| 1 | /** |
| 2 | * Licensed to jclouds, Inc. (jclouds) under one or more |
| 3 | * contributor license agreements. See the NOTICE file |
| 4 | * distributed with this work for additional information |
| 5 | * regarding copyright ownership. jclouds licenses this file |
| 6 | * to you under the Apache License, Version 2.0 (the |
| 7 | * "License"); you may not use this file except in compliance |
| 8 | * with the License. You may obtain a copy of the License at |
| 9 | * |
| 10 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 11 | * |
| 12 | * Unless required by applicable law or agreed to in writing, |
| 13 | * software distributed under the License is distributed on an |
| 14 | * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| 15 | * KIND, either express or implied. See the License for the |
| 16 | * specific language governing permissions and limitations |
| 17 | * under the License. |
| 18 | */ |
| 19 | package org.jclouds.predicates; |
| 20 | |
| 21 | import static org.jclouds.util.Throwables2.getFirstThrowableOfType; |
| 22 | |
| 23 | import java.util.Date; |
| 24 | import java.util.concurrent.ExecutionException; |
| 25 | import java.util.concurrent.TimeUnit; |
| 26 | import java.util.concurrent.TimeoutException; |
| 27 | |
| 28 | import javax.annotation.Resource; |
| 29 | |
| 30 | import org.jclouds.logging.Logger; |
| 31 | |
| 32 | import com.google.common.base.Predicate; |
| 33 | |
| 34 | /** |
| 35 | * |
| 36 | * Retries a condition until it is met or a timeout occurs. |
| 37 | * |
| 38 | * @author Adrian Cole |
| 39 | */ |
| 40 | public class RetryablePredicate<T> implements Predicate<T> { |
| 41 | private final long maxWait; |
| 42 | private final long period; |
| 43 | private final long maxPeriod; |
| 44 | private final Predicate<T> predicate; |
| 45 | |
| 46 | @Resource |
| 47 | protected Logger logger = Logger.NULL; |
| 48 | |
| 49 | public RetryablePredicate(Predicate<T> predicate, long maxWait, long period, long maxPeriod, TimeUnit unit) { |
| 50 | this.predicate = predicate; |
| 51 | this.maxWait = unit.toMillis(maxWait); |
| 52 | this.period = unit.toMillis(period); |
| 53 | this.maxPeriod = unit.toMillis(maxPeriod); |
| 54 | } |
| 55 | |
| 56 | public RetryablePredicate(Predicate<T> predicate, long maxWait, long period, TimeUnit unit) { |
| 57 | this(predicate, maxWait, period, period * 10l, unit); |
| 58 | } |
| 59 | |
| 60 | public RetryablePredicate(Predicate<T> predicate, long maxWait) { |
| 61 | this(predicate, maxWait, 50l, 1000l, TimeUnit.MILLISECONDS); |
| 62 | } |
| 63 | |
| 64 | @Override |
| 65 | public boolean apply(T input) { |
| 66 | try { |
| 67 | long i = 1l; |
| 68 | for (Date end = new Date(System.currentTimeMillis() + maxWait); before(end); Thread.sleep(nextMaxInterval(i++, |
| 69 | end))) { |
| 70 | if (predicate.apply(input)) { |
| 71 | return true; |
| 72 | } else if (atOrAfter(end)) { |
| 73 | return false; |
| 74 | } |
| 75 | } |
| 76 | } catch (InterruptedException e) { |
| 77 | logger.warn(e, "predicate %s on %s interrupted, returning false", input, predicate); |
| 78 | } catch (RuntimeException e) { |
| 79 | if (getFirstThrowableOfType(e, ExecutionException.class) != null) { |
| 80 | logger.warn(e, "predicate %s on %s errored [%s], returning false", input, predicate, e.getMessage()); |
| 81 | return false; |
| 82 | } else if (getFirstThrowableOfType(e, IllegalStateException.class) != null) { |
| 83 | logger.warn(e, "predicate %s on %s illegal state [%s], returning false", input, predicate, e.getMessage()); |
| 84 | return false; |
| 85 | } else if (getFirstThrowableOfType(e, TimeoutException.class) != null) { |
| 86 | logger.warn(e, "predicate %s on %s timed out [%s], returning false", input, predicate, e.getMessage()); |
| 87 | return false; |
| 88 | } else |
| 89 | throw e; |
| 90 | } |
| 91 | return false; |
| 92 | } |
| 93 | |
| 94 | protected long nextMaxInterval(long attempt, Date end) { |
| 95 | long interval = (period * (long) Math.pow(attempt, 1.5)); |
| 96 | interval = interval > maxPeriod ? maxPeriod : interval; |
| 97 | long max = end.getTime() - System.currentTimeMillis(); |
| 98 | return (interval > max) ? max : interval; |
| 99 | } |
| 100 | |
| 101 | protected boolean before(Date end) { |
| 102 | return new Date().compareTo(end) <= 1; |
| 103 | } |
| 104 | |
| 105 | protected boolean atOrAfter(Date end) { |
| 106 | return new Date().compareTo(end) >= 0; |
| 107 | } |
| 108 | } |