C3P0属性设置和数据库连接池的获取

在C3p0构建时，有驱动相关信息及数据库连接池相关的属性设置，及连接的获取，今天我们先来看一下，驱动相关信息及数据库连接池相关的属性设置，在连接的获取。
从下面几句开始,

Java代码

1. cpDSource = new ComboPooledDataSource();

2. //设置DriverManagerDataSource驱动相关信息

3. cpDSource.setDriverClass(props.getProperty("driver"));

4. cpDSource.setJdbcUrl(props.getProperty("url"));

5. cpDSource.setUser(props.getProperty("user"));

6. cpDSource.setPassword(props.getProperty("password"));

//AbstractComboPooledDataSource的两个关键内部成员DriverManagerDataSource，WrapperConnectionPoolDataSource

Java代码下载

1. public AbstractComboPooledDataSource(boolean autoregister)

2. {

3. //

4. super(autoregister);

5. //新建驱动数据源管理器

6. dmds = new DriverManagerDataSource();

7. //新建数据库连接池

8. wcpds = new WrapperConnectionPoolDataSource();

9. //设置数据连接池的数据源驱动管理器

10. wcpds.setNestedDataSource(dmds);

11. try

12. {

13. setConnectionPoolDataSource(wcpds);

14. }

15. catch(PropertyVetoException e)

16. {

17. logger.log(MLevel.WARNING, "Hunh??? This can't happen. We haven't set up any listeners to veto the property change yet!", e);

18. throw new RuntimeException((new StringBuilder()).append("Hunh??? This can't happen. We haven't set up any listeners to veto the property change yet! ").append(e).toString());

19. }

20. setUpPropertyEvents();

21. }

22. }

23. //设置driverClass

24. public void setDriverClass(String driverClass)

25. throws PropertyVetoException

26. {

27. dmds.setDriverClass(driverClass);

28. }

29. //设置jdbcUrl

30. public void setJdbcUrl(String jdbcUrl)

31. {

32. if(diff(dmds.getJdbcUrl(), jdbcUrl))

33. {

34. dmds.setJdbcUrl(jdbcUrl);

35. resetPoolManager(false);

36. }

37. }

38. //设置user

39. public void setUser(String user)

40. {

41. if(diff(dmds.getUser(), user))

42. {

43. dmds.setUser(user);

44. resetPoolManager(false);

45. }

46. }

47. //设置password

48. public void setPassword(String password)

49. {

50. if(diff(dmds.getPassword(), password))

51. {

52. dmds.setPassword(password);

53. resetPoolManager(false);

54. }

55. }

//设置WrapperConnectionPoolDataSource相关属性

Java代码 下载

1. cpDSource.setInitialPoolSize(5);

2. cpDSource.setMaxPoolSize(30);

3. cpDSource.setMinPoolSize(5);

4. cpDSource.setMaxStatements(100);

5. cpDSource.setIdleConnectionTestPeriod(60);

6. cpDSource.setBreakAfterAcquireFailure(false);

7. cpDSource.setAcquireRetryAttempts(30);

8. cpDSource.setTestConnectionOnCheckout(false);

//设置连接失败尝试连接数

Java代码

1. public void setAcquireRetryAttempts(int acquireRetryAttempts)

2. {

3. if(diff(wcpds.getAcquireRetryAttempts(), acquireRetryAttempts))

4. {

5. wcpds.setAcquireRetryAttempts(acquireRetryAttempts);

6. resetPoolManager(false);

7. }

8. }

9. public int getAcquireRetryDelay()

10. {

11. return wcpds.getAcquireRetryDelay();

12. }

13. public void setAcquireRetryDelay(int acquireRetryDelay)

14. {

15. if(diff(wcpds.getAcquireRetryDelay(), acquireRetryDelay))

16. {

17. wcpds.setAcquireRetryDelay(acquireRetryDelay);

18. resetPoolManager(false);

19. }

20. }

21. public boolean isAutoCommitOnClose()

22. {

23. return wcpds.isAutoCommitOnClose();

24. }

25. //设置是否自动提交

26. public void setAutoCommitOnClose(boolean autoCommitOnClose)

27. {

28. if(diff(wcpds.isAutoCommitOnClose(), autoCommitOnClose))

29. {

30. wcpds.setAutoCommitOnClose(autoCommitOnClose);

31. resetPoolManager(false);

32. }

33. }

34. public int getInitialPoolSize()

35. {

36. return wcpds.getInitialPoolSize();

