subprojects/s4-comm/src/main/java/org/apache/s4/comm/topology/ClusterFromHelix.java

/**
 * 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.s4.comm.topology;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.atomic.AtomicReference;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.inject.Inject;
import com.google.inject.name.Named;

import org.apache.helix.ConfigAccessor;
import org.apache.helix.ConfigScopeBuilder;
import org.apache.helix.HelixDataAccessor;
import org.apache.helix.HelixManager;
import org.apache.helix.HelixProperty;
import org.apache.helix.NotificationContext;
import org.apache.helix.PropertyKey.Builder;
import org.apache.helix.model.ExternalView;
import org.apache.helix.model.IdealState;
import org.apache.helix.model.InstanceConfig;
import org.apache.helix.spectator.RoutingTableProvider;

/**
 * Represents a logical cluster definition fetched from Zookeeper. Notifies listeners of runtime changes in the
 * configuration.
 * 
 */
public class ClusterFromHelix extends RoutingTableProvider implements Cluster {

    private static Logger logger = LoggerFactory.getLogger(ClusterFromHelix.class);

    private final String clusterName;
    private final AtomicReference<PhysicalCluster> clusterRef;
    private final List<ClusterChangeListener> listeners;
    private final Lock lock;
    private final AtomicReference<Map<String, Integer>> partitionCountMapRef;

    /**
     * only the local topology
     */
    @Inject
    public ClusterFromHelix(@Named("s4.cluster.name") String clusterName,
            @Named("s4.cluster.zk_address") String zookeeperAddress,
            @Named("s4.cluster.zk_session_timeout") int sessionTimeout,
            @Named("s4.cluster.zk_connection_timeout") int connectionTimeout) throws Exception {
        this.clusterName = clusterName;
        Map<String, Integer> map = Collections.emptyMap();
        partitionCountMapRef = new AtomicReference<Map<String, Integer>>(map);
        this.clusterRef = new AtomicReference<PhysicalCluster>();
        this.listeners = new ArrayList<ClusterChangeListener>();
        lock = new ReentrantLock();

    }

    /**
     * any topology
     */
    public ClusterFromHelix(String clusterName, ZkClient zkClient, String machineId) {
        this.clusterName = clusterName;
        Map<String, Integer> map = Collections.emptyMap();
        partitionCountMapRef = new AtomicReference<Map<String, Integer>>(map);
        this.clusterRef = new AtomicReference<PhysicalCluster>();
        this.listeners = new ArrayList<ClusterChangeListener>();
        lock = new ReentrantLock();

    }

    @Override
    public void onExternalViewChange(List<ExternalView> externalViewList, NotificationContext changeContext) {
        lock.lock();
        try {
            logger.info("Start:Processing change in cluster topology");
            super.onExternalViewChange(externalViewList, changeContext);
            HelixManager manager = changeContext.getManager();
            HelixDataAccessor helixDataAccessor = manager.getHelixDataAccessor();
            ConfigAccessor configAccessor = manager.getConfigAccessor();
            ConfigScopeBuilder builder = new ConfigScopeBuilder();
            Builder keyBuilder = helixDataAccessor.keyBuilder();
            List<String> resources = helixDataAccessor.getChildNames(keyBuilder.idealStates());
            Map<String, Integer> map = new HashMap<String, Integer>();
            for (String resource : resources) {
                String resourceType = configAccessor.get(builder.forCluster(clusterName).forResource(resource).build(),
                        "type");
                if ("Task".equalsIgnoreCase(resourceType)) {
                    String streamName = configAccessor.get(builder.forCluster(clusterName).forResource(resource)
                            .build(), "streamName");
                    IdealState idealstate = helixDataAccessor.getProperty(keyBuilder.idealStates(resource));
                    map.put(streamName, idealstate.getNumPartitions());
                }
            }
            partitionCountMapRef.set(map);
            for (ClusterChangeListener listener : listeners) {
                listener.onChange();
            }
            logger.info("End:Processing change in cluster topology");

        } catch (Exception e) {
            logger.error("", e);
        } finally {
            lock.unlock();
        }
    }

    @Override
    public PhysicalCluster getPhysicalCluster() {
        return clusterRef.get();
    }

    @Override
    public void addListener(ClusterChangeListener listener) {
        logger.info("Adding topology change listener:" + listener);
        listeners.add(listener);
    }

    @Override
    public void removeListener(ClusterChangeListener listener) {
        logger.info("Removing topology change listener:" + listener);
        listeners.remove(listener);
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((clusterName == null) ? 0 : clusterName.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        ClusterFromHelix other = (ClusterFromHelix) obj;
        if (clusterName == null) {
            if (other.clusterName != null)
                return false;
        } else if (!clusterName.equals(other.clusterName))
            return false;
        return true;
    }

    @Override
    public InstanceConfig getDestination(String streamName, int partitionId) {
        List<InstanceConfig> instances = getInstances(streamName, streamName + "_" + partitionId, "LEADER");
        if (instances.size() == 1) {
            return instances.get(0);
        } else {
            return null;
        }
    }

    @Override
    public Integer getPartitionCount(String streamName) {
        Integer numPartitions = partitionCountMapRef.get().get(streamName);
        if (numPartitions == null) {
            return -1;
        }
        return numPartitions;
    }

}