org.apache.hive.jdbc.ZooKeeperHiveClientHelper Maven / Gradle / Ivy
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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.hive.jdbc;
import java.nio.charset.Charset;
import java.sql.SQLException;
import java.util.List;
import java.util.Random;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.retry.ExponentialBackoffRetry;
import org.apache.hive.jdbc.Utils.JdbcConnectionParams;
import org.apache.zookeeper.Watcher;
public class ZooKeeperHiveClientHelper {
public static final Log LOG = LogFactory.getLog(ZooKeeperHiveClientHelper.class.getName());
/**
* A no-op watcher class
*/
public static class DummyWatcher implements Watcher {
public void process(org.apache.zookeeper.WatchedEvent event) {
}
}
/**
* Resolve to a host:port by connecting to ZooKeeper and picking a host randomly.
*
* @param uri
* @param connParams
* @return
* @throws SQLException
*/
static String getNextServerUriFromZooKeeper(JdbcConnectionParams connParams)
throws ZooKeeperHiveClientException {
String zooKeeperEnsemble = connParams.getZooKeeperEnsemble();
String zooKeeperNamespace =
connParams.getSessionVars().get(JdbcConnectionParams.ZOOKEEPER_NAMESPACE);
if ((zooKeeperNamespace == null) || (zooKeeperNamespace.isEmpty())) {
zooKeeperNamespace = JdbcConnectionParams.ZOOKEEPER_DEFAULT_NAMESPACE;
}
List serverHosts;
Random randomizer = new Random();
String serverNode;
CuratorFramework zooKeeperClient =
CuratorFrameworkFactory.builder().connectString(zooKeeperEnsemble)
.retryPolicy(new ExponentialBackoffRetry(1000, 3)).build();
try {
zooKeeperClient.start();
serverHosts = zooKeeperClient.getChildren().forPath("/" + zooKeeperNamespace);
// Remove the znodes we've already tried from this list
serverHosts.removeAll(connParams.getRejectedHostZnodePaths());
if (serverHosts.isEmpty()) {
throw new ZooKeeperHiveClientException(
"Tried all existing HiveServer2 uris from ZooKeeper.");
}
// Now pick a host randomly
serverNode = serverHosts.get(randomizer.nextInt(serverHosts.size()));
connParams.setCurrentHostZnodePath(serverNode);
String serverUri =
new String(
zooKeeperClient.getData().forPath("/" + zooKeeperNamespace + "/" + serverNode),
Charset.forName("UTF-8"));
LOG.info("Selected HiveServer2 instance with uri: " + serverUri);
return serverUri;
} catch (Exception e) {
throw new ZooKeeperHiveClientException("Unable to read HiveServer2 uri from ZooKeeper", e);
} finally {
// Close the client connection with ZooKeeper
if (zooKeeperClient != null) {
zooKeeperClient.close();
}
}
}
}