Interface PooledDataSource
- All Superinterfaces:
CommonDataSource
,DataSource
,Wrapper
- All Known Implementing Classes:
com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource
,ComboPooledDataSource
,PoolBackedDataSource
Most clients need never use or know about this interface -- c3p0 pooled DataSources can be treated like any other DataSource.
The functionality in this interface will be only be of interest if 1) for administrative reasons you like to keep close track of the number and status of all Connections your application is using; 2) to work around problems encountered while managing a DataSource whose clients are poorly coded applications that leak Connections, but which you are not permitted to fix; or 3) to work around problems that may occur if an underlying jdbc driver / DBMS system is unreliable. In the third case, most users will be better off not using the present interface at all, and using the DataSources' maxIdleTime, idleConnectionTestPeriod, or testConnectionOnCheckout parameters to help your DataSources "automatically" heal. But for those who prefer a more direct, manual approach, this interface is for you. It is anticipated that the methods of this interface will primarily be of use to administrators managing c3p0 PooledDataSources via JMX MBeans.
Method Names & Per-User Pools
To understand this interface, you need to realize that a c3p0 PooledDataSource may represent not just one pool of Connections, but many, if users call the method Connection getConnection(String username, String password) rather than the no-argument getConnection() method. If users make use of non-default username, password combinations, there will be a separate pool for each set of authentification criteria supplied.
Many methods in this interface have three variants:
- <method-name>DefaultUser()
- <method-name>(String username, String password)
- <method-name>AllUsers()
The first variant makes use of the pool maintained for the default user -- Connections created by calls to the no argument getConnection(), the second variant lets you keeps track of pools created by calling getConnection( username, password ), and the third variant provides aggregate information or performs operation on all pools.
Under most circumstances, non-default authentication credentials will not be used, and methods of the first variant are sufficient to manage the DataSource.
Soft and Hard Resets
A properly configured PooledDataSource whose applications are careful to close all checked-out Connections would never need to use these methods. But, sometimes applications are untrustworthy and leak Connections, or database administrators suspect that Connections may be corrupt or invalid, and would like to force a pool to flush and acquire fresh Connections. This interface provides two ways to do so.
- hardReset() immediately closes all Connections managed by the DataSource, including
those that are currently checked out, bringing the DataSource back to the state it was in before
the first client called getConnection(). This method is obviously disruptive, and should be with
great care. Administrators who need to work around client applications that leak Connections, can
periodically poll for pool exhaustion (using the methods of this class, or by attempting to retrieve
a Connection and timing out) and use this method clean-up all Connections and start over. But calling
this method risks breaking Connections in current use by valid applications.
- softResetDefaultUser(), softReset( username, password ) and softResetAllUsers() asks the DataSource to flush its current pool of Connections and reacquire without invalidating currently checked-out Connections. Currently checked out Connections are logically removed from the pool, but their destruction is deferred until a client attempts to close() / check-in the Connection. Administrators who suspect that some Connections in the pool may be invalid, but who do not wish to rely upon c3p0's automatic testing and detection mechanisms to resolve the problem, may call these methods to force a refresh without disrupting current clients. Administrators who suspect that clients may be leaking Connections may minimize disruptive hardReset() calls by using softReset() until the number of unclosed orphaned connections reaches an unacceptable level. (See above to understand why there are three variants of this method.)
Understanding Connection Counts
For each per-user pool, four different statistics are available:
- numConnections represents the total number of Connections in the pool.
- numIdleConnections represents the number of Connections in the pool that are currently available for checkout.
- numBusyConnections represents the number of Connections in the pool that are currently checked out. The
invariant numIdleConnections + numBusyConnections == numConnections should always hold.
- numUnclosedOrphanedConnections will only be non-zero following a call to softReset(). It represents the number of Connections that were checked out when a soft reset occurred and were therefore silently excluded from the pool, and which remain unclosed by the client application.
