Shulou(Shulou.com)06/01 Report--

During the construction of C3p0, there are driver-related information and database connection pool-related property settings, and connection acquisition. Today, let's take a look at driver-related information and database connection pool-related property settings in connection acquisition.

Start with the following sentences

Java code

CpDSource = new ComboPooledDataSource ()

/ / set DriverManagerDataSource driver related information

CpDSource.setDriverClass (props.getProperty ("driver"))

CpDSource.setJdbcUrl (props.getProperty ("url"))

CpDSource.setUser (props.getProperty ("user"))

CpDSource.setPassword (props.getProperty ("password"))

/ / DriverManagerDataSource,WrapperConnectionPoolDataSource, two key internal members of AbstractComboPooledDataSource

Java code download

Public AbstractComboPooledDataSource (boolean autoregister)

{

/ /

Super (autoregister)

/ / create a new driver data source manager

Dmds = new DriverManagerDataSource ()

/ / create a new database connection pool

Wcpds = new WrapperConnectionPoolDataSource ()

/ / set the data source driver manager for the data connection pool

Wcpds.setNestedDataSource (dmds)

Try

{

SetConnectionPoolDataSource (wcpds)

}

Catch (PropertyVetoException e)

{

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

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) .append ()

}

SetUpPropertyEvents ()

}

}

/ / set driverClass

Public void setDriverClass (String driverClass)

Throws PropertyVetoException

{

Dmds.setDriverClass (driverClass)

}

/ / set jdbcUrl

Public void setJdbcUrl (String jdbcUrl)

{

If (diff (dmds.getJdbcUrl (), jdbcUrl))

{

Dmds.setJdbcUrl (jdbcUrl)

ResetPoolManager (false)

}

}

/ / set user

Public void setUser (String user)

{

If (diff (dmds.getUser (), user))

{

Dmds.setUser (user)

ResetPoolManager (false)

}

}

/ / set password

Public void setPassword (String password)

{

If (diff (dmds.getPassword (), password))

{

Dmds.setPassword (password)

ResetPoolManager (false)

}

}

/ / set WrapperConnectionPoolDataSource related properties

Java code download

CpDSource.setInitialPoolSize (5)

CpDSource.setMaxPoolSize (30)

CpDSource.setMinPoolSize (5)

CpDSource.setMaxStatements (100)

CpDSource.setIdleConnectionTestPeriod (60)

CpDSource.setBreakAfterAcquireFailure (false)

CpDSource.setAcquireRetryAttempts (30)

CpDSource.setTestConnectionOnCheckout (false)

/ / set the number of failed connection attempts

Java code

Public void setAcquireRetryAttempts (int acquireRetryAttempts)

{

If (diff (wcpds.getAcquireRetryAttempts (), acquireRetryAttempts))

{

Wcpds.setAcquireRetryAttempts (acquireRetryAttempts)

ResetPoolManager (false)

}

}

Public int getAcquireRetryDelay ()

{

Return wcpds.getAcquireRetryDelay ()

}

Public void setAcquireRetryDelay (int acquireRetryDelay)

{

If (diff (wcpds.getAcquireRetryDelay (), acquireRetryDelay))

{

Wcpds.setAcquireRetryDelay (acquireRetryDelay)

ResetPoolManager (false)

}

}

Public boolean isAutoCommitOnClose ()

{

Return wcpds.isAutoCommitOnClose ()

}

/ / set whether to submit automatically

Public void setAutoCommitOnClose (boolean autoCommitOnClose)

{

If (diff (wcpds.isAutoCommitOnClose (), autoCommitOnClose))

{

Wcpds.setAutoCommitOnClose (autoCommitOnClose)

ResetPoolManager (false)

}

}

Public int getInitialPoolSize ()

{

Return wcpds.getInitialPoolSize ()

}

/ / connection pool initialization size

Public void setInitialPoolSize (int initialPoolSize)

{

If (diff (wcpds.getInitialPoolSize (), initialPoolSize))

{

Wcpds.setInitialPoolSize (initialPoolSize)

ResetPoolManager (false)

}

}

download

Public int getMaxIdleTime ()

{

Return wcpds.getMaxIdleTime ()

}

/ / maxIdleTime

Public void setMaxIdleTime (int maxIdleTime)

{

If (diff (wcpds.getMaxIdleTime (), maxIdleTime))

{

Wcpds.setMaxIdleTime (maxIdleTime)

ResetPoolManager (false)

}

}

/ / maxPoolSize

Public void setMaxPoolSize (int maxPoolSize)

{

If (diff (wcpds.getMaxPoolSize (), maxPoolSize))

{

Wcpds.setMaxPoolSize (maxPoolSize)

ResetPoolManager (false)

}

}

/ / maxStatements

Public void setMaxStatements (int maxStatements)

{

If (diff (wcpds.getMaxStatements (), maxStatements))

{

Wcpds.setMaxStatements (maxStatements)

ResetPoolManager (false)

}

}

From the above, you can see that cpDSource initializes the attributes related to driver, which initializes the attributes of the data source driver manager DriverManagerDataSource, and initializes the attributes related to poolConnection, which initializes the database connection pool wrapper class WrapperConnectionPoolDataSource.

