeDispatcher nd = new FileDispatcherImpl();
// keep track of mapped buffer usage
static volatile int count;
static volatile long totalSize;
static volatile long totalCapacity;
private volatile long address;
private final long size;
private final int cap;
private final FileDescriptor fd;
private Unmapper(long address, long size, int cap,
FileDescriptor fd)
{
assert (address != 0);
this.address = address;
this.size = size;
this.cap = cap;
this.fd = fd;
synchronized (Unmapper.class) {
count++;
totalSize += size;
totalCapacity += cap;
}
}
public void run() {
if (address == 0)
return;
unmap0(address, size);
address = 0;
// if this mapping has a valid file descriptor then we close it
if (fd.valid()) {
try {
nd.close(fd);
} catch (IOException ignore) {
// nothing we can do
}
}
synchronized (Unmapper.class) {
count--;
totalSize -= size;
totalCapacity -= cap;
}
}
}
private static void unmap(MappedByteBuffer bb) {
Cleaner cl = ((DirectBuffer)bb).cleaner();
if (cl != null)
cl.clean();
}
private static final int MAP_RO = 0;
private static final int MAP_RW = 1;
private static final int MAP_PV = 2;
public MappedByteBuffer map(MapMode mode, long position, long size)
throws IOException
{
ensureOpen();
if (mode == null)
throw new NullPointerException("Mode is null");
if (position < 0L)
throw new IllegalArgumentException("Negative position");
if (size < 0L)
throw new IllegalArgumentException("Negative size");
if (position + size < 0)
throw new IllegalArgumentException("Position + size overflow");
if (size > Integer.MAX_VALUE)
throw new IllegalArgumentException("Size exceeds Integer.MAX_VALUE");
int imode = -1;
if (mode == MapMode.READ_ONLY)
imode = MAP_RO;
else if (mode == MapMode.READ_WRITE)
imode = MAP_RW;
else if (mode == MapMode.PRIVATE)
imode = MAP_PV;
assert (imode >= 0);
if ((mode != MapMode.READ_ONLY) && !writable)
throw new NonWritableChannelException();
if (!readable)
throw new NonReadableChannelException();
long addr = -1;
int ti = -1;
try {
begin();
ti = threads.add();
if (!isOpen())
return null;
long filesize;
do {
filesize = nd.size(fd);
} while ((filesize == IOStatus.INTERRUPTED) && isOpen());
if (!isOpen())
return null;
if (filesize < position + size) { // Extend file size
if (!writable) {
throw new IOException("Channel not open for writing " +
"- cannot extend file to required size");
}
int rv;
do {
rv = nd.truncate(fd, position + size);
} while ((rv == IOStatus.INTERRUPTED) && isOpen());
if (!isOpen())
return null;
}
if (size == 0) {
addr = 0;
// a valid file descriptor is not required
FileDescriptor dummy = new FileDescriptor();
if ((!writable) || (imode == MAP_RO))
return Util.newMappedByteBufferR(0, 0, dummy, null);
else
return Util.newMappedByteBuffer(0, 0, dummy, null);
}
int pagePosition = (int)(position % allocationGranularity);
long mapPosition = position - pagePosition;
long mapSize = size + pagePosition;
try {
// If no exception was thrown from map0, the address is valid
addr = map0(imode, mapPosition, mapSize);
} catch (OutOfMemoryError x) {
// An OutOfMemoryError may indicate that we've exhausted memory
// so force gc and re-attempt map
System.gc();
try {
Thread.sleep(100);
} catch (InterruptedException y) {
Thread.currentThread().interrupt();
}
try {
addr = map0(imode, mapPosition, mapSize);
} catch (OutOfMemoryError y) {
// After a second OOME, fail
throw new IOException("Map failed", y);
}
}
// On Windows, and potentially other platforms, we need an open
// file descriptor for some mapping operations.
FileDescriptor mfd;
try {
mfd = nd.duplicateForMapping(fd);
} catch (IOException ioe) {
unmap0(addr, mapSize);
throw ioe;
}
assert (IOStatus.checkAll(addr));
assert (addr % allocationGranularity == 0);
int isize = (int)size;
Unmapper um = new Unmapper(addr, mapSize, isize, mfd);
if ((!writable) || (imode == MAP_RO)) {
return Util.newMappedByteBufferR(isize,
addr + pagePosition,
mfd,
um);
} else {
return Util.newMappedByteBuffer(isize,
addr + pagePosition,
mfd,
um);
}
} finally {
threads.remove(ti);
end(IOStatus.checkAll(addr));
}
}
/**
* Invoked by sun.management.ManagementFactoryHelper to create the management
* interface for mapped buffers.
