org.jgroups.util

Class ConcurrentLinkedBlockingQueue2<T>

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractQueue<E>

java.util.concurrent.ConcurrentLinkedQueue<T>

org.jgroups.util.ConcurrentLinkedBlockingQueue2<T>

All Implemented Interfaces:

java.io.Serializable, java.lang.Iterable<T>, java.util.Collection<T>, java.util.concurrent.BlockingQueue<T>, java.util.Queue<T>

public class ConcurrentLinkedBlockingQueue2<T>
extends java.util.concurrent.ConcurrentLinkedQueue<T>
implements java.util.concurrent.BlockingQueue<T>

Attempt at writing a fast transfer queue, which is bounded. The take() method blocks until there is an element, but the offer() method drops the element and returns if the queue is full (doesn't block).

The design assumes a number of producers but only one consumer. The consumer only blocks when the queue is empty (on the not-empty condition), the producers block when the queue is full (on the not-full condition). The producers increment a count atomically and if the count is greater than the capacity, they block on the not-full condition. The consumer decrements the condition and signals the not-full condition when the count is capacity -1 (from capacity to capacity-1). The producers signal not-empty when the count is 1 (from 0 to 1)

Since:

3.5

Author:

Bela Ban

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected int	capacity
protected java.util.concurrent.atomic.AtomicInteger	count
protected java.util.concurrent.locks.Condition	not_empty
protected java.util.concurrent.locks.Lock	not_empty_lock

Constructor Summary

Constructors

Constructor and Description
ConcurrentLinkedBlockingQueue2(int capacity)

Method Summary

Modifier and Type	Method and Description
protected void	decrCount()
int	drainTo(java.util.Collection<? super T> c)
int	drainTo(java.util.Collection<? super T> c, int maxElements)
protected void	incrCount()
boolean	offer(T t) Drops elements if capacity has been reached.
boolean	offer(T t, long timeout, java.util.concurrent.TimeUnit unit)
T	poll()
T	poll(long timeout, java.util.concurrent.TimeUnit unit)
void	put(T t)
int	remainingCapacity()
boolean	remove(java.lang.Object o)
int	size()
T	take()
protected void	waitForNotEmpty()

Methods inherited from class java.util.concurrent.ConcurrentLinkedQueue

add, addAll, contains, isEmpty, iterator, peek, spliterator, toArray, toArray

Methods inherited from class java.util.AbstractQueue

clear, element, remove

Methods inherited from class java.util.AbstractCollection

containsAll, removeAll, retainAll, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.concurrent.BlockingQueue

add, contains

Methods inherited from interface java.util.Queue

element, peek, remove

Methods inherited from interface java.util.Collection

addAll, clear, containsAll, equals, hashCode, isEmpty, iterator, parallelStream, removeAll, removeIf, retainAll, spliterator, stream, toArray, toArray

Methods inherited from interface java.lang.Iterable

forEach

Field Detail

capacity

protected final int capacity

count

protected final java.util.concurrent.atomic.AtomicInteger count

not_empty_lock

protected final java.util.concurrent.locks.Lock not_empty_lock

not_empty

protected final java.util.concurrent.locks.Condition not_empty

Constructor Detail

ConcurrentLinkedBlockingQueue2

public ConcurrentLinkedBlockingQueue2(int capacity)

Method Detail

offer

public boolean offer(T t)

Drops elements if capacity has been reached. That's OK for the ThreadPoolExecutor as dropped messages will get retransmitted

Specified by:

offer in interface java.util.concurrent.BlockingQueue<T>

Specified by:

offer in interface java.util.Queue<T>

Overrides:

offer in class java.util.concurrent.ConcurrentLinkedQueue<T>

Parameters:

t -

Returns:

take

public T take()
       throws java.lang.InterruptedException

Specified by:

take in interface java.util.concurrent.BlockingQueue<T>

Throws:

java.lang.InterruptedException

poll

public T poll()

Specified by:

poll in interface java.util.Queue<T>

Overrides:

poll in class java.util.concurrent.ConcurrentLinkedQueue<T>

poll

public T poll(long timeout,
              java.util.concurrent.TimeUnit unit)
       throws java.lang.InterruptedException

Specified by:

poll in interface java.util.concurrent.BlockingQueue<T>

Throws:

java.lang.InterruptedException

remove

public boolean remove(java.lang.Object o)

Specified by:

remove in interface java.util.Collection<T>

Specified by:

remove in interface java.util.concurrent.BlockingQueue<T>

Overrides:

remove in class java.util.concurrent.ConcurrentLinkedQueue<T>

remainingCapacity

public int remainingCapacity()

Specified by:

remainingCapacity in interface java.util.concurrent.BlockingQueue<T>

drainTo

public int drainTo(java.util.Collection<? super T> c)

Specified by:

drainTo in interface java.util.concurrent.BlockingQueue<T>

put

public void put(T t)
         throws java.lang.InterruptedException

Specified by:

put in interface java.util.concurrent.BlockingQueue<T>

Throws:

java.lang.InterruptedException

offer

public boolean offer(T t,
                     long timeout,
                     java.util.concurrent.TimeUnit unit)
              throws java.lang.InterruptedException

Specified by:

offer in interface java.util.concurrent.BlockingQueue<T>

Throws:

java.lang.InterruptedException

size

public int size()

Specified by:

size in interface java.util.Collection<T>

Overrides:

size in class java.util.concurrent.ConcurrentLinkedQueue<T>

drainTo

public int drainTo(java.util.Collection<? super T> c,
                   int maxElements)

Specified by:

drainTo in interface java.util.concurrent.BlockingQueue<T>

waitForNotEmpty

protected void waitForNotEmpty()
                        throws java.lang.InterruptedException

Throws:

java.lang.InterruptedException

decrCount

protected void decrCount()

incrCount

protected void incrCount()