/*******************************************************************************
* Copyright (c) 2005, 2007 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.core.internal.filesystem;
import java.io.File;
import java.io.IOException;
import org.eclipse.core.filesystem.*;
import org.eclipse.core.filesystem.provider.FileStore;
import org.eclipse.core.internal.filesystem.local.LocalFile;
import org.eclipse.core.runtime.*;
import org.eclipse.osgi.util.NLS;
/**
* An instance of this class represents a directory on disk where cached
* files can be stored. Files in the cache expire on VM exit.
*/
public class FileCache {
private static final String CACHE_DIR_NAME = "filecache";//$NON-NLS-1$
/**
* Thread safety for lazy instantiation of the cache
*/
private static final Object creationLock = new Object();
/**
* The singleton file cache instance.
*/
private static FileCache instance = null;
private File cacheDir;
/**
* Public accessor to obtain the singleton file cache instance,
* creating the cache lazily if necessary.
* @return The file cache instance
* @throws CoreException
*/
public static FileCache getCache() throws CoreException {
synchronized (creationLock) {
if (instance == null)
instance = new FileCache();
return instance;
}
}
/**
* Creates a new file cache.
*
* @throws CoreException If the file cache could not be created
*/
private FileCache() throws CoreException {
IPath location = Activator.getCacheLocation();
File cacheParent = new File(location.toFile(), CACHE_DIR_NAME);
cleanOldCache(cacheParent);
cacheParent.mkdirs();
//make sure we have a unique non-existing cache directory
cacheDir = getUniqueDirectory(cacheParent, true);
}
/**
* Implements {@link FileStore#toLocalFile(int, IProgressMonitor)}
* @param source
* @param monitor
* @return The cached file
* @throws CoreException
*/
public java.io.File cache(IFileStore source, IProgressMonitor monitor) throws CoreException {
try {
monitor.beginTask(NLS.bind(Messages.copying, toString()), 100);
IFileInfo myInfo = source.fetchInfo(EFS.NONE, Policy.subMonitorFor(monitor, 25));
if (!myInfo.exists())
return new File(cacheDir, "Non-Existent-" + System.currentTimeMillis()); //$NON-NLS-1$
File result;
if (myInfo.isDirectory()) {
result = getUniqueDirectory(cacheDir, false);
} else {
result = File.createTempFile(source.getFileSystem().getScheme(), "efs", cacheDir); //$NON-NLS-1$
}
monitor.worked(25);
IFileStore resultStore = new LocalFile(result);
source.copy(resultStore, EFS.OVERWRITE, Policy.subMonitorFor(monitor, 25));
result.deleteOnExit();
return result;
} catch (IOException e) {
Policy.error(EFS.ERROR_WRITE, NLS.bind(Messages.couldNotWrite, toString()));
return null;//can't get here
} finally {
monitor.done();
}
}
/**
* Performs initial cleanup of any old cached state left over from previous
* sessions.
*/
private void cleanOldCache(File cacheParent) throws CoreException {
//clear any old cache - this could be moved to a background thread
new LocalFile(cacheParent).delete(EFS.NONE, null);
}
/**
* Returns a new unique directory in the given parent directory.
*
* @param parent
* @param create <code>true</code> if the directory should
* be created, and false otherwise.
* @return The unique directory
*/
private File getUniqueDirectory(File parent, boolean create) {
File dir;
long i = 0;
//find an unused directory name
do {
dir = new File(parent, Long.toString(System.currentTimeMillis() + i++));
} while (dir.exists());
if (create)
dir.mkdir();
return dir;
}
}