Package org.apache.tomcat.jdbc.pool
Class ConnectionPool
java.lang.Object
org.apache.tomcat.jdbc.pool.ConnectionPool
Implementation of simple connection pool.
The ConnectionPool uses a
PoolProperties object for storing all the meta information about the connection pool.
As the underlying implementation, the connection pool uses BlockingQueue to store active and idle connections.
A custom implementation of a fair FairBlockingQueue blocking queue is provided with the connection pool itself.-
Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionprotected classThread safe wrapper around a future for the regular queue This one retrieves the pooled connection object and performs the initialization according to interceptors and validation rules.protected static class -
Field Summary
FieldsModifier and TypeFieldDescriptionprotected ConnectionPoolreference to the JMX mbeanstatic final StringDefault domain for objects registering with an mbean serverstatic final StringPrefix type for JMX registration -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionprotected voidabandon(PooledConnection con) thread safe way to abandon a connection signals a connection to be abandoned.protected PooledConnectionborrowConnection(long now, PooledConnection con, String username, String password) Validates and configures a previously idle connectionvoidIterates through all the busy connections and checks for connections that have timed outvoidIterates through the idle connections and resizes the idle pool based on parametersPoolProperties.maxIdle,PoolProperties.minIdle,PoolProperties.minEvictableIdleTimeMillisvoidcheckIdle(boolean ignoreMinSize) voidcheckPoolConfiguration(PoolConfiguration properties) protected voidclose(boolean force) Closes the pool and all disconnects all idle connections Active connections will be closed upon theclosemethod is called on the underlying connection instead of being returned to the poolprotected PooledConnectioncreate(boolean incrementCounter) Create a new pooled connection object.protected PooledConnectioncreateConnection(long now, PooledConnection notUsed, String username, String password) Creates a JDBC connection and tries to connect to the database.protected voidCreate MBean object that can be registered.protected voiddisconnectEvent(PooledConnection con, boolean finalizing) Hook to perform final actions on a pooled connection object once it has been disconnected and will be discardedprotected voidfinalize(PooledConnection con) Hook to perform final actions on a pooled connection object once it has been disconnected and will be discardedintReturns the number of connections that are in uselongThe total number of connections borrowed from this pool.Borrows a connection from the pool.getConnection(String username, String password) Borrows a connection from the pool.Retrieves a Connection future.longThe total number of connections created by this pool.intgetIdle()Returns the number of idle connectionsReturn the object that is potentially registered in JMX for notificationsgetName()Returns the name of this poolReturns the pool properties associated with this connection poolstatic TimerlongConstructor<?>getProxyConstructor(boolean xa) Creates and caches aConstructorused to instantiate the proxy object.longThe total number of connections reconnected by this pool.longThe total number of connections released from this pool.longThe total number of connections released by eviction.longThe total number of connections released by remove abandoned.longThe total number of connections returned to this pool.intgetSize()Returns the total size of this pool, this includes both busy and idle connectionsstatic StringConvert an exception into a Stringprotected static StringCreates a stack trace representing the existing thread's current state.intReturn the number of threads waiting for a connectionprotected voidinit(PoolConfiguration properties) Initialize the connection pool - called from the constructorvoidinitializePoolCleaner(PoolConfiguration properties) booleanisClosed()Returns true ifclosehas been called, and the connection pool is unusablevoidpurge()Purges all connections in the pool.voidPurges connections when they are returned from the pool.protected voidrelease(PooledConnection con) thread safe way to release a connectionvoidreset the statistics of this pool.protected voidReturns a connection to the pool If the pool is closed, the connection will be released If the connection is not part of the busy queue, it will be released.protected Connectionconfigures a pooled connection as a proxy.protected booleanDetermines if a connection should be abandoned based onPoolProperties.abandonWhenPercentageFullsetting.protected booleanshouldClose(PooledConnection con, int action) Determines if a connection should be closed upon return to the pool.protected booleanshouldReleaseIdle(long now, PooledConnection con, long time) protected voidsuspect(PooledConnection con) Thread safe way to suspect a connection.voidprotected booleanTerminate the current transaction for the given connection.voidForces a validation of all idle connections ifPoolProperties.testWhileIdleis set.
