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org.apache.torque.pool.ConnectionPool$Monitor |
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1 | package org.apache.torque.pool; |
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2 | ||
3 | /* |
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4 | * Copyright 2001-2004 The Apache Software Foundation. |
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5 | * |
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6 | * Licensed under the Apache License, Version 2.0 (the "License") |
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7 | * you may not use this file except in compliance with the License. |
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8 | * You may obtain a copy of the License at |
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9 | * |
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10 | * http://www.apache.org/licenses/LICENSE-2.0 |
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11 | * |
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12 | * Unless required by applicable law or agreed to in writing, software |
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13 | * distributed under the License is distributed on an "AS IS" BASIS, |
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14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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15 | * See the License for the specific language governing permissions and |
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16 | * limitations under the License. |
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17 | */ |
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18 | ||
19 | import java.sql.SQLException; |
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20 | import java.util.HashMap; |
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21 | import java.util.Map; |
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22 | import java.util.Stack; |
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23 | ||
24 | import javax.sql.ConnectionEvent; |
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25 | import javax.sql.ConnectionEventListener; |
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26 | import javax.sql.ConnectionPoolDataSource; |
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27 | import javax.sql.PooledConnection; |
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28 | ||
29 | import org.apache.commons.logging.Log; |
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30 | import org.apache.commons.logging.LogFactory; |
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31 | ||
32 | /** |
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33 | * This class implements a simple connection pooling scheme. |
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34 | * |
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35 | * @author <a href="mailto:csterg@aias.gr">Costas Stergiou</a> |
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36 | * @author <a href="mailto:frank.kim@clearink.com">Frank Y. Kim</a> |
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37 | * @author <a href="mailto:bmclaugh@algx.net">Brett McLaughlin</a> |
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38 | * @author <a href="mailto:greg@shwoop.com">Greg Ritter</a> |
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39 | * @author <a href="mailto:dlr@collab.net">Daniel L. Rall</a> |
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40 | * @author <a href="mailto:paul@evolventtech.com">Paul O'Leary</a> |
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41 | * @author <a href="mailto:magnus@handtolvur.is">Magn�s ��r Torfason</a> |
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42 | * @author <a href="mailto:jon@latchkey.com">Jon S. Stevens</a> |
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43 | * @author <a href="mailto:jmcnally@collab.net">John McNally</a> |
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44 | * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a> |
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45 | * @version $Id: ConnectionPool.java,v 1.27.2.2 2004/05/20 04:36:05 seade Exp $ |
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46 | * @deprecated as of version 3.1 |
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47 | */ |
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48 | class ConnectionPool implements ConnectionEventListener |
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49 | { |
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50 | ||
51 | /** Default maximum Number of connections from this pool: One */ |
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52 | public static final int DEFAULT_MAX_CONNECTIONS = 1; |
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53 | ||
54 | /** Default Expiry Time for a pool: 1 hour */ |
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55 | public static final int DEFAULT_EXPIRY_TIME = 60 * 60 * 1000; |
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56 | ||
57 | /** Default Connect Wait Timeout: 10 Seconds */ |
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58 | public static final int DEFAULT_CONNECTION_WAIT_TIMEOUT = 10 * 1000; |
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59 | ||
60 | /** Pool containing database connections. */ |
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61 | private Stack pool; |
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62 | ||
63 | /** The url for this pool. */ |
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64 | private String url; |
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65 | ||
66 | /** The user name for this pool. */ |
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67 | private String username; |
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68 | ||
69 | /** The password for this pool. */ |
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70 | private String password; |
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71 | ||
72 | /** The current number of database connections that have been created. */ |
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73 | private int totalConnections; |
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74 | ||
75 | /** The maximum number of database connections that can be created. */ |
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76 | private int maxConnections = DEFAULT_MAX_CONNECTIONS; |
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77 | ||
78 | /** The amount of time in milliseconds that a connection will be pooled. */ |
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79 | private long expiryTime = DEFAULT_EXPIRY_TIME; |
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80 | ||
81 | /** |
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82 | * Counter that keeps track of the number of threads that are in |
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83 | * the wait state, waiting to aquire a connection. |
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84 | */ |
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85 | private int waitCount = 0; |
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86 | ||
87 | /** The logging logger. */ |
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88 | private static Log log = LogFactory.getLog(ConnectionPool.class); |
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89 | ||
90 | /** Interval (in seconds) that the monitor thread reports the pool state */ |
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91 | private int logInterval = 0; |
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92 | ||
93 | /** Monitor thread reporting the pool state */ |
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94 | private Monitor monitor; |
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95 | ||
96 | /** |
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97 | * Amount of time a thread asking the pool for a cached connection will |
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98 | * wait before timing out and throwing an error. |
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99 | */ |
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100 | private long connectionWaitTimeout = DEFAULT_CONNECTION_WAIT_TIMEOUT; |
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101 | ||
102 | /** The ConnectionPoolDataSource */ |
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103 | private ConnectionPoolDataSource cpds; |
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104 | ||
