jerryshao commented on a change in pull request #274: [LIVY-721][SERVER] Distributed session id generation URL: https://github.com/apache/incubator-livy/pull/274#discussion_r375038681
########## File path: server/src/main/scala/org/apache/livy/sessions/SessionIdGenerator.scala ########## @@ -0,0 +1,87 @@ +/* + * 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.livy.sessions + +import java.util.concurrent.atomic.AtomicInteger + +import org.apache.curator.framework.recipes.locks.InterProcessSemaphoreMutex + +import org.apache.livy.server.recovery.{SessionStore, ZooKeeperManager} + +/** + * Interface of session id generator. + */ +abstract class SessionIdGenerator( + sessionType: String, + sessionStore: SessionStore) { + + /** + * Get next session id, then increase next session id and save it in store. + */ + def getNextSessionId(): Int + + protected def getAndIncreaseId(): Int + + protected def persist(id: Int): Unit = { + sessionStore.saveNextSessionId(sessionType, id) + } +} + +class LocalSessionIdGenerator( + sessionType: String, + sessionStore: SessionStore) extends SessionIdGenerator(sessionType, sessionStore) { + + private val idCounter = new AtomicInteger(0) + idCounter.set(sessionStore.getNextSessionId(sessionType)) + + override def getNextSessionId(): Int = { + val result = getAndIncreaseId() + persist(result + 1) + result + } + + override def getAndIncreaseId(): Int = { + idCounter.getAndIncrement() + } +} + +class DistributedSessionIdGenerator( + sessionType: String, + sessionStore: SessionStore, + zkManager: ZooKeeperManager, + mockLock: Option[InterProcessSemaphoreMutex] = None) + extends SessionIdGenerator(sessionType, sessionStore) { + + require(sessionStore.getStore.isDistributed(), + "Choose a distributed store such as hdfs or zookeeper") + + val distributedLock = mockLock.getOrElse( + zkManager.createLock(SessionStore.sessionIdLockPath(sessionType))) + + override def getNextSessionId(): Int = { + distributedLock.acquire() + val result = getAndIncreaseId() + persist(result + 1) + distributedLock.release() Review comment: What if there's an exception thrown in the above code, are we going to lose the lock? ---------------------------------------------------------------- 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
