/**
*
* 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.hadoop.hbase.client.replication;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.Abortable;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.client.HConnection;
import org.apache.hadoop.hbase.client.HConnectionManager;
import org.apache.hadoop.hbase.replication.ReplicationZookeeper;
import org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher;
import org.apache.zookeeper.KeeperException;
import java.io.Closeable;
import java.io.IOException;
import java.util.Map;
/**
* <p>
* This class provides the administrative interface to HBase cluster
* replication. In order to use it, the cluster and the client using
* ReplicationAdmin must be configured with <code>hbase.replication</code>
* set to true.
* </p>
* <p>
* Adding a new peer results in creating new outbound connections from every
* region server to a subset of region servers on the slave cluster. Each
* new stream of replication will start replicating from the beginning of the
* current HLog, meaning that edits from that past will be replicated.
* </p>
* <p>
* Removing a peer is a destructive and irreversible operation that stops
* all the replication streams for the given cluster and deletes the metadata
* used to keep track of the replication state.
* </p>
* <p>
* Enabling and disabling peers is currently not supported.
* </p>
* <p>
* As cluster replication is still experimental, a kill switch is provided
* in order to stop all replication-related operations, see
* {@link #setReplicating(boolean)}. When setting it back to true, the new
* state of all the replication streams will be unknown and may have holes.
* Use at your own risk.
* </p>
* <p>
* To see which commands are available in the shell, type
* <code>replication</code>.
* </p>
*/
public class ReplicationAdmin implements Closeable {
private static final Log LOG = LogFactory.getLog(ReplicationAdmin.class);
private final ReplicationZookeeper replicationZk;
private final HConnection connection;
/**
* Constructor that creates a connection to the local ZooKeeper ensemble.
* @param conf Configuration to use
* @throws IOException if the connection to ZK cannot be made
* @throws RuntimeException if replication isn't enabled.
*/
public ReplicationAdmin(Configuration conf) throws IOException {
if (!conf.getBoolean(HConstants.REPLICATION_ENABLE_KEY, false)) {
throw new RuntimeException("hbase.replication isn't true, please " +
"enable it in order to use replication");
}
this.connection = HConnectionManager.getConnection(conf);
ZooKeeperWatcher zkw = createZooKeeperWatcher();
try {
this.replicationZk = new ReplicationZookeeper(this.connection, conf, zkw);
} catch (KeeperException e) {
throw new IOException("Unable setup the ZooKeeper connection", e);
}
}
private ZooKeeperWatcher createZooKeeperWatcher() throws IOException {
return new ZooKeeperWatcher(connection.getConfiguration(),
"Replication Admin", new Abortable() {
@Override
public void abort(String why, Throwable e) {
LOG.error(why, e);
System.exit(1);
}
@Override
public boolean isAborted() {
return false;
}
});
}
/**
* Add a new peer cluster to replicate to.
* @param id a short that identifies the cluster
* @param clusterKey the concatenation of the slave cluster's
* <code>hbase.zookeeper.quorum:hbase.zookeeper.property.clientPort:zookeeper.znode.parent</code>
* @throws IllegalStateException if there's already one slave since
* multi-slave isn't supported yet.
*/
public void addPeer(String id, String clusterKey) throws IOException {
this.replicationZk.addPeer(id, clusterKey);
}
/**
* Removes a peer cluster and stops the replication to it.
* @param id a short that identifies the cluster
*/
public void removePeer(String id) throws IOException {
this.replicationZk.removePeer(id);
}
/**
* Restart the replication stream to the specified peer.
* @param id a short that identifies the cluster
*/
public void enablePeer(String id) throws IOException {
this.replicationZk.enablePeer(id);
}
/**
* Stop the replication stream to the specified peer.
* @param id a short that identifies the cluster
*/
public void disablePeer(String id) throws IOException {
this.replicationZk.disablePeer(id);
}
/**
* Get the number of slave clusters the local cluster has.
* @return number of slave clusters
*/
public int getPeersCount() {
return this.replicationZk.listPeersIdsAndWatch().size();
}
/**
* Map of this cluster's peers for display.
* @return A map of peer ids to peer cluster keys
*/
public Map<String, String> listPeers() {
return this.replicationZk.listPeers();
}
/**
* Get the current status of the kill switch, if the cluster is replicating
* or not.
* @return true if the cluster is replicated, otherwise false
*/
public boolean getReplicating() throws IOException {
try {
return this.replicationZk.getReplication();
} catch (KeeperException e) {
throw new IOException("Couldn't get the replication status");
}
}
/**
* Kill switch for all replication-related features
* @param newState true to start replication, false to stop it.
* completely
* @return the previous state
*/
public boolean setReplicating(boolean newState) throws IOException {
boolean prev = true;
try {
prev = getReplicating();
this.replicationZk.setReplication(newState);
} catch (KeeperException e) {
throw new IOException("Unable to set the replication state", e);
}
return prev;
}
/**
* Get the ZK-support tool created and used by this object for replication.
* @return the ZK-support tool
*/
ReplicationZookeeper getReplicationZk() {
return replicationZk;
}
@Override
public void close() throws IOException {
if (this.connection != null) {
this.connection.close();
}
}
}