| /* |
| * 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.storm.policy; |
| |
| import java.util.Map; |
| import org.apache.storm.Config; |
| import org.apache.storm.utils.ReflectionUtils; |
| |
| |
| public interface IWaitStrategy { |
| static IWaitStrategy createBackPressureWaitStrategy(Map<String, Object> topologyConf) { |
| IWaitStrategy producerWaitStrategy = |
| ReflectionUtils.newInstance((String) topologyConf.get(Config.TOPOLOGY_BACKPRESSURE_WAIT_STRATEGY)); |
| producerWaitStrategy.prepare(topologyConf, WaitSituation.BACK_PRESSURE_WAIT); |
| return producerWaitStrategy; |
| } |
| |
| void prepare(Map<String, Object> conf, WaitSituation waitSituation); |
| |
| /** |
| * Implementations of this method should be thread-safe (preferably no side-effects and lock-free). |
| * |
| * <p>Supports static or dynamic backoff. Dynamic backoff relies on idleCounter to estimate how long caller has been idling. |
| * <pre> |
| * <code> |
| * int idleCounter = 0; |
| * int consumeCount = consumeFromQ(); |
| * while (consumeCount==0) { |
| * idleCounter = strategy.idle(idleCounter); |
| * consumeCount = consumeFromQ(); |
| * } |
| * </code> |
| * </pre> |
| * |
| * @param idleCounter managed by the idle method until reset |
| * @return new counter value to be used on subsequent idle cycle |
| */ |
| int idle(int idleCounter) throws InterruptedException; |
| |
| enum WaitSituation { |
| SPOUT_WAIT, |
| BOLT_WAIT, |
| BACK_PRESSURE_WAIT |
| } |
| } |