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/*******************************************************************************
* Copyright (c) 2004 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Common Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/cpl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.core.runtime.adaptor;
import java.io.File;
import java.io.IOException;
import java.net.URL;
import org.eclipse.osgi.service.datalocation.Location;
/**
* Internal class.
*/
public class BasicLocation implements Location {
private static class MockLocker implements Locker {
public boolean lock() throws IOException {
// locking always successful
return true;
}
public void release() {
// nothing to release
}
}
private boolean isReadOnly;
private URL location = null;
private Location parent;
private URL defaultValue;
private String property;
// locking related fields
private File lockFile;
private Locker locker;
public static final String PROP_OSGI_LOCKING = "osgi.locking"; //$NON-NLS-1$
private static String LOCK_FILENAME = ".metadata/.lock"; //$NON-NLS-1$
public static boolean DEBUG;
private static boolean isRunningWithNio() {
try {
Class.forName("java.nio.channels.FileLock"); //$NON-NLS-1$
} catch (ClassNotFoundException e) {
return false;
}
return true;
}
public static Locker createLocker(File lock, String lockMode) {
if (lockMode == null)
lockMode = System.getProperties().getProperty(PROP_OSGI_LOCKING);
if ("none".equals(lockMode)) //$NON-NLS-1$
return new MockLocker();
if ("java.io".equals(lockMode)) //$NON-NLS-1$
return new Locker_JavaIo(lock);
if ("java.nio".equals(lockMode)) { //$NON-NLS-1$
if (isRunningWithNio()) {
return new Locker_JavaNio(lock);
} else {
// TODO should we return null here. NIO was requested but we could not do it...
return new Locker_JavaIo(lock);
}
}
// Backup case if an invalid value has been specified
if (isRunningWithNio()) {
return new Locker_JavaNio(lock);
} else {
return new Locker_JavaIo(lock);
}
}
public BasicLocation(String property, URL defaultValue, boolean isReadOnly) {
super();
this.property = property;
this.defaultValue = defaultValue;
this.isReadOnly = isReadOnly;
}
public boolean allowsDefault() {
return defaultValue != null;
}
public URL getDefault() {
return defaultValue;
}
public Location getParentLocation() {
return parent;
}
public synchronized URL getURL() {
if (location == null && defaultValue != null)
setURL(defaultValue, false);
return location;
}
public synchronized boolean isSet() {
return location != null;
}
public boolean isReadOnly() {
return isReadOnly;
}
public synchronized boolean setURL(URL value, boolean lock) throws IllegalStateException {
if (location != null)
throw new IllegalStateException(EclipseAdaptorMsg.formatter.getString("ECLIPSE_CANNOT_CHANGE_LOCATION")); //$NON-NLS-1$
File file = null;
if (value.getProtocol().equalsIgnoreCase("file")) //$NON-NLS-1$
file = new File(value.getFile(), LOCK_FILENAME);
lock = lock && !isReadOnly;
if (lock) {
try {
if (!lock(file))
return false;
} catch (IOException e) {
return false;
}
}
lockFile = file;
location = LocationManager.buildURL(value.toExternalForm(), true);
if (property != null)
System.getProperties().put(property, location.toExternalForm());
return lock;
}
public synchronized void setParent(Location value) {
parent = value;
}
public synchronized boolean lock() throws IOException {
if (!isSet())
return false;
return lock(lockFile);
}
private boolean lock(File lock) throws IOException {
if (lock == null || isReadOnly)
return false;
File parentFile = new File(lock.getParent());
if (!parentFile.exists())
if (!parentFile.mkdirs())
return false;
setLocker(lock);
if (locker == null)
return true;
boolean locked = false;
try {
locked = locker.lock();
return locked;
} finally {
if (!locked)
locker = null;
}
}
private void setLocker(File lock) {
if (locker != null)
return;
String lockMode = System.getProperties().getProperty(PROP_OSGI_LOCKING);
locker = createLocker(lock, lockMode);
}
public synchronized void release() {
if (locker != null)
locker.release();
}
}
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