jiajunwang commented on a change in pull request #718: Implement Helix nonblocking lock URL: https://github.com/apache/helix/pull/718#discussion_r379661469
########## File path: helix-lock/src/main/java/org/apache/helix/lock/helix/ZKHelixNonblockingLock.java ########## @@ -0,0 +1,186 @@ +/* + * 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.helix.lock.helix; + +import java.util.Date; + +import org.I0Itec.zkclient.DataUpdater; +import org.apache.helix.AccessOption; +import org.apache.helix.BaseDataAccessor; +import org.apache.helix.HelixException; +import org.apache.helix.ZNRecord; +import org.apache.helix.lock.HelixLock; +import org.apache.helix.lock.LockInfo; +import org.apache.helix.lock.LockScope; +import org.apache.helix.manager.zk.ZkBaseDataAccessor; +import org.apache.log4j.Logger; + + +/** + * Helix nonblocking lock implementation based on Zookeeper + */ +public class ZKHelixNonblockingLock implements HelixLock { + + private static final Logger LOG = Logger.getLogger(ZKHelixNonblockingLock.class); + + private final String _lockPath; + private final String _userId; + private final long _timeout; + private final String _lockMsg; + private final BaseDataAccessor<ZNRecord> _baseDataAccessor; + + /** + * Initialize the lock with user provided information, e.g.,cluster, scope, etc. + * @param scope the scope to lock + * @param zkAddress the zk address the cluster connects to + * @param timeout the timeout period of the lcok + * @param lockMsg the reason for having this lock + * @param userId a universal unique userId for lock owner identity + */ + public ZKHelixNonblockingLock(LockScope scope, String zkAddress, Long timeout, String lockMsg, + String userId) { + this(scope.getPath(), zkAddress, timeout, lockMsg, userId); + } + + /** + * Initialize the lock with user provided information, e.g., lock path under zookeeper, etc. + * @param lockPath the path of the lock under Zookeeper + * @param zkAddress the zk address of the cluster + * @param timeout the timeout period of the lcok + * @param lockMsg the reason for having this lock + * @param userId a universal unique userId for lock owner identity + */ + private ZKHelixNonblockingLock(String lockPath, String zkAddress, Long timeout, String lockMsg, + String userId) { + _lockPath = lockPath; + _timeout = timeout; + _lockMsg = lockMsg; + _userId = userId; + _baseDataAccessor = new ZkBaseDataAccessor<>(zkAddress); + } + + @Override + public boolean acquireLock() { + + // Set lock information fields + long deadline; + // Prevent value overflow + if (_timeout > Long.MAX_VALUE - System.currentTimeMillis()) { + deadline = Long.MAX_VALUE; + } else { + deadline = System.currentTimeMillis() + _timeout; + } + LockInfo lockInfo = new LockInfo(_userId); + lockInfo.setLockInfoFields(_userId, _lockMsg, deadline); + + LockUpdater updater = new LockUpdater(lockInfo); + return _baseDataAccessor.update(_lockPath, updater, AccessOption.PERSISTENT); + } + + @Override + public boolean releaseLock() { + // Initialize the lock updater with a default lock info represents the state of a unlocked lock + LockUpdater updater = new LockUpdater(LockInfo.defaultLockInfo); + return _baseDataAccessor.update(_lockPath, updater, AccessOption.PERSISTENT); + } + + @Override + public LockInfo getLockInfo() { Review comment: GetCurrentLockInfo? Since this method is not returning this instance's lock info. Actually, keep it a static method could be cleaner. Also for the following method isOwner(). ---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@helix.apache.org For additional commands, e-mail: reviews-h...@helix.apache.org
