| /* |
| * Copyright 2015, Google Inc. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are |
| * met: |
| * |
| * * Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * * Redistributions in binary form must reproduce the above |
| * copyright notice, this list of conditions and the following disclaimer |
| * in the documentation and/or other materials provided with the |
| * distribution. |
| * |
| * * Neither the name of Google Inc. nor the names of its |
| * contributors may be used to endorse or promote products derived from |
| * this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| package io.grpc.internal; |
| |
| import static com.google.common.base.Preconditions.checkArgument; |
| |
| import com.google.common.annotations.VisibleForTesting; |
| import java.util.Random; |
| import java.util.concurrent.TimeUnit; |
| |
| /** |
| * Retry Policy for Transport reconnection. Initial parameters from |
| * https://github.com/grpc/grpc/blob/master/doc/connection-backoff.md |
| * |
| * <p>TODO(carl-mastrangelo): add unit tests for this class |
| */ |
| final class ExponentialBackoffPolicy implements BackoffPolicy { |
| static final class Provider implements BackoffPolicy.Provider { |
| @Override |
| public BackoffPolicy get() { |
| return new ExponentialBackoffPolicy(); |
| } |
| } |
| |
| private Random random = new Random(); |
| private long initialBackoffMillis = TimeUnit.SECONDS.toMillis(1); |
| private long maxBackoffMillis = TimeUnit.MINUTES.toMillis(2); |
| private double multiplier = 1.6; |
| private double jitter = .2; |
| |
| private long nextBackoffMillis = initialBackoffMillis; |
| |
| @Override |
| public long nextBackoffMillis() { |
| long currentBackoffMillis = nextBackoffMillis; |
| nextBackoffMillis = Math.min((long) (currentBackoffMillis * multiplier), maxBackoffMillis); |
| return currentBackoffMillis |
| + uniformRandom(-jitter * currentBackoffMillis, jitter * currentBackoffMillis); |
| } |
| |
| private long uniformRandom(double low, double high) { |
| checkArgument(high >= low); |
| double mag = high - low; |
| return (long) (random.nextDouble() * mag + low); |
| } |
| |
| /* |
| * No guice and no flags means we get to implement these setters for testing ourselves. Do not |
| * call these from non-test code. |
| */ |
| |
| @VisibleForTesting |
| ExponentialBackoffPolicy setRandom(Random random) { |
| this.random = random; |
| return this; |
| } |
| |
| @VisibleForTesting |
| ExponentialBackoffPolicy setInitialBackoffMillis(long initialBackoffMillis) { |
| this.initialBackoffMillis = initialBackoffMillis; |
| return this; |
| } |
| |
| @VisibleForTesting |
| ExponentialBackoffPolicy setMaxBackoffMillis(long maxBackoffMillis) { |
| this.maxBackoffMillis = maxBackoffMillis; |
| return this; |
| } |
| |
| @VisibleForTesting |
| ExponentialBackoffPolicy setMultiplier(double multiplier) { |
| this.multiplier = multiplier; |
| return this; |
| } |
| |
| @VisibleForTesting |
| ExponentialBackoffPolicy setJitter(double jitter) { |
| this.jitter = jitter; |
| return this; |
| } |
| } |
| |