zhaijack commented on a change in pull request #509: Issue 508: Introduce lifecycle components for managing components in bookie server URL: https://github.com/apache/bookkeeper/pull/509#discussion_r139260129
########## File path: bookkeeper-common/src/main/java/org/apache/bookkeeper/common/component/Lifecycle.java ########## @@ -0,0 +1,196 @@ +/* + * 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.bookkeeper.common.component; + +/** + * Lifecycle state. Allows the following transitions: + * + * <ul> + * <li>INITIALIZED -> STARTED, STOPPED, CLOSED</li> + * <li>STARTED -> STOPPED</li> + * <li>STOPPED -> STARTED, CLOSED</li> + * <li>CLOSED -> </li> + * </ul> + * + * <p>Also allows to stay in the same state. For example, when calling stop on a component, the + * following logic can be applied: + * + * <pre> + * public void stop() { + * if (!lifecycleState.moveToStopped()) { + * return; + * } + * // continue with stop logic + * } + * </pre> + * + * <p>Note, closed is only allowed to be called when stopped, so make sure to stop the component first. + * Here is how the logic can be applied: + * + * <pre> + * public void close() { + * if (lifecycleState.started()) { + * stop(); + * } + * if (!lifecycleState.moveToClosed()) { + * return; + * } + * // perform close logic here + * } + * </pre> + */ +public class Lifecycle { Review comment: this class usually used during statup and teardown. it is usually done by one thread. there is really need a lot of concurrency control attentions. and the caller can take care of this concurrency control in the place when it is used. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services
