org.apache.commons.pool.impl
public class GenericObjectPool extends BaseObjectPool implements ObjectPool
When coupled with the appropriate PoolableObjectFactory, GenericObjectPool provides robust pooling functionality for arbitrary objects.
A GenericObjectPool provides a number of configurable parameters:
maxActive
controls the maximum number of objects that can
be borrowed from the pool at one time. When non-positive, there
is no limit to the number of objects that may be active at one time.
When maxActive
is exceeded, the pool is said to be exhausted.
maxIdle
controls the maximum number of objects that can
sit idle in the pool at any time. When negative, there
is no limit to the number of objects that may be idle at one time.
whenExhaustedAction
specifies the
behaviour of the GenericObjectPool method when the pool is exhausted:
whenExhaustedAction
is
WHEN_EXHAUSTED_FAIL, GenericObjectPool will throw
a NoSuchElementException
whenExhaustedAction
is
WHEN_EXHAUSTED_GROW, GenericObjectPool will create a new
object and return it(essentially making maxActive
meaningless.)
whenExhaustedAction
is WHEN_EXHAUSTED_BLOCK, GenericObjectPool will block
(invoke Object#wait until a new or idle object is available.
If a positive maxWait
value is supplied, the GenericObjectPool will block for at
most that many milliseconds, after which a NoSuchElementException
will be thrown. If maxWait
is non-positive,
the GenericObjectPool method will block indefinitely.
testOnBorrow
is set, the pool will
attempt to validate each object before it is returned from the
GenericObjectPool method. (Using the provided factory's
PoolableObjectFactory method.) Objects that fail
to validate will be dropped from the pool, and a different object will
be borrowed.
testOnReturn
is set, the pool will
attempt to validate each object before it is returned to the pool in the
GenericObjectPool method. (Using the provided factory's
PoolableObjectFactory
method.) Objects that fail to validate will be dropped from the pool.
Optionally, one may configure the pool to examine and possibly evict objects as they sit idle in the pool. This is performed by an "idle object eviction" thread, which runs asychronously. The idle object eviction thread may be configured using the following attributes:
timeBetweenEvictionRunsMillis
indicates how long the eviction thread should sleep before "runs" of examining
idle objects. When non-positive, no eviction thread will be launched.
minEvictableIdleTimeMillis
specifies the minimum amount of time that an object may sit idle in the pool
before it is eligable for eviction due to idle time. When non-positive, no object
will be dropped from the pool due to idle time alone.
testWhileIdle
indicates whether or not idle
objects should be validated using the factory's
PoolableObjectFactory method. Objects
that fail to validate will be dropped from the pool.
GenericObjectPool is not usable without a PoolableObjectFactory. A
non-null
factory must be provided either as a constructor argument
or via a call to GenericObjectPool before the pool is used.
Version: $Revision: 390563 $ $Date: 2006-03-31 20:28:14 -0500 (Fri, 31 Mar 2006) $
See Also: GenericKeyedObjectPool
Nested Class Summary | |
---|---|
static class | GenericObjectPool.Config
A simple "struct" encapsulating the
configuration information for a GenericObjectPool. |
Field Summary | |
---|---|
static int | DEFAULT_MAX_ACTIVE
The default cap on the total number of active instances from the pool. |
static int | DEFAULT_MAX_IDLE
The default cap on the number of "sleeping" instances in the pool. |
static long | DEFAULT_MAX_WAIT
The default maximum amount of time (in millis) the
GenericObjectPool method should block before throwing
an exception when the pool is exhausted and the
"when exhausted" action is
WHEN_EXHAUSTED_BLOCK. |
static long | DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS
The default value for GenericObjectPool. |
static int | DEFAULT_MIN_IDLE
The default minimum number of "sleeping" instances in the pool
before before the evictor thread (if active) spawns new objects. |
static int | DEFAULT_NUM_TESTS_PER_EVICTION_RUN
The default number of objects to examine per run in the
idle object evictor. |
static long | DEFAULT_SOFT_MIN_EVICTABLE_IDLE_TIME_MILLIS
The default value for GenericObjectPool. |
static boolean | DEFAULT_TEST_ON_BORROW
The default "test on borrow" value. |
static boolean | DEFAULT_TEST_ON_RETURN
The default "test on return" value. |
static boolean | DEFAULT_TEST_WHILE_IDLE
The default "test while idle" value. |
