Package org.apache.hadoop.hbase.master.normalizer

Class RegionNormalizerWorkQueue<E>

java.lang.Object

org.apache.hadoop.hbase.master.normalizer.RegionNormalizerWorkQueue<E>

@Private
class RegionNormalizerWorkQueue<E>
extends Object

A specialized collection that holds pending work for the RegionNormalizerWorker. It is an ordered collection class that has the following properties:

• Guarantees uniqueness of elements, as a Set.
• Consumers retrieve objects from the head, as a Queue, via take().
• Work is retrieved on a FIFO policy.
• Work retrieval blocks the calling thread until new work is available, as a BlockingQueue.
• Allows a producer to insert an item at the head of the queue, if desired.

Field Summary

Fields

Modifier and Type	Field	Description
private LinkedHashSet<E>	delegate	Underlying storage structure that gives us the Set behavior and FIFO retrieval policy.
private final ReentrantReadWriteLock	lock	Lock for puts and takes
private final Condition	notEmpty	Wait queue for waiting takes

Constructor Summary

Constructors

Constructor	Description
RegionNormalizerWorkQueue()

Method Summary

Modifier and Type	Method	Description
void	clear()	Atomically removes all of the elements from this queue.
void	put(E e)	Inserts the specified element at the tail of the queue, if it's not already present.
void	putAll(Collection<? extends E> c)	Inserts the specified elements at the tail of the queue.
void	putAllFirst(Collection<? extends E> c)	Inserts the specified elements at the head of the queue.
void	putFirst(E e)	Inserts the specified element at the head of the queue.
int	size()	Returns the number of elements in this queue.
E	take()	Retrieves and removes the head of this queue, waiting if necessary until an element becomes available.
String	toString()

Methods inherited from class java.lang.Object

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

Field Details

delegate

private LinkedHashSet<E> delegate

Underlying storage structure that gives us the Set behavior and FIFO retrieval policy.

lock

private final ReentrantReadWriteLock lock

Lock for puts and takes

notEmpty

private final Condition notEmpty

Wait queue for waiting takes

Constructor Details

RegionNormalizerWorkQueue

RegionNormalizerWorkQueue()

Method Details

put

public void put(E e)

Inserts the specified element at the tail of the queue, if it's not already present.

Parameters:

e - the element to add

putFirst

public void putFirst(E e)

Inserts the specified element at the head of the queue.

Parameters:

e - the element to add

putAll

public void putAll(Collection<? extends E> c)

Inserts the specified elements at the tail of the queue. Any elements already present in the queue are ignored.

Parameters:

c - the elements to add

putAllFirst

public void putAllFirst(Collection<? extends E> c)

Inserts the specified elements at the head of the queue.

Parameters:

c - the elements to add

take

public E take()
       throws InterruptedException

Retrieves and removes the head of this queue, waiting if necessary until an element becomes available.

Returns:

the head of this queue

Throws:

InterruptedException - if interrupted while waiting

clear

public void clear()

Atomically removes all of the elements from this queue. The queue will be empty after this call returns.

size

public int size()

Returns the number of elements in this queue.

Returns:

the number of elements in this queue

toString

public String toString()

Overrides:

toString in class Object