org.datanucleus.store.rdbms.datasource.dbcp.pool.impl

Class StackKeyedObjectPool

java.lang.Object

org.datanucleus.store.rdbms.datasource.dbcp.pool.BaseKeyedObjectPool

org.datanucleus.store.rdbms.datasource.dbcp.pool.impl.StackKeyedObjectPool

All Implemented Interfaces:

KeyedObjectPool

public class StackKeyedObjectPool
extends BaseKeyedObjectPool
implements KeyedObjectPool

A simple, Stack-based KeyedObjectPool implementation.

Given a KeyedPoolableObjectFactory, this class will maintain a simple pool of instances. A finite number of "sleeping" or inactive instances is enforced, but when the pool is empty, new instances are created to support the new load. Hence this class places no limit on the number of "active" instances created by the pool, but is quite useful for re-using Objects without introducing artificial limits.

Since:

Pool 1.0

Version:

$Revision: 990437 $ $Date: 2010-08-28 16:17:57 -0400 (Sat, 28 Aug 2010) $

Author:

Rodney Waldhoff, Sandy McArthur

See Also:

Stack

Field Summary

Fields

Modifier and Type	Field and Description
protected HashMap	_activeCount Deprecated. to be removed in pool 2.0. Use getActiveCount().
protected KeyedPoolableObjectFactory	_factory Deprecated. to be removed in pool 2.0. Use getFactory()
protected int	_initSleepingCapacity Deprecated. to be removed in pool 2.0. Use getInitSleepingCapacity().
protected int	_maxSleeping Deprecated. to be removed in pool 2.0. Use getMaxSleeping()
protected HashMap	_pools Deprecated. to be removed in pool 2.0. Use getPools()
protected int	_totActive Deprecated. to be removed in pool 2.0. Use getTotActive().
protected int	_totIdle Deprecated. to be removed in pool 2.0. Use getTotIdle().
protected static int	DEFAULT_INIT_SLEEPING_CAPACITY The default initial size of the pool (this specifies the size of the container, it does not cause the pool to be pre-populated.)
protected static int	DEFAULT_MAX_SLEEPING The default cap on the number of "sleeping" instances in the pool.

Constructor Summary

Constructors

Constructor and Description
StackKeyedObjectPool() Create a new pool using no factory.
StackKeyedObjectPool(int max) Create a new pool using no factory.
StackKeyedObjectPool(int max, int init) Create a new pool using no factory.
StackKeyedObjectPool(KeyedPoolableObjectFactory factory) Create a new SimpleKeyedObjectPool using the specified factory to create new instances.
StackKeyedObjectPool(KeyedPoolableObjectFactory factory, int max) Create a new SimpleKeyedObjectPool using the specified factory to create new instances.
StackKeyedObjectPool(KeyedPoolableObjectFactory factory, int max, int init) Create a new SimpleKeyedObjectPool using the specified factory to create new instances.

Method Summary

Modifier and Type	Method and Description
void	addObject(Object key) Create an object using the factory, passivate it, and then placed in the idle object pool.
Object	borrowObject(Object key) Borrows an object 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	close() Close this pool, and free any resources associated with it.
Map	getActiveCount()
KeyedPoolableObjectFactory	getFactory()
int	getInitSleepingCapacity()
int	getMaxSleeping()
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.
Map	getPools()
int	getTotActive()
int	getTotIdle()
void	invalidateObject(Object key, Object obj)
void	returnObject(Object key, Object obj) Returns obj to the pool under key.
void	setFactory(KeyedPoolableObjectFactory factory) Deprecated. to be removed in pool 2.0
String	toString() Returns a string representation of this StackKeyedObjectPool, including the number of pools, the keys and the size of each keyed pool.

Methods inherited from class org.datanucleus.store.rdbms.datasource.dbcp.pool.BaseKeyedObjectPool

assertOpen, isClosed

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_MAX_SLEEPING

protected static final int DEFAULT_MAX_SLEEPING

The default cap on the number of "sleeping" instances in the pool.

See Also:

Constant Field Values

DEFAULT_INIT_SLEEPING_CAPACITY

protected static final int DEFAULT_INIT_SLEEPING_CAPACITY

The default initial size of the pool (this specifies the size of the container, it does not cause the pool to be pre-populated.)

See Also:

Constant Field Values

_pools

protected HashMap _pools

Deprecated. to be removed in pool 2.0. Use getPools()

My named-set of pools.

_factory

protected KeyedPoolableObjectFactory _factory

Deprecated. to be removed in pool 2.0. Use getFactory()

My KeyedPoolableObjectFactory.

_maxSleeping

protected int _maxSleeping

Deprecated. to be removed in pool 2.0. Use getMaxSleeping()

The cap on the number of "sleeping" instances in each pool.

_initSleepingCapacity

protected int _initSleepingCapacity

Deprecated. to be removed in pool 2.0. Use getInitSleepingCapacity().

The initial capacity of each pool.

_totActive

protected int _totActive

Deprecated. to be removed in pool 2.0. Use getTotActive().

Total number of object borrowed and not yet returned for all pools.

_totIdle

protected int _totIdle

Deprecated. to be removed in pool 2.0. Use getTotIdle().

Total number of objects "sleeping" for all pools

_activeCount

protected HashMap _activeCount

Deprecated. to be removed in pool 2.0. Use getActiveCount().

