org.apache.commons.pool.impl
Class GenericKeyedObjectPool

java.lang.Object
  org.apache.commons.pool.BaseKeyedObjectPool
      org.apache.commons.pool.impl.GenericKeyedObjectPool

All Implemented Interfaces:

KeyedObjectPool

public class GenericKeyedObjectPool
extends BaseKeyedObjectPool
implements KeyedObjectPool

A configurable KeyedObjectPool implementation.

When coupled with the appropriate KeyedPoolableObjectFactory, GenericKeyedObjectPool provides robust pooling functionality for keyed objects. A GenericKeyedObjectPool can be viewed as a map of pools, keyed on the (unique) key values provided to the preparePool, addObject or borrowObject methods. Each time a new key value is provided to one of these methods, a new pool is created under the given key to be managed by the containing GenericKeyedObjectPool.

A GenericKeyedObjectPool provides a number of configurable parameters:

• maxActive controls the maximum number of objects (per key) that can allocated by the pool (checked out to client threads, or idle in the pool) at one time. When non-positive, there is no limit to the number of objects per key. When maxActive is reached, the keyed pool is said to be exhausted. The default setting for this parameter is 8.
• maxTotal sets a global limit on the number of objects that can be in circulation (active or idle) within the combined set of pools. When non-positive, there is no limit to the total number of objects in circulation. When maxTotal is exceeded, all keyed pools are exhausted. When maxTotal is set to a positive value and borrowObject is invoked when at the limit with no idle instances available, an attempt is made to create room by clearing the oldest 15% of the elements from the keyed pools. The default setting for this parameter is -1 (no limit).
• maxIdle controls the maximum number of objects that can sit idle in the pool (per key) at any time. When negative, there is no limit to the number of objects that may be idle per key. The default setting for this parameter is 8.
• whenExhaustedAction specifies the behavior of the borrowObject method when a keyed pool is exhausted:
  • When whenExhaustedAction is WHEN_EXHAUSTED_FAIL, borrowObject will throw a NoSuchElementException
  • When whenExhaustedAction is WHEN_EXHAUSTED_GROW, borrowObject will create a new object and return it (essentially making maxActive meaningless.)
  • When whenExhaustedAction is WHEN_EXHAUSTED_BLOCK, borrowObject will block (invoke wait until a new or idle object is available. If a positive maxWait value is supplied, the borrowObject will block for at most that many milliseconds, after which a NoSuchElementException will be thrown. If maxWait is non-positive, the borrowObject method will block indefinitely.
  The default whenExhaustedAction setting is WHEN_EXHAUSTED_BLOCK.
• When testOnBorrow is set, the pool will attempt to validate each object before it is returned from the borrowObject method. (Using the provided factory's validateObject method.) Objects that fail to validate will be dropped from the pool, and a different object will be borrowed. The default setting for this parameter is false.
• When testOnReturn is set, the pool will attempt to validate each object before it is returned to the pool in the returnObject method. (Using the provided factory's validateObject method.) Objects that fail to validate will be dropped from the pool. The default setting for this parameter is false.

Optionally, one may configure the pool to examine and possibly evict objects as they sit idle in the pool and to ensure that a minimum number of idle objects is maintained for each key. This is performed by an "idle object eviction" thread, which runs asynchronously. Caution should be used when configuring this optional feature. Eviction runs require an exclusive synchronization lock on the pool, so if they run too frequently and / or incur excessive latency when creating, destroying or validating object instances, performance issues may result. 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. The default setting for this parameter is -1 (i.e., by default, idle object eviction is disabled).
• minEvictableIdleTimeMillis specifies the minimum amount of time that an object may sit idle in the pool before it is eligible for eviction due to idle time. When non-positive, no object will be dropped from the pool due to idle time alone. This setting has no effect unless timeBetweenEvictionRunsMillis > 0. The default setting for this parameter is 30 minutes.
• testWhileIdle indicates whether or not idle objects should be validated using the factory's validateObject method during idle object eviction runs. Objects that fail to validate will be dropped from the pool. This setting has no effect unless timeBetweenEvictionRunsMillis > 0. The default setting for this parameter is false.
• minIdle sets a target value for the minimum number of idle objects (per key) that should always be available. If this parameter is set to a positive number and timeBetweenEvictionRunsMillis > 0, each time the idle object eviction thread runs, it will try to create enough idle instances so that there will be minIdle idle instances available under each key. This parameter is also used by preparePool if true is provided as that method's populateImmediately parameter. The default setting for this parameter is 0.

The pools can be configured to behave as LIFO queues with respect to idle objects - always returning the most recently used object from the pool, or as FIFO queues, where borrowObject always returns the oldest object in the idle object pool.

• Lifo determines whether or not the pools return idle objects in last-in-first-out order. The default setting for this parameter is true.

GenericKeyedObjectPool is not usable without a KeyedPoolableObjectFactory. A non-null factory must be provided either as a constructor argument or via a call to setFactory before the pool is used.

Implementation note: To prevent possible deadlocks, care has been taken to ensure that no call to a factory method will occur within a synchronization block. See POOL-125 and DBCP-44 for more information.

Since:

Pool 1.0

Version:

$Revision: 784441 $ $Date: 2009-06-13 13:42:28 -0400 (Sat, 13 Jun 2009) $

Author:

Rodney Waldhoff, Dirk Verbeeck, Sandy McArthur

See Also:

GenericObjectPool

Nested Class Summary

static class

GenericKeyedObjectPool.Config A simple "struct" encapsulating the configuration information for a GenericKeyedObjectPool.

