Oops, missed some new files required for Issue 37

git-svn-id: http://jclouds.googlecode.com/svn/trunk@851 3d8758e0-26b5-11de-8745-db77d3ebf521

core/src/main/java/org/jclouds/http/HttpRetryHandler.java

@@ -0,0 +1,53 @@
+/**
+ *
+ * Copyright (C) 2009 Adrian Cole <adrian@jclouds.org>
+ *
+ * ====================================================================
+ * 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.jclouds.http;
+
+/**
+ * Indicate whether a request should be retried after a server
+ * error response (HTTP status code >= 500) based on the request's
+ * replayable status and the number of attempts already performed.
+ * 
+ * @author James Murty
+ */
+public interface HttpRetryHandler {
+   public static final HttpRetryHandler ALWAYS_RETRY = new HttpRetryHandler() {
+      public boolean retryRequest(HttpFutureCommand<?> command, HttpResponse response) 
+      {
+         return true;
+      } 
+   };
+
+   /**
+    * Return true if the command should be retried. This method should only be 
+    * invoked when the response has failed with a HTTP 5xx error indicating a
+    * server-side error.
+    * 
+    * @param command
+    * @param response
+    * @return
+    * @throws InterruptedException
+    */
+   boolean retryRequest(HttpFutureCommand<?> command, HttpResponse response)
+      throws InterruptedException;
+}

core/src/main/java/org/jclouds/http/annotation/RetryHandler.java

@@ -0,0 +1,43 @@
+/**
+ *
+ * Copyright (C) 2009 Adrian Cole <adrian@jclouds.org>
+ *
+ * ====================================================================
+ * 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.jclouds.http.annotation;
+
+import com.google.inject.BindingAnnotation;
+import java.lang.annotation.Target;
+import java.lang.annotation.Retention;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+
+/**
+ * Implies that the object can address {@link org.jclouds.http.HttpRetryHandler}s.
+ * 
+ * @author James Murty
+ */
+@BindingAnnotation
+@Target( { FIELD, PARAMETER, METHOD })
+@Retention(RUNTIME)
+public @interface RetryHandler {
+}

core/src/main/java/org/jclouds/http/handlers/BackoffLimitedRetryHandler.java

@@ -0,0 +1,93 @@
+/**
+ *
+ * Copyright (C) 2009 Adrian Cole <adrian@jclouds.org>
+ *
+ * ====================================================================
+ * 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.jclouds.http.handlers;
+
+import javax.annotation.Resource;
+
+import org.apache.commons.io.IOUtils;
+import org.jclouds.http.HttpFutureCommand;
+import org.jclouds.http.HttpResponse;
+import org.jclouds.http.HttpRetryHandler;
+import org.jclouds.logging.Logger;
+
+import com.google.inject.Inject;
+import com.google.inject.name.Named;
+
+/**
+ * Allow replayable request to be retried a limited number of times, and 
+ * impose an exponential back-off delay before returning.
+ * <p>
+ * The back-off delay grows rapidly according to the formula 
+ * <code>50 * (<i>{@link HttpFutureCommand#getFailureCount()}</i> ^ 2)</code>. For example:
+ * <table>
+ * <tr><th>Number of Attempts</th><th>Delay in milliseconds</th></tr>
+ * <tr><td>1</td><td>50</td></tr>
+ * <tr><td>2</td><td>200</td></tr>
+ * <tr><td>3</td><td>450</td></tr>
+ * <tr><td>4</td><td>800</td></tr>
+ * <tr><td>5</td><td>1250</td></tr>
+ * </table>
+ * <p>
+ * This implementation has two side-effects. It increments the command's failure count
+ * with {@link HttpFutureCommand#incrementFailureCount()}, because this failure count 
+ * value is used to determine how many times the command has already been tried. It 
+ * also closes the response's content input stream to ensure connections are cleaned up.  
+ * 
+ * @author James Murty
+ */
+public class BackoffLimitedRetryHandler implements HttpRetryHandler {
+   private final int retryCountLimit;
+   
+   @Resource
+   protected Logger logger = Logger.NULL;
+
+   @Inject
+   public BackoffLimitedRetryHandler(@Named("jclouds.http.max-retries") int retryCountLimit) {
+      this.retryCountLimit = retryCountLimit;
+   }
+
+   public boolean retryRequest(HttpFutureCommand<?> command, HttpResponse response) 
+      throws InterruptedException
+   {
+      IOUtils.closeQuietly(response.getContent());
+     
+      command.incrementFailureCount();
+
+      if (!command.getRequest().isReplayable()) {
+         logger.warn("Cannot retry after server error, command is not replayable: %1$s", command);
+         return false;
+      } else if (command.getFailureCount() > retryCountLimit) {
+         logger.warn("Cannot retry after server error, command has exceeded retry limit %1$d: %2$s",
+                     retryCountLimit, command);
+         return false;
+      } else {
+         long delayMs = (long) (50L * Math.pow(command.getFailureCount(), 2));
+         logger.debug("Retry %1$d/%2$d after server error, delaying for %3$d ms: %4$s", 
+        		      command.getFailureCount(), retryCountLimit, delayMs, command);
+         Thread.sleep(delayMs);
+         return true;
+      }
+   }
+
+}