static long | DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS
The default "time between eviction runs" value. |
static byte | DEFAULT_WHEN_EXHAUSTED_ACTION
The default "when exhausted action" for the pool. |
static byte | WHEN_EXHAUSTED_BLOCK
A "when exhausted action" type indicating that when the pool
is exhausted (i.e., the maximum number
of active objects has been reached), the GenericObjectPool
method should block until a new object is available, or the
maximum wait time has been reached. |
static byte | WHEN_EXHAUSTED_FAIL
A "when exhausted action" type indicating that when the pool is
exhausted (i.e., the maximum number of active objects has
been reached), the GenericObjectPool
method should fail, throwing a NoSuchElementException. |
static byte | WHEN_EXHAUSTED_GROW
A "when exhausted action" type indicating that when the pool is
exhausted (i.e., the maximum number
of active objects has been reached), the GenericObjectPool
method should simply create a new object anyway. |
Constructor Summary | |
---|---|
GenericObjectPool()
Create a new GenericObjectPool. | |
GenericObjectPool(PoolableObjectFactory factory)
Create a new GenericObjectPool using the specified values. | |
GenericObjectPool(PoolableObjectFactory factory, GenericObjectPool.Config config)
Create a new GenericObjectPool using the specified values. | |
GenericObjectPool(PoolableObjectFactory factory, int maxActive)
Create a new GenericObjectPool using the specified values. | |
GenericObjectPool(PoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait)
Create a new GenericObjectPool using the specified values. | |
GenericObjectPool(PoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait, boolean testOnBorrow, boolean testOnReturn)
Create a new GenericObjectPool using the specified values. | |
GenericObjectPool(PoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait, int maxIdle)
Create a new GenericObjectPool using the specified values. | |
GenericObjectPool(PoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait, int maxIdle, boolean testOnBorrow, boolean testOnReturn)
Create a new GenericObjectPool using the specified values. | |
GenericObjectPool(PoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait, int maxIdle, boolean testOnBorrow, boolean testOnReturn, long timeBetweenEvictionRunsMillis, int numTestsPerEvictionRun, long minEvictableIdleTimeMillis, boolean testWhileIdle)
Create a new GenericObjectPool using the specified values. | |
GenericObjectPool(PoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait, int maxIdle, int minIdle, boolean testOnBorrow, boolean testOnReturn, long timeBetweenEvictionRunsMillis, int numTestsPerEvictionRun, long minEvictableIdleTimeMillis, boolean testWhileIdle)
Create a new GenericObjectPool using the specified values. | |
GenericObjectPool(PoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait, int maxIdle, int minIdle, boolean testOnBorrow, boolean testOnReturn, long timeBetweenEvictionRunsMillis, int numTestsPerEvictionRun, long minEvictableIdleTimeMillis, boolean testWhileIdle, long softMinEvictableIdleTimeMillis)
Create a new GenericObjectPool using the specified values. |
Method Summary | |
---|---|
void | addObject()
Create an object, and place it into the pool.
addObject() is useful for "pre-loading" a pool with idle objects. |
Object | borrowObject() |
void | clear() |
void | close() |
void | evict() |
int | getMaxActive()
Returns the cap on the total number of active instances from my pool. |
int | getMaxIdle()
Returns the cap on the number of "idle" instances in the pool. |
long | getMaxWait()
Returns the maximum amount of time (in milliseconds) the
GenericObjectPool method should block before throwing
an exception when the pool is exhausted and the
"when exhausted" action is
WHEN_EXHAUSTED_BLOCK.
|
long | getMinEvictableIdleTimeMillis()
Returns the minimum amount of time an object may sit idle in the pool
before it is eligable for eviction by the idle object evictor
(if any).
|
int | getMinIdle()
Returns the minimum number of objects allowed in the pool
before the evictor thread (if active) spawns new objects.
|
int | getNumActive() |
int | getNumIdle() |
int | getNumTestsPerEvictionRun()
Returns the max number of objects to examine during each run of the
idle object evictor thread (if any).
|
long | getSoftMinEvictableIdleTimeMillis()
Returns the minimum amount of time an object may sit idle in the pool
before it is eligable for eviction by the idle object evictor
(if any), with the extra condition that at least
"minIdle" amount of object remain in the pool.
