org.apache.hdt.dfs.core.DFSLocationsRoot.java Source code

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Here is the source code for org.apache.hdt.dfs.core.DFSLocationsRoot.java

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/**
 * 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.hdt.dfs.core;

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

import org.apache.hdt.core.cluster.IHadoopClusterListener;
import org.apache.hdt.core.cluster.ServerRegistry;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hdt.core.cluster.HadoopCluster;

/**
 * Representation of the root element containing all DFS servers. This
 * content registers an observer on Hadoop servers so as to update itself
 * when servers are updated.
 */
public class DFSLocationsRoot implements DFSContent, IHadoopClusterListener {

    /**
     * 
     */
    private final DFSContentProvider provider;

    private Map<HadoopCluster, DFSLocation> map = new HashMap<HadoopCluster, DFSLocation>();

    /**
     * Register a listeners to track DFS locations updates
     * 
     * @param provider the content provider this content is the root of
     */
    DFSLocationsRoot(DFSContentProvider provider) {
        this.provider = provider;
        ServerRegistry.getInstance().addListener(this);
        this.refresh();
    }

    /*
     * Implementation of IHadoopServerListener
     */

    /* @inheritDoc */
    public synchronized void serverChanged(final HadoopCluster location, final int type) {

        switch (type) {
        case ServerRegistry.SERVER_STATE_CHANGED: {
            this.provider.refresh(map.get(location));
            break;
        }

        case ServerRegistry.SERVER_ADDED: {
            DFSLocation dfsLoc = new DFSLocation(provider, location);
            map.put(location, dfsLoc);
            this.provider.refresh(this);
            break;
        }

        case ServerRegistry.SERVER_REMOVED: {
            map.remove(location);
            this.provider.refresh(this);
            break;
        }
        }
    }

    /**
     * Recompute the map of Hadoop locations
     */
    private synchronized void reloadLocations() {
        map.clear();
        for (HadoopCluster location : ServerRegistry.getInstance().getServers())
            map.put(location, new DFSLocation(provider, location));
    }

    /* @inheritDoc */
    @Override
    public String toString() {
        return "DFS Locations";
    }

    /*
     * Implementation of DFSContent
     */

    /* @inheritDoc */
    public synchronized DFSContent[] getChildren() {
        return this.map.values().toArray(new DFSContent[this.map.size()]);
    }

    /* @inheritDoc */
    public boolean hasChildren() {
        return (this.map.size() > 0);
    }

    /* @inheritDoc */
    public void refresh() {
        reloadLocations();
        this.provider.refresh(this);
    }

    /*
     * Actions
     */

    public void disconnect() {
        Thread closeThread = new Thread() {
            /* @inheritDoc */
            @Override
            public void run() {
                try {
                    System.out.printf("Closing all opened File Systems...\n");
                    FileSystem.closeAll();
                    System.out.printf("File Systems closed\n");

                } catch (IOException ioe) {
                    ioe.printStackTrace();
                }
            }
        };

        // Wait 5 seconds for the connections to be closed
        closeThread.start();
        try {
            closeThread.join(5000);

        } catch (InterruptedException ie) {
            // Ignore
        }
    }

}