Number of active objects borrowed and not yet returned by pool

Constructor Detail

StackKeyedObjectPool

public StackKeyedObjectPool()

Create a new pool using no factory. Clients must first set the factory or may populate the pool using returnObject before they can be borrowed.

See Also:

StackKeyedObjectPool(KeyedPoolableObjectFactory), setFactory(KeyedPoolableObjectFactory)

StackKeyedObjectPool

public StackKeyedObjectPool(int max)

Create a new pool using no factory. Clients must first set the factory or may populate the pool using returnObject before they can be borrowed.

Parameters:

max - cap on the number of "sleeping" instances in the pool

See Also:

StackKeyedObjectPool(KeyedPoolableObjectFactory, int), setFactory(KeyedPoolableObjectFactory)

StackKeyedObjectPool

public StackKeyedObjectPool(int max,
                            int init)

Create a new pool using no factory. Clients must first set the factory or may populate the pool using returnObject before they can be borrowed.

Parameters:

max - cap on the number of "sleeping" instances in the pool

init - initial size of the pool (this specifies the size of the container, it does not cause the pool to be pre-populated.)

See Also:

StackKeyedObjectPool(KeyedPoolableObjectFactory, int, int), setFactory(KeyedPoolableObjectFactory)

StackKeyedObjectPool

public StackKeyedObjectPool(KeyedPoolableObjectFactory factory)

Create a new SimpleKeyedObjectPool using the specified factory to create new instances.

Parameters:

factory - the KeyedPoolableObjectFactory used to populate the pool

StackKeyedObjectPool

public StackKeyedObjectPool(KeyedPoolableObjectFactory factory,
                            int max)

Create a new SimpleKeyedObjectPool using the specified factory to create new instances. capping the number of "sleeping" instances to max

Parameters:

factory - the KeyedPoolableObjectFactory used to populate the pool

max - cap on the number of "sleeping" instances in the pool

StackKeyedObjectPool

public StackKeyedObjectPool(KeyedPoolableObjectFactory factory,
                            int max,
                            int init)

Create a new SimpleKeyedObjectPool using the specified factory to create new instances. capping the number of "sleeping" instances to max, and initially allocating a container capable of containing at least init instances.

Parameters:

factory - the KeyedPoolableObjectFactory used to populate the pool

max - cap on the number of "sleeping" instances in the pool

init - initial size of the pool (this specifies the size of the container, it does not cause the pool to be pre-populated.)

Method Detail

borrowObject

public Object borrowObject(Object key)
                    throws Exception

Borrows an object with the given key. If there are no idle instances under the given key, a new one is created.

Specified by:

borrowObject in interface KeyedObjectPool

Specified by:

borrowObject in class BaseKeyedObjectPool

Parameters:

key - the pool key

Returns:

keyed poolable object instance

Throws:

Exception

returnObject

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

Returns obj to the pool under key. If adding the returning instance to the pool results in maxSleeping exceeded for the given key, the oldest instance in the idle object pool is destroyed to make room for the returning instance.

Specified by:

returnObject in interface KeyedObjectPool

Specified by:

returnObject in class BaseKeyedObjectPool

Parameters:

key - the pool key

obj - returning instance

Throws:

Exception

invalidateObject

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

Specified by:

invalidateObject in interface KeyedObjectPool

Specified by:

invalidateObject in class BaseKeyedObjectPool

Throws:

Exception

addObject

public void addObject(Object key)
               throws Exception

Create an object using the factory, passivate it, and then placed 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.

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()

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

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

clear

public void clear()

Clears the pool, removing all pooled instances.

Specified by:

clear in interface KeyedObjectPool

Overrides:

clear in class BaseKeyedObjectPool

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

toString

public String toString()

Returns a string representation of this StackKeyedObjectPool, including the number of pools, the keys and the size of each keyed pool.

Overrides:

toString in class Object

Returns:

Keys and pool sizes

close

public void close()
           throws Exception

Close this pool, and free any resources associated with it.

Calling addObject or borrowObject after invoking this method on a pool will cause them to throw an IllegalStateException.

Specified by:

close in interface KeyedObjectPool

Overrides:

close in class BaseKeyedObjectPool

Throws:

Exception - deprecated: implementations should silently fail if not all resources can be freed.

setFactory

public void setFactory(KeyedPoolableObjectFactory factory)
                throws IllegalStateException

Deprecated. to be removed in pool 2.0

Sets the factory the pool uses to create new instances. Trying to change the factory after a pool has been used will frequently throw an UnsupportedOperationException.

Specified by:

setFactory in interface KeyedObjectPool

Overrides:

setFactory in class BaseKeyedObjectPool

Parameters:

factory - the KeyedPoolableObjectFactory used to manage object instances

Throws:

IllegalStateException - when the factory cannot be set at this time

getFactory

public KeyedPoolableObjectFactory getFactory()

Returns:

the KeyedPoolableObjectFactory used by this pool to manage object instances.

Since:

1.5.5

getPools

public Map getPools()

Returns:

map of keyed pools

Since:

1.5.5

getMaxSleeping

public int getMaxSleeping()

Returns:

the cap on the number of "sleeping" instances in each pool.

Since:

1.5.5

getInitSleepingCapacity

public int getInitSleepingCapacity()

Returns:

the initial capacity of each pool.

Since:

1.5.5

getTotActive

public int getTotActive()

Returns:

the _totActive

getTotIdle

public int getTotIdle()

Returns:

the _totIdle

getActiveCount

public Map getActiveCount()

Returns:

the _activeCount

Since:

1.5.5