voldemort.utils.pool
Class QueuedKeyedResourcePool<K,V>

java.lang.Object
  voldemort.utils.pool.KeyedResourcePool<K,V>
      voldemort.utils.pool.QueuedKeyedResourcePool<K,V>

public class QueuedKeyedResourcePool<K,V>
extends KeyedResourcePool<K,V>

Extends simple implementation of a per-key resource pool with a non-blocking interface to enqueue requests for a resource when one becomes available.

• Allocates resources in FIFOish order: blocking requests via checkout are FIFO and non-blocking enqueued requests are FIFO, however, there is no ordering between blocking (checkout) and non-blocking (requestResource).
• Pools and Queues are per key and there is no global maximum pool or queue limit.

Beyond the expectations documented in KeyedResourcePool, the following is expected of the user of this class:

• A resource acquired via #checkout(K)) or via equestResource(K , ResourceRequest) requestResource is checked in exactly once.
• A resource that is checked in was previously checked out or requested.
• Also, reqeustResource is never called after close.

Nested Class Summary

Nested classes/interfaces inherited from class voldemort.utils.pool.KeyedResourcePool

KeyedResourcePool.Pool<V>

Constructor Summary

QueuedKeyedResourcePool(ResourceFactory<K,V> objectFactory, ResourcePoolConfig config)

Method Summary

void	checkin(K key, V resource) Check the given resource back into the pool
void	close() Close the queue and the pool.
static <K,V> QueuedKeyedResourcePool<K,V>	create(ResourceFactory<K,V> factory) Create a new queued pool using the defaults for key of tyep K, request of type R, and value of Type V.
static <K,V> QueuedKeyedResourcePool<K,V>	create(ResourceFactory<K,V> factory, ResourcePoolConfig config) Create a new queued pool with key type K, request type R, and value type V.
protected void	destroyRequest(AsyncResourceRequest<V> resourceRequest) A safe wrapper to destroy the given resource request.
int	getRegisteredResourceRequestCount() Count the total number of queued resource requests for all queues.
int	getRegisteredResourceRequestCount(K key) Count the number of queued resource requests for a specific pool.
protected java.util.Queue<AsyncResourceRequest<V>>	getRequestQueueForExistingKey(K key)
protected java.util.Queue<AsyncResourceRequest<V>>	getRequestQueueForKey(K key)
protected boolean	internalClose()
void	registerResourceRequest(K key, AsyncResourceRequest<V> resourceRequest) This method is the asynchronous (nonblocking) version of KeyedResourcePool.checkout.

Methods inherited from class voldemort.utils.pool.KeyedResourcePool

attemptNonBlockingCheckout, checkNotClosed, checkout, destroyResource, getBlockingGetsCount, getBlockingGetsCount, getCheckedInResourceCount, getCheckedInResourcesCount, getResourcePoolForExistingKey, getResourcePoolForKey, getTotalResourceCount, getTotalResourceCount, isOpenAndValid, reset

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

QueuedKeyedResourcePool

public QueuedKeyedResourcePool(ResourceFactory<K,V> objectFactory,
                               ResourcePoolConfig config)

Method Detail

create

public static <K,V> QueuedKeyedResourcePool<K,V> create(ResourceFactory<K,V> factory,
                                                        ResourcePoolConfig config)

Create a new queued pool with key type K, request type R, and value type V.

Parameters:

factory - The factory that creates objects

config - The pool config

Returns:

The created pool

create

public static <K,V> QueuedKeyedResourcePool<K,V> create(ResourceFactory<K,V> factory)

Create a new queued pool using the defaults for key of tyep K, request of type R, and value of Type V.

Parameters:

factory - The factory that creates objects

Returns:

The created pool

registerResourceRequest

public void registerResourceRequest(K key,
                                    AsyncResourceRequest<V> resourceRequest)

This method is the asynchronous (nonblocking) version of KeyedResourcePool.checkout. This method necessarily has a different function declaration (i.e., arguments passed and return type). This method either checks out a resource and uses that resource or enqueues a request to checkout the resource. I.e., there is a non-blocking fast-path that is tried optimistically.

Parameters:

key - The key to checkout the resource for

checkin

public void checkin(K key,
                    V resource)
             throws java.lang.Exception

Check the given resource back into the pool

Overrides:

checkin in class KeyedResourcePool<K,V>

Parameters:

key - The key for the resource

resource - The resource

Throws:

java.lang.Exception

destroyRequest

protected void destroyRequest(AsyncResourceRequest<V> resourceRequest)

A safe wrapper to destroy the given resource request.

internalClose

protected boolean internalClose()

Overrides:

internalClose in class KeyedResourcePool<K,V>

close

public void close()

Close the queue and the pool.

Overrides:

close in class KeyedResourcePool<K,V>

getRequestQueueForKey

protected java.util.Queue<AsyncResourceRequest<V>> getRequestQueueForKey(K key)

getRequestQueueForExistingKey

protected java.util.Queue<AsyncResourceRequest<V>> getRequestQueueForExistingKey(K key)

getRegisteredResourceRequestCount

public int getRegisteredResourceRequestCount(K key)

Count the number of queued resource requests for a specific pool.

Parameters:

key - The key

Returns:

The count of queued resource requests. Returns 0 if no queue exists for given key.

getRegisteredResourceRequestCount

public int getRegisteredResourceRequestCount()

Count the total number of queued resource requests for all queues. The result is "approximate" in the face of concurrency since individual queues can change size during the aggregate count.

Returns:

The (approximate) aggregate count of queued resource requests.