CommunicationsException


1   /*
2    Copyright (C) 2002-2004 MySQL AB
3   
4    This program is free software; you can redistribute it and/or modify
5    it under the terms of version 2 of the GNU General Public License as 
6    published by the Free Software Foundation.
7   
8    There are special exceptions to the terms and conditions of the GPL 
9    as it is applied to this software. View the full text of the 
10   exception in file EXCEPTIONS-CONNECTOR-J in the directory of this 
11   software distribution.
12  
13   This program is distributed in the hope that it will be useful,
14   but WITHOUT ANY WARRANTY; without even the implied warranty of
15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16   GNU General Public License for more details.
17  
18   You should have received a copy of the GNU General Public License
19   along with this program; if not, write to the Free Software
20   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
21  
22  
23  
24   */
25  package com.mysql.jdbc;
26  
27  import java.net.BindException  ;
28  
29  import java.sql.SQLException  ;
30  
31  /**
32   * An exception to represent communications errors with the database.
33   * 
34   * Attempts to provide 'friendler' error messages to end-users, including last
35   * time a packet was sent to the database, what the client-timeout is set to,
36   * and whether the idle time has been exceeded.
37   * 
38   * @author Mark Matthews
39   * 
40   * @version $Id: CommunicationsException.java,v 1.1.2.1 2005/05/13 18:58:37
41   *          mmatthews Exp $
42   */
43  public class CommunicationsException extends SQLException   {
44  
45      private static final long DEFAULT_WAIT_TIMEOUT_SECONDS = 28800;
46  
47      private static final int DUE_TO_TIMEOUT_FALSE = 0;
48  
49      private static final int DUE_TO_TIMEOUT_MAYBE = 2;
50  
51      private static final int DUE_TO_TIMEOUT_TRUE = 1;
52  
53      private String   exceptionMessage;
54  
55      public CommunicationsException(Connection conn, long lastPacketSentTimeMs,
56              Exception   underlyingException) {
57  
58          long serverTimeoutSeconds = 0;
59          boolean isInteractiveClient = false;
60  
61          if (conn != null) {
62              isInteractiveClient = conn.getInteractiveClient();
63  
64              String   serverTimeoutSecondsStr = null;
65  
66              if (isInteractiveClient) {
67                  serverTimeoutSecondsStr = conn
68                          .getServerVariable("interactive_timeout"); //$NON-NLS-1$
69              } else {
70                  serverTimeoutSecondsStr = conn
71                          .getServerVariable("wait_timeout"); //$NON-NLS-1$
72              }
73  
74              if (serverTimeoutSecondsStr != null) {
75                  try {
76                      serverTimeoutSeconds = Long
77                              .parseLong(serverTimeoutSecondsStr);
78                  } catch (NumberFormatException   nfe) {
79                      serverTimeoutSeconds = 0;
80                  }
81              }
82          }
83  
84          StringBuffer   exceptionMessageBuf = new StringBuffer  ();
85  
86          if (lastPacketSentTimeMs == 0) {
87              lastPacketSentTimeMs = System.currentTimeMillis();
88          }
89  
90          long timeSinceLastPacket = (System.currentTimeMillis() - lastPacketSentTimeMs) / 1000;
91  
92          int dueToTimeout = DUE_TO_TIMEOUT_FALSE;
93  
94          StringBuffer   timeoutMessageBuf = null;
95  
96          if (serverTimeoutSeconds != 0) {
97              if (timeSinceLastPacket > serverTimeoutSeconds) {
98                  dueToTimeout = DUE_TO_TIMEOUT_TRUE;
99  
100                 timeoutMessageBuf = new StringBuffer  ();
101 
102                 timeoutMessageBuf.append(Messages
103                         .getString("CommunicationsException.2")); //$NON-NLS-1$
104 
105                 if (!isInteractiveClient) {
106                     timeoutMessageBuf.append(Messages
107                             .getString("CommunicationsException.3")); //$NON-NLS-1$
108                 } else {
109                     timeoutMessageBuf.append(Messages
110                             .getString("CommunicationsException.4")); //$NON-NLS-1$
111                 }
112 
113             }
114         } else if (timeSinceLastPacket > DEFAULT_WAIT_TIMEOUT_SECONDS) {
115             dueToTimeout = DUE_TO_TIMEOUT_MAYBE;
