org.apache.commons.pool
Interface KeyedObjectPool

All Known Implementing Classes:
BaseKeyedObjectPool, GenericKeyedObjectPool, StackKeyedObjectPool

public interface KeyedObjectPool

A "keyed" pooling interface.

A keyed pool pools instances of multiple types. Each type may be accessed using an arbitrary key.

Example of use:
 Object obj = null;
 Object key = "Key";

 try {
    obj = pool.borrowObject(key);
    //...use the object...
 } catch(Exception e) {
    //...handle any exceptions...
 } finally {
    // make sure the object is returned to the pool
    if(null != obj) {
       pool.returnObject(key,obj);
    }
 }

KeyedObjectPool implementations may choose to store at most one instance per key value, or may choose to maintain a pool of instances for each key (essentially creating a Map of pools).

Version:
$Revision: 1.14 $ $Date: 2004/02/28 12:16:21 $
See Also:
KeyedPoolableObjectFactory, KeyedObjectPoolFactory, ObjectPool

Method Summary
 void addObject(Object key)
          Create an object using my factory or other implementation dependent mechanism, and place it into the pool.
 Object borrowObject(Object key)
          Obtain an instance from my pool for the specified key.
 void clear()
          Clears my pool, removing all pooled instances (optional operation).
 void clear(Object key)
          Clears the specified pool, removing all pooled instances corresponding to the given key (optional operation).
 void close()
          Close this pool, and free any resources associated with it.
 int getNumActive()
          Returns the total number of instances current borrowed from my pool but not yet returned (optional operation).
 int getNumActive(Object key)
          Returns the number of instances currently borrowed from but not yet returned to my pool corresponding to the given key (optional operation).
 int getNumIdle()
          Returns the total number of instances currently idle in my pool (optional operation).
 int getNumIdle(Object key)
          Returns the number of instances corresponding to the given key currently idle in my pool (optional operation).
 void invalidateObject(Object key, Object obj)
          Invalidates an object from the pool By contract, obj MUST have been obtained using borrowObject or a related method as defined in an implementation or sub-interface using a key that is equivalent to the one used to borrow the Object in the first place.
 void returnObject(Object key, Object obj)
          Return an instance to my pool.
 void setFactory(org.apache.commons.pool.KeyedPoolableObjectFactory factory)
          Sets the factory I use to create new instances (optional operation).
 

Method Detail

borrowObject

public Object borrowObject(Object key)
                    throws Exception
Obtain an instance from my pool for the specified key. By contract, clients MUST return the borrowed object using returnObject, or a related method as defined in an implementation or sub-interface, using a key that is equivalent to the one used to borrow the instance in the first place.

Parameters:
key - the key used to obtain the object
Returns:
an instance from my pool.
Exception

returnObject

public void returnObject(Object key,
                         Object obj)
                  throws Exception
Return an instance to my pool. By contract, obj MUST have been obtained using borrowObject or a related method as defined in an implementation or sub-interface using a key that is equivalent to the one used to borrow the Object in the first place.

Parameters:
key - the key used to obtain the object
obj - a borrowed instance to be returned.
Exception

invalidateObject

public void invalidateObject(Object key,
                             Object obj)
                      throws Exception
Invalidates an object from the pool By contract, obj MUST have been obtained using borrowObject or a related method as defined in an implementation or sub-interface using a key that is equivalent to the one used to borrow the Object in the first place.

This method should be used when an object that has been borrowed is determined (due to an exception or other problem) to be invalid. If the connection should be validated before or after borrowing, then the PoolableObjectFactory.validateObject(java.lang.Object) method should be used instead.

Parameters:
obj - a borrowed instance to be returned.
Exception

addObject

public void addObject(Object key)
               throws Exception
Create an object using my factory or other implementation dependent mechanism, and place it into the pool. addObject() is useful for "pre-loading" a pool with idle objects. (Optional operation).

Exception

getNumIdle

public int getNumIdle(Object key)
               throws UnsupportedOperationException
Returns the number of instances corresponding to the given key currently idle in my pool (optional operation). Throws UnsupportedOperationException if this information is not available.

Parameters:
key - the key
Returns:
the number of instances corresponding to the given key currently idle in my pool
Throws:
UnsupportedOperationException - when this implementation doesn't support the operation

getNumActive

public int getNumActive(Object key)
                 throws UnsupportedOperationException
Returns the number of instances currently borrowed from but not yet returned to my pool corresponding to the given key (optional operation). Throws UnsupportedOperationException if this information is not available.

Parameters:
key - the key
Returns:
the number of instances corresponding to the given key currently borrowed in my pool
Throws:
UnsupportedOperationException - when this implementation doesn't support the operation

getNumIdle

public int getNumIdle()
               throws UnsupportedOperationException
Returns the total number of instances currently idle in my pool (optional operation). Throws UnsupportedOperationException if this information is not available.

Returns:
the total number of instances currently idle in my pool
Throws:
UnsupportedOperationException - when this implementation doesn't support the operation

getNumActive

public int getNumActive()
                 throws UnsupportedOperationException
Returns the total number of instances current borrowed from my pool but not yet returned (optional operation). Throws UnsupportedOperationException if this information is not available.

Returns:
the total number of instances currently borrowed from my pool
Throws:
UnsupportedOperationException - when this implementation doesn't support the operation

clear

public void clear()
           throws Exception,
                  UnsupportedOperationException
Clears my pool, removing all pooled instances (optional operation). Throws UnsupportedOperationException if the pool cannot be cleared.

Throws:
UnsupportedOperationException - when this implementation doesn't support the operation
Exception

clear

public void clear(Object key)
           throws Exception,
                  UnsupportedOperationException
Clears the specified pool, removing all pooled instances corresponding to the given key (optional operation). Throws UnsupportedOperationException if the pool cannot be cleared.

Parameters:
key - the key to clear
Throws:
UnsupportedOperationException - when this implementation doesn't support the operation
Exception

close

public void close()
           throws Exception
Close this pool, and free any resources associated with it.

Exception

setFactory

public void setFactory(org.apache.commons.pool.KeyedPoolableObjectFactory factory)
                throws IllegalStateException,
                       UnsupportedOperationException
Sets the factory I use to create new instances (optional operation).

Parameters:
factory - the KeyedPoolableObjectFactory I use to create new instances.
Throws:
IllegalStateException - when the factory cannot be set at this time
UnsupportedOperationException - when this implementation doesn't support the operation


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