SoftReferenceObjectPool (Apache Tomcat 7.0.109 API Documentation)

java.lang.Object
- org.apache.tomcat.dbcp.pool.BaseObjectPool<T>
- - org.apache.tomcat.dbcp.pool.impl.SoftReferenceObjectPool<T>

Type Parameters:
T - the type of objects held in this pool

All Implemented Interfaces:

ObjectPool<T>
```
public class SoftReferenceObjectPool<T>
extends BaseObjectPool<T>
```
A SoftReference based ObjectPool.

Since:

Pool 1.0

Author:

Rodney Waldhoff, Sandy McArthur

Constructor Summary

Constructors
Constructor and Description
`SoftReferenceObjectPool()` Deprecated. to be removed in pool 2.0. Use `SoftReferenceObjectPool(PoolableObjectFactory)`.
`SoftReferenceObjectPool(PoolableObjectFactory<T> factory)` Create a `SoftReferenceObjectPool` with the specified factory.
`SoftReferenceObjectPool(PoolableObjectFactory<T> factory, int initSize)` Deprecated. because this is a SoftReference pool, prefilled idle obejects may be garbage collected before they are used. To be removed in Pool 2.0.

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`addObject()` Create an object, and place it into the pool.
`T`	`borrowObject()` Borrow an object from the pool.
`void`	`clear()` Clears any objects sitting idle in the pool.
`void`	`close()` Close this pool, and free any resources associated with it.
`PoolableObjectFactory<T>`	`getFactory()` Returns the `PoolableObjectFactory` used by this pool to create and manage object instances.
`int`	`getNumActive()` Return the number of instances currently borrowed from this pool.
`int`	`getNumIdle()` Returns an approximation not less than the of the number of idle instances in the pool.
`void`	`invalidateObject(T obj)` Invalidates an object from the pool.
`void`	`returnObject(T obj)` Returns an instance to the pool after successful validation and passivation.
`void`	`setFactory(PoolableObjectFactory<T> factory)` Deprecated. to be removed in pool 2.0

Methods inherited from class org.apache.tomcat.dbcp.pool.BaseObjectPool
assertOpen, isClosed

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - SoftReferenceObjectPool
```
@Deprecated
public SoftReferenceObjectPool()
```
    Deprecated. to be removed in pool 2.0. Use SoftReferenceObjectPool(PoolableObjectFactory).
    
    Create a SoftReferenceObjectPool without a factory. setFactory should be called before any attempts to use the pool are made. Generally speaking you should prefer the SoftReferenceObjectPool(PoolableObjectFactory) constructor.
    
    See Also:
    SoftReferenceObjectPool(PoolableObjectFactory)
  - SoftReferenceObjectPool
```
public SoftReferenceObjectPool(PoolableObjectFactory<T> factory)
```
    Create a SoftReferenceObjectPool with the specified factory.
    
    Parameters:
    factory - object factory to use.
  - SoftReferenceObjectPool
```
@Deprecated
public SoftReferenceObjectPool(PoolableObjectFactory<T> factory,
                                  int initSize)
                        throws Exception,
                               IllegalArgumentException
```
    Deprecated. because this is a SoftReference pool, prefilled idle obejects may be garbage collected before they are used. To be removed in Pool 2.0.
    
    Create a SoftReferenceObjectPool with the specified factory and initial idle object count.
    
    Parameters:
    factory - object factory to use.
    initSize - initial size to attempt to prefill the pool.
    
    Throws:
    
    Exception - when there is a problem prefilling the pool.
    
    IllegalArgumentException - when factory is null.
- Method Detail
  - borrowObject
```
public T borrowObject()
               throws Exception
```
    Borrow an object from the pool. If there are no idle instances available in the pool, the configured factory's PoolableObjectFactory.makeObject() method is invoked to create a new instance.
    
    All instances are activated and validated before being returned by this method. If validation fails or an exception occurs activating or validating an idle instance, the failing instance is destroyed and another instance is retrieved from the pool, validated and activated. This process continues until either the pool is empty or an instance passes validation. If the pool is empty on activation or it does not contain any valid instances, the factory's makeObject method is used to create a new instance. If the created instance either raises an exception on activation or fails validation, NoSuchElementException is thrown. Exceptions thrown by MakeObject are propagated to the caller; but other than ThreadDeath or VirtualMachineError, exceptions generated by activation, validation or destroy methods are swallowed silently.
    
