Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
OutboundConnectionCache |
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| 0.0;0 |
1 | /* | |
2 | * | |
3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER. | |
4 | * | |
5 | * Copyright 2007-2008 Sun Microsystems, Inc. All rights reserved. | |
6 | * | |
7 | * The contents of this file are subject to the terms of either the GNU | |
8 | * General Public License Version 2 only ("GPL") or the Common Development | |
9 | * and Distribution License("CDDL") (collectively, the "License"). You | |
10 | * may not use this file except in compliance with the License. You can obtain | |
11 | * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html | |
12 | * or glassfish/bootstrap/legal/LICENSE.txt. See the License for the specific | |
13 | * language governing permissions and limitations under the License. | |
14 | * | |
15 | * When distributing the software, include this License Header Notice in each | |
16 | * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt. | |
17 | * Sun designates this particular file as subject to the "Classpath" exception | |
18 | * as provided by Sun in the GPL Version 2 section of the License file that | |
19 | * accompanied this code. If applicable, add the following below the License | |
20 | * Header, with the fields enclosed by brackets [] replaced by your own | |
21 | * identifying information: "Portions Copyrighted [year] | |
22 | * [name of copyright owner]" | |
23 | * | |
24 | * Contributor(s): | |
25 | * | |
26 | * If you wish your version of this file to be governed by only the CDDL or | |
27 | * only the GPL Version 2, indicate your decision by adding "[Contributor] | |
28 | * elects to include this software in this distribution under the [CDDL or GPL | |
29 | * Version 2] license." If you don't indicate a single choice of license, a | |
30 | * recipient has the option to distribute your version of this file under | |
31 | * either the CDDL, the GPL Version 2 or to extend the choice of license to | |
32 | * its licensees as provided above. However, if you add GPL Version 2 code | |
33 | * and therefore, elected the GPL Version 2 license, then the option applies | |
34 | * only if the new code is made subject to such option by the copyright | |
35 | * holder. | |
36 | * | |
37 | */ | |
38 | ||
39 | package com.sun.grizzly.connectioncache.spi.transport; | |
40 | ||
41 | import java.io.Closeable; | |
42 | import java.io.IOException ; | |
43 | ||
44 | /** A concurrent mostly non-blocking connection cache. Here a Connection is an | |
45 | * abstraction of a Socket or SocketChannel: basically some sort of resource | |
46 | * that is expensive to acquire, and can be re-used freely. The cache | |
47 | * maintains a loose upper bound on the number of cached connections, and | |
48 | * reclaims connections as needed. | |
49 | * <P> | |
50 | * This cache places minimal requirements on the Connections that it contains: | |
51 | * <ol> | |
52 | * <li>A Connection must implement a close() method. This is called when idle | |
53 | * connections are reclaimed. | |
54 | * <li>A Connection must be usable as a HashMap key. | |
55 | * <li>There must be a ContactInfo class that is used to create Connection | |
56 | * instances. The ContactInfo class must support a create() method that | |
57 | * returns a Connection. | |
58 | * <li>The ContactInfo must be usable as a HashMap key. | |
59 | * <li>All instances created from a ContactInfo are equal; that is, any request | |
60 | * sent to a particular ContactInfo can used an instance created from that | |
61 | * ContactInfo. For example, in the CORBA case, IP host and port is not always | |
62 | * sufficient: we may also need the Codeset type that indicates how Strings are | |
63 | * encoded. Basically, protocols (like GIOP) that bind session state to a | |
64 | * Connection may need more than transport information in the ContactInfo. | |
65 | * </ol> | |
66 | * <P> | |
67 | * Some simple methods are provided for monitoring the state of the cache: | |
68 | * numbers of busy and idle connections, and the total number of connections in | |
69 | * the cache. | |
70 | * | |
71 | * @param C a connection | |
72 | */ | |
73 | public interface OutboundConnectionCache<C extends Closeable> | |
74 | extends ConnectionCache<C> { | |
75 | /** Configured maximum number of connections supported per ContactInfo. | |
76 | * @return maximum number of connections supported per <code>ContactInfo</code> | |
77 | */ | |
