/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.stratos.cloud.controller.topology;
import com.google.gson.Gson;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.stratos.cloud.controller.util.CloudControllerUtil;
import org.apache.stratos.messaging.domain.topology.Topology;
import java.util.concurrent.locks.ReentrantReadWriteLock;
/**
* Persistence and retrieval of Topology from Registry
*/
public class TopologyManager {
private static final Log log = LogFactory.getLog(TopologyManager.class);
private static volatile ReentrantReadWriteLock lock = new ReentrantReadWriteLock(true);
private static volatile ReentrantReadWriteLock.ReadLock readLock = lock.readLock();
private static volatile ReentrantReadWriteLock.WriteLock writeLock = lock.writeLock();
private static volatile Topology topology;
private TopologyManager() {
}
public static void acquireReadLock() {
if(log.isDebugEnabled()) {
log.debug("Read lock acquired");
}
readLock.lock();
}
public static void releaseReadLock() {
if(log.isDebugEnabled()) {
log.debug("Read lock released");
}
readLock.unlock();
}
public static void acquireWriteLock() {
if(log.isDebugEnabled()) {
log.debug("Write lock acquired");
}
writeLock.lock();
}
public static void releaseWriteLock() {
if(log.isDebugEnabled()) {
log.debug("Write lock released");
}
writeLock.unlock();
}
public static Topology getTopology() {
if (topology == null) {
synchronized (TopologyManager.class) {
if (topology == null) {
if (log.isDebugEnabled()) {
log.debug("Trying to retrieve topology from registry");
}
topology = CloudControllerUtil.retrieveTopology();
if (topology == null) {
if (log.isDebugEnabled()) {
log.debug("Topology not found in registry, creating new");
}
topology = new Topology();
}
if (log.isDebugEnabled()) {
log.debug("Topology initialized");
}
}
}
}
return topology;
}
/**
* Update in-memory topology and persist it in registry.
* @param topology_
*/
public static void updateTopology(Topology topology_) {
synchronized (TopologyManager.class) {
if (log.isDebugEnabled()) {
log.debug("Updating topology");
}
topology = topology_;
CloudControllerUtil.persistTopology(topology);
if (log.isDebugEnabled()) {
log.debug(String.format("Topology updated: %s", toJson(topology)));
}
}
}
private static String toJson(Object object) {
Gson gson = new Gson();
return gson.toJson(object);
}
}