Field Summary

static boolean	DEFAULT_LIFO The default LIFO status.
static int	DEFAULT_MAX_ACTIVE The default cap on the total number of active instances (per key) from the pool.
static int	DEFAULT_MAX_IDLE The default cap on the number of idle instances (per key) in the pool.
static int	DEFAULT_MAX_TOTAL The default cap on the the overall maximum number of objects that can exist at one time.
static long	DEFAULT_MAX_WAIT The default maximum amount of time (in milliseconds) the borrowObject(java.lang.Object) 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 getMinEvictableIdleTimeMillis().
static int	DEFAULT_MIN_IDLE The default minimum level of idle objects in the pool.
static int	DEFAULT_NUM_TESTS_PER_EVICTION_RUN The default number of objects to examine per run in the idle object evictor.
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 borrowObject(java.lang.Object) 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 borrowObject(java.lang.Object) 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 borrowObject(java.lang.Object) method should simply create a new object anyway.

Constructor Summary

GenericKeyedObjectPool()
Create a new GenericKeyedObjectPool with no factory.

GenericKeyedObjectPool(KeyedPoolableObjectFactory factory)
Create a new GenericKeyedObjectPool using the specified values.

GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, GenericKeyedObjectPool.Config config)
Create a new GenericKeyedObjectPool using the specified values.

GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive)
Create a new GenericKeyedObjectPool using the specified values.

GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait)
Create a new GenericKeyedObjectPool using the specified values.

GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait, boolean testOnBorrow, boolean testOnReturn)
Create a new GenericKeyedObjectPool using the specified values.

GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait, int maxIdle)
Create a new GenericKeyedObjectPool using the specified values.

GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait, int maxIdle, boolean testOnBorrow, boolean testOnReturn)
Create a new GenericKeyedObjectPool using the specified values.

GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait, int maxIdle, boolean testOnBorrow, boolean testOnReturn, long timeBetweenEvictionRunsMillis, int numTestsPerEvictionRun, long minEvictableIdleTimeMillis, boolean testWhileIdle)
Create a new GenericKeyedObjectPool using the specified values.

GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait, int maxIdle, int maxTotal, boolean testOnBorrow, boolean testOnReturn, long timeBetweenEvictionRunsMillis, int numTestsPerEvictionRun, long minEvictableIdleTimeMillis, boolean testWhileIdle)
Create a new GenericKeyedObjectPool using the specified values.

GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait, int maxIdle, int maxTotal, int minIdle, boolean testOnBorrow, boolean testOnReturn, long timeBetweenEvictionRunsMillis, int numTestsPerEvictionRun, long minEvictableIdleTimeMillis, boolean testWhileIdle)
Create a new GenericKeyedObjectPool using the specified values.

GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait, int maxIdle, int maxTotal, int minIdle, boolean testOnBorrow, boolean testOnReturn, long timeBetweenEvictionRunsMillis, int numTestsPerEvictionRun, long minEvictableIdleTimeMillis, boolean testWhileIdle, boolean lifo)
Create a new GenericKeyedObjectPool using the specified values.

Method Summary

void	addObject(Object key) Create an object using the factory, passivate it, and then place it in the idle object pool.
Object	borrowObject(Object key) Borrows an object from the keyed pool associated with the given key.
void	clear() Clears the pool, removing all pooled instances.
void	clear(Object key) Clears the specified pool, removing all pooled instances corresponding to the given key.
void	clearOldest() Clears oldest 15% of objects in pool.
void	close() Closes the keyed object pool.
void	evict() Perform numTests idle object eviction tests, evicting examined objects that meet the criteria for eviction.
boolean	getLifo() Whether or not the idle object pools act as LIFO queues.
int	getMaxActive() Returns the cap on the number of object instances allocated by the pool (checked out or idle), per key.
int	getMaxIdle() Returns the cap on the number of "idle" instances per key.
int	getMaxTotal() Returns the overall maximum number of objects (across pools) that can exist at one time.
long	getMaxWait() Returns the maximum amount of time (in milliseconds) the borrowObject(java.lang.Object) 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 eligible for eviction by the idle object evictor (if any).
int	getMinIdle() Returns the minimum number of idle objects to maintain in each of the keyed pools.
int	getNumActive() Returns the total number of instances current borrowed from this pool but not yet returned.
int	getNumActive(Object key) Returns the number of instances currently borrowed from but not yet returned to the pool corresponding to the given key.
int	getNumIdle() Returns the total number of instances currently idle in this pool.
int	getNumIdle(Object key) Returns the number of instances corresponding to the given key currently idle in this pool.
int	getNumTestsPerEvictionRun() Returns the number of objects to examine during each run of the idle object evictor thread (if any).
boolean	getTestOnBorrow() When true, objects will be validated before being returned by the borrowObject(java.lang.Object) method.
boolean	getTestOnReturn() When true, objects will be validated before being returned to the pool within the returnObject(java.lang.Object, java.lang.Object).
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 borrowObject(java.lang.Object) method is invoked when the pool is exhausted (the maximum number of "active" objects has been reached).
void	invalidateObject(Object key, Object obj) Invalidates the object instance associated with the given key.
void	preparePool(Object key, boolean populateImmediately) Registers a key for pool control.
void	returnObject(Object key, Object obj) Returns an object to a keyed pool.
void	setConfig(GenericKeyedObjectPool.Config conf) Sets the configuration.
void	setFactory(KeyedPoolableObjectFactory factory) Sets the keyed poolable object factory associated with this pool.
void	setLifo(boolean lifo) Sets the LIFO property of the pools.
void	setMaxActive(int maxActive) Sets the cap on the number of object instances managed by the pool per key.
void	setMaxIdle(int maxIdle) Sets the cap on the number of "idle" instances in the pool.
void	setMaxTotal(int maxTotal) Sets the cap on the total number of instances from all pools combined.
void	setMaxWait(long maxWait) Sets the maximum amount of time (in milliseconds) the borrowObject(java.lang.Object) 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 eligible for eviction by the idle object evictor (if any).
void	setMinIdle(int poolSize) Sets the minimum number of idle objects to maintain in each of the keyed pools.
void	setNumTestsPerEvictionRun(int numTestsPerEvictionRun) Sets the number of objects to examine during each run of the idle object evictor thread (if any).
void	setTestOnBorrow(boolean testOnBorrow) When true, objects will be validated before being returned by the borrowObject(java.lang.Object) method.
void	setTestOnReturn(boolean testOnReturn) When true, objects will be validated before being returned to the pool within the returnObject(java.lang.Object, java.lang.Object).
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 borrowObject(java.lang.Object) method is invoked when the pool is exhausted (the maximum number of "active" objects has been reached).
protected void	startEvictor(long delay) Start the eviction thread or service, or when delay is non-positive, stop it if it is already running.