Let's look at the acquisition of the connection, starting with the following sentence.

Java code

Con = cpDSource.getConnection ()

This method is not found in ComboPooledDataSource or its parent class, dating back to the

Parent class AbstractPoolBackedDataSource

/ / AbstractPoolBackedDataSource

Java code

Public abstract class AbstractPoolBackedDataSource extends PoolBackedDataSourceBase

Implements PooledDataSource

{

Public Connection getConnection ()

Throws SQLException

{

/ / get the database connection pool manager

PooledConnection pc = getPoolManager (). GetPool (). CheckoutPooledConnection ()

/ / return the database connection from the database connection pool

Return pc.getConnection ()

}

}

Let's take a look at getting the database connection pool manager.

/ / get the database connection pool manager

PooledConnection pc = getPoolManager (). GetPool (). CheckoutPooledConnection ()

/ / get the database connection pool manager

download

Java code

Private synchronized C3P0PooledConnectionPoolManager getPoolManager ()

Throws SQLException

{

If (poolManager = = null)

{

/ / get data source database connection pool

ConnectionPoolDataSource cpds = assertCpds ()

/ / build a database connection pool manager

PoolManager = new C3P0PooledConnectionPoolManager (cpds, null, null, getNumHelperThreads (), getIdentityToken (), getDataSourceName ())

If (logger.isLoggable (MLevel.INFO))

Logger.info ((new StringBuilder ()) .append ("Initializing c3p0 pool...") .append (toString (true)) .toString ())

}

Return poolManager

}

/ / determine the data source database connection pool

Private synchronized ConnectionPoolDataSource assertCpds ()

Throws SQLException

{

If (is_closed)

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

/ / get data source database connection pool

ConnectionPoolDataSource out = getConnectionPoolDataSource ()

If (out = = null)

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

Else

Return out

}

/ / PoolBackedDataSourceBase

Java code

Public class PoolBackedDataSourceBase extends IdentityTokenResolvable

Implements Referenceable, Serializable

{

/ / get data source database connection pool

Public synchronized ConnectionPoolDataSource getConnectionPoolDataSource ()

{

Return connectionPoolDataSource

}

Public synchronized void setConnectionPoolDataSource (ConnectionPoolDataSource connectionPoolDataSource)

Throws PropertyVetoException

{

ConnectionPoolDataSource oldVal = this.connectionPoolDataSource

If (! eqOrBothNull (oldVal, connectionPoolDataSource))

Vcs.fireVetoableChange ("connectionPoolDataSource", oldVal, connectionPoolDataSource)

This.connectionPoolDataSource = connectionPoolDataSource

If (! eqOrBothNull (oldVal, connectionPoolDataSource))

Pcs.firePropertyChange ("connectionPoolDataSource", oldVal, connectionPoolDataSource)

}

}

What is this data source data connection pool? Remember before, we talked about the construction of AbstractComboPooledDataSource.

Java code download

Public AbstractComboPooledDataSource (boolean autoregister)

{

Super (autoregister)

Dmds = new DriverManagerDataSource ()

Wcpds = new WrapperConnectionPoolDataSource ()

Wcpds.setNestedDataSource (dmds)

Try

{

/ / set the data source database connection pool to WrapperConnectionPoolDataSource

SetConnectionPoolDataSource (wcpds)

}

}

Now go back to the sentence of getPoolManager's build database connection pool manager

Java code

PoolManager = new C3P0PooledConnectionPoolManager (cpds, null, null, getNumHelperThreads (), getIdentityToken (), getDataSourceName ())

/ / C3P0PooledConnectionPoolManager

Java code

Public final class C3P0PooledConnectionPoolManager

{

Private static final boolean POOL_EVENT_SUPPORT = false

Private static final CoalesceChecker COALESCE_CHECKER

Static final Coalescer COALESCER

Static final int DFLT_NUM_TASK_THREADS_PER_DATA_SOURCE = 3

ThreadPoolAsynchronousRunner taskRunner;//

ThreadPoolAsynchronousRunner deferredStatementDestroyer

Timer timer

ResourcePoolFactory rpfact

Map authsToPools

Final ConnectionPoolDataSource cpds

Final Map propNamesToReadMethods

Final Map flatPropertyOverrides

Final Map userOverrides

Final DbAuth defaultAuth

Final String parentDataSourceIdentityToken

Final String parentDataSourceName

Int num_task_threads

Static

{

COALESCE_CHECKER = IdentityTokenizedCoalesceChecker.INSTANCE

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

}

/ / initialize C3P0PooledConnectionPoolManagerJournal cpds to WrapperConnectionPoolDataSource