37. }

38. //连接池初始化大小

39. public void setInitialPoolSize(int initialPoolSize)

40. {

41. if(diff(wcpds.getInitialPoolSize(), initialPoolSize))

42. {

43. wcpds.setInitialPoolSize(initialPoolSize);

44. resetPoolManager(false);

45. }

46. }

47. 下载

48. public int getMaxIdleTime()

49. {

50. return wcpds.getMaxIdleTime();

51. }

52. //maxIdleTime

53. public void setMaxIdleTime(int maxIdleTime)

54. {

55. if(diff(wcpds.getMaxIdleTime(), maxIdleTime))

56. {

57. wcpds.setMaxIdleTime(maxIdleTime);

58. resetPoolManager(false);

59. }

60. }

61. //maxPoolSize

62. public void setMaxPoolSize(int maxPoolSize)

63. {

64. if(diff(wcpds.getMaxPoolSize(), maxPoolSize))

65. {

66. wcpds.setMaxPoolSize(maxPoolSize);

67. resetPoolManager(false);

68. }

69. }

70. //maxStatements

71. public void setMaxStatements(int maxStatements)

72. {

73. if(diff(wcpds.getMaxStatements(), maxStatements))

74. {

75. wcpds.setMaxStatements(maxStatements);

76. resetPoolManager(false);

77. }

78. }

从上面可以看出cpDSource初始化driver相关属性，是初始化数据源驱动管理器DriverManagerDataSource的属性；初始化poolConnection相关属性，是初始化数据库连接池包装类WrapperConnectionPoolDataSource的属性。

再看连接的获取，从下面一句开始，

Java代码

1. con = cpDSource.getConnection();

此方法在ComboPooledDataSource和其父类中都没，追溯到AbstractComboPooledDataSource的
父类AbstractPoolBackedDataSource
//AbstractPoolBackedDataSource

Java代码

1. public abstract class AbstractPoolBackedDataSource extends PoolBackedDataSourceBase

2. implements PooledDataSource

3. {

4. public Connection getConnection()

5. throws SQLException

6. {

7. //获取数据库连接池管理器

8. PooledConnection pc = getPoolManager().getPool().checkoutPooledConnection();

9. //从数据库连接池，返回数据库连接

10. return pc.getConnection();

11. }

12. }

先看获取数据库连接池管理器
//获取数据库连接池管理器
PooledConnection pc = getPoolManager().getPool().checkoutPooledConnection();

//获取数据库连接池管理器
下载

Java代码

1. private synchronized C3P0PooledConnectionPoolManager getPoolManager()

2. throws SQLException

3. {

4. if(poolManager == null)

5. {

6. //获取数据源数据库连接池

7. ConnectionPoolDataSource cpds = assertCpds();

8. //构建数据库连接池管理器

9. poolManager = new C3P0PooledConnectionPoolManager(cpds, null, null, getNumHelperThreads(), getIdentityToken(), getDataSourceName());

10. if(logger.isLoggable(MLevel.INFO))

11. logger.info((new StringBuilder()).append("Initializing c3p0 pool... ").append(toString(true)).toString());

12. }

13. return poolManager;

14. }

15. //确定数据源数据库连接池

16. private synchronized ConnectionPoolDataSource assertCpds()

17. throws SQLException

18. {

19. if(is_closed)

20. throw new SQLException((new StringBuilder()).append(this).append(" has been closed() -- you can no longer use it.").toString());

21. //获取数据源数据库连接池

22. ConnectionPoolDataSource out = getConnectionPoolDataSource();

23. if(out == null)

24. throw new SQLException("Attempted to use an uninitialized PoolBackedDataSource. Please call setConnectionPoolDataSource( ... ) to initialize.");

25. else

26. return out;

27. }

//PoolBackedDataSourceBase

Java代码

1. public class PoolBackedDataSourceBase extends IdentityTokenResolvable

2. implements Referenceable, Serializable

3. {

4. //获取数据源数据库连接池

5. public synchronized ConnectionPoolDataSource getConnectionPoolDataSource()

6. {

7. return connectionPoolDataSource;

8. }

9. public synchronized void setConnectionPoolDataSource(ConnectionPoolDataSource connectionPoolDataSource)

10. throws PropertyVetoException

11. {

12. ConnectionPoolDataSource oldVal = this.connectionPoolDataSource;

13. if(!eqOrBothNull(oldVal, connectionPoolDataSource))