Methods inherited from class org.apache.commons.pool.BaseKeyedObjectPool

assertOpen, isClosed

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

WHEN_EXHAUSTED_FAIL

public static final 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 borrowObject(java.lang.Object) method should fail, throwing a NoSuchElementException.

See Also:

WHEN_EXHAUSTED_BLOCK, WHEN_EXHAUSTED_GROW, setWhenExhaustedAction(byte), Constant Field Values

WHEN_EXHAUSTED_BLOCK

public static final 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 borrowObject(java.lang.Object) method should block until a new object is available, or the maximum wait time has been reached.

See Also:

WHEN_EXHAUSTED_FAIL, WHEN_EXHAUSTED_GROW, setMaxWait(long), getMaxWait(), setWhenExhaustedAction(byte), Constant Field Values

WHEN_EXHAUSTED_GROW

public static final 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 borrowObject(java.lang.Object) method should simply create a new object anyway.

See Also:

WHEN_EXHAUSTED_FAIL, WHEN_EXHAUSTED_GROW, setWhenExhaustedAction(byte), Constant Field Values

DEFAULT_MAX_IDLE

public static final int DEFAULT_MAX_IDLE

The default cap on the number of idle instances (per key) in the pool.

See Also:

getMaxIdle(), setMaxIdle(int), Constant Field Values

DEFAULT_MAX_ACTIVE

public static final int DEFAULT_MAX_ACTIVE

The default cap on the total number of active instances (per key) from the pool.

See Also:

getMaxActive(), setMaxActive(int), Constant Field Values

DEFAULT_MAX_TOTAL

public static final int DEFAULT_MAX_TOTAL

The default cap on the the overall maximum number of objects that can exist at one time.

See Also:

getMaxTotal(), setMaxTotal(int), Constant Field Values

DEFAULT_WHEN_EXHAUSTED_ACTION

public static final byte DEFAULT_WHEN_EXHAUSTED_ACTION

The default "when exhausted action" for the pool.

See Also:

WHEN_EXHAUSTED_BLOCK, WHEN_EXHAUSTED_FAIL, WHEN_EXHAUSTED_GROW, setWhenExhaustedAction(byte), Constant Field Values

DEFAULT_MAX_WAIT

public static final long DEFAULT_MAX_WAIT

The default maximum amount of time (in milliseconds) the borrowObject(java.lang.Object) method should block before throwing an exception when the pool is exhausted and the "when exhausted" action is WHEN_EXHAUSTED_BLOCK.

See Also:

getMaxWait(), setMaxWait(long), Constant Field Values

DEFAULT_TEST_ON_BORROW

public static final boolean DEFAULT_TEST_ON_BORROW

The default "test on borrow" value.

See Also:

getTestOnBorrow(), setTestOnBorrow(boolean), Constant Field Values

DEFAULT_TEST_ON_RETURN

public static final boolean DEFAULT_TEST_ON_RETURN

The default "test on return" value.

See Also:

getTestOnReturn(), setTestOnReturn(boolean), Constant Field Values

DEFAULT_TEST_WHILE_IDLE

public static final boolean DEFAULT_TEST_WHILE_IDLE

The default "test while idle" value.

See Also:

getTestWhileIdle(), setTestWhileIdle(boolean), getTimeBetweenEvictionRunsMillis(), setTimeBetweenEvictionRunsMillis(long), Constant Field Values

DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS

public static final long DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS

The default "time between eviction runs" value.

See Also:

getTimeBetweenEvictionRunsMillis(), setTimeBetweenEvictionRunsMillis(long), Constant Field Values

DEFAULT_NUM_TESTS_PER_EVICTION_RUN

public static final int DEFAULT_NUM_TESTS_PER_EVICTION_RUN

The default number of objects to examine per run in the idle object evictor.

See Also:

getNumTestsPerEvictionRun(), setNumTestsPerEvictionRun(int), getTimeBetweenEvictionRunsMillis(), setTimeBetweenEvictionRunsMillis(long), Constant Field Values

DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS

public static final long DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS

The default value for getMinEvictableIdleTimeMillis().

See Also:

getMinEvictableIdleTimeMillis(), setMinEvictableIdleTimeMillis(long), Constant Field Values

DEFAULT_MIN_IDLE

public static final int DEFAULT_MIN_IDLE

The default minimum level of idle objects in the pool.

Since:

Pool 1.3

See Also:

setMinIdle(int), getMinIdle(), Constant Field Values

DEFAULT_LIFO

public static final boolean DEFAULT_LIFO

The default LIFO status. True means that borrowObject returns the most recently used ("last in") idle object in a pool (if there are idle instances available). False means that pools behave as FIFO queues - objects are taken from idle object pools in the order that they are returned.

See Also:

setLifo(boolean), Constant Field Values

Constructor Detail

GenericKeyedObjectPool

public GenericKeyedObjectPool()

Create a new GenericKeyedObjectPool with no factory.

See Also:

GenericKeyedObjectPool(KeyedPoolableObjectFactory), setFactory(KeyedPoolableObjectFactory)

GenericKeyedObjectPool

public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory)

Create a new GenericKeyedObjectPool using the specified values.

Parameters:

factory - the KeyedPoolableObjectFactory to use to create, validate, and destroy objects if not null

GenericKeyedObjectPool

public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory,
                              GenericKeyedObjectPool.Config config)

Create a new GenericKeyedObjectPool using the specified values.