Public C3P0PooledConnectionPoolManager (ConnectionPoolDataSource cpds, Map flatPropertyOverrides, Map forceUserOverrides, int num_task_threads, String parentDataSourceIdentityToken, String parentDataSourceName)

Throws SQLException

{

/ / number of task threads

This.num_task_threads = 3

Try

{

This.cpds = cpds;// initializes the database connection pool

This.flatPropertyOverrides = flatPropertyOverrides

This.num_task_threads = num_task_threads

This.parentDataSourceIdentityToken = parentDataSourceIdentityToken

This.parentDataSourceName = parentDataSourceName

DbAuth auth = null

If (flatPropertyOverrides! = null)

{

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

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

If (overrideUser = = null)

{

OverrideUser = (String) flatPropertyOverrides.get ("user")

OverridePassword = (String) flatPropertyOverrides.get ("password")

}

If (overrideUser! = null)

Auth = new DbAuth (overrideUser, overridePassword)

}

If (auth = = null)

/ / initialize database verification

Auth = C3P0ImplUtils.findAuth (cpds)

DefaultAuth = auth

Map tmp = new HashMap ()

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

PropertyDescriptor pds [] = bi.getPropertyDescriptors ()

PropertyDescriptor pd = null

Int I = 0

For (int len = pds.length; I

< len; i++) { 下载 pd = pds[i]; String name = pd.getName(); Method m = pd.getReadMethod(); if(m != null) tmp.put(name, m); } propNamesToReadMethods = tmp; if(forceUserOverrides == null) { Method uom = (Method)propNamesToReadMethods.get("userOverridesAsString"); if(uom != null) { String uoas = (String)uom.invoke(cpds, (Object[])null); Map uo = C3P0ImplUtils.parseUserOverridesAsString(uoas); userOverrides = uo; } else { userOverrides = Collections.EMPTY_MAP; } } else { userOverrides = forceUserOverrides; } poolsInit(); } catch(Exception e) { logger.log(MLevel.FINE, null, e); throw SqlUtils.toSQLException(e); } } } //连接池初始化 private void poolsInit() { boolean privilege_spawned_threads = getPrivilegeSpawnedThreads(); String contextClassLoaderSource = getContextClassLoaderSource(); class _cls1ContextClassLoaderPoolsInitThread extends Thread { public void run() { // maybePrivilegedPoolsInit(privilege_spawned_threads); } final boolean val$privilege_spawned_threads; final C3P0PooledConnectionPoolManager this$0; _cls1ContextClassLoaderPoolsInitThread(boolean flag) { this.this$0 = C3P0PooledConnectionPoolManager.this; privilege_spawned_threads = flag; super(); setContextClassLoader(ccl); } } try { if("library".equalsIgnoreCase(contextClassLoaderSource)) { // Thread t = new _cls1ContextClassLoaderPoolsInitThread(privilege_spawned_threads); t.start(); t.join(); } else if("none".equalsIgnoreCase(contextClassLoaderSource)) { Thread t = new _cls1ContextClassLoaderPoolsInitThread(privilege_spawned_threads); t.start(); t.join(); } else { if(logger.isLoggable(MLevel.WARNING) && !"caller".equalsIgnoreCase(contextClassLoaderSource)) logger.log(MLevel.WARNING, (new StringBuilder()).append("Unknown contextClassLoaderSource: ").append(contextClassLoaderSource).append(" -- should be 'caller', 'library', or 'none'. Using default value 'caller'.").toString()); maybePrivilegedPoolsInit(privilege_spawned_threads); } } } private void maybePrivilegedPoolsInit(boolean privilege_spawned_threads) { if(privilege_spawned_threads) { PrivilegedAction privilegedPoolsInit = new PrivilegedAction() { public Void run() { //委托给_poolsInit _poolsInit(); return null; } public volatile Object run() { return run(); } final C3P0PooledConnectionPoolManager this$0; { this.this$0 = C3P0PooledConnectionPoolManager.this; super(); } }; AccessController.doPrivileged(privilegedPoolsInit); } else { _poolsInit(); } } //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 private synchronized void _poolsInit() { String idStr = idString(); timer = new Timer((new StringBuilder()).append(idStr).append("-AdminTaskTimer").toString(), true); int matt = getMaxAdministrativeTaskTime(); //创建任务线程调度器 taskRunner = createTaskRunner(num_task_threads, matt, timer, (new StringBuilder()).append(idStr).append("-HelperThread").toString()); int num_deferred_close_threads = getStatementCacheNumDeferredCloseThreads(); if(num_deferred_close_threads >

0)

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

Else

DeferredStatementDestroyer = null

Rpfact = BasicResourcePoolFactory.createNoEventSupportInstance (taskRunner, timer)

AuthsToPools = new HashMap ()

}

You can see from the above that getPoolManager () actually initializes the database connection pool manager C3P0PooledConnectionPoolManager and initializes the C3P0PooledConnectionPoolManager

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