78 | int maxParallelConnections() ; | |
79 | ||
80 | /** Determine whether a new connection could be created by the | |
81 | * ConnectionCache or not. | |
82 | * @param cinfo a <code>ContactInfo</code> | |
83 | * @return true if new connection could be created by {@link ConnectionCache}, otherwise false. | |
84 | */ | |
85 | boolean canCreateNewConnection( ContactInfo<C> cinfo ) ; | |
86 | ||
87 | /** Return a Connection corresponding to the given ContactInfo. | |
88 | * This works as follows: | |
89 | * <ul> | |
90 | * <li>Call the finder. If it returns non-null, use that connection; | |
91 | * (Note that this may be a new connection, created in the finder) | |
92 | * <li>otherwise, Use an idle connection, if one is available; | |
93 | * <li>otherwise, create a new connection, if not too many connections are | |
94 | * open; | |
95 | * <li>otherwise, use a busy connection. | |
96 | * </ul> | |
97 | * Note that creating a new connection requires EITHER: | |
98 | * <ul> | |
99 | * <li>there is no existing connection for the ContactInfo | |
100 | * <li> OR the total number of connections in the cache is less than the | |
101 | * HighWaterMark and the number of connections for this ContactInfo | |
102 | * is less than MaxParallelConnections. | |
103 | * </ul> | |
104 | * We will always return a | |
105 | * Connection for a get call UNLESS we have no existing connection and | |
106 | * an attempt to create a new connection fails. In this case, the | |
107 | * IOException thrown by ContactInfo.create is propagated out of this | |
108 | * method. | |
109 | * <P> | |
110 | * It is possible that the cache contains connections that no longer connect | |
111 | * to their destination. In this case, it is the responsibility of the | |
112 | * client of the cache to close the broken connection as they are detected. | |
113 | * Connection reclamation may also handle the cleanup, but note that a | |
114 | * broken connection with pending responses will never be reclaimed. | |
115 | * <P> | |
116 | * Note that the idle and busy connection collections that are | |
117 | * passed to the finder are unmodifiable collections. They have iterators | |
118 | * that return connections in LRU order, with the least recently used | |
119 | * connection first. This is done to aid a finder that wishes to consider | |
120 | * load balancing in its determination of an appropriate connection. | |
121 | * <P> | |
122 | * @param cinfo a <code>ContactInfo</code> | |
123 | * @param finder a <code>ConnectionFinder</code> | |
124 | * @return a connection | |
125 | * @throws java.io.IOException | |
126 | */ | |
127 | C get( ContactInfo<C> cinfo, ConnectionFinder<C> finder | |
128 | ) throws IOException ; | |
129 | ||
130 | /** Behaves the same as get( ContactInfo<C>, ConnectionFinder<C> ) | |
131 | * except that no connection finder is provided, so that step is | |
132 | * ignored. | |
133 | * @param cinfo a <code>ContactInfo</code> | |
134 | * @return a connection | |
135 | * @throws java.io.IOException | |
136 | */ | |
137 | C get( ContactInfo<C> cinfo ) throws IOException ; | |
138 | ||
139 | /** Release a Connection previously obtained from get. Connections that | |
140 | * have been released as many times as they have been returned by | |
141 | * get are idle; otherwise a Connection is busy. Some number of | |
142 | * responses (usually 0 or 1) may be expected ON THE SAME CONNECTION | |
143 | * even for an idle connection. We maintain a count of the number of | |
144 | * outstanding responses we expect for protocols that return the response | |
145 | * on the same connection on which the request was received. This is | |
146 | * necessary to prevent reclamation of a Connection that is idle, but | |
147 | * still needed to send responses to old requests. | |
148 | * @param conn a connection | |
149 | * @param numResponseExpected number of connections in which a response is expected | |
150 | */ | |
151 | void release( C conn, int numResponseExpected ) ; | |
152 | ||
153 | /** Inform the cache that a response has been received on a particular | |
154 | * connection. This must also be called in the event that no response | |
155 | * is received, but the client times out waiting for a response, and | |
156 | * decides to abandon the request. | |
157 | * <P> | |
158 | * When a Connection is idle, and has no pending responses, it is | |
159 | * eligible for reclamation. | |
160 | * @param conn a connection | |
161 | */ | |
162 | void responseReceived( C conn ) ; | |
163 | } |