Interface KeyedObjectPool<K,V>
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- Type Parameters:
K- The type of keys maintained by this pool.V- Type of element pooled in this pool.
- All Superinterfaces:
AutoCloseable,Closeable
- All Known Implementing Classes:
GenericKeyedObjectPool
public interface KeyedObjectPool<K,V> extends Closeable
A "keyed" pooling interface.A keyed pool maintains a pool of instances for each key value.
Example of use:
Object obj =
null; Object key ="Key";try{ obj = pool.borrowObject(key);//...use the object...}catch(Exception e) {// invalidate the objectpool.invalidateObject(key, obj);// do not return the object to the pool twiceobj =null; }finally{// make sure the object is returned to the poolif(null!= obj) { pool.returnObject(key, obj); } }KeyedObjectPoolimplementations 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 aMapofpools).See
GenericKeyedObjectPoolfor an implementation.- Since:
- 2.0
- See Also:
KeyedPooledObjectFactory,ObjectPool,GenericKeyedObjectPool
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Method Summary
All Methods Instance Methods Abstract Methods Default Methods Modifier and Type Method Description voidaddObject(K key)Creates an object using thefactoryor other implementation dependent mechanism, passivate it, and then place it in the idle object pool.default voidaddObjects(Collection<K> keys, int count)default voidaddObjects(K key, int count)VborrowObject(K key)Borrows an instance from this pool for the specifiedkey.voidclear()Clears the pool, removing all pooled instances (optional operation).voidclear(K key)Clears the specified pool, removing all pooled instances corresponding to the givenkey(optional operation).voidclose()Closes this pool, and free any resources associated with it.intgetNumActive()Gets the total number of instances currently borrowed from this pool but not yet returned.intgetNumActive(K key)Gets the number of instances currently borrowed from but not yet returned to the pool corresponding to the givenkey.intgetNumIdle()Gets the total number of instances currently idle in this pool.intgetNumIdle(K key)Gets the number of instances corresponding to the givenkeycurrently idle in this pool.voidinvalidateObject(K key, V obj)Invalidates an object from the pool.default voidinvalidateObject(K key, V obj, DestroyMode destroyMode)Invalidates an object from the pool, using the providedDestroyMode.voidreturnObject(K key, V obj)Return an instance to the pool.
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Method Detail
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addObject
void addObject(K key) throws Exception, IllegalStateException, UnsupportedOperationException
Creates an object using thefactoryor other implementation dependent mechanism, passivate it, and then place it in the idle object pool.addObjectis useful for "pre-loading" a pool with idle objects (Optional operation).- Parameters:
key- the key a new instance should be added to- Throws:
Exception- whenKeyedPooledObjectFactory.makeObject(K)fails.IllegalStateException- afterclose()has been called on this pool.UnsupportedOperationException- when this pool cannot add new idle objects.
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addObjects
default void addObjects(Collection<K> keys, int count) throws Exception, IllegalArgumentException
CallsaddObject(Object)with each key inkeysforcountnumber of times. This has the same effect as callingaddObjects(Object, int)for each key in thekeyscollection.- Parameters:
keys-Collectionof keys to add objects for.count- the number of idle objects to add for eachkey.- Throws:
Exception- whenaddObject(Object)fails.IllegalArgumentException- whenkeyedPool,keys, or any value inkeysisnull.- See Also:
addObjects(Object, int)
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addObjects
default void addObjects(K key, int count) throws Exception, IllegalArgumentException
- Parameters:
key- the key to add objects for.count- the number of idle objects to add forkey.- Throws:
Exception- whenaddObject(Object)fails.IllegalArgumentException- whenkeyisnull.- Since:
- 2.8.0
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borrowObject
V borrowObject(K key) throws Exception, NoSuchElementException, IllegalStateException
Borrows an instance from this pool for the specifiedkey.Instances returned from this method will have been either newly created with
makeObjector will be a previously idle object and have been activated withactivateObjectand then (optionally) validated withvalidateObject.By contract, clients must return the borrowed object using
returnObject,invalidateObject, or a related method as defined in an implementation or sub-interface, using akeythat isequivalentto the one used to borrow the instance in the first place.The behavior of this method when the pool has been exhausted is not strictly specified (although it may be specified by implementations).
- Parameters:
key- the key used to obtain the object- Returns:
- an instance from this pool.
- Throws:
IllegalStateException- afterclosehas been called on this poolException- whenmakeObjectthrows an exceptionNoSuchElementException- when the pool is exhausted and cannot or will not return another instance
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clear
void clear() throws Exception, UnsupportedOperationExceptionClears the pool, removing all pooled instances (optional operation).- Throws:
UnsupportedOperationException- when this implementation doesn't support the operationException- if the pool cannot be cleared
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clear
void clear(K key) throws Exception, UnsupportedOperationException
Clears the specified pool, removing all pooled instances corresponding to the givenkey(optional operation).- Parameters:
key- the key to clear- Throws:
UnsupportedOperationException- when this implementation doesn't support the operationException- if the key cannot be cleared
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close
void close()
Closes this pool, and free any resources associated with it.Calling
addObjectorborrowObjectafter invoking this method on a pool will cause them to throw anIllegalStateException.Implementations should silently fail if not all resources can be freed.
- Specified by:
closein interfaceAutoCloseable- Specified by:
closein interfaceCloseable
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getNumActive
int getNumActive()
Gets the total number of instances currently borrowed from this pool but not yet returned. Returns a negative value if this information is not available.- Returns:
- the total number of instances currently borrowed from this pool but not yet returned.
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getNumActive
int getNumActive(K key)
Gets the number of instances currently borrowed from but not yet returned to the pool corresponding to the givenkey. Returns a negative value if this information is not available.- Parameters:
key- the key to query- Returns:
- the number of instances currently borrowed from but not yet
returned to the pool corresponding to the given
key.
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getNumIdle
int getNumIdle()
Gets the total number of instances currently idle in this pool. Returns a negative value if this information is not available.- Returns:
- the total number of instances currently idle in this pool.
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getNumIdle
int getNumIdle(K key)
Gets the number of instances corresponding to the givenkeycurrently idle in this pool. Returns a negative value if this information is not available.- Parameters:
key- the key to query- Returns:
- the number of instances corresponding to the given
keycurrently idle in this pool.
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invalidateObject
void invalidateObject(K key, V obj) throws Exception
Invalidates an object from the pool.By contract,
objmust have been obtained usingborrowObjector a related method as defined in an implementation or sub-interface using akeythat is equivalent to the one used to borrow theObjectin 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.
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invalidateObject
default void invalidateObject(K key, V obj, DestroyMode destroyMode) throws Exception
Invalidates an object from the pool, using the providedDestroyMode.By contract,
objmust have been obtained usingborrowObjector a related method as defined in an implementation or sub-interface using akeythat is equivalent to the one used to borrow theObjectin 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.
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returnObject
void returnObject(K key, V obj) throws Exception
Return an instance to the pool. By contract,objmust have been obtained usingborrowObjector a related method as defined in an implementation or sub-interface using akeythat is equivalent to the one used to borrow the instance in the first place.- Parameters:
key- the key used to obtain the objectobj- aborrowedinstance to be returned.- Throws:
IllegalStateException- if an attempt is made to return an object to the pool that is in any state other than allocated (i.e. borrowed). Attempting to return an object more than once or attempting to return an object that was never borrowed from the pool will trigger this exception.Exception- if an instance cannot be returned to the pool
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