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
Modifier and TypeClassDescriptionprotected class
Thread 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
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Field Summary
Modifier and TypeFieldDescriptionprotected ConnectionPool
reference to the JMX mbeanstatic final String
Default domain for objects registering with an mbean serverstatic final String
Prefix type for JMX registration -
Constructor Summary
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Method Summary
Modifier and TypeMethodDescriptionprotected void
abandon
(PooledConnection con) thread safe way to abandon a connection signals a connection to be abandoned.protected PooledConnection
borrowConnection
(long now, PooledConnection con, String username, String password) Validates and configures a previously idle connectionvoid
Iterates through all the busy connections and checks for connections that have timed outvoid
Iterates through the idle connections and resizes the idle pool based on parametersPoolProperties.maxIdle
,PoolProperties.minIdle
,PoolProperties.minEvictableIdleTimeMillis
void
checkIdle
(boolean ignoreMinSize) void
checkPoolConfiguration
(PoolConfiguration properties) protected void
close
(boolean force) Closes the pool and all disconnects all idle connections Active connections will be closed upon theclose
method is called on the underlying connection instead of being returned to the poolprotected PooledConnection
create
(boolean incrementCounter) Create a new pooled connection object.protected PooledConnection
createConnection
(long now, PooledConnection notUsed, String username, String password) Creates a JDBC connection and tries to connect to the database.protected void
Create MBean object that can be registered.protected void
disconnectEvent
(PooledConnection con, boolean finalizing) Hook to perform final actions on a pooled connection object once it has been disconnected and will be discardedprotected void
finalize
(PooledConnection con) Hook to perform final actions on a pooled connection object once it has been disconnected and will be discardedint
Returns the number of connections that are in uselong
The 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.long
The total number of connections created by this pool.int
getIdle()
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 Timer
long
Constructor
<?> getProxyConstructor
(boolean xa) Creates and caches aConstructor
used to instantiate the proxy object.long
The total number of connections reconnected by this pool.long
The total number of connections released from this pool.long
The total number of connections released by eviction.long
The total number of connections released by remove abandoned.long
The total number of connections returned to this pool.int
getSize()
Returns the total size of this pool, this includes both busy and idle connectionsstatic String
Convert an exception into a Stringprotected static String
Creates a stack trace representing the existing thread's current state.int
Return the number of threads waiting for a connectionprotected void
init
(PoolConfiguration properties) Initialize the connection pool - called from the constructorvoid
initializePoolCleaner
(PoolConfiguration properties) boolean
isClosed()
Returns true ifclose
has been called, and the connection pool is unusablevoid
purge()
Purges all connections in the pool.void
Purges connections when they are returned from the pool.protected boolean
Checks whether this connection hasexpired
and tries to reconnect if it has.protected void
release
(PooledConnection con) thread safe way to release a connectionvoid
reset the statistics of this pool.protected void
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.protected Connection
configures a pooled connection as a proxy.protected boolean
Determines if a connection should be abandoned based onPoolProperties.abandonWhenPercentageFull
setting.protected boolean
shouldClose
(PooledConnection con, int action) Determines if a connection should be closed upon return to the pool.protected boolean
shouldReleaseIdle
(long now, PooledConnection con, long time) protected void
suspect
(PooledConnection con) Thread safe way to suspect a connection.void
protected boolean
Terminate the current transaction for the given connection.void
Forces a validation of all idle connections ifPoolProperties.testWhileIdle
is set.void
testAllIdle
(boolean checkMaxAgeOnly) Forces a validation of all idle connections ifPoolProperties.testWhileIdle
is 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
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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. ThePoolProperties
should 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 reachedmaxActive
connections a connection is returned immediately. If no connection is available, the pool will attempt to fetch a connection formaxWait
milliseconds.- 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 reachedmaxActive
connections a connection is returned immediately. If no connection is available, the pool will attempt to fetch a connection formaxWait
milliseconds.- 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
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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 ifclose
has been called, and the connection pool is unusable- Returns:
- boolean
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setupConnection
configures a pooled connection as a proxy. This Proxy implementsConnection
andPooledConnection
interfaces. All calls onConnection
methods will be propagated down to the actual JDBC connection except for theConnection.close()
method.- Parameters:
con
- aPooledConnection
to wrap in a Proxy- Returns:
- a
Connection
object 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 aConstructor
used 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 theclose
method 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 thePooledConnection
if 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:
true
if 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:
true
if the connection should be closed
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reconnectIfExpired
Checks whether this connection hasexpired
and tries to reconnect if it has.- Parameters:
con
- PooledConnection- Returns:
- true if the connection was either not expired or expired but reconnecting succeeded, false if reconnecting failed (either because a new connection could not be established or validating the newly created connection failed)
- See Also:
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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.testOnReturn
is 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.abandonWhenPercentageFull
setting.- Returns:
true
if 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
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checkIdle
public void checkIdle(boolean ignoreMinSize) -
shouldReleaseIdle
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testAllIdle
public void testAllIdle()Forces a validation of all idle connections ifPoolProperties.testWhileIdle
is set. -
testAllIdle
public void testAllIdle(boolean checkMaxAgeOnly) Forces a validation of all idle connections ifPoolProperties.testWhileIdle
is set.- Parameters:
checkMaxAgeOnly
- whether to only checkPooledConnection.isMaxAgeExpired()
but not invokePooledConnection.validate(int)
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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
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create
Create a new pooled connection object. Not connected nor validated.- Parameters:
incrementCounter
-true
to 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()
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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()
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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
-true
if finalizing the connection
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getJmxPool
Return the object that is potentially registered in JMX for notifications- Returns:
- the object implementing the
ConnectionPoolMBean
interface
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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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