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1   /*
2    * ====================================================================
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *   http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing,
14   * software distributed under the License is distributed on an
15   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16   * KIND, either express or implied.  See the License for the
17   * specific language governing permissions and limitations
18   * under the License.
19   * ====================================================================
20   *
21   * This software consists of voluntary contributions made by many
22   * individuals on behalf of the Apache Software Foundation.  For more
23   * information on the Apache Software Foundation, please see
24   * <http://www.apache.org/>.
25   *
26   */
27  package org.apache.http.client;
28  
29  import org.apache.http.HttpResponse;
30  
31  /**
32   * When managing a dynamic number of connections for a given route, this
33   * strategy assesses whether a given request execution outcome should
34   * result in a backoff signal or not, based on either examining the
35   * {@code Throwable} that resulted or by examining the resulting
36   * response (e.g. for its status code).
37   *
38   * @since 4.2
39   *
40   */
41  public interface ConnectionBackoffStrategy {
42  
43      /**
44       * Determines whether seeing the given {@code Throwable} as
45       * a result of request execution should result in a backoff
46       * signal.
47       * @param t the {@code Throwable} that happened
48       * @return {@code true} if a backoff signal should be
49       *   given
50       */
51      boolean shouldBackoff(Throwable t);
52  
53      /**
54       * Determines whether receiving the given {@link HttpResponse} as
55       * a result of request execution should result in a backoff
56       * signal. Implementations MUST restrict themselves to examining
57       * the response header and MUST NOT consume any of the response
58       * body, if any.
59       * @param resp the {@code HttpResponse} that was received
60       * @return {@code true} if a backoff signal should be
61       *   given
62       */
63      boolean shouldBackoff(HttpResponse resp);
64  }