ObjectPool

A pooling simple interface. Example of use: <pre style="border:solid thin; padding: 1ex;" > Object obj = <code style="color:#00C">null</code>;

<code style="color:#00C">try</code> { obj = pool.borrowObject(); <code style="color:#00C">try</code> { <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(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(obj); } } } <code style="color:#00C">catch</code>(Exception e) { <code style="color:#0C0">// failed to borrow an object</code> }</pre> See {@link BaseObjectPool} for a simple base implementation.

@param <T> Type of element pooled in this pool.

@see PooledObjectFactory @see KeyedObjectPool @see BaseObjectPool

interface ObjectPool : Closeable(

) {

T borrowObject();

void returnObject(T obj);

void invalidateObject(T obj);

void addObject();

int getNumIdle();

int getNumActive();

void clear();

void close();

}

Members

Functions

addObject void addObject(): Creates an object using the {@link PooledObjectFactory 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 T borrowObject(): Obtains an instance from this pool. Instances returned from this method will have been either newly created with {@link PooledObjectFactory#makeObject} or will be a previously idle object and have been activated with {@link PooledObjectFactory#activateObject} and then validated with {@link PooledObjectFactory#validateObject}. By contract, clients must return the borrowed instance using {@link #returnObject}, {@link #invalidateObject}, or a related method as defined in an implementation or sub-interface. 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 any objects sitting idle in the pool, releasing any associated resources (optional operation). Idle objects cleared must be {@link PooledObjectFactory#destroyObject(PooledObject)}.
close void close(): Closes this pool, and free any resources associated with it. Calling {@link #addObject} or {@link #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(): Returns the number of instances currently borrowed from this pool. Returns a negative value if this information is not available. @return the number of instances currently borrowed from this pool.
getNumIdle int getNumIdle(): Returns the number of instances currently idle in this pool. This may be considered an approximation of the number of objects that can be {@link #borrowObject borrowed} without creating any new instances. Returns a negative value if this information is not available. @return the number of instances currently idle in this pool.
invalidateObject void invalidateObject(T obj): Invalidates an object from the pool. By contract, <code>obj</code> must have been obtained using {@link #borrowObject} or a related method as defined in an implementation or sub-interface. 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(T obj): Returns an instance to the pool. By contract, <code>obj</code> must have been obtained using {@link #borrowObject()} or a related method as defined in an implementation or sub-interface.

ObjectPool

Members

Functions

Meta

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