Package io.pravega.common.util

Class PriorityBlockingDrainingQueue<T extends PriorityBlockingDrainingQueue.Item>

java.lang.Object

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

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

Type Parameters:

T - Type of item,

public class PriorityBlockingDrainingQueue<T extends PriorityBlockingDrainingQueue.Item>
extends AbstractDrainingQueue<T>

AbstractDrainingQueue implementation with multiple priority levels. Supports up to Byte.MAX_VALUE priority levels, with Priority 0 being the highest.

Important notes: - AbstractDrainingQueue.poll(int) and AbstractDrainingQueue.take(int) will return items with the highest available priority and will never mix items with different priorities. That means that, even if there are more items (with lower priority), those will not be included in the result even if the requested number of items exceeds what we can return. These (lower priority) items may be retrieved using a subsequent call (assuming no higher priority items are added in the meantime).

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	PriorityBlockingDrainingQueue.Item	Defines an Item that can be added to a PriorityBlockingDrainingQueue.

Constructor Summary

Constructors

Constructor	Description
PriorityBlockingDrainingQueue(byte maxPriorityValue)	Creates a new instance of the PriorityBlockingDrainingQueue class.

Method Summary

Modifier and Type	Method	Description
protected void	addInternal(T item)	Updates the internal data structure to include the given item.
protected java.util.Queue<T>	fetch(int maxCount)	Extracts a number of items from the queue.
protected T	peekInternal()	Returns the first item in the Queue.
protected int	sizeInternal()	Returns the size of the queue.

Methods inherited from class io.pravega.common.util.AbstractDrainingQueue

add, cancelPendingTake, close, newTakeResult, peek, poll, size, take, take

Methods inherited from class java.lang.Object

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

Constructor Detail

PriorityBlockingDrainingQueue

public PriorityBlockingDrainingQueue(byte maxPriorityValue)

Creates a new instance of the PriorityBlockingDrainingQueue class.

Parameters:

maxPriorityValue - Maximum allowed priority value.

Method Detail

addInternal

protected void addInternal(T item)

Description copied from class: AbstractDrainingQueue

Updates the internal data structure to include the given item. NOTE: this is invoked while holding the lock. There is no need for additional synchronization in the implementation.

Specified by:

addInternal in class AbstractDrainingQueue<T extends PriorityBlockingDrainingQueue.Item>

Parameters:

item - The item to include.

sizeInternal

protected int sizeInternal()

Description copied from class: AbstractDrainingQueue

Returns the size of the queue. NOTE: this is invoked while holding the lock. There is no need for additional synchronization in the implementation.

Specified by:

sizeInternal in class AbstractDrainingQueue<T extends PriorityBlockingDrainingQueue.Item>

Returns:

The size of the queue.

peekInternal

protected T peekInternal()

Description copied from class: AbstractDrainingQueue

Returns the first item in the Queue. NOTE: this is invoked while holding the lock. There is no need for additional synchronization in the implementation.

Specified by:

peekInternal in class AbstractDrainingQueue<T extends PriorityBlockingDrainingQueue.Item>

Returns:

The first item, or null if AbstractDrainingQueue.size() is 0.

fetch

protected java.util.Queue<T> fetch(int maxCount)

Description copied from class: AbstractDrainingQueue

Extracts a number of items from the queue. NOTE: this is invoked while holding the lock. There is no need for additional synchronization in the implementation.

Specified by:

fetch in class AbstractDrainingQueue<T extends PriorityBlockingDrainingQueue.Item>

Parameters:

maxCount - The maximum number of items to extract.

Returns:

The extracted items, in order.