116 
117             timeoutMessageBuf = new StringBuffer  ();
118 
119             timeoutMessageBuf.append(Messages
120                     .getString("CommunicationsException.5")); //$NON-NLS-1$
121             timeoutMessageBuf.append(Messages
122                     .getString("CommunicationsException.6")); //$NON-NLS-1$
123             timeoutMessageBuf.append(Messages
124                     .getString("CommunicationsException.7")); //$NON-NLS-1$
125             timeoutMessageBuf.append(Messages
126                     .getString("CommunicationsException.8")); //$NON-NLS-1$
127         }
128 
129         if (dueToTimeout == DUE_TO_TIMEOUT_TRUE
130                 || dueToTimeout == DUE_TO_TIMEOUT_MAYBE) {
131 
132             exceptionMessageBuf.append(Messages
133                     .getString("CommunicationsException.9")); //$NON-NLS-1$
134             exceptionMessageBuf.append(timeSinceLastPacket);
135             exceptionMessageBuf.append(Messages
136                     .getString("CommunicationsException.10")); //$NON-NLS-1$
137 
138             if (timeoutMessageBuf != null) {
139                 exceptionMessageBuf.append(timeoutMessageBuf);
140             }
141 
142             exceptionMessageBuf.append(Messages
143                     .getString("CommunicationsException.11")); //$NON-NLS-1$
144             exceptionMessageBuf.append(Messages
145                     .getString("CommunicationsException.12")); //$NON-NLS-1$
146             exceptionMessageBuf.append(Messages
147                     .getString("CommunicationsException.13")); //$NON-NLS-1$
148 
149         } else {
150             //
151             // Attempt to determine the reason for the underlying exception
152             // (we can only make a best-guess here)
153             //
154 
155             if (underlyingException instanceof BindException  ) {
156                 // too many client connections???
157                 exceptionMessageBuf.append(Messages
158                         .getString("CommunicationsException.14")); //$NON-NLS-1$
159                 exceptionMessageBuf.append(Messages
160                         .getString("CommunicationsException.15")); //$NON-NLS-1$
161                 exceptionMessageBuf.append(Messages
162                         .getString("CommunicationsException.16")); //$NON-NLS-1$
163                 exceptionMessageBuf.append(Messages
164                         .getString("CommunicationsException.17")); //$NON-NLS-1$
165                 exceptionMessageBuf.append(Messages
166                         .getString("CommunicationsException.18")); //$NON-NLS-1$
167                 exceptionMessageBuf.append(Messages
168                         .getString("CommunicationsException.19")); //$NON-NLS-1$
169             }
170         }
171 
172         if (exceptionMessageBuf.length() == 0) {
173             // We haven't figured out a good reason, so copy it.
174             exceptionMessageBuf.append(Messages
175                     .getString("CommunicationsException.20")); //$NON-NLS-1$
176 
177             if (underlyingException != null) {
178                 exceptionMessageBuf.append(Messages
179                         .getString("CommunicationsException.21")); //$NON-NLS-1$
180                 exceptionMessageBuf.append(Util
181                         .stackTraceToString(underlyingException));
182             }
183             
184             if (conn != null && conn.getMaintainTimeStats() && 
185                     !conn.getParanoid()) {
186                 exceptionMessageBuf.append("\n\nLast packet sent to the server was ");
187                 exceptionMessageBuf.append(System.currentTimeMillis() - lastPacketSentTimeMs);
188                 exceptionMessageBuf.append(" ms ago.");
189             }
190         }
191 
192         this.exceptionMessage = exceptionMessageBuf.toString();
193     }
194 
195     /*
196      * (non-Javadoc)
197      * 
198      * @see java.lang.Throwable#getMessage()
199      */
200     public String   getMessage() {
201         return this.exceptionMessage;
202     }
203 
204     /*
205      * (non-Javadoc)
206      * 
207      * @see java.sql.SQLException#getSQLState()
208      */
209     public String   getSQLState() {
210         return SQLError.SQL_STATE_COMMUNICATION_LINK_FAILURE;
211     }
212 
213 }
214
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