Parameters:

factory - the KeyedPoolableObjectFactory to use to create, validate, and destroy objects if not null

config - a non-null GenericKeyedObjectPool.Config describing the configuration

GenericKeyedObjectPool

public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory,
                              int maxActive)

Create a new GenericKeyedObjectPool using the specified values.

Parameters:

factory - the KeyedPoolableObjectFactory to use to create, validate, and destroy objects if not null

maxActive - the maximum number of objects that can be borrowed from me at one time (see setMaxActive(int))

GenericKeyedObjectPool

public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory,
                              int maxActive,
                              byte whenExhaustedAction,
                              long maxWait)

Create a new GenericKeyedObjectPool using the specified values.

Parameters:

factory - the KeyedPoolableObjectFactory to use to create, validate, and destroy objects if not null

maxActive - the maximum number of objects that can be borrowed from me at one time (see setMaxActive(int))

whenExhaustedAction - the action to take when the pool is exhausted (see setWhenExhaustedAction(byte))

maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted and whenExhaustedAction is WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see setMaxWait(long))

GenericKeyedObjectPool

public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory,
                              int maxActive,
                              byte whenExhaustedAction,
                              long maxWait,
                              boolean testOnBorrow,
                              boolean testOnReturn)

Create a new GenericKeyedObjectPool using the specified values.

Parameters:

factory - the KeyedPoolableObjectFactory to use to create, validate, and destroy objects if not null

maxActive - the maximum number of objects that can be borrowed from me at one time (see setMaxActive(int))

maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted and whenExhaustedAction is WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see setMaxWait(long))

whenExhaustedAction - the action to take when the pool is exhausted (see setWhenExhaustedAction(byte))

testOnBorrow - whether or not to validate objects before they are returned by the borrowObject(java.lang.Object) method (see setTestOnBorrow(boolean))

testOnReturn - whether or not to validate objects after they are returned to the returnObject(java.lang.Object, java.lang.Object) method (see setTestOnReturn(boolean))

GenericKeyedObjectPool

public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory,
                              int maxActive,
                              byte whenExhaustedAction,
                              long maxWait,
                              int maxIdle)

Create a new GenericKeyedObjectPool using the specified values.

Parameters:

factory - the KeyedPoolableObjectFactory to use to create, validate, and destroy objects if not null

maxActive - the maximum number of objects that can be borrowed from me at one time (see setMaxActive(int))

whenExhaustedAction - the action to take when the pool is exhausted (see setWhenExhaustedAction(byte))

maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted and whenExhaustedAction is WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see setMaxWait(long))

maxIdle - the maximum number of idle objects in my pool (see setMaxIdle(int))

GenericKeyedObjectPool

public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory,
                              int maxActive,
                              byte whenExhaustedAction,
                              long maxWait,
                              int maxIdle,
                              boolean testOnBorrow,
                              boolean testOnReturn)

Create a new GenericKeyedObjectPool using the specified values.

Parameters:

factory - the KeyedPoolableObjectFactory to use to create, validate, and destroy objects if not null

maxActive - the maximum number of objects that can be borrowed from me at one time (see setMaxActive(int))

whenExhaustedAction - the action to take when the pool is exhausted (see setWhenExhaustedAction(byte))

maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted and whenExhaustedAction is WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see getMaxWait())

maxIdle - the maximum number of idle objects in my pool (see setMaxIdle(int))

testOnBorrow - whether or not to validate objects before they are returned by the borrowObject(java.lang.Object) method (see setTestOnBorrow(boolean))

testOnReturn - whether or not to validate objects after they are returned to the returnObject(java.lang.Object, java.lang.Object) method (see setTestOnReturn(boolean))

GenericKeyedObjectPool

public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory,
                              int maxActive,
                              byte whenExhaustedAction,
                              long maxWait,
                              int maxIdle,
                              boolean testOnBorrow,
                              boolean testOnReturn,
                              long timeBetweenEvictionRunsMillis,
                              int numTestsPerEvictionRun,
                              long minEvictableIdleTimeMillis,
                              boolean testWhileIdle)

Create a new GenericKeyedObjectPool using the specified values.

Parameters:

factory - the KeyedPoolableObjectFactory to use to create, validate, and destroy objects if not null

maxActive - the maximum number of objects that can be borrowed from me at one time (see setMaxActive(int))

whenExhaustedAction - the action to take when the pool is exhausted (see setWhenExhaustedAction(byte))

maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted and whenExhaustedAction is WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see setMaxWait(long))

maxIdle - the maximum number of idle objects in my pool (see setMaxIdle(int))

testOnBorrow - whether or not to validate objects before they are returned by the borrowObject(java.lang.Object) method (see setTestOnBorrow(boolean))

testOnReturn - whether or not to validate objects after they are returned to the returnObject(java.lang.Object, java.lang.Object) method (see setTestOnReturn(boolean))

timeBetweenEvictionRunsMillis - the amount of time (in milliseconds) to sleep between examining idle objects for eviction (see setTimeBetweenEvictionRunsMillis(long))

numTestsPerEvictionRun - the number of idle objects to examine per run within the idle object eviction thread (if any) (see setNumTestsPerEvictionRun(int))

minEvictableIdleTimeMillis - the minimum number of milliseconds an object can sit idle in the pool before it is eligible for eviction (see setMinEvictableIdleTimeMillis(long))

testWhileIdle - whether or not to validate objects in the idle object eviction thread, if any (see setTestWhileIdle(boolean))

GenericKeyedObjectPool

public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory,
                              int maxActive,
                              byte whenExhaustedAction,
                              long maxWait,
                              int maxIdle,
                              int maxTotal,
                              boolean testOnBorrow,
                              boolean testOnReturn,
                              long timeBetweenEvictionRunsMillis,
                              int numTestsPerEvictionRun,
                              long minEvictableIdleTimeMillis,
                              boolean testWhileIdle)

Create a new GenericKeyedObjectPool using the specified values.