|
boolean | getTestOnBorrow()
When true, objects will be
validated
before being returned by the GenericObjectPool
method. |
boolean | getTestOnReturn()
When true, objects will be
validated
before being returned to the pool within the
GenericObjectPool.
|
boolean | getTestWhileIdle()
When true, objects will be
validated
by the idle object evictor (if any). |
long | getTimeBetweenEvictionRunsMillis()
Returns the number of milliseconds to sleep between runs of the
idle object evictor thread.
|
byte | getWhenExhaustedAction()
Returns the action to take when the GenericObjectPool method
is invoked when the pool is exhausted (the maximum number
of "active" objects has been reached).
|
void | invalidateObject(Object obj) |
void | returnObject(Object obj) |
void | setConfig(GenericObjectPool.Config conf)
Sets my configuration. |
void | setFactory(PoolableObjectFactory factory) |
void | setMaxActive(int maxActive)
Sets the cap on the total number of active instances from my pool. |
void | setMaxIdle(int maxIdle)
Sets the cap on the number of "idle" instances in the pool. |
void | setMaxWait(long maxWait)
Sets the maximum amount of time (in milliseconds) the
GenericObjectPool method should block before throwing
an exception when the pool is exhausted and the
"when exhausted" action is
WHEN_EXHAUSTED_BLOCK.
|
void | setMinEvictableIdleTimeMillis(long minEvictableIdleTimeMillis)
Sets the minimum amount of time an object may sit idle in the pool
before it is eligable for eviction by the idle object evictor
(if any).
|
void | setMinIdle(int minIdle)
Sets the minimum number of objects allowed in the pool
before the evictor thread (if active) spawns new objects.
|
void | setNumTestsPerEvictionRun(int numTestsPerEvictionRun)
Sets the max number of objects to examine during each run of the
idle object evictor thread (if any).
|
void | setSoftMinEvictableIdleTimeMillis(long softMinEvictableIdleTimeMillis)
Sets the minimum amount of time an object may sit idle in the pool
before it is eligable for eviction by the idle object evictor
(if any), with the extra condition that at least
"minIdle" amount of object remain in the pool.
|
void | setTestOnBorrow(boolean testOnBorrow)
When true, objects will be
validated
before being returned by the GenericObjectPool
method. |
void | setTestOnReturn(boolean testOnReturn)
When true, objects will be
validated
before being returned to the pool within the
GenericObjectPool.
|
void | setTestWhileIdle(boolean testWhileIdle)
When true, objects will be
validated
by the idle object evictor (if any). |
void | setTimeBetweenEvictionRunsMillis(long timeBetweenEvictionRunsMillis)
Sets the number of milliseconds to sleep between runs of the
idle object evictor thread.
|
void | setWhenExhaustedAction(byte whenExhaustedAction)
Sets the action to take when the GenericObjectPool method
is invoked when the pool is exhausted (the maximum number
of "active" objects has been reached).
|
See Also: GenericObjectPool
See Also: GenericObjectPool GenericObjectPool
"when exhausted" action
is
WHEN_EXHAUSTED_BLOCK.See Also: GenericObjectPool GenericObjectPool
See Also: GenericObjectPool GenericObjectPool
See Also: GenericObjectPool GenericObjectPool
See Also: GenericObjectPool GenericObjectPool GenericObjectPool GenericObjectPool
See Also: GenericObjectPool GenericObjectPool
See Also: GenericObjectPool GenericObjectPool
See Also: GenericObjectPool GenericObjectPool
See Also: GenericObjectPool GenericObjectPool GenericObjectPool GenericObjectPool
See Also: GenericObjectPool GenericObjectPool
See Also: WHEN_EXHAUSTED_BLOCK WHEN_EXHAUSTED_FAIL WHEN_EXHAUSTED_GROW GenericObjectPool
maximum wait time
has been reached.See Also: WHEN_EXHAUSTED_FAIL WHEN_EXHAUSTED_GROW GenericObjectPool GenericObjectPool GenericObjectPool
See Also: WHEN_EXHAUSTED_BLOCK WHEN_EXHAUSTED_GROW GenericObjectPool
See Also: WHEN_EXHAUSTED_FAIL WHEN_EXHAUSTED_GROW GenericObjectPool
Parameters: factory the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects
Parameters: factory the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects config a non-null Config describing my configuration
Parameters: factory the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects maxActive the maximum number of objects that can be borrowed from me at one time (see GenericObjectPool)
Parameters: factory the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects maxActive the maximum number of objects that can be borrowed from me at one time (see GenericObjectPool) whenExhaustedAction the action to take when the pool is exhausted (see GenericObjectPool) maxWait the maximum amount of time to wait for an idle object when the pool is exhausted an and whenExhaustedAction is WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see GenericObjectPool)