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Field Details
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POOL_JMX_DOMAIN
Default domain for objects registering with an mbean server- See Also:
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POOL_JMX_TYPE_PREFIX
Prefix type for JMX registration- See Also:
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jmxPool
reference to the JMX mbean
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Constructor Details
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ConnectionPool
Instantiate a connection pool. This will create connections if initialSize is larger than 0. ThePoolPropertiesshould not be reused for another connection pool.- Parameters:
prop- PoolProperties - all the properties for this connection pool- Throws:
SQLException- Pool initialization error
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Method Details
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getConnectionAsync
Retrieves a Connection future. If a connection is not available, one can block using future.get() until a connection has become available. If a connection is not retrieved, the Future must be cancelled in order for the connection to be returned to the pool.- Returns:
- a Future containing a reference to the connection or the future connection
- Throws:
SQLException- Cannot use asynchronous connect
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getConnection
Borrows a connection from the pool. If a connection is available (in the idle queue) or the pool has not reachedmaxActiveconnections a connection is returned immediately. If no connection is available, the pool will attempt to fetch a connection formaxWaitmilliseconds.- Returns:
- Connection - a java.sql.Connection/javax.sql.PooledConnection reflection proxy, wrapping the underlying object.
- Throws:
SQLException- - if the wait times out or a failure occurs creating a connection
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getConnection
Borrows a connection from the pool. If a connection is available (in the idle queue) or the pool has not reachedmaxActiveconnections a connection is returned immediately. If no connection is available, the pool will attempt to fetch a connection formaxWaitmilliseconds.- Parameters:
username- The user name to use for the connectionpassword- The password for the connection- Returns:
- Connection - a java.sql.Connection/javax.sql.PooledConnection reflection proxy, wrapping the underlying object.
- Throws:
SQLException- - if the wait times out or a failure occurs creating a connection
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getName
Returns the name of this pool- Returns:
- String - the name of the pool
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getWaitCount
public int getWaitCount()Return the number of threads waiting for a connection- Returns:
- number of threads waiting for a connection
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getPoolProperties
Returns the pool properties associated with this connection pool- Returns:
- PoolProperties
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getSize
public int getSize()Returns the total size of this pool, this includes both busy and idle connections- Returns:
- int - number of established connections to the database
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getActive
public int getActive()Returns the number of connections that are in use- Returns:
- int - number of established connections that are being used by the application
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getIdle
public int getIdle()Returns the number of idle connections- Returns:
- int - number of established connections not being used
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isClosed
public boolean isClosed()Returns true ifclosehas been called, and the connection pool is unusable- Returns:
- boolean
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setupConnection
configures a pooled connection as a proxy. This Proxy implementsConnectionandPooledConnectioninterfaces. All calls onConnectionmethods will be propagated down to the actual JDBC connection except for theConnection.close()method.- Parameters:
con- aPooledConnectionto wrap in a Proxy- Returns:
- a
Connectionobject wrapping a pooled connection. - Throws:
SQLException- if an interceptor can't be configured, if the proxy can't be instantiated
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getProxyConstructor
Creates and caches aConstructorused to instantiate the proxy object. We cache this, since the creation of a constructor is fairly slow.- Parameters:
xa- Use a XA connection- Returns:
- constructor used to instantiate the wrapper object
- Throws:
NoSuchMethodException- Failed to get a constructor
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close
protected void close(boolean force) Closes the pool and all disconnects all idle connections Active connections will be closed upon theclosemethod is called on the underlying connection instead of being returned to the pool- Parameters:
force- - true to even close the active connections
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init
Initialize the connection pool - called from the constructor- Parameters:
properties- PoolProperties - properties used to initialize the pool with- Throws:
SQLException- if initialization fails
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checkPoolConfiguration
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initializePoolCleaner
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terminatePoolCleaner
public void terminatePoolCleaner() -
abandon
thread safe way to abandon a connection signals a connection to be abandoned. this will disconnect the connection, and log the stack trace if logAbandoned=true- Parameters:
con- PooledConnection
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suspect
Thread safe way to suspect a connection. Similar toabandon(PooledConnection), but instead of actually abandoning the connection, this will log a warning and set the suspect flag on thePooledConnectionif logAbandoned=true- Parameters:
con- PooledConnection
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release
thread safe way to release a connection- Parameters:
con- PooledConnection
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createConnection