*/
public static sun.misc.JavaNioAccess.BufferPool getMappedBufferPool() {
return new sun.misc.JavaNioAccess.BufferPool() {
@Override
public String getName() {
return "mapped";
}
@Override
public long getCount() {
return Unmapper.count;
}
@Override
public long getTotalCapacity() {
return Unmapper.totalCapacity;
}
@Override
public long getMemoryUsed() {
return Unmapper.totalSize;
}
};
}
// -- Locks --
// keeps track of locks on this file
private volatile FileLockTable fileLockTable;
// indicates if file locks are maintained system-wide (as per spec)
private static boolean isSharedFileLockTable;
// indicates if the disableSystemWideOverlappingFileLockCheck property
// has been checked
private static volatile boolean propertyChecked;
// The lock list in J2SE 1.4/5.0 was local to each FileChannel instance so
// the overlap check wasn't system wide when there were multiple channels to
// the same file. This property is used to get 1.4/5.0 behavior if desired.
private static boolean isSharedFileLockTable() {
if (!propertyChecked) {
synchronized (FileChannelImpl.class) {
if (!propertyChecked) {
String value = AccessController.doPrivileged(
new GetPropertyAction(
"sun.nio.ch.disableSystemWideOverlappingFileLockCheck"));
isSharedFileLockTable = ((value == null) || value.equals("false"));
propertyChecked = true;
}
}
}
return isSharedFileLockTable;
}
private FileLockTable fileLockTable() throws IOException {
if (fileLockTable == null) {
synchronized (this) {
if (fileLockTable == null) {
if (isSharedFileLockTable()) {
int ti = threads.add();
try {
ensureOpen();
fileLockTable = FileLockTable.newSharedFileLockTable(this, fd);
} finally {
threads.remove(ti);
}
} else {
fileLockTable = new SimpleFileLockTable();
}
}
}
}
return fileLockTable;
}
public FileLock lock(long position, long size, boolean shared)
throws IOException
{
ensureOpen();
if (shared && !readable)
throw new NonReadableChannelException();
if (!shared && !writable)
throw new NonWritableChannelException();
FileLockImpl fli = new FileLockImpl(this, position, size, shared);
FileLockTable flt = fileLockTable();
flt.add(fli);
boolean completed = false;
int ti = -1;
try {
begin();
ti = threads.add();
if (!isOpen())
return null;
int n;
do {
n = nd.lock(fd, true, position, size, shared);
} while ((n == FileDispatcher.INTERRUPTED) && isOpen());
if (isOpen()) {
if (n == FileDispatcher.RET_EX_LOCK) {
assert shared;
FileLockImpl fli2 = new FileLockImpl(this, position, size,
false);
flt.replace(fli, fli2);
fli = fli2;
}
completed = true;
}
} finally {
if (!completed)
flt.remove(fli);
threads.remove(ti);
try {
end(completed);
} catch (ClosedByInterruptException e) {
throw new FileLockInterruptionException();
}
}
return fli;
}
public FileLock tryLock(long position, long size, boolean shared)
throws IOException
{
ensureOpen();
if (shared && !readable)
throw new NonReadableChannelException();
if (!shared && !writable)
throw new NonWritableChannelException();
FileLockImpl fli = new FileLockImpl(this, position, size, shared);
FileLockTable flt = fileLockTable();
flt.add(fli);
int result;
int ti = threads.add();
try {
try {
ensureOpen();
result = nd.lock(fd, false, position, size, shared);
} catch (IOException e) {
flt.remove(fli);
throw e;
}
if (result == FileDispatcher.NO_LOCK) {
flt.remove(fli);
return null;
}
if (result == FileDispatcher.RET_EX_LOCK) {
assert shared;
FileLockImpl fli2 = new FileLockImpl(this, position, size,
false);
flt.replace(fli, fli2);
return fli2;
}
return fli;
} finally {
threads.remove(ti);
}
}
void release(FileLockImpl fli) throws IOException {
int ti = threads.add();
try {
ensureOpen();
nd.release(fd, fli.position(), fli.size());
} finally {
threads.remove(ti);
}
assert fileLockTable != null;
fileLockTable.remove(fli);
}
// -- File lock support --
/**
* A simple file lock table that maintains a list of FileLocks obtained by a
* FileChannel. Use to get 1.4/5.0 behaviour.
*/
private static class SimpleFileLockTable extends FileLockTable {
// synchronize on list for access
private final List<FileLock> lockList = new ArrayList
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