org.apache.curator.framework.recipes.queue

Class DistributedPriorityQueue<T>

java.lang.Object

org.apache.curator.framework.recipes.queue.DistributedPriorityQueue<T>

All Implemented Interfaces:

Closeable, AutoCloseable, QueueBase<T>

public class DistributedPriorityQueue<T>
extends Object
implements Closeable, QueueBase<T>

An implementation of the Distributed Priority Queue ZK recipe.

Internally, this uses a DistributedQueue. The only difference is that you specify a priority when putting into the queue.

IMPORTANT NOTE: The priority queue will perform far worse than a standard queue. Every time an item is added to/removed from the queue, every watcher must re-get all the nodes

Method Summary

Modifier and Type	Method and Description
void	close()
boolean	flushPuts(long waitTime, TimeUnit timeUnit) Wait until any pending puts are committed
int	getLastMessageCount() Return the most recent message count from the queue.
org.apache.curator.framework.listen.ListenerContainer<QueuePutListener<T>>	getPutListenerContainer() Return the manager for put listeners
void	put(T item, int priority) Add an item into the queue.
boolean	put(T item, int priority, int maxWait, TimeUnit unit) Same as put(Object, int) but allows a maximum wait time if an upper bound was set via QueueBuilder.maxItems.
void	putMulti(MultiItem<T> items, int priority) Add a set of items with the same priority into the queue.
boolean	putMulti(MultiItem<T> items, int priority, int maxWait, TimeUnit unit) Same as putMulti(MultiItem, int) but allows a maximum wait time if an upper bound was set via QueueBuilder.maxItems.
void	setErrorMode(ErrorMode newErrorMode) Used when the queue is created with a QueueBuilder.lockPath(String).
void	start() Start the queue.

Methods inherited from class java.lang.Object

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

Method Detail

start

public void start()
           throws Exception

Start the queue. No other methods work until this is called

Specified by:

start in interface QueueBase<T>

Throws:

Exception - startup errors

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException

put

public void put(T item,
                int priority)
         throws Exception

Add an item into the queue. Adding is done in the background - thus, this method will return quickly.

NOTE: if an upper bound was set via QueueBuilder.maxItems, this method will block until there is available space in the queue.

Parameters:

item - item to add

priority - item's priority - lower numbers come out of the queue first

Throws:

Exception - connection issues

put

public boolean put(T item,
                   int priority,
                   int maxWait,
                   TimeUnit unit)
            throws Exception

Same as put(Object, int) but allows a maximum wait time if an upper bound was set via QueueBuilder.maxItems.

Parameters:

item - item to add

priority - item's priority - lower numbers come out of the queue first

maxWait - maximum wait

unit - wait unit

Returns:

true if items was added, false if timed out

Throws:

Exception

putMulti

public void putMulti(MultiItem<T> items,
                     int priority)
              throws Exception

Add a set of items with the same priority into the queue. Adding is done in the background - thus, this method will return quickly.

NOTE: if an upper bound was set via QueueBuilder.maxItems, this method will block until there is available space in the queue.

Parameters:

items - items to add

priority - item priority - lower numbers come out of the queue first

Throws:

Exception - connection issues

putMulti

public boolean putMulti(MultiItem<T> items,
                        int priority,
                        int maxWait,
                        TimeUnit unit)
                 throws Exception

Same as putMulti(MultiItem, int) but allows a maximum wait time if an upper bound was set via QueueBuilder.maxItems.

Parameters:

items - items to add

priority - item priority - lower numbers come out of the queue first

maxWait - maximum wait

unit - wait unit

Returns:

true if items was added, false if timed out

Throws:

Exception

setErrorMode

public void setErrorMode(ErrorMode newErrorMode)

Description copied from interface: QueueBase

Used when the queue is created with a QueueBuilder.lockPath(String). Determines the behavior when the queue consumer throws an exception

Specified by:

setErrorMode in interface QueueBase<T>

Parameters:

newErrorMode - the new error mode (the default is ErrorMode.REQUEUE

flushPuts

public boolean flushPuts(long waitTime,
                         TimeUnit timeUnit)
                  throws InterruptedException

Description copied from interface: QueueBase

Wait until any pending puts are committed

Specified by:

flushPuts in interface QueueBase<T>

Parameters:

waitTime - max wait time

timeUnit - time unit

Returns:

true if the flush was successful, false if it timed out first

Throws:

InterruptedException - if thread was interrupted

getPutListenerContainer

public org.apache.curator.framework.listen.ListenerContainer<QueuePutListener<T>> getPutListenerContainer()

Return the manager for put listeners

Specified by:

getPutListenerContainer in interface QueueBase<T>

Returns:

put listener container

getLastMessageCount

public int getLastMessageCount()

Return the most recent message count from the queue. This is useful for debugging/information purposes only.

Specified by:

getLastMessageCount in interface QueueBase<T>

Returns:

count (can be 0)