1/*
2 * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package com.sun.jndi.ldap.pool;
27
28/**
29 * Represents a description of PooledConnection in Connections.
30 * Contains a PooledConnection, its state (busy, idle, expired), and idle time.
31 *
32 * Any access or update to a descriptor's state is synchronized.
33 *
34 * @author Rosanna Lee
35 */
36final class ConnectionDesc {
37    private final static boolean debug = Pool.debug;
38
39    // Package private because used by Pool.showStats()
40    static final byte BUSY = (byte)0;
41    static final byte IDLE = (byte)1;
42    static final byte EXPIRED = (byte)2;
43
44    final private PooledConnection conn;
45
46    private byte state = IDLE;  // initial state
47    private long idleSince;
48    private long useCount = 0;  // for stats & debugging only
49
50    ConnectionDesc(PooledConnection conn) {
51        this.conn = conn;
52    }
53
54    ConnectionDesc(PooledConnection conn, boolean use) {
55        this.conn = conn;
56        if (use) {
57            state = BUSY;
58            ++useCount;
59        }
60    }
61
62    /**
63     * Two desc are equal if their PooledConnections are the same.
64     * This is useful when searching for a ConnectionDesc using only its
65     * PooledConnection.
66     */
67    public boolean equals(Object obj) {
68        return obj != null
69            && obj instanceof ConnectionDesc
70            && ((ConnectionDesc)obj).conn == conn;
71    }
72
73    /**
74     * Hashcode is that of PooledConnection to facilitate
75     * searching for a ConnectionDesc using only its PooledConnection.
76     */
77    public int hashCode() {
78        return conn.hashCode();
79    }
80
81    /**
82     * Changes the state of a ConnectionDesc from BUSY to IDLE and
83     * records the current time so that we will know how long it has been idle.
84     * @return true if state change occurred.
85     */
86    synchronized boolean release() {
87        d("release()");
88        if (state == BUSY) {
89            state = IDLE;
90
91            idleSince = System.currentTimeMillis();
92            return true;  // Connection released, ready for reuse
93        } else {
94            return false; // Connection wasn't busy to begin with
95        }
96    }
97
98    /**
99     * If ConnectionDesc is IDLE, change its state to BUSY and return
100     * its connection.
101     *
102     * @return ConnectionDesc's PooledConnection if it was idle; null otherwise.
103     */
104    synchronized PooledConnection tryUse() {
105        d("tryUse()");
106
107        if (state == IDLE) {
108            state = BUSY;
109            ++useCount;
110            return conn;
111        }
112
113        return null;
114    }
115
116    /**
117     * If ConnectionDesc is IDLE and has expired, close the corresponding
118     * PooledConnection.
119     *
120     * @param threshold a connection that has been idle before this time
121     *     have expired.
122     *
123     * @return true if entry is idle and has expired; false otherwise.
124     */
125    synchronized boolean expire(long threshold) {
126        if (state == IDLE && idleSince < threshold) {
127
128            d("expire(): expired");
129
130            state = EXPIRED;
131            conn.closeConnection();  // Close real connection
132
133            return true;  // Expiration successful
134        } else {
135            d("expire(): not expired");
136            return false; // Expiration did not occur
137        }
138    }
139
140    public String toString() {
141        return conn.toString() + " " +
142            (state == BUSY ? "busy" : (state == IDLE ? "idle" : "expired"));
143    }
144
145    // Used by Pool.showStats()
146    int getState() {
147        return state;
148    }
149
150    // Used by Pool.showStats()
151    long getUseCount() {
152        return useCount;
153    }
154
155    private void d(String msg) {
156        if (debug) {
157            System.err.println("ConnectionDesc." + msg + " " + toString());
158        }
159    }
160}
161