Revert "Remove deprecated BackOffPolicy interface (#506)" (#521)

This reverts commit d5effe8.

Author: chingor13

clirr-ignored-differences.xml

@@ -7,22 +7,4 @@
     <differenceType>8001</differenceType>
     <className>com/google/api/client/repackaged/**</className>
   </difference>
-  <difference>
-    <differenceType>7002</differenceType>
-    <className>com/google/api/client/http/HttpRequest</className>
-    <method>com.google.api.client.http.BackOffPolicy getBackOffPolicy()</method>
-  </difference>
-  <difference>
-    <differenceType>7002</differenceType>
-    <className>com/google/api/client/http/HttpRequest</className>
-    <method>com.google.api.client.http.HttpRequest setBackOffPolicy(com.google.api.client.http.BackOffPolicy)</method>
-  </difference>
-  <difference>
-    <differenceType>8001</differenceType>
-    <className>com/google/api/client/http/BackOffPolicy</className>
-  </difference>
-  <difference>
-    <differenceType>8001</differenceType>
-    <className>com/google/api/client/http/ExponentialBackOffPolicy*</className>
-  </difference>
 </differences>

google-http-client/src/main/java/com/google/api/client/http/BackOffPolicy.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2011 Google Inc.
+ *
+ * Licensed 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 com.google.api.client.http;
+
+import com.google.api.client.util.Beta;
+
+import java.io.IOException;
+
+/**
+ * {@link Beta} <br/>
+ * Strategy interface to control back off between retry attempts.
+ *
+ * @since 1.7
+ * @author Ravi Mistry
+ * @deprecated (scheduled to be removed in 1.18) Use {@link HttpBackOffUnsuccessfulResponseHandler}
+ *             instead.
+ */
+@Deprecated
+@Beta
+public interface BackOffPolicy {
+
+  /**
+   * Value indicating that no more retries should be made, see {@link #getNextBackOffMillis()}.
+   */
+  public static final long STOP = -1L;
+
+  /**
+   * Determines if back off is required based on the specified status code.
+   *
+   * <p>
+   * Implementations may want to back off on server or product-specific errors.
+   * </p>
+   *
+   * @param statusCode HTTP status code
+   */
+  public boolean isBackOffRequired(int statusCode);
+
+  /**
+   * Reset Back off counters (if any) in an implementation-specific fashion.
+   */
+  public void reset();
+
+  /**
+   * Gets the number of milliseconds to wait before retrying an HTTP request. If {@link #STOP} is
+   * returned, no retries should be made.
+   *
+   * This method should be used as follows:
+   *
+   * <pre>
+   *  long backoffTime = backoffPolicy.getNextBackoffMs();
+   *  if (backoffTime == BackoffPolicy.STOP) {
+   *    // Stop retrying.
+   *  } else {
+   *    // Retry after backoffTime.
+   *  }
+   *</pre>
+   *
+   * @return the number of milliseconds to wait when backing off requests, or {@link #STOP} if no
+   *         more retries should be made
+   */
+  public long getNextBackOffMillis() throws IOException;
+}