14. vcs.fireVetoableChange("connectionPoolDataSource", oldVal, connectionPoolDataSource);

15. this.connectionPoolDataSource = connectionPoolDataSource;

16. if(!eqOrBothNull(oldVal, connectionPoolDataSource))

17. pcs.firePropertyChange("connectionPoolDataSource", oldVal, connectionPoolDataSource);

18. }

19. }

这个数据源数据连接池是什么呢？还记得我们前面，有讲过AbstractComboPooledDataSource的构造有这么一段

Java代码下载

1. public AbstractComboPooledDataSource(boolean autoregister)

2. {

3. super(autoregister);

4. dmds = new DriverManagerDataSource();

5. wcpds = new WrapperConnectionPoolDataSource();

6. wcpds.setNestedDataSource(dmds);

7. try

8. {

9. //设置数据源数据库连接池为WrapperConnectionPoolDataSource

10. setConnectionPoolDataSource(wcpds);

11. }

12. }

现在回到getPoolManager的构建数据库连接池管理器这一句

Java代码

1. poolManager = new C3P0PooledConnectionPoolManager(cpds, null, null, getNumHelperThreads(), getIdentityToken(), getDataSourceName());

//C3P0PooledConnectionPoolManager

Java代码

1. public final class C3P0PooledConnectionPoolManager

2. {

3. private static final boolean POOL_EVENT_SUPPORT = false;

4. private static final CoalesceChecker COALESCE_CHECKER;

5. static final Coalescer COALESCER;

6. static final int DFLT_NUM_TASK_THREADS_PER_DATA_SOURCE = 3;

7. ThreadPoolAsynchronousRunner taskRunner;//

8. ThreadPoolAsynchronousRunner deferredStatementDestroyer;

9. Timer timer;

10. ResourcePoolFactory rpfact;

11. Map authsToPools;

12. final ConnectionPoolDataSource cpds;

13. final Map propNamesToReadMethods;

14. final Map flatPropertyOverrides;

15. final Map userOverrides;

16. final DbAuth defaultAuth;

17. final String parentDataSourceIdentityToken;

18. final String parentDataSourceName;

19. int num_task_threads;

20. static

21. {

22. COALESCE_CHECKER = IdentityTokenizedCoalesceChecker.INSTANCE;

23. COALESCER = CoalescerFactory.createCoalescer(COALESCE_CHECKER, true, false);

24. }

25. //初始化C3P0PooledConnectionPoolManager，cpds为WrapperConnectionPoolDataSource

26. public C3P0PooledConnectionPoolManager(ConnectionPoolDataSource cpds, Map flatPropertyOverrides, Map forceUserOverrides, int num_task_threads, String parentDataSourceIdentityToken, String parentDataSourceName)

27. throws SQLException

28. {

29. //任务线程数

30. this.num_task_threads = 3;

31. try

32. {

33. this.cpds = cpds;//初始化数据库连接池

34. this.flatPropertyOverrides = flatPropertyOverrides;

35. this.num_task_threads = num_task_threads;

36. this.parentDataSourceIdentityToken = parentDataSourceIdentityToken;

37. this.parentDataSourceName = parentDataSourceName;

38. DbAuth auth = null;

39. if(flatPropertyOverrides != null)

40. {

41. String overrideUser = (String)flatPropertyOverrides.get("overrideDefaultUser");

42. String overridePassword = (String)flatPropertyOverrides.get("overrideDefaultPassword");

43. if(overrideUser == null)

44. {

45. overrideUser = (String)flatPropertyOverrides.get("user");

46. overridePassword = (String)flatPropertyOverrides.get("password");

47. }

48. if(overrideUser != null)

49. auth = new DbAuth(overrideUser, overridePassword);

50. }

51. if(auth == null)

52. //初始化数据库验证

53. auth = C3P0ImplUtils.findAuth(cpds);

54. defaultAuth = auth;

55. Map tmp = new HashMap();

56. BeanInfo bi = Introspector.getBeanInfo(cpds.getClass());

57. PropertyDescriptor pds[] = bi.getPropertyDescriptors();

58. PropertyDescriptor pd = null;

59. int i = 0;

60. for(int len = pds.length; i < len; i++)

61. { 下载

62. pd = pds[i];

63. String name = pd.getName();

64. Method m = pd.getReadMethod();

65. if(m != null)

66. tmp.put(name, m);

67. }

68. propNamesToReadMethods = tmp;

69. if(forceUserOverrides == null)