Parameters:

factory - the KeyedPoolableObjectFactory to use to create, validate, and destroy objects if not null

maxActive - the maximum number of objects that can be borrowed from me at one time (see setMaxActive(int))

whenExhaustedAction - the action to take when the pool is exhausted (see setWhenExhaustedAction(byte))

maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted and whenExhaustedAction is WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see setMaxWait(long))

maxIdle - the maximum number of idle objects in my pool (see setMaxIdle(int))

maxTotal - the maximum number of objects that can exists at one time (see setMaxTotal(int))

testOnBorrow - whether or not to validate objects before they are returned by the borrowObject(java.lang.Object) method (see setTestOnBorrow(boolean))

testOnReturn - whether or not to validate objects after they are returned to the returnObject(java.lang.Object, java.lang.Object) method (see setTestOnReturn(boolean))

timeBetweenEvictionRunsMillis - the amount of time (in milliseconds) to sleep between examining idle objects for eviction (see setTimeBetweenEvictionRunsMillis(long))

numTestsPerEvictionRun - the number of idle objects to examine per run within the idle object eviction thread (if any) (see setNumTestsPerEvictionRun(int))

minEvictableIdleTimeMillis - the minimum number of milliseconds an object can sit idle in the pool before it is eligible for eviction (see setMinEvictableIdleTimeMillis(long))

testWhileIdle - whether or not to validate objects in the idle object eviction thread, if any (see setTestWhileIdle(boolean))

GenericKeyedObjectPool

public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory,
                              int maxActive,
                              byte whenExhaustedAction,
                              long maxWait,
                              int maxIdle,
                              int maxTotal,
                              int minIdle,
                              boolean testOnBorrow,
                              boolean testOnReturn,
                              long timeBetweenEvictionRunsMillis,
                              int numTestsPerEvictionRun,
                              long minEvictableIdleTimeMillis,
                              boolean testWhileIdle)

Create a new GenericKeyedObjectPool using the specified values.

Parameters:

factory - the KeyedPoolableObjectFactory to use to create, validate, and destroy objects if not null

maxActive - the maximum number of objects that can be borrowed at one time (see setMaxActive(int))

whenExhaustedAction - the action to take when the pool is exhausted (see setWhenExhaustedAction(byte))

maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted and whenExhaustedAction is WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see setMaxWait(long))

maxIdle - the maximum number of idle objects in my pool (see setMaxIdle(int))

maxTotal - the maximum number of objects that can exists at one time (see setMaxTotal(int))

minIdle - the minimum number of idle objects to have in the pool at any one time (see setMinIdle(int))

testOnBorrow - whether or not to validate objects before they are returned by the borrowObject(java.lang.Object) method (see setTestOnBorrow(boolean))

testOnReturn - whether or not to validate objects after they are returned to the returnObject(java.lang.Object, java.lang.Object) method (see setTestOnReturn(boolean))

timeBetweenEvictionRunsMillis - the amount of time (in milliseconds) to sleep between examining idle objects for eviction (see setTimeBetweenEvictionRunsMillis(long))

numTestsPerEvictionRun - the number of idle objects to examine per run within the idle object eviction thread (if any) (see setNumTestsPerEvictionRun(int))

minEvictableIdleTimeMillis - the minimum number of milliseconds an object can sit idle in the pool before it is eligible for eviction (see setMinEvictableIdleTimeMillis(long))

testWhileIdle - whether or not to validate objects in the idle object eviction thread, if any (see setTestWhileIdle(boolean))

Since:

Pool 1.3

GenericKeyedObjectPool

public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory,
                              int maxActive,
                              byte whenExhaustedAction,
                              long maxWait,
                              int maxIdle,
                              int maxTotal,
                              int minIdle,
                              boolean testOnBorrow,
                              boolean testOnReturn,
                              long timeBetweenEvictionRunsMillis,
                              int numTestsPerEvictionRun,
                              long minEvictableIdleTimeMillis,
                              boolean testWhileIdle,
                              boolean lifo)

Create a new GenericKeyedObjectPool using the specified values.

Parameters:

factory - the KeyedPoolableObjectFactory to use to create, validate, and destroy objects if not null

maxActive - the maximum number of objects that can be borrowed at one time (see setMaxActive(int))

whenExhaustedAction - the action to take when the pool is exhausted (see setWhenExhaustedAction(byte))

maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted and whenExhaustedAction is WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see setMaxWait(long))

maxIdle - the maximum number of idle objects in my pool (see setMaxIdle(int))

maxTotal - the maximum number of objects that can exists at one time (see setMaxTotal(int))

minIdle - the minimum number of idle objects to have in the pool at any one time (see setMinIdle(int))

testOnBorrow - whether or not to validate objects before they are returned by the borrowObject(java.lang.Object) method (see setTestOnBorrow(boolean))

testOnReturn - whether or not to validate objects after they are returned to the returnObject(java.lang.Object, java.lang.Object) method (see setTestOnReturn(boolean))

timeBetweenEvictionRunsMillis - the amount of time (in milliseconds) to sleep between examining idle objects for eviction (see setTimeBetweenEvictionRunsMillis(long))

numTestsPerEvictionRun - the number of idle objects to examine per run within the idle object eviction thread (if any) (see setNumTestsPerEvictionRun(int))

minEvictableIdleTimeMillis - the minimum number of milliseconds an object can sit idle in the pool before it is eligible for eviction (see setMinEvictableIdleTimeMillis(long))

testWhileIdle - whether or not to validate objects in the idle object eviction thread, if any (see setTestWhileIdle(boolean))

lifo - whether or not the pools behave as LIFO (last in first out) queues (see setLifo(boolean))

Since:

Pool 1.4

Method Detail

getMaxActive

public int getMaxActive()

Returns the cap on the number of object instances allocated by the pool (checked out or idle), per key. A negative value indicates no limit.