Parameters: factory the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects maxActive the maximum number of objects that can be borrowed from me at one time (see GenericObjectPool) whenExhaustedAction the action to take when the pool is exhausted (see GenericObjectPool) maxWait the maximum amount of time to wait for an idle object when the pool is exhausted an and whenExhaustedAction is WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see GenericObjectPool) testOnBorrow whether or not to validate objects before they are returned by the GenericObjectPool method (see GenericObjectPool) testOnReturn whether or not to validate objects after they are returned to the GenericObjectPool method (see GenericObjectPool)
Parameters: factory the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects maxActive the maximum number of objects that can be borrowed from me at one time (see GenericObjectPool) whenExhaustedAction the action to take when the pool is exhausted (see GenericObjectPool) maxWait the maximum amount of time to wait for an idle object when the pool is exhausted an and whenExhaustedAction is WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see GenericObjectPool) maxIdle the maximum number of idle objects in my pool (see GenericObjectPool)
Parameters: factory the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects maxActive the maximum number of objects that can be borrowed from me at one time (see GenericObjectPool) whenExhaustedAction the action to take when the pool is exhausted (see GenericObjectPool) maxWait the maximum amount of time to wait for an idle object when the pool is exhausted an and whenExhaustedAction is WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see GenericObjectPool) maxIdle the maximum number of idle objects in my pool (see GenericObjectPool) testOnBorrow whether or not to validate objects before they are returned by the GenericObjectPool method (see GenericObjectPool) testOnReturn whether or not to validate objects after they are returned to the GenericObjectPool method (see GenericObjectPool)
Parameters: factory the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects maxActive the maximum number of objects that can be borrowed from me at one time (see GenericObjectPool) whenExhaustedAction the action to take when the pool is exhausted (see GenericObjectPool) maxWait the maximum amount of time to wait for an idle object when the pool is exhausted an and whenExhaustedAction is WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see GenericObjectPool) maxIdle the maximum number of idle objects in my pool (see GenericObjectPool) testOnBorrow whether or not to validate objects before they are returned by the GenericObjectPool method (see GenericObjectPool) testOnReturn whether or not to validate objects after they are returned to the GenericObjectPool method (see GenericObjectPool) timeBetweenEvictionRunsMillis the amount of time (in milliseconds) to sleep between examining idle objects for eviction (see GenericObjectPool) numTestsPerEvictionRun the number of idle objects to examine per run within the idle object eviction thread (if any) (see GenericObjectPool) minEvictableIdleTimeMillis the minimum number of milliseconds an object can sit idle in the pool before it is eligable for evcition (see GenericObjectPool) testWhileIdle whether or not to validate objects in the idle object eviction thread, if any (see GenericObjectPool)
Parameters: factory the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects maxActive the maximum number of objects that can be borrowed from me at one time (see GenericObjectPool) whenExhaustedAction the action to take when the pool is exhausted (see GenericObjectPool) maxWait the maximum amount of time to wait for an idle object when the pool is exhausted an and whenExhaustedAction is WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see GenericObjectPool) maxIdle the maximum number of idle objects in my pool (see GenericObjectPool) minIdle the minimum number of idle objects in my pool (see GenericObjectPool) testOnBorrow whether or not to validate objects before they are returned by the GenericObjectPool method (see GenericObjectPool) testOnReturn whether or not to validate objects after they are returned to the GenericObjectPool method (see GenericObjectPool) timeBetweenEvictionRunsMillis the amount of time (in milliseconds) to sleep between examining idle objects for eviction (see GenericObjectPool) numTestsPerEvictionRun the number of idle objects to examine per run within the idle object eviction thread (if any) (see GenericObjectPool) minEvictableIdleTimeMillis the minimum number of milliseconds an object can sit idle in the pool before it is eligable for evcition (see GenericObjectPool) testWhileIdle whether or not to validate objects in the idle object eviction thread, if any (see GenericObjectPool)