105 | /** |
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106 | * Keep track of when connections were created. Keyed by a |
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107 | * PooledConnection and value is a java.util.Date |
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108 | */ |
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109 | private Map timeStamps; |
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110 | ||
111 | /** |
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112 | * Creates a <code>ConnectionPool</code> with the default |
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113 | * attributes. |
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114 | * |
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115 | * @param cpds The datasource |
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116 | * @param username The user name for this pool. |
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117 | * @param password The password for this pool. |
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118 | * @param maxConnections max number of connections |
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119 | * @param expiryTime connection expiry time |
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120 | * @param connectionWaitTimeout timeout |
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121 | * @param logInterval log interval |
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122 | */ |
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123 | ConnectionPool(ConnectionPoolDataSource cpds, String username, |
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124 | String password, int maxConnections, class="keyword">int expiryTime, |
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125 | int connectionWaitTimeout, class="keyword">int logInterval) |
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126 | { |
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127 | totalConnections = 0; |
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128 | pool = new Stack(); |
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129 | timeStamps = new HashMap(); |
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130 | ||
131 | this.cpds = cpds; |
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132 | this.username = username; |
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133 | this.password = password; |
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134 | ||
135 | this.maxConnections = |
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136 | (maxConnections > 0) ? maxConnections : DEFAULT_MAX_CONNECTIONS; |
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137 | ||
138 | this.expiryTime = |
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139 | ((expiryTime > 0) ? expiryTime * 1000 : DEFAULT_EXPIRY_TIME); |
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140 | ||
141 | this.connectionWaitTimeout = |
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142 | ((connectionWaitTimeout > 0) |
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143 | ? connectionWaitTimeout * 1000 |
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144 | : DEFAULT_CONNECTION_WAIT_TIMEOUT); |
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145 | ||
146 | this.logInterval = 1000 * logInterval; |
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147 | ||
148 | if (logInterval > 0) |
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149 | { |
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150 | log.debug("Starting Pool Monitor Thread with Log Interval " |
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151 | + logInterval + " Milliseconds"); |
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152 | ||
153 | // Create monitor thread |
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154 | monitor = new Monitor(); |
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155 | ||
156 | // Indicate that this is a system thread. JVM will quit only |
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157 | // when there are no more active user threads. Settings threads |
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158 | // spawned internally by Torque as daemons allows commandline |
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159 | // applications using Torque to terminate in an orderly manner. |
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160 | monitor.setDaemon(true); |
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161 | monitor.start(); |
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162 | } |
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163 | } |
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164 | ||
165 | /** |
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166 | * Returns a connection that maintains a link to the pool it came from. |
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167 | * |
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168 | * @param username The name of the database user. |
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169 | * @param password The password of the database user. |
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170 | * @return A database connection. |
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171 | * @exception SQLException if there is aproblem with the db connection |
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172 | */ |
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173 | final synchronized PooledConnection getConnection(String username, |
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174 | String password) |
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175 | throws SQLException |
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176 | { |
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177 | if (username != this.username || password != class="keyword">this.password) |
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178 | { |
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179 | throw new SQLException("Username and password are invalid."); |
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180 | } |
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181 | ||
182 | PooledConnection pcon = null; |
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183 | if (pool.empty() && totalConnections < maxConnections) |
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184 | { |
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185 | pcon = getNewConnection(); |
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186 | } |
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187 | else |
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188 | { |
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189 | try |
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190 | { |
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191 | pcon = getInternalPooledConnection(); |
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192 | } |
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193 | catch (Exception e) |
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194 | { |
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195 | throw new SQLException(e.getMessage()); |
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196 | } |
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197 | } |
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198 | return pcon; |
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199 | } |
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200 | ||
201 | /** |
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202 | * Returns a fresh connection to the database. The database type |
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203 | * is specified by <code>driver</code>, and its connection |
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204 | * information by <code>url</code>, <code>username</code>, and |
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205 | * <code>password</code>. |
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206 | * |
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207 | * @return A database connection. |
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208 | * @exception SQLException if there is aproblem with the db connection |
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209 | */ |
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210 | private PooledConnection getNewConnection() |
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211 | throws SQLException |