Returns:

the cap on the number of active instances per key.

See Also:

setMaxActive(int)

setMaxActive

public void setMaxActive(int maxActive)

Sets the cap on the number of object instances managed by the pool per key.

Parameters:

maxActive - The cap on the number of object instances per key. Use a negative value for no limit.

See Also:

getMaxActive()

getMaxTotal

public int getMaxTotal()

Returns the overall maximum number of objects (across pools) that can exist at one time. A negative value indicates no limit.

Returns:

the maximum number of instances in circulation at one time.

See Also:

setMaxTotal(int)

setMaxTotal

public void setMaxTotal(int maxTotal)

Sets the cap on the total number of instances from all pools combined. When maxTotal is set to a positive value and borrowObject is invoked when at the limit with no idle instances available, an attempt is made to create room by clearing the oldest 15% of the elements from the keyed pools.

Parameters:

maxTotal - The cap on the total number of instances across pools. Use a negative value for no limit.

See Also:

getMaxTotal()

getWhenExhaustedAction

public byte getWhenExhaustedAction()

Returns the action to take when the borrowObject(java.lang.Object) method is invoked when the pool is exhausted (the maximum number of "active" objects has been reached).

Returns:

one of WHEN_EXHAUSTED_BLOCK, WHEN_EXHAUSTED_FAIL or WHEN_EXHAUSTED_GROW

See Also:

setWhenExhaustedAction(byte)

setWhenExhaustedAction

public void setWhenExhaustedAction(byte whenExhaustedAction)

Sets the action to take when the borrowObject(java.lang.Object) method is invoked when the pool is exhausted (the maximum number of "active" objects has been reached).

Parameters:

whenExhaustedAction - the action code, which must be one of WHEN_EXHAUSTED_BLOCK, WHEN_EXHAUSTED_FAIL, or WHEN_EXHAUSTED_GROW

See Also:

getWhenExhaustedAction()

getMaxWait

public long getMaxWait()

Returns the maximum amount of time (in milliseconds) the borrowObject(java.lang.Object) method should block before throwing an exception when the pool is exhausted and the "when exhausted" action is WHEN_EXHAUSTED_BLOCK. When less than or equal to 0, the borrowObject(java.lang.Object) method may block indefinitely.

Returns:

the maximum number of milliseconds borrowObject will block.

See Also:

setMaxWait(long), setWhenExhaustedAction(byte), WHEN_EXHAUSTED_BLOCK

setMaxWait

public void setMaxWait(long maxWait)

Sets the maximum amount of time (in milliseconds) the borrowObject(java.lang.Object) method should block before throwing an exception when the pool is exhausted and the "when exhausted" action is WHEN_EXHAUSTED_BLOCK. When less than or equal to 0, the borrowObject(java.lang.Object) method may block indefinitely.

Parameters:

maxWait - the maximum number of milliseconds borrowObject will block or negative for indefinitely.

See Also:

getMaxWait(), setWhenExhaustedAction(byte), WHEN_EXHAUSTED_BLOCK

getMaxIdle

public int getMaxIdle()

Returns the cap on the number of "idle" instances per key.

Returns:

the maximum number of "idle" instances that can be held in a given keyed pool.

See Also:

setMaxIdle(int)

setMaxIdle

public void setMaxIdle(int maxIdle)

Sets the cap on the number of "idle" instances in the pool. If maxIdle is set too low on heavily loaded systems it is possible you will see objects being destroyed and almost immediately new objects being created. This is a result of the active threads momentarily returning objects faster than they are requesting them them, causing the number of idle objects to rise above maxIdle. The best value for maxIdle for heavily loaded system will vary but the default is a good starting point.

Parameters:

maxIdle - the maximum number of "idle" instances that can be held in a given keyed pool. Use a negative value for no limit.

See Also:

getMaxIdle(), DEFAULT_MAX_IDLE

setMinIdle

public void setMinIdle(int poolSize)

Sets the minimum number of idle objects to maintain in each of the keyed pools. This setting has no effect unless timeBetweenEvictionRunsMillis > 0 and attempts to ensure that each pool has the required minimum number of instances are only made during idle object eviction runs.

Parameters:

poolSize - - The minimum size of the each keyed pool

Since:

Pool 1.3

See Also:

getMinIdle(), setTimeBetweenEvictionRunsMillis(long)

getMinIdle

public int getMinIdle()

Returns the minimum number of idle objects to maintain in each of the keyed pools. This setting has no effect unless timeBetweenEvictionRunsMillis > 0 and attempts to ensure that each pool has the required minimum number of instances are only made during idle object eviction runs.

Returns:

minimum size of the each keyed pool

Since:

Pool 1.3

See Also:

setTimeBetweenEvictionRunsMillis(long)

getTestOnBorrow

public boolean getTestOnBorrow()

When true, objects will be validated before being returned by the borrowObject(java.lang.Object) method. If the object fails to validate, it will be dropped from the pool, and we will attempt to borrow another.

Returns:

true if objects are validated before being borrowed.

See Also:

setTestOnBorrow(boolean)

setTestOnBorrow

public void setTestOnBorrow(boolean testOnBorrow)

When true, objects will be validated before being returned by the borrowObject(java.lang.Object) method. If the object fails to validate, it will be dropped from the pool, and we will attempt to borrow another.

Parameters:

testOnBorrow - whether object should be validated before being returned by borrowObject.

See Also:

getTestOnBorrow()

getTestOnReturn

public boolean getTestOnReturn()

When true, objects will be validated before being returned to the pool within the returnObject(java.lang.Object, java.lang.Object).

Returns:

true when objects will be validated before being returned.

See Also:

setTestOnReturn(boolean)

setTestOnReturn

public void setTestOnReturn(boolean testOnReturn)

When true, objects will be validated before being returned to the pool within the returnObject(java.lang.Object, java.lang.Object).