Parameters: factory the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects maxActive the maximum number of objects that can be borrowed from me at one time (see GenericObjectPool) whenExhaustedAction the action to take when the pool is exhausted (see GenericObjectPool) maxWait the maximum amount of time to wait for an idle object when the pool is exhausted an and whenExhaustedAction is WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see GenericObjectPool) maxIdle the maximum number of idle objects in my pool (see GenericObjectPool) minIdle the minimum number of idle objects in my pool (see GenericObjectPool) testOnBorrow whether or not to validate objects before they are returned by the GenericObjectPool method (see GenericObjectPool) testOnReturn whether or not to validate objects after they are returned to the GenericObjectPool method (see GenericObjectPool) timeBetweenEvictionRunsMillis the amount of time (in milliseconds) to sleep between examining idle objects for eviction (see GenericObjectPool) numTestsPerEvictionRun the number of idle objects to examine per run within the idle object eviction thread (if any) (see GenericObjectPool) minEvictableIdleTimeMillis the minimum number of milliseconds an object can sit idle in the pool before it is eligable for evcition (see GenericObjectPool) testWhileIdle whether or not to validate objects in the idle object eviction thread, if any (see GenericObjectPool) softMinEvictableIdleTimeMillis the minimum number of milliseconds an object can sit idle in the pool before it is eligable for evcition with the extra condition that at least "minIdle" amount of object remain in the pool. (see GenericObjectPool)
Returns: the cap on the total number of active instances from my pool.
See Also: GenericObjectPool
Returns: the cap on the number of "idle" instances in the pool.
See Also: GenericObjectPool
"when exhausted" action
is
WHEN_EXHAUSTED_BLOCK.
When less than 0, the GenericObjectPool method
may block indefinitely.
See Also: GenericObjectPool GenericObjectPool WHEN_EXHAUSTED_BLOCK
See Also: GenericObjectPool GenericObjectPool
Returns: The minimum number of objects.
See Also: GenericObjectPool
See Also: GenericObjectPool GenericObjectPool
See Also: GenericObjectPool
validated
before being returned by the GenericObjectPool
method. If the object fails to validate,
it will be dropped from the pool, and we will attempt
to borrow another.
See Also: GenericObjectPool
validated
before being returned to the pool within the
GenericObjectPool.
See Also: GenericObjectPool
validated
by the idle object evictor (if any). If an object
fails to validate, it will be dropped from the pool.
See Also: GenericObjectPool GenericObjectPool
See Also: GenericObjectPool
Returns: one of WHEN_EXHAUSTED_BLOCK, WHEN_EXHAUSTED_FAIL or WHEN_EXHAUSTED_GROW
See Also: GenericObjectPool
See Also: Config
Parameters: maxActive The cap on the total number of active instances from my pool. Use a negative value for an infinite number of instances.
See Also: GenericObjectPool
Parameters: maxIdle The cap on the number of "idle" instances in the pool. Use a negative value to indicate an unlimited number of idle instances.
See Also: GenericObjectPool
"when exhausted" action
is
WHEN_EXHAUSTED_BLOCK.
When less than 0, the GenericObjectPool method
may block indefinitely.
See Also: GenericObjectPool GenericObjectPool WHEN_EXHAUSTED_BLOCK
See Also: GenericObjectPool GenericObjectPool
Parameters: minIdle The minimum number of objects.
See Also: GenericObjectPool
When a negative value is supplied, ceil(GenericObjectPool)/abs(GenericObjectPool) tests will be run. I.e., when the value is -n, roughly one nth of the idle objects will be tested per run.
See Also: GenericObjectPool GenericObjectPool
See Also: GenericObjectPool
validated
before being returned by the GenericObjectPool
method. If the object fails to validate,
it will be dropped from the pool, and we will attempt
to borrow another.
See Also: GenericObjectPool
validated
before being returned to the pool within the
GenericObjectPool.
See Also: GenericObjectPool
validated
by the idle object evictor (if any). If an object
fails to validate, it will be dropped from the pool.
See Also: GenericObjectPool GenericObjectPool
See Also: GenericObjectPool
Parameters: whenExhaustedAction the action code, which must be one of WHEN_EXHAUSTED_BLOCK, WHEN_EXHAUSTED_FAIL, or WHEN_EXHAUSTED_GROW
See Also: GenericObjectPool