KeyedObjectPool

A "keyed" pooling interface. A keyed pool maintains a pool of instances for each key value. Example of use: <pre style="border:solid thin; padding: 1ex;" > Object obj = <code style="color:#00C">null</code>; Object key = <code style="color:#C00">"Key"</code>;

<code style="color:#00C">try</code> { obj = pool.borrowObject(key); <code style="color:#0C0">//...use the object...</code> } <code style="color:#00C">catch</code>(Exception e) { <code style="color:#0C0">// invalidate the object</code> pool.invalidateObject(key, obj); <code style="color:#0C0">// do not return the object to the pool twice</code> obj = <code style="color:#00C">null</code>; } <code style="color:#00C">finally</code> { <code style="color:#0C0">// make sure the object is returned to the pool</code> <code style="color:#00C">if</code>(<code style="color:#00C">null</code> != obj) { pool.returnObject(key, obj); } }</pre> {@link 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 {@link java.util.Map Map} of {@link ObjectPool pools}). See {@link hunt.pool.impl.GenericKeyedObjectPool GenericKeyedObjectPool} for an implementation.

@param <K> The type of keys maintained by this pool. @param <V> Type of element pooled in this pool.

@see KeyedPooledObjectFactory @see ObjectPool @see hunt.pool.impl.GenericKeyedObjectPool GenericKeyedObjectPool

interface KeyedObjectPool : Closeable(

) {

V borrowObject(K key);

void returnObject(K key, V obj);

void invalidateObject(K key, V obj);

void addObject(K key);

int getNumIdle(K key);

int getNumActive(K key);

int getNumIdle();

int getNumActive();

void clear();

void clear(K key);

void close();

}

Members

Functions

addObject void addObject(K key): Create an object using the {@link KeyedPooledObjectFactory factory} or other implementation dependent mechanism, passivate it, and then place it in the idle object pool. <code>addObject</code> is useful for "pre-loading" a pool with idle objects (Optional operation).
borrowObject V borrowObject(K key): Obtains an instance from this pool for the specified <code>key</code>. Instances returned from this method will have been either newly created with {@link KeyedPooledObjectFactory#makeObject makeObject} or will be a previously idle object and have been activated with {@link KeyedPooledObjectFactory#activateObject activateObject} and then (optionally) validated with {@link KeyedPooledObjectFactory#validateObject validateObject}. By contract, clients must return the borrowed object using {@link #returnObject returnObject}, {@link #invalidateObject invalidateObject}, or a related method as defined in an implementation or sub-interface, using a <code>key</code> that is {@link Object#equals equivalent} to the one used to borrow the instance in the first place. The behaviour of this method when the pool has been exhausted is not strictly specified (although it may be specified by implementations).
clear void clear(): Clears the pool, removing all pooled instances (optional operation).
clear void clear(K key): Clears the specified pool, removing all pooled instances corresponding to the given <code>key</code> (optional operation).
close void close(): Close this pool, and free any resources associated with it. Calling {@link #addObject addObject} or {@link #borrowObject borrowObject} after invoking this method on a pool will cause them to throw an {@link IllegalStateException}. Implementations should silently fail if not all resources can be freed.
getNumActive int getNumActive(K key): Returns the number of instances currently borrowed from but not yet returned to the pool corresponding to the given <code>key</code>. Returns a negative value if this information is not available.
getNumActive int getNumActive(): Returns the total number of instances currently borrowed from this pool but not yet returned. Returns a negative value if this information is not available. @return the total number of instances currently borrowed from this pool but not yet returned.
getNumIdle int getNumIdle(K key): Returns the number of instances corresponding to the given <code>key</code> currently idle in this pool. Returns a negative value if this information is not available.
getNumIdle int getNumIdle(): Returns the total number of instances currently idle in this pool. Returns a negative value if this information is not available. @return the total number of instances currently idle in this pool.
invalidateObject void invalidateObject(K key, V obj): Invalidates an object from the pool. By contract, <code>obj</code> must have been obtained using {@link #borrowObject borrowObject} or a related method as defined in an implementation or sub-interface using a <code>key</code> that is equivalent to the one used to borrow the <code>Object</code> 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.
returnObject void returnObject(K key, V obj): Return an instance to the pool. By contract, <code>obj</code> must have been obtained using {@link #borrowObject borrowObject} or a related method as defined in an implementation or sub-interface using a <code>key</code> that is equivalent to the one used to borrow the instance in the first place.

KeyedObjectPool

Members

Functions

Meta

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