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.hc.client5.http;
28
29 import org.apache.hc.core5.annotation.Contract;
30 import org.apache.hc.core5.annotation.ThreadingBehavior;
31 import org.apache.hc.core5.http.HttpResponse;
32 import org.apache.hc.core5.http.protocol.HttpContext;
33 import org.apache.hc.core5.util.TimeValue;
34
35 /**
36 * Interface for deciding how long a connection can remain
37 * idle before being reused.
38 * <p>
39 * Implementations of this interface must be thread-safe. Access to shared
40 * data must be synchronized as methods of this interface may be executed
41 * from multiple threads.
42 *
43 * @since 4.0
44 */
45 @Contract(threading = ThreadingBehavior.STATELESS)
46 public interface ConnectionKeepAliveStrategy {
47
48 /**
49 * Returns the duration of time which this connection can be safely kept
50 * idle. If the connection is left idle for longer than this period of time,
51 * it MUST not reused. A value of 0 or less may be returned to indicate that
52 * there is no suitable suggestion.
53 *
54 * When coupled with a {@link org.apache.hc.core5.http.ConnectionReuseStrategy}, if
55 * {@link org.apache.hc.core5.http.ConnectionReuseStrategy#keepAlive(
56 * org.apache.hc.core5.http.HttpRequest, HttpResponse, HttpContext)} returns true,
57 * this allows you to control how long the reuse will last. If keepAlive returns
58 * false, this should have no meaningful impact
59 *
60 * @param response
61 * The last response received over the connection.
62 * @param context
63 * the context in which the connection is being used.
64 *
65 * @return the duration in ms for which it is safe to keep the connection
66 * idle, or <=0 if no suggested duration.
67 */
68 TimeValue getKeepAliveDuration(HttpResponse response, HttpContext context);
69
70 }