net.imglib2.cache.queue

Class BlockingFetchQueues<E>

java.lang.Object

net.imglib2.cache.queue.BlockingFetchQueues<E>

Type Parameters:

E - element type.

public class BlockingFetchQueues<E>
extends Object

TODO revise javadoc Queueing structure (intended for cache entries to be fetched). There is an array of ArrayDeques, ordered by priority. Elements are put(Object, int, boolean) with a priority and added to one of the queues, accordingly. take() returns an element from the highest priority non-empty queue. Furthermore, there is a prefetch deque of bounded size to provides elements when all the queues are exhausted. clearToPrefetch() empties all queues, and moves the removed elements to the prefetch queue.

Locking is adapted from ArrayBlockingQueue.

BlockingFetchQueues is constructed with the number of priority levels n. Priorities are consecutive integers 0 ... n-1, where 0 is the highest priority. Priorities of enqueued entries are clamped to the range 0 ... n-1.

Author:

Tobias Pietzsch

Constructor Summary

Constructors

Constructor and Description
BlockingFetchQueues(int numPriorities, int numConsumers)
BlockingFetchQueues(int numPriorities, int numConsumers, int prefetchCapacity)

Method Summary

Modifier and Type	Method and Description
void	clear() Atomically removes all of the elements from this queue.
void	clearToPrefetch() Atomically removes all of the elements from this queue.
long	getCurrentFrame()
int	getNumPriorities()
void	pause() Pause the queue.
void	put_unsafe(E element, int priority, boolean enqueuToFront) Equivalent to put(Object, int, boolean), but priorities are not clamped to the allowed range.
void	put(E element, int priority, boolean enqueuToFront) Add element to the queue of the specified priority.
void	resume()
E	take() Remove and return an element from the highest priority non-empty queue.

Methods inherited from class java.lang.Object

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

Constructor Detail

BlockingFetchQueues

public BlockingFetchQueues(int numPriorities,
                           int numConsumers)

BlockingFetchQueues

public BlockingFetchQueues(int numPriorities,
                           int numConsumers,
                           int prefetchCapacity)

Method Detail

put

public void put(E element,
                int priority,
                boolean enqueuToFront)

Add element to the queue of the specified priority. The element can be added to the front or back of the queue.

Parameters:

element - the element to enqueue

priority - lower values mean higher priority

enqueuToFront - if true, enqueue element at the front (LIFO). if false, enqueue element at the back (FIFO)

put_unsafe

public void put_unsafe(E element,
                       int priority,
                       boolean enqueuToFront)

Equivalent to put(Object, int, boolean), but priorities are not clamped to the allowed range. Will throw an ArrayIndexOutOfBoundsException if priority < 0 or priority >= numPriorities.

Add element to the queue of the specified priority. The element can be added to the front or back of the queue.

Parameters:

element - the element to enqueue

priority - lower values mean higher priority

enqueuToFront - if true, enqueue element at the front (LIFO). if false, enqueue element at the back (FIFO)

take

public E take()
       throws InterruptedException

Remove and return an element from the highest priority non-empty queue. If all queues are empty, then return an element from the prefetch deque. If the prefetch deque is also empty, then block.

Returns:

element.

Throws:

InterruptedException

pause

public void pause()
           throws InterruptedException

Pause the queue. While the queue is paused, all consumer threads are held in take(). The pause() method itself blocks until all (of the pre-defined number of) consumer threads have arrived in take().

While the queue is paused, all calls to take() block. (Calls to put() are not affected.)

Throws:

InterruptedException

resume

public void resume()
            throws InterruptedException

Throws:

InterruptedException

clearToPrefetch

public void clearToPrefetch()

Atomically removes all of the elements from this queue. All queues will be empty after this call returns. Removed elements are moved to the prefetch deque.

clear

public void clear()

Atomically removes all of the elements from this queue. All queues, as well as the prefetch deque, will be empty after this call returns.

getNumPriorities

public int getNumPriorities()

getCurrentFrame

public long getCurrentFrame()