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212 | { |
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213 | PooledConnection pc = null; |
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214 | if (username == null) |
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215 | { |
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216 | pc = cpds.getPooledConnection(); |
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217 | } |
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218 | else |
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219 | { |
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220 | pc = cpds.getPooledConnection(username, password); |
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221 | } |
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222 | pc.addConnectionEventListener(this); |
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223 | ||
224 | // Age some connections so that there will not be a run on the db, |
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225 | // when connections start expiring |
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226 | // |
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227 | // I did some experimentation here with integers but as this |
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228 | // is not a really time critical path, we keep the floating |
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229 | // point calculation. |
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230 | long currentTime = System.currentTimeMillis(); |
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231 | ||
232 | double ratio = new Long(maxConnections - totalConnections).class="keyword">doubleValue() |
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233 | / maxConnections; |
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234 | ||
235 | long ratioTime = new Double(currentTime - (expiryTime * ratio) / 4) |
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236 | .longValue(); |
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237 | ||
238 | ratioTime = (expiryTime < 0) ? currentTime : ratioTime; |
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239 | ||
240 | timeStamps.put(pc, new Long(ratioTime)); |
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241 | totalConnections++; |
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242 | return pc; |
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243 | } |
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244 | ||
245 | /** |
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246 | * Gets a pooled database connection. |
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247 | * |
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248 | * @return A database connection. |
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249 | * @exception ConnectionWaitTimeoutException Wait time exceeded. |
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250 | * @exception Exception No pooled connections. |
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251 | */ |
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252 | private synchronized PooledConnection getInternalPooledConnection() |
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253 | throws ConnectionWaitTimeoutException, Exception |
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254 | { |
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255 | // We test waitCount > 0 to make sure no other threads are |
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256 | // waiting for a connection. |
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257 | if (waitCount > 0 || pool.empty()) |
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258 | { |
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259 | // The connection pool is empty and we cannot allocate any new |
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260 | // connections. Wait the prescribed amount of time and see if |
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261 | // a connection is returned. |
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262 | try |
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263 | { |
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264 | waitCount++; |
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265 | wait(connectionWaitTimeout); |
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266 | } |
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267 | catch (InterruptedException ignored) |
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268 | { |
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269 | // Don't care how we come out of the wait state. |
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270 | } |
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271 | finally |
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272 | { |
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273 | waitCount--; |
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274 | } |
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275 | ||
276 | // Check for a returned connection. |
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277 | if (pool.empty()) |
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278 | { |
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279 | // If the pool is still empty here, we were not awoken by |
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280 | // someone returning a connection. |
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281 | throw new ConnectionWaitTimeoutException(url); |
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282 | } |
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283 | } |
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284 | return popConnection(); |
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285 | } |
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286 | /** |
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287 | * Helper function that attempts to pop a connection off the pool's stack, |
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288 | * handling the case where the popped connection has become invalid by |
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289 | * creating a new connection. |
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290 | * |
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291 | * @return An existing or new database connection. |
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292 | * @throws Exception if the pool is empty |
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293 | */ |
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294 | private PooledConnection popConnection() |
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295 | throws Exception |
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296 | { |
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297 | while (!pool.empty()) |
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298 | { |
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299 | PooledConnection con = (PooledConnection) pool.pop(); |
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300 | ||
301 | // It's really not safe to assume this connection is |
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302 | // valid even though it's checked before being pooled. |
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303 | if (isValid(con)) |
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304 | { |
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305 | return con; |
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306 | } |
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307 | else |
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308 | { |
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309 | // Close invalid connection. |
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310 | con.close(); |
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311 | totalConnections--; |
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312 | ||
313 | // If the pool is now empty, create a new connection. We're |
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314 | // guaranteed not to exceed the connection limit since we |
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315 | // just killed off one or more invalid connections, and no |
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316 | // one else can be accessing this cache right now. |
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317 | if (pool.empty()) |
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318 | { |
