org.eclipse.gyrex.preferences.internal.CloudPreferencesScopeFactory.java Source code

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Here is the source code for org.eclipse.gyrex.preferences.internal.CloudPreferencesScopeFactory.java

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/*******************************************************************************
 * Copyright (c) 2008, 2012 Gunnar Wagenknecht 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:
 *     Gunnar Wagenknecht - initial API and implementation
 *******************************************************************************/
package org.eclipse.gyrex.preferences.internal;

import java.util.concurrent.atomic.AtomicReference;

import org.eclipse.gyrex.cloud.internal.preferences.ZooKeeperPreferencesService;
import org.eclipse.gyrex.common.lifecycle.IShutdownParticipant;
import org.eclipse.gyrex.preferences.CloudScope;
import org.eclipse.gyrex.server.Platform;

import org.eclipse.core.runtime.preferences.IEclipsePreferences;
import org.eclipse.core.runtime.preferences.IScope;

import org.apache.commons.lang.exception.ExceptionUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * {@link IScope} factory for the cloud scope.
 */
public class CloudPreferencesScopeFactory implements IScope, IShutdownParticipant {

    private static final Logger LOG = LoggerFactory.getLogger(CloudPreferencesScopeFactory.class);
    private static final AtomicReference<CloudPreferences> rootCloudNode = new AtomicReference<CloudPreferences>();
    private static final ZooKeeperPreferencesService service = new ZooKeeperPreferencesService(CloudScope.NAME);

    @Override
    public IEclipsePreferences create(final IEclipsePreferences parent, final String name) {
        // sanity check
        if (!CloudScope.NAME.equals(name)) {
            LOG.error("Cloud preference factory called with illegal node name {} for parent {}.",
                    new Object[] { name, parent.absolutePath(), new Exception("Call Stack") });
            throw new IllegalArgumentException("invalid node name");
        }

        // allow explicit fallback to instance based preferences
        if (Platform.inDevelopmentMode() && Boolean.getBoolean("gyrex.preferences.instancebased")) {
            LOG.info("Using instance based preferences as specified via system property!");
            return new InstanceBasedPreferences(parent, name);
        }

        // check if already created
        final CloudPreferences node = rootCloudNode.get();
        if (null != node) {
            if (PreferencesDebug.debug) {
                LOG.debug("Cloud preference factory called multiple times for name {} and parent {}.",
                        new Object[] { name, parent.absolutePath(), new Exception("Call Stack") });
            }
            return node;
        }

        if (PreferencesDebug.debug) {
            LOG.debug("Creating ZooKeeper preferences '{}' (parent {})", name, parent);
        }

        // create
        rootCloudNode.compareAndSet(null, new CloudPreferences(parent, name, service));

        // register shut-down hook
        PreferencesActivator.getInstance().addShutdownParticipant(this);

        // done
        return rootCloudNode.get();
    }

    @Override
    public void shutdown() throws Exception {
        // flush the preferences
        // TODO this is actually too late
        // when the bundle is stopped the cloud is likely already disconnected
        // for now there is some logic in ZooKeeperBasedPreferences
        final CloudPreferences node = rootCloudNode.get();
        if (node != null) {
            try {
                node.flush();
            } catch (final Exception e) {
                LOG.debug("Failed to flush cloud preferences. Changes migt be lost. {}",
                        ExceptionUtils.getRootCauseMessage(e));
            }
        }

        // stop the service
        service.shutdown();
    }
}