io.pravega.common.util

Class BlockingDrainingQueue<T>

java.lang.Object

io.pravega.common.util.BlockingDrainingQueue<T>

Type Parameters:

T - The type of the items in the queue.

public class BlockingDrainingQueue<T>
extends java.lang.Object

Represents a thread-safe queue that dequeues all elements at once. Blocks the Dequeue if empty until new elements arrive.

Constructor Summary

Constructors

Constructor and Description
BlockingDrainingQueue() Creates a new instance of the BlockingDrainingQueue class.

Method Summary

Modifier and Type	Method and Description
void	add(T item) Adds a new item to the queue.
void	cancelPendingTake() Cancels any pending Future from a take() operation.
java.util.Queue<T>	close() Closes the queue and prevents any other access to it.
java.util.Queue<T>	poll(int maxCount) Returns the next items from the queue, if any.
int	size() Gets a value indicating the size of this queue.
java.util.concurrent.CompletableFuture<java.util.Queue<T>>	take(int maxCount) Returns the next items from the queue.

Methods inherited from class java.lang.Object

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

Constructor Detail

BlockingDrainingQueue

public BlockingDrainingQueue()

Creates a new instance of the BlockingDrainingQueue class.

Method Detail

close

public java.util.Queue<T> close()

Closes the queue and prevents any other access to it. Any blocked call to takeAllItems() will fail with InterruptedException.

Returns:

If the queue has any more items in it, these will be returned here in the order in which they were inserted. The items are guaranteed not to be returned both here and via take()/poll().

cancelPendingTake

public void cancelPendingTake()

Cancels any pending Future from a take() operation.

add

public void add(T item)

Adds a new item to the queue.

Parameters:

item - The item to add.

Throws:

ObjectClosedException - If the Queue is closed.

poll

public java.util.Queue<T> poll(int maxCount)

Returns the next items from the queue, if any.

Parameters:

maxCount - The maximum number of items to return.

Returns:

A Queue containing at most maxCount items, or empty if there is nothing in the queue.

Throws:

java.lang.IllegalStateException - If there is a pending take() operation which hasn't completed yet.

take

public java.util.concurrent.CompletableFuture<java.util.Queue<T>> take(int maxCount)

Returns the next items from the queue. If the queue is empty, it blocks the call until at least one item is added.

Parameters:

maxCount - The maximum number of items to return. This argument will be ignored if the queue is currently empty, but in that case the result will always be completed with exactly one element.

Returns:

A CompletableFuture that, when completed, will contain the requested result. If the queue is not currently empty, this Future will already be completed, otherwise it will be completed the next time the add() method is called. If the queue is closed and this Future is not yet completed, it will be cancelled.

Throws:

ObjectClosedException - If the Queue is closed.

java.lang.IllegalStateException - If another call to take() is in progress.

size

public int size()

Gets a value indicating the size of this queue.

Returns:

The size.