Parameters:

testOnReturn - true so objects will be validated before being returned.

See Also:

getTestOnReturn()

getTimeBetweenEvictionRunsMillis

public long getTimeBetweenEvictionRunsMillis()

Returns the number of milliseconds to sleep between runs of the idle object evictor thread. When non-positive, no idle object evictor thread will be run.

Returns:

milliseconds to sleep between evictor runs.

See Also:

setTimeBetweenEvictionRunsMillis(long)

setTimeBetweenEvictionRunsMillis

public void setTimeBetweenEvictionRunsMillis(long timeBetweenEvictionRunsMillis)

Sets the number of milliseconds to sleep between runs of the idle object evictor thread. When non-positive, no idle object evictor thread will be run.

Parameters:

timeBetweenEvictionRunsMillis - milliseconds to sleep between evictor runs.

See Also:

getTimeBetweenEvictionRunsMillis()

getNumTestsPerEvictionRun

public int getNumTestsPerEvictionRun()

Returns the number of objects to examine during each run of the idle object evictor thread (if any).

Returns:

number of objects to examine each eviction run.

See Also:

setNumTestsPerEvictionRun(int), setTimeBetweenEvictionRunsMillis(long)

setNumTestsPerEvictionRun

public void setNumTestsPerEvictionRun(int numTestsPerEvictionRun)

Sets the number of objects to examine during each run of the idle object evictor thread (if any).

When a negative value is supplied, ceil(getNumIdle())/abs(getNumTestsPerEvictionRun()) tests will be run. I.e., when the value is -n, roughly one nth of the idle objects will be tested per run.

Parameters:

numTestsPerEvictionRun - number of objects to examine each eviction run.

See Also:

getNumTestsPerEvictionRun(), setTimeBetweenEvictionRunsMillis(long)

getMinEvictableIdleTimeMillis

public long getMinEvictableIdleTimeMillis()

Returns the minimum amount of time an object may sit idle in the pool before it is eligible for eviction by the idle object evictor (if any).

Returns:

minimum amount of time an object may sit idle in the pool before it is eligible for eviction.

See Also:

setMinEvictableIdleTimeMillis(long), setTimeBetweenEvictionRunsMillis(long)

setMinEvictableIdleTimeMillis

public void setMinEvictableIdleTimeMillis(long minEvictableIdleTimeMillis)

Sets the minimum amount of time an object may sit idle in the pool before it is eligible for eviction by the idle object evictor (if any). When non-positive, no objects will be evicted from the pool due to idle time alone.

Parameters:

minEvictableIdleTimeMillis - minimum amount of time an object may sit idle in the pool before it is eligible for eviction.

See Also:

getMinEvictableIdleTimeMillis(), setTimeBetweenEvictionRunsMillis(long)

getTestWhileIdle

public boolean getTestWhileIdle()

When true, objects will be validated by the idle object evictor (if any). If an object fails to validate, it will be dropped from the pool.

Returns:

true when objects are validated when borrowed.

See Also:

setTestWhileIdle(boolean), setTimeBetweenEvictionRunsMillis(long)

setTestWhileIdle

public void setTestWhileIdle(boolean testWhileIdle)

When true, objects will be validated by the idle object evictor (if any). If an object fails to validate, it will be dropped from the pool.

Parameters:

testWhileIdle - true so objects are validated when borrowed.

See Also:

getTestWhileIdle(), setTimeBetweenEvictionRunsMillis(long)

setConfig

public void setConfig(GenericKeyedObjectPool.Config conf)

Sets the configuration.

Parameters:

conf - the new configuration to use.

See Also:

GenericKeyedObjectPool.Config

getLifo

public boolean getLifo()

Whether or not the idle object pools act as LIFO queues. True means that borrowObject returns the most recently used ("last in") idle object in a pool (if there are idle instances available). False means that the pools behave as FIFO queues - objects are taken from idle object pools in the order that they are returned.

Returns:

true if the pools are configured to act as LIFO queues

Since:

1.4

setLifo

public void setLifo(boolean lifo)

Sets the LIFO property of the pools. True means that borrowObject returns the most recently used ("last in") idle object in a pool (if there are idle instances available). False means that the pools behave as FIFO queues - objects are taken from idle object pools in the order that they are returned.

Parameters:

lifo - the new value for the lifo property

Since:

1.4

borrowObject

public Object borrowObject(Object key)
                    throws Exception

Borrows an object from the keyed pool associated with the given key.

If there is an idle instance available in the pool associated with the given key, then either the most-recently returned (if lifo == true) or "oldest" (lifo == false) instance sitting idle in the pool will be activated and returned. If activation fails, or testOnBorrow is set to true and validation fails, the instance is destroyed and the next available instance is examined. This continues until either a valid instance is returned or there are no more idle instances available.

If there are no idle instances available in the pool associated with the given key, behavior depends on the maxActive, maxTotal, and (if applicable) whenExhaustedAction and maxWait properties. If the number of instances checked out from the pool under the given key is less than maxActive and the total number of instances in circulation (under all keys) is less than maxTotal, a new instance is created, activated and (if applicable) validated and returned to the caller.

If the associated keyed pool is exhausted (no available idle instances and no capacity to create new ones), this method will either block (WHEN_EXHAUSTED_BLOCK), throw a NoSuchElementException (WHEN_EXHAUSTED_FAIL), or grow (WHEN_EXHAUSTED_GROW - ignoring maxActive, maxTotal properties). The length of time that this method will block when whenExhaustedAction == WHEN_EXHAUSTED_BLOCK is determined by the maxWait property.

When the pool is exhausted, multiple calling threads may be simultaneously blocked waiting for instances to become available. As of pool 1.5, a "fairness" algorithm has been implemented to ensure that threads receive available instances in request arrival order.

Specified by:

borrowObject in interface KeyedObjectPool

Specified by:

borrowObject in class BaseKeyedObjectPool

Parameters:

key - pool key

Returns:

object instance from the keyed pool

Throws:

NoSuchElementException - if a keyed object instance cannot be returned.