    Specified by:
    
    borrowObject in interface ObjectPool<T>
    
    Specified by:
    
    borrowObject in class BaseObjectPool<T>
    
    Returns:
    a valid, activated object instance
    
    Throws:
    
    NoSuchElementException - if a valid object cannot be provided
    
    IllegalStateException - if invoked on a closed pool
    
    Exception - if an exception occurs creating a new instance
  - returnObject
```
public void returnObject(T obj)
                  throws Exception
```
    Returns an instance to the pool after successful validation and passivation. The returning instance is destroyed if any of the following are true:
    - the pool is closed
    - validation fails
    - passivation throws an exception
    Exceptions passivating or destroying instances are silently swallowed. Exceptions validating instances are propagated to the client.
    Specified by:
    
    returnObject in interface ObjectPool<T>
    
    Specified by:
    
    returnObject in class BaseObjectPool<T>
    
    Parameters:
    obj - instance to return to the pool
    
    Throws:
    
    Exception
  - invalidateObject
```
public void invalidateObject(T obj)
                      throws Exception
```
    Invalidates an object from the pool.
    
    By contract, obj must have been obtained using borrowObject.
    
    This method should be used when an object that has been borrowed is determined (due to an exception or other problem) to be invalid.
    
    Specified by:
    
    invalidateObject in interface ObjectPool<T>
    
    Specified by:
    
    invalidateObject in class BaseObjectPool<T>
    
    Parameters:
    obj - a borrowed instance to be disposed.
    
    Throws:
    
    Exception
  - addObject
```
public void addObject()
               throws Exception
```
    Create an object, and place it into the pool. addObject() is useful for "pre-loading" a pool with idle objects.
    
    Before being added to the pool, the newly created instance is validated and passivated. If validation fails, the new instance is destroyed. Exceptions generated by the factory makeObject or passivate are propagated to the caller. Exceptions destroying instances are silently swallowed.
    
    Specified by:
    
    addObject in interface ObjectPool<T>
    
    Overrides:
    
    addObject in class BaseObjectPool<T>
    
    Throws:
    
    IllegalStateException - if invoked on a closed pool
    
    Exception - when the factory has a problem creating or passivating an object.
  - getNumIdle
```
public int getNumIdle()
```
    Returns an approximation not less than the of the number of idle instances in the pool.
    
    Specified by:
    
    getNumIdle in interface ObjectPool<T>
    
    Overrides:
    
    getNumIdle in class BaseObjectPool<T>
    
    Returns:
    estimated number of idle instances in the pool
  - getNumActive
```
public int getNumActive()
```
    Return the number of instances currently borrowed from this pool.
    
    Specified by:
    
    getNumActive in interface ObjectPool<T>
    
    Overrides:
    
    getNumActive in class BaseObjectPool<T>
    
    Returns:
    the number of instances currently borrowed from this pool
  - clear
```
public void clear()
```
    Clears any objects sitting idle in the pool.
    
    Specified by:
    
    clear in interface ObjectPool<T>
    
    Overrides:
    
    clear in class BaseObjectPool<T>
  - close
```
public void close()
           throws Exception
```
    Close this pool, and free any resources associated with it. Invokes clear() to destroy and remove instances in the pool.
    
    Calling addObject() or borrowObject() after invoking this method on a pool will cause them to throw an IllegalStateException.
    
    Specified by:
    
    close in interface ObjectPool<T>
    
    Overrides:
    
    close in class BaseObjectPool<T>
    
    Throws:
    
    Exception - never - exceptions clearing the pool are swallowed
  - setFactory
```
@Deprecated
public void setFactory(PoolableObjectFactory<T> factory)
                throws IllegalStateException
```
    Deprecated. to be removed in pool 2.0
    
    Sets the factory this pool uses to create new instances. Trying to change the factory while there are borrowed objects will throw an IllegalStateException.
    
    Specified by:
    
    setFactory in interface ObjectPool<T>
    
    Overrides:
    
    setFactory in class BaseObjectPool<T>
    
    Parameters:
    factory - the PoolableObjectFactory used to create new instances.
    
    Throws:
    
    IllegalStateException - when the factory cannot be set at this time
  - getFactory
```
public PoolableObjectFactory<T> getFactory()
```
    Returns the PoolableObjectFactory used by this pool to create and manage object instances.
    
    Returns:
    the factory
    Since:
    
    1.5.5

Class SoftReferenceObjectPool<T>

Constructor Summary

Method Summary

Methods inherited from class org.apache.tomcat.dbcp.pool.BaseObjectPool

Methods inherited from class java.lang.Object

Constructor Detail

SoftReferenceObjectPool

SoftReferenceObjectPool

SoftReferenceObjectPool

Method Detail

borrowObject

returnObject

invalidateObject

addObject

getNumIdle

getNumActive

clear

close

setFactory

getFactory