ReadRoot.java

/*******************************************************************************
 *  Copyright (c)2011 REMAIN B.V. The Netherlands. (http://www.remainsoftware.com).
 *  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:
 *     Wim Jongman - initial API and implementation 
 *     Ahmed Aadel - initial API and implementation     
 *******************************************************************************/
package org.eclipse.ecf.provider.zookeeper.node.internal;

import java.io.IOException;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.zookeeper.AsyncCallback.ChildrenCallback;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;
import org.eclipse.core.runtime.Assert;
import org.eclipse.ecf.provider.zookeeper.core.DiscoverdService;
import org.eclipse.ecf.provider.zookeeper.core.ZooDiscoveryContainer;
import org.eclipse.ecf.provider.zookeeper.util.Geo;
import org.eclipse.ecf.provider.zookeeper.util.Logger;
import org.osgi.service.log.LogService;

public class ReadRoot implements Watcher, ChildrenCallback {
	ZooKeeper readKeeper;
	String ip;
	private final WatchManager watchManager;
	private boolean isConnected;
	private final Map<String, NodeReader> nodeReaders = Collections
			.synchronizedMap(new HashMap<String, NodeReader>());
	private final Map<String, DiscoverdService> discoverdServices;
	private final Map<String, List<DiscoverdService>> perTypeDiscoverdServices;
	private final Object connectionLock = new Object();

	ReadRoot(String ip, WatchManager watchManager) {
		Assert.isNotNull(ip);
		Assert.isNotNull(watchManager);
		this.ip = ip;
		this.watchManager = watchManager;
		discoverdServices = Collections
				.synchronizedMap(new HashMap<String, DiscoverdService>());
		perTypeDiscoverdServices = Collections
				.synchronizedMap(new HashMap<String, List<DiscoverdService>>());
		connect();
	}

	public void process(final WatchedEvent event) {
		ZooDiscoveryContainer.CACHED_THREAD_POOL.execute(new Runnable() {
			public void run() {
				synchronized (connectionLock) {
					if (watchManager.isDisposed())
						return;

					switch (event.getState()) {
					case Disconnected:
						if (!ReadRoot.this.readKeeper.getState().isAlive()) {
							ReadRoot.this.isConnected = false;
							connect();
						}
						break;
					case Expired:
						ReadRoot.this.isConnected = false;
						connect();
						break;
					case SyncConnected:
						if (!ReadRoot.this.isConnected) {
							ReadRoot.this.isConnected = true;
							ReadRoot.this.watchManager
									.addZooKeeper(ReadRoot.this.readKeeper);
							ReadRoot.this.readKeeper.exists(INode.ROOT,
									ReadRoot.this, null, null);
							ReadRoot.this.readKeeper.getChildren(INode.ROOT,
									ReadRoot.this, ReadRoot.this, null);
						}
						break;

					// ignore @deprecated cases
					}
					switch (event.getType()) {
					case NodeDeleted:
						if (event.getPath() == null
								|| event.getPath().equals(INode.ROOT))
							break;
						ReadRoot.this.nodeReaders.remove(event.getPath());
						break;
					case NodeChildrenChanged:
						if (ReadRoot.this.isConnected) {
							ReadRoot.this.readKeeper.exists(INode.ROOT,
									ReadRoot.this, null, null);
							ReadRoot.this.readKeeper.getChildren(INode.ROOT,
									ReadRoot.this, ReadRoot.this, null);
						}
						break;
					}
				}
			}
		});
	}

	private void connect() {
		synchronized (connectionLock) {
			if (this.isConnected || watchManager.isDisposed())
				return;

			this.nodeReaders.clear();
			if (this.readKeeper != null) {
				// discard the current stale reader
				try {
					this.readKeeper.close();
				} catch (InterruptedException e) {
					Logger.log(
							LogService.LOG_ERROR,
							"Error while closing the current ZooKeeper: "
									+ e.getMessage(), e);
				}
				this.watchManager.removeZooKeeper(this.readKeeper);
				this.readKeeper = null;
			}
			try {
				// try reconnecting
				this.readKeeper = new ZooKeeper(this.ip, 3000, this);
			} catch (IOException ioe) {
				Logger.log(LogService.LOG_ERROR,
						"Cannot initiate a new ZooKeeper: " + ioe.getMessage(),
						ioe);
			}
		}
	}

	public void processResult(int rc, final String path, Object ctx,
			final List<String> children) {
		ZooDiscoveryContainer.CACHED_THREAD_POOL.execute(new Runnable() {
			public void run() {
				synchronized (connectionLock) {
					if (watchManager.isDisposed())
						return;
					if (path == null || children == null
							|| children.size() == 0) {
						return;
					}
					for (String p : children) {
						if (Geo.isOwnPublication(p)) {
							/* own publications need not to be discovered */
							continue;
						}
						if (!ReadRoot.this.nodeReaders.containsKey(p)) {
							/* launch a new reader to handle this node's data */
							NodeReader nr = new NodeReader(p, ReadRoot.this);
							/* watch this very path for deletion */
							ReadRoot.this.readKeeper.exists(
									nr.getAbsolutePath(), ReadRoot.this, null,
									null);
							ReadRoot.this.nodeReaders.put(nr.getPath(), nr);
						}
					}
				}
			}
		});
	}

	public ZooKeeper getReadKeeper() {
		return this.readKeeper;
	}

	public String getIp() {
		return this.ip;
	}

	public Map<String, DiscoverdService> getDiscoverdServices() {
		return discoverdServices;
	}

	public Map<String, List<DiscoverdService>> getPerTypeDiscoverdServices() {
		return perTypeDiscoverdServices;
	}
}