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/*******************************************************************************
* Copyright (c) 2004, 2012 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
*******************************************************************************/
package org.eclipse.osgi.internal.location;
import java.io.*;
/**
* Internal class.
*/
public class Locker_JavaIo implements Locker {
private File lockFile;
private RandomAccessFile lockRAF;
public Locker_JavaIo(File lockFile) {
this.lockFile = lockFile;
}
public synchronized boolean lock() throws IOException {
//if the lock file already exists, try to delete,
//assume failure means another eclipse has it open
if (lockFile.exists())
lockFile.delete();
if (lockFile.exists())
return false;
//open the lock file so other instances can't co-exist
lockRAF = new RandomAccessFile(lockFile, "rw"); //$NON-NLS-1$
try {
lockRAF.writeByte(0);
} catch (IOException e) {
lockRAF.close();
lockRAF = null;
throw e;
}
return true;
}
public synchronized void release() {
try {
if (lockRAF != null) {
lockRAF.close();
lockRAF = null;
}
} catch (IOException e) {
//don't complain, we're making a best effort to clean up
}
if (lockFile != null)
lockFile.delete();
}
public synchronized boolean isLocked() throws IOException {
if (lockRAF != null)
return true;
try {
return !lock();
} finally {
release();
}
}
}
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