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/*******************************************************************************
* Copyright (c) 2009, 2010 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.equinox.internal.p2.update;
import java.io.File;
import java.net.URL;
import org.eclipse.equinox.p2.core.ProvisionException;
/*
* Class which controls the reading and writing of Configuration (platform.xml) objects.
* We keep a local cached copy to avoid multiple reads. When we install new features we
* seem to only write out the platform.xml in the "commit" phase so we don't need to
* batch the writes.
*/
public class ConfigurationIO {
private static CacheEntry cache = null;
// class used to represent cache values
static class CacheEntry {
Configuration config;
URL osgiInstallArea;
File location;
long timestamp;
}
/*
* Return the configuration object which is represented by the given file.
*/
static Configuration read(File file, URL osgiInstallArea) throws ProvisionException {
// check the cached copy first
if (cache != null && file.lastModified() == cache.timestamp)
return cache.config;
// cache miss or file is out of date, read from disk
Configuration config = ConfigurationParser.parse(file, osgiInstallArea);
if (config == null)
return null;
// successful read, store in the cache before we return
cache(file, config, osgiInstallArea);
return config;
}
/*
* Store the given configuration file in the local cache.
*/
private static void cache(File location, Configuration config, URL osgiInstallArea) {
CacheEntry entry = new CacheEntry();
entry.config = config;
entry.osgiInstallArea = osgiInstallArea;
entry.location = location;
entry.timestamp = location.lastModified();
cache = entry;
}
/*
* Save the given configuration to the file-system.
*/
static void write(File location, Configuration config, URL osgiInstallArea) throws ProvisionException {
// write it to disk
ConfigurationWriter.save(config, location, osgiInstallArea);
// save a copy in the cache
cache(location, config, osgiInstallArea);
}
}
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