| /* |
| * 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.curator.framework.state; |
| |
| import java.time.Duration; |
| import java.util.Objects; |
| import java.util.concurrent.ScheduledExecutorService; |
| import java.util.concurrent.TimeUnit; |
| import org.apache.curator.RetryPolicy; |
| import org.apache.curator.RetrySleeper; |
| import org.apache.curator.utils.ThreadUtils; |
| |
| class CircuitBreaker { |
| private final RetryPolicy retryPolicy; |
| private final ScheduledExecutorService service; |
| |
| private boolean isOpen = false; |
| private int retryCount = 0; |
| private long startNanos = 0; |
| |
| static CircuitBreaker build(RetryPolicy retryPolicy) { |
| return new CircuitBreaker( |
| retryPolicy, ThreadUtils.newSingleThreadScheduledExecutor("CircuitBreakingConnectionStateListener")); |
| } |
| |
| static CircuitBreaker build(RetryPolicy retryPolicy, ScheduledExecutorService service) { |
| return new CircuitBreaker(retryPolicy, service); |
| } |
| |
| // IMPORTANT - all methods below MUST be guarded by synchronization |
| |
| boolean isOpen() { |
| return isOpen; |
| } |
| |
| int getRetryCount() { |
| return retryCount; |
| } |
| |
| boolean tryToOpen(Runnable completion) { |
| if (isOpen) { |
| return false; |
| } |
| |
| isOpen = true; |
| retryCount = 0; |
| startNanos = System.nanoTime(); |
| if (tryToRetry(completion)) { |
| return true; |
| } |
| close(); |
| return false; |
| } |
| |
| boolean tryToRetry(Runnable completion) { |
| if (!isOpen) { |
| return false; |
| } |
| |
| long[] sleepTimeNanos = new long[] {0L}; |
| RetrySleeper retrySleeper = (time, unit) -> sleepTimeNanos[0] = unit.toNanos(time); |
| Duration elapsedTime = Duration.ofNanos(System.nanoTime() - startNanos); |
| if (retryPolicy.allowRetry(retryCount, elapsedTime.toMillis(), retrySleeper)) { |
| ++retryCount; |
| service.schedule(completion, sleepTimeNanos[0], TimeUnit.NANOSECONDS); |
| return true; |
| } |
| return false; |
| } |
| |
| boolean close() { |
| boolean wasOpen = isOpen; |
| retryCount = 0; |
| isOpen = false; |
| startNanos = 0; |
| return wasOpen; |
| } |
| |
| private CircuitBreaker(RetryPolicy retryPolicy, ScheduledExecutorService service) { |
| this.retryPolicy = Objects.requireNonNull(retryPolicy, "retryPolicy cannot be null"); |
| this.service = Objects.requireNonNull(service, "service cannot be null"); |
| } |
| } |