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/*******************************************************************************
* Copyright (c) 2004, 2013 IBM Corporation and others.
*
* This program and the accompanying materials
* are made available under the terms of the Eclipse Public License 2.0
* which accompanies this distribution, and is available at
* https://www.eclipse.org/legal/epl-2.0/
*
* SPDX-License-Identifier: EPL-2.0
*
* Contributors:
* IBM Corporation - initial API and implementation
* Danail Nachev (Prosyst) - bug 185654
* Andrei Loskutov - bug 44735
*******************************************************************************/
package org.eclipse.osgi.internal.location;
import java.io.*;
import java.nio.channels.FileLock;
import java.nio.channels.OverlappingFileLockException;
import org.eclipse.osgi.internal.messages.Msg;
import org.eclipse.osgi.util.NLS;
/**
* Internal class.
*/
public class Locker_JavaNio implements Locker {
private final File lockFile;
private final boolean debug;
private FileLock fileLock;
private RandomAccessFile raFile;
public Locker_JavaNio(File lockFile, boolean debug) {
this.lockFile = lockFile;
this.debug = debug;
}
public synchronized boolean lock() throws IOException {
raFile = new RandomAccessFile(lockFile, "rw"); //$NON-NLS-1$
try {
/*
* fix for bug http://bugs.sun.com/view_bug.do?bug_id=6628575 and
* https://bugs.eclipse.org/bugs/show_bug.cgi?id=44735#c17
*/
fileLock = raFile.getChannel().tryLock(0, 1, false);
} catch (IOException ioe) {
// print exception if debugging
if (debug)
System.out.println(NLS.bind(Msg.location_cannotLock, lockFile));
// produce a more specific message for clients
String specificMessage = NLS.bind(Msg.location_cannotLockNIO, new Object[] {lockFile, ioe.getMessage(), "\"-D" + LocationHelper.PROP_OSGI_LOCKING + "=none\""}); //$NON-NLS-1$ //$NON-NLS-2$
throw new IOException(specificMessage);
} catch (OverlappingFileLockException e) {
// handle it as null result
fileLock = null;
} finally {
if (fileLock != null)
return true;
raFile.close();
raFile = null;
}
return false;
}
public synchronized void release() {
if (fileLock != null) {
try {
fileLock.release();
} catch (IOException e) {
//don't complain, we're making a best effort to clean up
}
fileLock = null;
}
if (raFile != null) {
try {
raFile.close();
} catch (IOException e) {
//don't complain, we're making a best effort to clean up
}
raFile = null;
}
}
public synchronized boolean isLocked() throws IOException {
if (fileLock != null)
return true;
try {
RandomAccessFile temp = new RandomAccessFile(lockFile, "rw"); //$NON-NLS-1$
FileLock tempLock = null;
try {
/*
* fix for bug http://bugs.sun.com/view_bug.do?bug_id=6628575 and
* https://bugs.eclipse.org/bugs/show_bug.cgi?id=44735#c17
*/
try {
tempLock = temp.getChannel().tryLock(0, 1, false);
} catch (IOException ioe) {
if (debug)
System.out.println(NLS.bind(Msg.location_cannotLock, lockFile));
// produce a more specific message for clients
String specificMessage = NLS.bind(Msg.location_cannotLockNIO, new Object[] {lockFile, ioe.getMessage(), "\"-D" + LocationHelper.PROP_OSGI_LOCKING + "=none\""}); //$NON-NLS-1$ //$NON-NLS-2$
throw new IOException(specificMessage);
}
if (tempLock != null) {
tempLock.release(); // allow IOException to propagate because that would mean it is still locked
return false;
}
return true;
} catch (OverlappingFileLockException e) {
return true;
} finally {
temp.close();
}
} catch (FileNotFoundException e) {
return false;
}
}
}
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