protected PooledConnection createConnection(long now, PooledConnection notUsed, String username, String password) throws SQLException Creates a JDBC connection and tries to connect to the database.- Parameters:
now- timestamp of when this was callednotUsed- Argument not usedusername- The user name to use for the connectionpassword- The password for the connection- Returns:
- a PooledConnection that has been connected
- Throws:
SQLException- Failed to get a connection
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borrowConnection
protected PooledConnection borrowConnection(long now, PooledConnection con, String username, String password) throws SQLException Validates and configures a previously idle connection- Parameters:
now- - timestampcon- - the connection to validate and configureusername- The user name to use for the connectionpassword- The password for the connection- Returns:
- a connection
- Throws:
SQLException- if a validation error happens
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terminateTransaction
Terminate the current transaction for the given connection.- Parameters:
con- The connection- Returns:
trueif the connection TX termination succeeded otherwisefalse
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shouldClose
Determines if a connection should be closed upon return to the pool.- Parameters:
con- - the connectionaction- - the validation action that should be performed- Returns:
trueif the connection should be closed
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returnConnection
Returns a connection to the pool If the pool is closed, the connection will be released If the connection is not part of the busy queue, it will be released. IfPoolProperties.testOnReturnis set to true it will be validated- Parameters:
con- PooledConnection to be returned to the pool
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shouldAbandon
protected boolean shouldAbandon()Determines if a connection should be abandoned based onPoolProperties.abandonWhenPercentageFullsetting.- Returns:
trueif the connection should be abandoned
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checkAbandoned
public void checkAbandoned()Iterates through all the busy connections and checks for connections that have timed out -
checkIdle
public void checkIdle()Iterates through the idle connections and resizes the idle pool based on parametersPoolProperties.maxIdle,PoolProperties.minIdle,PoolProperties.minEvictableIdleTimeMillis -
checkIdle
public void checkIdle(boolean ignoreMinSize) -
shouldReleaseIdle
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testAllIdle
public void testAllIdle()Forces a validation of all idle connections ifPoolProperties.testWhileIdleis set. -
getThreadDump
Creates a stack trace representing the existing thread's current state.- Returns:
- a string object representing the current state.
TODO investigate if we simply should store
Thread.getStackTrace()elements
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getStackTrace
Convert an exception into a String- Parameters:
x- - the throwable- Returns:
- a string representing the stack trace
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create
Create a new pooled connection object. Not connected nor validated.- Parameters:
incrementCounter-trueto increment the connection count- Returns:
- a pooled connection object
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purge
public void purge()Purges all connections in the pool. For connections currently in use, these connections will be purged when returned on the pool. This call also purges connections that are idle and in the pool To only purge used/active connections seepurgeOnReturn() -
purgeOnReturn
public void purgeOnReturn()Purges connections when they are returned from the pool. This call does not purge idle connections until they are used. To purge idle connections seepurge() -
finalize
Hook to perform final actions on a pooled connection object once it has been disconnected and will be discarded- Parameters:
con- The connection
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disconnectEvent
Hook to perform final actions on a pooled connection object once it has been disconnected and will be discarded- Parameters:
con- The connectionfinalizing-trueif finalizing the connection
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getJmxPool
Return the object that is potentially registered in JMX for notifications- Returns:
- the object implementing the
ConnectionPoolMBeaninterface
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createMBean
protected void createMBean()Create MBean object that can be registered. -
getBorrowedCount
public long getBorrowedCount()The total number of connections borrowed from this pool.- Returns:
- the borrowed connection count
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getReturnedCount
public long getReturnedCount()The total number of connections returned to this pool.- Returns:
- the returned connection count
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getCreatedCount
public long getCreatedCount()The total number of connections created by this pool.- Returns:
- the created connection count
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getReleasedCount
public long getReleasedCount()The total number of connections released from this pool.- Returns:
- the released connection count
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getReconnectedCount
public long getReconnectedCount()The total number of connections reconnected by this pool.- Returns:
- the reconnected connection count
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getRemoveAbandonedCount
public long getRemoveAbandonedCount()The total number of connections released by remove abandoned.- Returns:
- the PoolCleaner removed abandoned connection count
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getReleasedIdleCount
public long getReleasedIdleCount()The total number of connections released by eviction.- Returns:
- the PoolCleaner evicted idle connection count
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resetStats
public void resetStats()reset the statistics of this pool. -
getPoolCleaners
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getPoolVersion
public long getPoolVersion() -
getPoolTimer
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