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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.conn;
28  
29  import org.apache.http.HttpResponse;
30  import org.apache.http.protocol.HttpContext;
31  
32  /**
33   * Interface for deciding how long a connection can remain
34   * idle before being reused.
35   * <p>
36   * Implementations of this interface must be thread-safe. Access to shared
37   * data must be synchronized as methods of this interface may be executed
38   * from multiple threads.
39   *
40   * @since 4.0
41   */
42  public interface ConnectionKeepAliveStrategy {
43  
44      /**
45       * Returns the duration of time which this connection can be safely kept
46       * idle. If the connection is left idle for longer than this period of time,
47       * it MUST not reused. A value of 0 or less may be returned to indicate that
48       * there is no suitable suggestion.
49       *
50       * When coupled with a {@link org.apache.http.ConnectionReuseStrategy}, if
51       * {@link org.apache.http.ConnectionReuseStrategy#keepAlive(
52       *   HttpResponse, HttpContext)} returns true, this allows you to control
53       * how long the reuse will last. If keepAlive returns false, this should
54       * have no meaningful impact
55       *
56       * @param response
57       *            The last response received over the connection.
58       * @param context
59       *            the context in which the connection is being used.
60       *
61       * @return the duration in ms for which it is safe to keep the connection
62       *         idle, or &lt;=0 if no suggested duration.
63       */
64      long getKeepAliveDuration(HttpResponse response, HttpContext context);
65  
66  }