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319 | return getNewConnection(); |
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320 | } |
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321 | } |
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322 | } |
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323 | ||
324 | // The connection pool was empty to start with--don't call this |
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325 | // routine if there's no connection to pop! |
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326 | // TODO: Propose general Turbine assertion failure exception? -PGO |
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327 | throw new Exception("Assertion failure: Attempted to pop " |
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328 | + "connection from empty pool!"); |
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329 | } |
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330 | ||
331 | /** |
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332 | * Helper method which determines whether a connection has expired. |
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333 | * |
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334 | * @param pc The connection to test. |
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335 | * @return True if the connection is expired, false otherwise. |
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336 | */ |
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337 | private boolean isExpired(PooledConnection pc) |
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338 | { |
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339 | // Test the age of the connection (defined as current time |
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340 | // minus connection birthday) against the connection pool |
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341 | // expiration time. |
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342 | long birth = ((Long) timeStamps.get(pc)).class="keyword">longValue(); |
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343 | long age = System.currentTimeMillis() - birth; |
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344 | ||
345 | boolean dead = (expiryTime > 0) |
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346 | ? age > expiryTime |
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347 | : age > DEFAULT_EXPIRY_TIME; |
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348 | ||
349 | return dead; // He is dead, Jim. |
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350 | } |
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351 | ||
352 | /** |
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353 | * Determines if a connection is still valid. |
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354 | * |
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355 | * @param connection The connection to test. |
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356 | * @return True if the connection is valid, false otherwise. |
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357 | */ |
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358 | private boolean isValid(PooledConnection connection) |
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359 | { |
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360 | // all this code is commented out because |
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361 | // connection.getConnection() is called when the connection |
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362 | // is returned to the pool and it will open a new logical Connection |
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363 | // which does not get closed, then when it is called again |
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364 | // when a connection is requested it likely fails because a |
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365 | // new Connection has been requested and the old one is still |
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366 | // open. need to either do it right or skip it. null check |
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367 | // was not working either. |
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368 | ||
369 | //try |
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370 | //{ |
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371 | // This will throw an exception if: |
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372 | // The connection is null |
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373 | // The connection is closed |
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374 | // Therefore, it would be false. |
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375 | //connection.getConnection(); |
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376 | // Check for expiration |
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377 | return !isExpired(connection); |
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378 | /* |
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379 | } |
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380 | catch (SQLException e) |
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381 | { |
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382 | return false; |
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383 | } |
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384 | */ |
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385 | } |
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386 | ||
387 | ||
388 | /** |
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389 | * Close any open connections when this object is garbage collected. |
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390 | * |
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391 | * @exception Throwable Anything might happen... |
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392 | */ |
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393 | protected void finalize() |
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394 | throws Throwable |
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395 | { |
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396 | shutdown(); |
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397 | } |
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398 | ||
399 | /** |
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400 | * Close all connections to the database, |
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401 | */ |
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402 | void shutdown() |
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403 | { |
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404 | if (pool != null) |
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405 | { |
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406 | while (!pool.isEmpty()) |
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407 | { |
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408 | try |
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409 | { |
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410 | ((PooledConnection) pool.pop()).close(); |
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411 | } |
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412 | catch (SQLException ignore) |
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413 | { |
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414 | } |
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415 | finally |
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416 | { |
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417 | totalConnections--; |
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418 | } |
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419 | } |
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420 | } |
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421 | monitor.shutdown(); |
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422 | } |
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423 | ||
424 | /** |
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425 | * Returns the Total connections in the pool |
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426 | * |
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427 | * @return total connections in the pool |
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428 | */ |
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429 | int getTotalCount() |
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430 | { |
