dengzhhu653 commented on code in PR #3567: URL: https://github.com/apache/hive/pull/3567#discussion_r980687027
########## standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/leader/LeaseLeaderElection.java: ########## @@ -0,0 +1,473 @@ +/* + * 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.hive.metastore.leader; + +import org.apache.hadoop.conf.Configuration; +import org.apache.hadoop.hive.common.TableName; +import org.apache.hadoop.hive.metastore.LockComponentBuilder; +import org.apache.hadoop.hive.metastore.api.CheckLockRequest; +import org.apache.hadoop.hive.metastore.api.DataOperationType; +import org.apache.hadoop.hive.metastore.api.HeartbeatRequest; +import org.apache.hadoop.hive.metastore.api.LockComponent; +import org.apache.hadoop.hive.metastore.api.LockRequest; +import org.apache.hadoop.hive.metastore.api.LockResponse; +import org.apache.hadoop.hive.metastore.api.LockState; +import org.apache.hadoop.hive.metastore.api.LockType; +import org.apache.hadoop.hive.metastore.api.MetaException; +import org.apache.hadoop.hive.metastore.api.NoSuchLockException; +import org.apache.hadoop.hive.metastore.api.NoSuchTxnException; +import org.apache.hadoop.hive.metastore.api.TxnAbortedException; +import org.apache.hadoop.hive.metastore.api.TxnOpenException; +import org.apache.hadoop.hive.metastore.api.UnlockRequest; +import org.apache.hadoop.hive.metastore.conf.MetastoreConf; +import org.apache.hadoop.hive.metastore.txn.TxnStore; +import org.apache.hadoop.hive.metastore.txn.TxnUtils; +import org.apache.hadoop.hive.metastore.utils.SecurityUtils; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.net.InetAddress; +import java.util.ArrayList; +import java.util.List; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicLong; + +import static java.util.Objects.requireNonNull; + +/** + * Hive Lock based leader election. + * If wins, the current instance becomes the leader, + * and a heartbeat daemon will be started to renew the lock before timeout. + * If loses, a non-leader watcher will also be started to check the + * lock periodically to see if he can grab the lock in order to be the leader. + * The change of Leadership can be received by registering the + * listeners through {@link LeaderElection#addStateListener}. + */ +public class LeaseLeaderElection implements LeaderElection<TableName> { + + private static final Logger LOG = LoggerFactory.getLogger(LeaseLeaderElection.class); + + private static final AtomicLong ID = new AtomicLong(); + + // Result of election + private volatile boolean isLeader; + + private TxnStore store; + + // Initial sleep time for locking the table at retrying. + private long nextSleep = 50; + + // A daemon used for renewing the lock before timeout, + // this happens when the current instance wins the election. + private LeaseWatcher heartbeater; + + // For non-leader instances to check the lock periodically to + // see if there is a chance to take over the leadership. + // At any time, only one of heartbeater and nonLeaderWatcher is alive. + private LeaseWatcher nonLeaderWatcher; + + // Current lock id + private volatile long lockId = -1; + + // Leadership change listeners + private List<LeadershipStateListener> listeners = new ArrayList<>(); + + // Property for testing only + public static final String METASTORE_RENEW_LEASE = "metastore.renew.leader.lease"; + + private String name; + + private void doWork(LockResponse resp, Configuration conf, + TableName tableName) throws LeaderException { + lockId = resp.getLockid(); + assert resp.getState() == LockState.ACQUIRED || resp.getState() == LockState.WAITING; + shutdownWatcher(); + + switch (resp.getState()) { + case ACQUIRED: + boolean renewLease = conf.getBoolean(METASTORE_RENEW_LEASE, true); + heartbeater = renewLease ? + new Heartbeater(conf, tableName) : new ReleaseAndRequireWatcher(conf, tableName); + heartbeater.perform(); + if (!isLeader) { + isLeader = true; + notifyListener(); + } + break; + case WAITING: + nonLeaderWatcher = new NonLeaderWatcher(conf, tableName); + nonLeaderWatcher.perform(); + if (isLeader) { + isLeader = false; + notifyListener(); + } + break; + default: + throw new IllegalStateException("Unexpected lock state: " + resp.getState()); + } + } + + private void notifyListener() { + listeners.forEach(listener -> { + try { + if (isLeader) { + listener.takeLeadership(this); + } else { + listener.lossLeadership(this); Review Comment: checked in: https://github.com/apache/hive/blob/bcbdd0c77f73ce7f46342cc30d6c565027fac311/standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/leader/LeaseLeaderElection.java#L114-L120 -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
