org.deploymentobjects.core.infrastructure.persistence.zookeeper.ZookeeperPersistence.java Source code

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Here is the source code for org.deploymentobjects.core.infrastructure.persistence.zookeeper.ZookeeperPersistence.java

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/************************************************************************
 ** 
 ** Copyright (C) 2011 Dave Thomas, PeopleMerge.
 ** All rights reserved.
 ** Contact: opensource@peoplemerge.com.
 **
 ** This file is part of the NGDS language.
 **
 ** Licensed 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.
 **  
 ** Other Uses
 ** Alternatively, this file may be used in accordance with the terms and
 ** conditions contained in a signed written agreement between you and the 
 ** copyright owner.
 ************************************************************************/
package org.deploymentobjects.core.infrastructure.persistence.zookeeper;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.ZooDefs.Ids;
import org.apache.zookeeper.data.Stat;
import org.deploymentobjects.core.infrastructure.persistence.Composite;
import org.deploymentobjects.core.infrastructure.persistence.Persistence;

public class ZookeeperPersistence implements Persistence, Watcher {

    private ZooKeeper zk;
    private String rootZnode = "/ngds";
    private boolean recurse = true;

    public class ZookeeperPersistenceException extends PersistenceException {
        public ZookeeperPersistenceException(Exception e) {
            super(e);
        }
    }

    /*
     * no good reason to enable these methods yet 
     * 
     * 
     * public boolean isRecursive() {
     * return recurse; }
     * 
     * public void setRecursive(boolean recurse) { this.recurse = recurse; }
     */

    public ZooKeeper getZookeeper() {
        return zk;
    }

    @Override
    public void process(WatchedEvent event) {
        // TODO handle connection/disconnection
        System.err.println(event.toString());
    }

    public ZookeeperPersistence(String zookeeperConnectString) throws IOException {
        zk = new ZooKeeper(zookeeperConnectString, 3000, this);
    }

    public Composite retrieve(String key) throws ZookeeperPersistenceException {
        Stat stat = null;
        String path = rootZnode + "/" + key;
        try {
            byte[] bytearray = zk.getData(path, false, stat);
            String data = new String(bytearray);
            Composite retval = new Composite(key, data);
            if (recurse) {
                List<String> children = zk.getChildren(path, false, stat);
                for (String childname : children) {
                    Composite child = retrieve(key + "/" + childname);
                    retval.addChild(child);
                }
            }
            return retval;
        } catch (KeeperException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            throw (new ZookeeperPersistenceException(e));
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            throw (new ZookeeperPersistenceException(e));
        }
        //return null;
    }

    public void save(Composite element) throws ZookeeperPersistenceException {
        try {
            Stat stat = zk.exists(rootZnode + "/" + element.getKey(), false);
            if (stat == null) {
                zk.create(rootZnode + "/" + element.getKey(), element.getValue().getBytes(), Ids.OPEN_ACL_UNSAFE,
                        CreateMode.PERSISTENT);
            } else {
                int version = stat.getVersion();
                zk.setData(rootZnode + "/" + element.getKey(), element.getValue().getBytes(), version);
            }
            if (recurse) {
                for (Composite child : element.getChildren()) {
                    save(child);
                }
            }
        } catch (KeeperException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            throw (new ZookeeperPersistenceException(e));
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            throw (new ZookeeperPersistenceException(e));
        }

    }

    public void watchData(String key, Watcher observer) throws ZookeeperPersistenceException {
        try {/*
             * zk.create(rootZnode + "/" +
             * key,"".getBytes(),Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
             */
            byte[] dataBytes = zk.getData(rootZnode + "/" + key, observer, null);
            String data = new String(dataBytes);
            System.err.println(data);
        } catch (KeeperException e) {
            // TODO Here we are swallowing the exceptions. FIXME!
            e.printStackTrace();
            throw (new ZookeeperPersistenceException(e));
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            throw (new ZookeeperPersistenceException(e));
        }

    }

    public List<String> watchChildren(Composite composite, Watcher observer) throws ZookeeperPersistenceException {
        try {/*
             * zk.create(rootZnode + "/" +
             * key,"".getBytes(),Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
             */
            return zk.getChildren(rootZnode + "/" + composite.getKey(), observer);
        } catch (KeeperException e) {
            // TODO Here we are swallowing the exceptions. FIXME!
            e.printStackTrace();
            throw (new ZookeeperPersistenceException(e));
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            throw (new ZookeeperPersistenceException(e));
        }
        //return new ArrayList<String>();

    }

    public void delete(Composite toDelete) throws ZookeeperPersistenceException {
        try {
            if (recurse) {
                // annihilate all ancestors
                for (Composite child : toDelete.getChildren()) {
                    delete(child);
                }
            } else {
                // TODO throw exception if there are any children
            }
            zk.delete(rootZnode + "/" + toDelete.getKey(), -1);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            throw (new ZookeeperPersistenceException(e));
        } catch (KeeperException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            throw (new ZookeeperPersistenceException(e));
        }
    }

}