70. {

71. Method uom = (Method)propNamesToReadMethods.get("userOverridesAsString");

72. if(uom != null)

73. {

74. String uoas = (String)uom.invoke(cpds, (Object[])null);

75. Map uo = C3P0ImplUtils.parseUserOverridesAsString(uoas);

76. userOverrides = uo;

77. } else

78. {

79. userOverrides = Collections.EMPTY_MAP;

80. }

81. } else

82. {

83. userOverrides = forceUserOverrides;

84. }

85. poolsInit();

86. }

87. catch(Exception e)

88. {

89. logger.log(MLevel.FINE, null, e);

90. throw SqlUtils.toSQLException(e);

91. }

92. }

93. }

94. //连接池初始化

95. private void poolsInit()

96. {

97. boolean privilege_spawned_threads = getPrivilegeSpawnedThreads();

98. String contextClassLoaderSource = getContextClassLoaderSource();

99. class _cls1ContextClassLoaderPoolsInitThread extends Thread

100. {

101. public void run()

102. {

103. //

104. maybePrivilegedPoolsInit(privilege_spawned_threads);

105. }

106. final boolean val$privilege_spawned_threads;

107. final C3P0PooledConnectionPoolManager this$0;

108. _cls1ContextClassLoaderPoolsInitThread(boolean flag)

109. {

110. this.this$0 = C3P0PooledConnectionPoolManager.this;

111. privilege_spawned_threads = flag;

112. super();

113. setContextClassLoader(ccl);

114. }

115. }

116. try

117. {

118. if("library".equalsIgnoreCase(contextClassLoaderSource))

119. {

120. //

121. Thread t = new _cls1ContextClassLoaderPoolsInitThread(privilege_spawned_threads);

122. t.start();

123. t.join();

124. } else

125. if("none".equalsIgnoreCase(contextClassLoaderSource))

126. {

127. Thread t = new _cls1ContextClassLoaderPoolsInitThread(privilege_spawned_threads);

128. t.start();

129. t.join();

130. } else

131. {

132. if(logger.isLoggable(MLevel.WARNING) && !"caller".equalsIgnoreCase(contextClassLoaderSource))

133. logger.log(MLevel.WARNING, (new StringBuilder()).append("Unknown contextClassLoaderSource: ").append(contextClassLoaderSource).append(" -- should be 'caller', 'library', or 'none'. Using default value 'caller'.").toString());

134. maybePrivilegedPoolsInit(privilege_spawned_threads);

135. }

136. }

137. }

138. private void maybePrivilegedPoolsInit(boolean privilege_spawned_threads)

139. {

140. if(privilege_spawned_threads)

141. {

142. PrivilegedAction privilegedPoolsInit = new PrivilegedAction() {

143. public Void run()

144. {

145. //委托给_poolsInit

146. _poolsInit();

147. return null;

148. }

149. public volatile Object run()

150. {

151. return run();

152. }

153. final C3P0PooledConnectionPoolManager this$0;

154. {

155. this.this$0 = C3P0PooledConnectionPoolManager.this;

156. super();

157. }

158. };

159. AccessController.doPrivileged(privilegedPoolsInit);

160. } else

161. {

162. _poolsInit();

163. }

164. }

165. //终于找个了poolsInit的关键，初始化定时任务调度器，及死锁检测线程，及延时死锁检测线程

166. private synchronized void _poolsInit()

167. {

168. String idStr = idString();

169. timer = new Timer((new StringBuilder()).append(idStr).append("-AdminTaskTimer").toString(), true);

170. int matt = getMaxAdministrativeTaskTime();

171. //创建任务线程调度器

172. taskRunner = createTaskRunner(num_task_threads, matt, timer, (new StringBuilder()).append(idStr).append("-HelperThread").toString());

173. int num_deferred_close_threads = getStatementCacheNumDeferredCloseThreads();

174. if(num_deferred_close_threads > 0)

175. deferredStatementDestroyer = createTaskRunner(num_deferred_close_threads, matt, timer, (new StringBuilder()).append(idStr).append("-DeferredStatementDestroyerThread").toString());

176. else

177. deferredStatementDestroyer = null;

178. rpfact = BasicResourcePoolFactory.createNoEventSupportInstance(taskRunner, timer);

179. authsToPools = new HashMap();

180. }

从上面可以看出getPoolManager()实际上，是初始化数据库连接池管理器C3P0PooledConnectionPoolManager，初始化C3P0PooledConnectionPoolManager的