-
Method Summary
Modifier and TypeMethodDescriptionvoid
close()
C3P0 pooled DataSources use no resources before they are actually used in a VM, and they close themselves in their finalize() method.void
close
(boolean force_destory) Deprecated.the force_destroy argument is now meaningless, as pools are no longer potentially shared between multiple DataSources.float
getEffectivePropertyCycle
(String username, String password) float
getLastAcquisitionFailure
(String username, String password) getLastCheckinFailure
(String username, String password) getLastCheckoutFailure
(String username, String password) getLastConnectionTestFailure
(String username, String password) getLastIdleTestFailure
(String username, String password) int
Deprecated.use getNumBusyConnectionsDefaultUser()int
getNumBusyConnections
(String username, String password) int
int
int
Deprecated.use getNumConnectionsDefaultUser()int
getNumConnections
(String username, String password) int
int
long
long
long
int
int
Deprecated.use getNumIdleConnectionsDefaultUser()int
getNumIdleConnections
(String username, String password) int
int
int
getNumThreadsAwaitingCheckout
(String username, String password) int
int
Deprecated.use getNumUnclosedOrphanedConnectionsDefaultUser()int
getNumUnclosedOrphanedConnections
(String username, String password) int
int
int
long
int
getStatementCacheNumCheckedOut
(String username, String password) int
int
int
getStatementCacheNumConnectionsWithCachedStatements
(String username, String password) int
int
int
getStatementCacheNumStatements
(String username, String password) int
int
int
int
int
int
long
void
Destroys all pooled and checked-out Connections associated with this DataSource immediately.sampleLastAcquisitionFailureStackTrace
(String username, String password) sampleLastCheckinFailureStackTrace
(String username, String password) sampleLastCheckoutFailureStackTrace
(String username, String password) sampleLastConnectionTestFailureStackTrace
(String username, String password) sampleLastIdleTestFailureStackTrace
(String username, String password) sampleStatementCacheStatus
(String username, String password) void
setDataSourceName
(String dataSourceName) void
Discards all Connections managed by the PooledDataSource with the specified authentication credentials and reacquires new Connections to populate.void
Discards all Connections managed by the PooledDataSource and reacquires new Connections to populate.void
Discards all Connections managed by the PooledDataSource's default-authentication pool and reacquires new Connections to populate.Methods inherited from interface javax.sql.CommonDataSource
createShardingKeyBuilder, getParentLogger
Methods inherited from interface javax.sql.DataSource
createConnectionBuilder, getConnection, getConnection, getLoginTimeout, getLogWriter, setLoginTimeout, setLogWriter
Methods inherited from interface java.sql.Wrapper
isWrapperFor, unwrap
-
Method Details
-
getIdentityToken
String getIdentityToken() -
getDataSourceName
String getDataSourceName() -
setDataSourceName
-
getNumConnections
Deprecated.use getNumConnectionsDefaultUser()- Throws:
SQLException
-
getNumIdleConnections
Deprecated.use getNumIdleConnectionsDefaultUser()- Throws:
SQLException
-
getNumBusyConnections
Deprecated.use getNumBusyConnectionsDefaultUser()- Throws:
SQLException
-
getNumUnclosedOrphanedConnections
Deprecated.use getNumUnclosedOrphanedConnectionsDefaultUser()- Throws:
SQLException
-
getNumConnectionsDefaultUser
- Throws:
SQLException
-
getNumIdleConnectionsDefaultUser
- Throws:
SQLException
-
getNumBusyConnectionsDefaultUser
- Throws:
SQLException
-
getNumUnclosedOrphanedConnectionsDefaultUser
- Throws:
SQLException
-
getStatementCacheNumStatementsDefaultUser
- Throws:
SQLException
-
getStatementCacheNumCheckedOutDefaultUser
- Throws:
SQLException
-
getStatementCacheNumConnectionsWithCachedStatementsDefaultUser
- Throws:
SQLException
-
getStartTimeMillisDefaultUser
- Throws:
SQLException
-
getUpTimeMillisDefaultUser
- Throws:
SQLException
-
getNumFailedCheckinsDefaultUser
- Throws:
SQLException
-
getNumFailedCheckoutsDefaultUser
- Throws:
SQLException
-
getNumFailedIdleTestsDefaultUser
- Throws:
SQLException
-
getEffectivePropertyCycleDefaultUser
- Throws:
SQLException
-
getNumThreadsAwaitingCheckoutDefaultUser
- Throws:
SQLException
-
softResetDefaultUser
Discards all Connections managed by the PooledDataSource's default-authentication pool and reacquires new Connections to populate. Current checked out Connections will still be valid, and should still be checked into the PooledDataSource (so the PooledDataSource can destroy them).- Throws:
SQLException
-
getNumConnections
- Throws:
SQLException
-
getNumIdleConnections
- Throws:
SQLException
-
getNumBusyConnections
- Throws:
SQLException
-
getNumUnclosedOrphanedConnections
- Throws:
SQLException
-
getStatementCacheNumStatements
- Throws:
SQLException
-
getStatementCacheNumCheckedOut
- Throws:
SQLException
-
getStatementCacheNumConnectionsWithCachedStatements
int getStatementCacheNumConnectionsWithCachedStatements(String username, String password) throws SQLException - Throws:
SQLException
-
getEffectivePropertyCycle
- Throws:
SQLException
-
