package org.apache.solr.cloud;
/*
* 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.
*/
import org.apache.solr.common.SolrException;
import org.apache.solr.common.SolrException.ErrorCode;
import org.apache.solr.common.cloud.SolrZkClient;
import org.apache.solr.common.cloud.ZkCmdExecutor;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooDefs;
import org.apache.zookeeper.data.ACL;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.List;
/**
* A distributed map.
* This supports basic map functions e.g. get, put, contains for interaction with zk which
* don't have to be ordered i.e. DistributedQueue.
*/
public class DistributedMap {
private static final Logger LOG = LoggerFactory
.getLogger(DistributedMap.class);
private static long DEFAULT_TIMEOUT = 5*60*1000;
private final String dir;
private SolrZkClient zookeeper;
private List<ACL> acl = ZooDefs.Ids.OPEN_ACL_UNSAFE;
private final String prefix = "mn-";
private final String response_prefix = "mnr-" ;
public DistributedMap(SolrZkClient zookeeper, String dir, List<ACL> acl) {
this.dir = dir;
ZkCmdExecutor cmdExecutor = new ZkCmdExecutor(zookeeper.getZkClientTimeout());
try {
cmdExecutor.ensureExists(dir, zookeeper);
} catch (KeeperException e) {
throw new SolrException(ErrorCode.SERVER_ERROR, e);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
throw new SolrException(ErrorCode.SERVER_ERROR, e);
}
if (acl != null) {
this.acl = acl;
}
this.zookeeper = zookeeper;
}
private class LatchChildWatcher implements Watcher {
Object lock = new Object();
private WatchedEvent event = null;
public LatchChildWatcher() {}
public LatchChildWatcher(Object lock) {
this.lock = lock;
}
@Override
public void process(WatchedEvent event) {
LOG.info("LatchChildWatcher fired on path: " + event.getPath() + " state: "
+ event.getState() + " type " + event.getType());
synchronized (lock) {
this.event = event;
lock.notifyAll();
}
}
public void await(long timeout) throws InterruptedException {
synchronized (lock) {
lock.wait(timeout);
}
}
public WatchedEvent getWatchedEvent() {
return event;
}
}
/**
* Inserts data into zookeeper.
*
* @return true if data was successfully added
*/
private String createData(String path, byte[] data, CreateMode mode)
throws KeeperException, InterruptedException {
for (;;) {
try {
return zookeeper.create(path, data, acl, mode, true);
} catch (KeeperException.NoNodeException e) {
try {
zookeeper.create(dir, new byte[0], acl, CreateMode.PERSISTENT, true);
} catch (KeeperException.NodeExistsException ne) {
// someone created it
}
}
}
}
public boolean put(String trackingId, byte[] data) throws KeeperException, InterruptedException {
return createData(dir + "/" + prefix + trackingId, data,
CreateMode.PERSISTENT) != null;
}
/**
* Offer the data and wait for the response
*
*/
public MapEvent put(String trackingId, byte[] data, long timeout) throws KeeperException,
InterruptedException {
String path = createData(dir + "/" + prefix + trackingId, data,
CreateMode.PERSISTENT);
String watchID = createData(
dir + "/" + response_prefix + path.substring(path.lastIndexOf("-") + 1),
null, CreateMode.EPHEMERAL);
Object lock = new Object();
LatchChildWatcher watcher = new LatchChildWatcher(lock);
synchronized (lock) {
if (zookeeper.exists(watchID, watcher, true) != null) {
watcher.await(timeout);
}
}
byte[] bytes = zookeeper.getData(watchID, null, null, true);
zookeeper.delete(watchID, -1, true);
return new MapEvent(watchID, bytes, watcher.getWatchedEvent());
}
public MapEvent get(String trackingId) throws KeeperException, InterruptedException {
return new MapEvent(trackingId, zookeeper.getData(dir + "/" + prefix + trackingId, null, null, true), null);
}
public boolean contains(String trackingId) throws KeeperException, InterruptedException {
return zookeeper.exists(dir + "/" + prefix + trackingId, true);
}
public void remove(String trackingId) throws KeeperException, InterruptedException {
zookeeper.delete(dir + "/" + prefix + trackingId, -1, true);
}
/**
* Helper method to clear all child nodes for a parent node.
*/
public void clear() throws KeeperException, InterruptedException {
List<String> childNames = zookeeper.getChildren(dir, null, true);
for(String childName: childNames) {
zookeeper.delete(dir + "/" + childName, -1, true);
}
}
public static class MapEvent {
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((id == null) ? 0 : id.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;
MapEvent other = (MapEvent) obj;
if (id == null) {
if (other.id != null) return false;
} else if (!id.equals(other.id)) return false;
return true;
}
private WatchedEvent event = null;
private String id;
private byte[] bytes;
MapEvent(String id, byte[] bytes, WatchedEvent event) {
this.id = id;
this.bytes = bytes;
this.event = event;
}
public void setId(String id) {
this.id = id;
}
public String getId() {
return id;
}
public void setBytes(byte[] bytes) {
this.bytes = bytes;
}
public byte[] getBytes() {
return bytes;
}
public WatchedEvent getWatchedEvent() {
return event;
}
}
}