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431 | return totalConnections; |
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432 | } |
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433 | ||
434 | /** |
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435 | * Returns the available connections in the pool |
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436 | * |
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437 | * @return number of available connections in the pool |
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438 | */ |
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439 | int getNbrAvailable() |
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440 | { |
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441 | return pool.size(); |
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442 | } |
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443 | ||
444 | /** |
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445 | * Returns the checked out connections in the pool |
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446 | * |
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447 | * @return number of checked out connections in the pool |
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448 | */ |
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449 | int getNbrCheckedOut() |
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450 | { |
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451 | return (totalConnections - pool.size()); |
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452 | } |
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453 | ||
454 | /** |
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455 | * Decreases the count of connections in the pool |
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456 | * and also calls <code>notify()</code>. |
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457 | */ |
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458 | void decrementConnections() |
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459 | { |
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460 | totalConnections--; |
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461 | notify(); |
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462 | } |
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463 | ||
464 | /** |
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465 | * Get the name of the pool |
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466 | * |
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467 | * @return the name of the pool |
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468 | */ |
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469 | String getPoolName() |
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470 | { |
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471 | return toString(); |
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472 | } |
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473 | ||
474 | // *********************************************************************** |
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475 | // java.sql.ConnectionEventListener implementation |
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476 | // *********************************************************************** |
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477 | ||
478 | /** |
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479 | * This will be called if the Connection returned by the getConnection |
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480 | * method came from a PooledConnection, and the user calls the close() |
|
481 | * method of this connection object. What we need to do here is to |
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482 | * release this PooledConnection from our pool... |
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483 | * |
|
484 | * @param event the connection event |
|
485 | */ |
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486 | public void connectionClosed(ConnectionEvent event) |
|
487 | { |
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488 | releaseConnection((PooledConnection) event.getSource()); |
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489 | } |
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490 | ||
491 | /** |
|
492 | * If a fatal error occurs, close the underlying physical connection so as |
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493 | * not to be returned in the future |
|
494 | * |
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495 | * @param event the connection event |
|
496 | */ |
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497 | public void connectionErrorOccurred(ConnectionEvent event) |
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498 | { |
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499 | try |
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500 | { |
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501 | System.err.println("CLOSING DOWN CONNECTION DUE TO INTERNAL ERROR"); |
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502 | //remove this from the listener list because we are no more |
|
503 | //interested in errors since we are about to close this connection |
|
504 | ((PooledConnection) event.getSource()) |
|
505 | .removeConnectionEventListener(this); |
|
506 | } |
|
507 | catch (Exception ignore) |
|
508 | { |
|
509 | //just ignore |
|
510 | } |
|
511 | ||
512 | try |
|
513 | { |
|
514 | closePooledConnection((PooledConnection) event.getSource()); |
|
515 | } |
|
516 | catch (Exception ignore) |
|
517 | { |
|
518 | //just ignore |
|
519 | } |
|
520 | } |
|
521 | ||
522 | /** |
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523 | * This method returns a connection to the pool, and <b>must</b> |
|
524 | * be called by the requestor when finished with the connection. |
|
525 | * |
|
526 | * @param pcon The database connection to release. |
|
527 | */ |
|
528 | private synchronized void releaseConnection(PooledConnection pcon) |
|
529 | { |
|
530 | if (isValid(pcon)) |
|
531 | { |
|
532 | pool.push(pcon); |
|
533 | notify(); |
|
534 | } |
|
535 | else |
|
536 | { |
|
537 | closePooledConnection(pcon); |
|
538 | } |
|
539 | } |
|
540 | ||
541 | /** |
|
542 | * |
|
543 | * @param pcon The database connection to close. |
|
544 | */ |
|
545 | private void closePooledConnection(PooledConnection pcon) |
|
546 | { |
|
547 | try |
|
548 | { |
|
549 | pcon.close(); |
|
550 | timeStamps.remove(pcon); |
|
551 | } |
|
552 | catch (Exception e) |
|
553 | { |
|
554 | log.error("Error occurred trying to close a PooledConnection.", e); |
|
555 | } |
|
556 | finally |
|
557 | { |
|
558 | decrementConnections(); |
|
559 | } |
|
560 | } |
|
561 | ||
562 | /////////////////////////////////////////////////////////////////////////// |
|
563 | ||
564 | /** |
|
565 | * This inner class monitors the <code>PoolBrokerService</code>. |
|
566 | * |
|
567 | * This class is capable of logging the number of connections available in |
|
568 | * the pool periodically. This can prove useful if you application |
|
569 | * frozes after certain amount of time/requests and you suspect |
|
570 | * that you have connection leakage problem. |
|
571 | * |
|
572 | * Set the <code>logInterval</code> property of your pool definition |
|
573 | * to the number of seconds you want to elapse between loging the number of |
|
574 | * connections. |
|
575 | */ |
|
576 | 0 | protected class Monitor extends Thread |
577 | { |
|
578 | /** true if the monot is running */ |
|
579 | 0 | private boolean isRun = true; |
580 | ||
581 | /** |
|
582 | * run method for the monitor thread |
|
583 | */ |
|
584 | public void run() |
|
585 | { |
|
586 | 0 | StringBuffer buf = new StringBuffer(); |
587 | 0 | while (logInterval > 0 && isRun) |
588 | { |
|
589 | 0 | buf.setLength(0); |
590 | ||
591 | 0 | buf.append(getPoolName()); |
592 | 0 | buf.append(" avail: ").append(getNbrAvailable()); |
593 | 0 | buf.append(" in use: ").append(getNbrCheckedOut()); |
594 | 0 | buf.append(" total: ").append(getTotalCount()); |
595 | 0 | log.info(buf.toString()); |
596 | ||
597 | // Wait for a bit. |
|
598 | try |
|
599 | { |
|
600 | 0 | Thread.sleep(logInterval); |
601 | } |
|
602 | 0 | catch (InterruptedException ignored) |
603 | { |
|
604 | 0 | } |
605 | } |
|
606 | 0 | } |
607 | ||
608 | /** |
|
609 | * Shut down the monitor |
|
610 | */ |
|
611 | public void shutdown() |
|
612 | { |
|
613 | 0 | isRun = false; |
614 | 0 | } |
615 | } |
|
616 | } |
This report is generated by jcoverage, Maven and Maven JCoverage Plugin. |