getNumThreadsAwaitingCheckout
- Throws:
SQLException
-
softReset
Discards all Connections managed by the PooledDataSource with the specified authentication credentials and reacquires new Connections to populate. Current checked out Connections will still be valid, and should still be checked into the PooledDataSource (so the PooledDataSource can destroy them).- Throws:
SQLException
-
getNumBusyConnectionsAllUsers
- Throws:
SQLException
-
getNumIdleConnectionsAllUsers
- Throws:
SQLException
-
getNumConnectionsAllUsers
- Throws:
SQLException
-
getNumUnclosedOrphanedConnectionsAllUsers
- Throws:
SQLException
-
getStatementCacheNumStatementsAllUsers
- Throws:
SQLException
-
getStatementCacheNumCheckedOutStatementsAllUsers
- Throws:
SQLException
-
getStatementCacheNumConnectionsWithCachedStatementsAllUsers
- Throws:
SQLException
-
getThreadPoolSize
- Throws:
SQLException
-
getThreadPoolNumActiveThreads
- Throws:
SQLException
-
getThreadPoolNumIdleThreads
- Throws:
SQLException
-
getThreadPoolNumTasksPending
- Throws:
SQLException
-
sampleThreadPoolStackTraces
- Throws:
SQLException
-
sampleThreadPoolStatus
- Throws:
SQLException
-
sampleStatementCacheStatusDefaultUser
- Throws:
SQLException
-
sampleStatementCacheStatus
- Throws:
SQLException
-
getLastAcquisitionFailureDefaultUser
- Throws:
SQLException
-
getLastCheckinFailureDefaultUser
- Throws:
SQLException
-
getLastCheckoutFailureDefaultUser
- Throws:
SQLException
-
getLastIdleTestFailureDefaultUser
- Throws:
SQLException
-
getLastConnectionTestFailureDefaultUser
- Throws:
SQLException
-
getLastAcquisitionFailure
- Throws:
SQLException
-
getLastCheckinFailure
- Throws:
SQLException
-
getLastCheckoutFailure
- Throws:
SQLException
-
getLastIdleTestFailure
- Throws:
SQLException
-
getLastConnectionTestFailure
- Throws:
SQLException
-
sampleLastAcquisitionFailureStackTraceDefaultUser
- Throws:
SQLException
-
sampleLastCheckinFailureStackTraceDefaultUser
- Throws:
SQLException
-
sampleLastCheckoutFailureStackTraceDefaultUser
- Throws:
SQLException
-
sampleLastIdleTestFailureStackTraceDefaultUser
- Throws:
SQLException
-
sampleLastConnectionTestFailureStackTraceDefaultUser
- Throws:
SQLException
-
sampleLastAcquisitionFailureStackTrace
- Throws:
SQLException
-
sampleLastCheckinFailureStackTrace
- Throws:
SQLException
-
sampleLastCheckoutFailureStackTrace
- Throws:
SQLException
-
sampleLastIdleTestFailureStackTrace
- Throws:
SQLException
-
sampleLastConnectionTestFailureStackTrace
String sampleLastConnectionTestFailureStackTrace(String username, String password) throws SQLException - Throws:
SQLException
-
softResetAllUsers
Discards all Connections managed by the PooledDataSource and reacquires new Connections to populate. Current checked out Connections will still be valid, and should still be checked into the PooledDataSource (so the PooledDataSource can destroy them).- Throws:
SQLException
-
getNumUserPools
- Throws:
SQLException
-
getNumHelperThreads
- Throws:
SQLException
-
getAllUsers
- Throws:
SQLException
-
hardReset
Destroys all pooled and checked-out Connections associated with this DataSource immediately. The PooledDataSource is reset to its initial state prior to first Connection acquisition, with no pools yet active, but ready for requests.- Throws:
SQLException
-
close
C3P0 pooled DataSources use no resources before they are actually used in a VM, and they close themselves in their finalize() method. When they are active and pooling, they may have open database connections and their pool may spawn several threads for its maintenance. You can use this method to clean these resource methods up quickly when you will no longer be using this DataSource. The resources will actually be cleaned up only if no other DataSources are sharing the same pool.
You can equivalently use the static method destroy() in the DataSources class to clean-up these resources.
This is equivalent to calling close( false ).
- Throws:
SQLException
- See Also:
-
close
Deprecated.the force_destroy argument is now meaningless, as pools are no longer potentially shared between multiple DataSources.Should be used only with great caution. If force_destroy is set to true, this immediately destroys any pool and cleans up all resources this DataSource may be using, even if other DataSources are sharing that pool! In general, it is difficult to know whether a pool is being shared by multiple DataSources. It may depend upon whether or not a JNDI implementation returns a single instance or multiple copies upon lookup (which is undefined by the JNDI spec).
In general, this method should be used only when you wish to wind down all c3p0 pools in a ClassLoader. For example, when shutting down and restarting a web application that uses c3p0, you may wish to kill all threads making use of classes loaded by a web-app specific ClassLoader, so that the ClassLoader can be cleanly garbage collected. In this case, you may wish to use force destroy. Otherwise, it is much safer to use the simple destroy() method, which will not shut down pools that may still be in use.
To close a pool normally, use the no argument close method, or set force_destroy to false.
- Throws:
SQLException
- See Also:
-