IllegalStateException - after close has been called on this pool

Exception - when makeObject throws an exception

clear

public void clear()

Clears the pool, removing all pooled instances.

Specified by:

clear in interface KeyedObjectPool

Overrides:

clear in class BaseKeyedObjectPool

clearOldest

public void clearOldest()

Clears oldest 15% of objects in pool. The method sorts the objects into a TreeMap and then iterates the first 15% for removal.

Since:

Pool 1.3

clear

public void clear(Object key)

Clears the specified pool, removing all pooled instances corresponding to the given key.

Specified by:

clear in interface KeyedObjectPool

Overrides:

clear in class BaseKeyedObjectPool

Parameters:

key - the key to clear

getNumActive

public int getNumActive()

Returns the total number of instances current borrowed from this pool but not yet returned.

Specified by:

getNumActive in interface KeyedObjectPool

Overrides:

getNumActive in class BaseKeyedObjectPool

Returns:

the total number of instances currently borrowed from this pool

getNumIdle

public int getNumIdle()

Returns the total number of instances currently idle in this pool.

Specified by:

getNumIdle in interface KeyedObjectPool

Overrides:

getNumIdle in class BaseKeyedObjectPool

Returns:

the total number of instances currently idle in this pool

getNumActive

public int getNumActive(Object key)

Returns the number of instances currently borrowed from but not yet returned to the pool corresponding to the given key.

Specified by:

getNumActive in interface KeyedObjectPool

Overrides:

getNumActive in class BaseKeyedObjectPool

Parameters:

key - the key to query

Returns:

the number of instances corresponding to the given key currently borrowed in this pool

getNumIdle

public int getNumIdle(Object key)

Returns the number of instances corresponding to the given key currently idle in this pool.

Specified by:

getNumIdle in interface KeyedObjectPool

Overrides:

getNumIdle in class BaseKeyedObjectPool

Parameters:

key - the key to query

Returns:

the number of instances corresponding to the given key currently idle in this pool

returnObject

public void returnObject(Object key,
                         Object obj)
                  throws Exception

Returns an object to a keyed pool.

For the pool to function correctly, the object instance must have been borrowed from the pool (under the same key) and not yet returned. Repeated returnObject calls on the same object/key pair (with no borrowObject calls in between) will result in multiple references to the object in the idle instance pool.

If maxIdle is set to a positive value and the number of idle instances under the given key has reached this value, the returning instance is destroyed.

If testOnReturn == true, the returning instance is validated before being returned to the idle instance pool under the given key. In this case, if validation fails, the instance is destroyed.

Specified by:

returnObject in interface KeyedObjectPool

Specified by:

returnObject in class BaseKeyedObjectPool

Parameters:

key - pool key

obj - instance to return to the keyed pool

Throws:

Exception

invalidateObject

public void invalidateObject(Object key,
                             Object obj)
                      throws Exception

Invalidates the object instance associated with the given key. Decrements the active count associated with the given keyed pool and destroys the instance.

Specified by:

invalidateObject in interface KeyedObjectPool

Specified by:

invalidateObject in class BaseKeyedObjectPool

Parameters:

key - pool key

obj - instance to invalidate

Throws:

Exception - if an exception occurs destroying the object

addObject

public void addObject(Object key)
               throws Exception

Create an object using the factory, passivate it, and then place it in the idle object pool. addObject is useful for "pre-loading" a pool with idle objects.

Specified by:

addObject in interface KeyedObjectPool

Overrides:

addObject in class BaseKeyedObjectPool

Parameters:

key - the key a new instance should be added to

Throws:

Exception - when KeyedPoolableObjectFactory.makeObject(java.lang.Object) fails.

IllegalStateException - when no factory has been set or after close() has been called on this pool.

preparePool

public void preparePool(Object key,
                        boolean populateImmediately)

Registers a key for pool control. If populateImmediately is true and minIdle > 0, the pool under the given key will be populated immediately with minIdle idle instances.

Parameters:

key - - The key to register for pool control.

populateImmediately - - If this is true, the pool will be populated immediately.

Since:

Pool 1.3

close

public void close()
           throws Exception

Closes the keyed object pool. Once the pool is closed, borrowObject(Object) will fail with IllegalStateException, but returnObject(Object, Object) and invalidateObject(Object, Object) will continue to work. This method does not clear() the pool. The method is idempotent - that is, it is OK to call it on a closed pool.

Specified by:

close in interface KeyedObjectPool

Overrides:

close in class BaseKeyedObjectPool

Throws:

Exception

setFactory

public void setFactory(KeyedPoolableObjectFactory factory)
                throws IllegalStateException

Sets the keyed poolable object factory associated with this pool.

If this method is called when objects are checked out of any of the keyed pools, an IllegalStateException is thrown. Calling this method also has the side effect of destroying any idle instances in existing keyed pools.

Specified by:

setFactory in interface KeyedObjectPool

Overrides:

setFactory in class BaseKeyedObjectPool

Parameters:

factory - KeyedPoolableObjectFactory to use when creating keyed object pool instances

Throws:

IllegalStateException - if there are active (checked out) instances associated with this keyed object pool

evict

public void evict()
           throws Exception

Perform numTests idle object eviction tests, evicting examined objects that meet the criteria for eviction. If testWhileIdle is true, examined objects are validated when visited (and removed if invalid); otherwise only objects that have been idle for more than minEvicableIdletimeMillis are removed.

Successive activations of this method examine objects in keyed pools in sequence, cycling through the keys and examining objects in oldest-to-youngest order within the keyed pools.

Throws:

Exception - when there is a problem evicting idle objects.

startEvictor

protected void startEvictor(long delay)

Start the eviction thread or service, or when delay is non-positive, stop it if it is already running.

Parameters:

delay - milliseconds between evictor runs.