| 1 | /** |
| 2 | * |
| 3 | * Copyright (C) 2011 Cloud Conscious, LLC. <info@cloudconscious.com> |
| 4 | * |
| 5 | * ==================================================================== |
| 6 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 7 | * you may not use this file except in compliance with the License. |
| 8 | * 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, software |
| 13 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 15 | * See the License for the specific language governing permissions and |
| 16 | * limitations under the License. |
| 17 | * ==================================================================== |
| 18 | */ |
| 19 | package org.jclouds.http.handlers; |
| 20 | |
| 21 | import static org.jclouds.http.HttpUtils.releasePayload; |
| 22 | |
| 23 | import java.io.IOException; |
| 24 | |
| 25 | import javax.annotation.Resource; |
| 26 | import javax.inject.Named; |
| 27 | import javax.inject.Singleton; |
| 28 | |
| 29 | import org.jclouds.Constants; |
| 30 | import org.jclouds.http.HttpCommand; |
| 31 | import org.jclouds.http.HttpResponse; |
| 32 | import org.jclouds.http.HttpRetryHandler; |
| 33 | import org.jclouds.http.IOExceptionRetryHandler; |
| 34 | import org.jclouds.http.TransformingHttpCommand; |
| 35 | import org.jclouds.logging.Logger; |
| 36 | |
| 37 | import com.google.common.base.Throwables; |
| 38 | import com.google.inject.Inject; |
| 39 | |
| 40 | /** |
| 41 | * Allow replayable request to be retried a limited number of times, and impose an exponential |
| 42 | * back-off delay before returning. |
| 43 | * <p> |
| 44 | * The back-off delay grows rapidly according to the formula |
| 45 | * <code>50 * (<i>{@link TransformingHttpCommand#getFailureCount()}</i> ^ 2)</code>. For example: |
| 46 | * <table> |
| 47 | * <tr> |
| 48 | * <th>Number of Attempts</th> |
| 49 | * <th>Delay in milliseconds</th> |
| 50 | * </tr> |
| 51 | * <tr> |
| 52 | * <td>1</td> |
| 53 | * <td>50</td> |
| 54 | * </tr> |
| 55 | * <tr> |
| 56 | * <td>2</td> |
| 57 | * <td>200</td> |
| 58 | * </tr> |
| 59 | * <tr> |
| 60 | * <td>3</td> |
| 61 | * <td>450</td> |
| 62 | * </tr> |
| 63 | * <tr> |
| 64 | * <td>4</td> |
| 65 | * <td>800</td> |
| 66 | * </tr> |
| 67 | * <tr> |
| 68 | * <td>5</td> |
| 69 | * <td>1250</td> |
| 70 | * </tr> |
| 71 | * </table> |
| 72 | * <p> |
| 73 | * This implementation has two side-effects. It increments the command's failure count with |
| 74 | * {@link TransformingHttpCommand#incrementFailureCount()}, because this failure count value is used |
| 75 | * to determine how many times the command has already been tried. It also closes the response's |
| 76 | * content input stream to ensure connections are cleaned up. |
| 77 | * |
| 78 | * @author James Murty |
| 79 | */ |
| 80 | @Singleton |
| 81 | public class BackoffLimitedRetryHandler implements HttpRetryHandler, IOExceptionRetryHandler { |
| 82 | |
| 83 | public static BackoffLimitedRetryHandler INSTANCE = new BackoffLimitedRetryHandler(); |
| 84 | |
| 85 | @Inject(optional = true) |
| 86 | @Named(Constants.PROPERTY_MAX_RETRIES) |
| 87 | private int retryCountLimit = 5; |
| 88 | |
| 89 | @Resource |
| 90 | protected Logger logger = Logger.NULL; |
| 91 | |
| 92 | public boolean shouldRetryRequest(HttpCommand command, IOException error) { |
| 93 | return ifReplayableBackoffAndReturnTrue(command); |
| 94 | } |
| 95 | |
| 96 | public boolean shouldRetryRequest(HttpCommand command, HttpResponse response) { |
| 97 | releasePayload(response); |
| 98 | return ifReplayableBackoffAndReturnTrue(command); |
| 99 | } |
| 100 | |
| 101 | private boolean ifReplayableBackoffAndReturnTrue(HttpCommand command) { |
| 102 | command.incrementFailureCount(); |
| 103 | |
| 104 | if (!command.isReplayable()) { |
| 105 | logger.warn("Cannot retry after server error, command is not replayable: %1$s", command); |
| 106 | return false; |
| 107 | } else if (command.getFailureCount() > retryCountLimit) { |
| 108 | logger.warn("Cannot retry after server error, command has exceeded retry limit %1$d: %2$s", retryCountLimit, |
| 109 | command); |
| 110 | return false; |
| 111 | } else { |
| 112 | imposeBackoffExponentialDelay(command.getFailureCount(), "server error: " + command.toString()); |
| 113 | return true; |
| 114 | } |
| 115 | } |
| 116 | |
| 117 | public void imposeBackoffExponentialDelay(int failureCount, String commandDescription) { |
| 118 | imposeBackoffExponentialDelay(50L, 2, failureCount, retryCountLimit, commandDescription); |
| 119 | } |
| 120 | |
| 121 | public void imposeBackoffExponentialDelay(long period, int pow, int failureCount, int max, String commandDescription) { |
| 122 | imposeBackoffExponentialDelay(period, period * 10l, pow, failureCount, max, commandDescription); |
| 123 | } |
| 124 | |
| 125 | public void imposeBackoffExponentialDelay(long period, long maxPeriod, int pow, int failureCount, int max, |
| 126 | String commandDescription) { |
| 127 | long delayMs = (long) (period * Math.pow(failureCount, pow)); |
| 128 | delayMs = delayMs > maxPeriod ? maxPeriod : delayMs; |
| 129 | logger.debug("Retry %d/%d: delaying for %d ms: %s", failureCount, max, delayMs, commandDescription); |
| 130 | try { |
| 131 | Thread.sleep(delayMs); |
| 132 | } catch (InterruptedException e) { |
| 133 | Throwables.propagate(e); |
| 134 | } |
| 135 | } |
| 136 | |
| 137 | } |