jsr166y
Class LinkedTransferQueue<E>

java.lang.Object
  java.util.AbstractCollection<E>
      java.util.AbstractQueue<E>
          jsr166y.LinkedTransferQueue<E>

Type Parameters:

E - the type of elements held in this collection

All Implemented Interfaces:

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

public class LinkedTransferQueue<E>
extends java.util.AbstractQueue<E>
implements TransferQueue<E>, java.io.Serializable

An unbounded TransferQueue based on linked nodes. This queue orders elements FIFO (first-in-first-out) with respect to any given producer. The head of the queue is that element that has been on the queue the longest time for some producer. The tail of the queue is that element that has been on the queue the shortest time for some producer.

Beware that, unlike in most collections, the size method is NOT a constant-time operation. Because of the asynchronous nature of these queues, determining the current number of elements requires a traversal of the elements.

This class and its iterator implement all of the optional methods of the Collection and Iterator interfaces.

Memory consistency effects: As with other concurrent collections, actions in a thread prior to placing an object into a LinkedTransferQueue happen-before actions subsequent to the access or removal of that element from the LinkedTransferQueue in another thread.

This class is a member of the Java Collections Framework.

Since:

1.7

See Also:

Serialized Form

Constructor Summary

LinkedTransferQueue()
Creates an initially empty LinkedTransferQueue.

LinkedTransferQueue(java.util.Collection<? extends E> c)
Creates a LinkedTransferQueue initially containing the elements of the given collection, added in traversal order of the collection's iterator.

Method Summary

int	drainTo(java.util.Collection<? super E> c)
int	drainTo(java.util.Collection<? super E> c, int maxElements)
int	getWaitingConsumerCount() Returns an estimate of the number of consumers waiting to dequeue elements via take or poll.
boolean	hasWaitingConsumer() Returns true if there is at least one consumer waiting to dequeue an element via take or poll.
boolean	isEmpty()
java.util.Iterator<E>	iterator()
boolean	offer(E e)
boolean	offer(E e, long timeout, java.util.concurrent.TimeUnit unit)
E	peek()
E	poll()
E	poll(long timeout, java.util.concurrent.TimeUnit unit)
void	put(E e)
int	remainingCapacity()
int	size() Returns the number of elements in this queue.
E	take()
void	transfer(E e) Inserts the specified element into this queue, waiting if necessary for space to become available and the element to be dequeued by a consumer invoking take or poll.
boolean	tryTransfer(E e) Transfers the specified element if there exists a consumer already waiting to receive it, otherwise returning false without enqueuing the element.
boolean	tryTransfer(E e, long timeout, java.util.concurrent.TimeUnit unit) Inserts the specified element into this queue, waiting up to the specified wait time if necessary for space to become available and the element to be dequeued by a consumer invoking take or poll.

Methods inherited from class java.util.AbstractQueue

add, addAll, clear, element, remove

Methods inherited from class java.util.AbstractCollection

contains, containsAll, remove, removeAll, retainAll, toArray, toArray, 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, remove

Methods inherited from interface java.util.Queue

element, remove

Methods inherited from interface java.util.Collection

addAll, clear, containsAll, equals, hashCode, removeAll, retainAll, toArray, toArray

Constructor Detail

LinkedTransferQueue

public LinkedTransferQueue()

Creates an initially empty LinkedTransferQueue.

LinkedTransferQueue

public LinkedTransferQueue(java.util.Collection<? extends E> c)

Creates a LinkedTransferQueue initially containing the elements of the given collection, added in traversal order of the collection's iterator.

Parameters:

c - the collection of elements to initially contain

Throws:

java.lang.NullPointerException - if the specified collection or any of its elements are null

Method Detail

put

public void put(E e)
         throws java.lang.InterruptedException

Specified by:

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

Throws:

java.lang.InterruptedException

offer

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

Specified by:

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

Throws:

java.lang.InterruptedException

offer

public boolean offer(E e)

Specified by:

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

Specified by:

offer in interface java.util.Queue<E>

transfer

public void transfer(E e)
              throws java.lang.InterruptedException

Description copied from interface: TransferQueue

Inserts the specified element into this queue, waiting if necessary for space to become available and the element to be dequeued by a consumer invoking take or poll.

Specified by:

transfer in interface TransferQueue<E>

Parameters:

e - the element to transfer

Throws:

java.lang.InterruptedException - if interrupted while waiting, in which case the element is not enqueued.

tryTransfer

public boolean tryTransfer(E e,
                           long timeout,
                           java.util.concurrent.TimeUnit unit)
                    throws java.lang.InterruptedException

Description copied from interface: TransferQueue

Inserts the specified element into this queue, waiting up to the specified wait time if necessary for space to become available and the element to be dequeued by a consumer invoking take or poll.

Specified by:

tryTransfer in interface TransferQueue<E>

Parameters:

e - the element to transfer

timeout - how long to wait before giving up, in units of unit

unit - a TimeUnit determining how to interpret the timeout parameter

Returns:

true if successful, or false if the specified waiting time elapses before completion, in which case the element is not enqueued.

Throws:

java.lang.InterruptedException - if interrupted while waiting, in which case the element is not enqueued.

tryTransfer

public boolean tryTransfer(E e)

Description copied from interface: TransferQueue

Transfers the specified element if there exists a consumer already waiting to receive it, otherwise returning false without enqueuing the element.

Specified by:

tryTransfer in interface TransferQueue<E>

Parameters:

e - the element to transfer

Returns:

true if the element was transferred, else false

take

public E take()
       throws java.lang.InterruptedException

Specified by:

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

Throws:

java.lang.InterruptedException

poll

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

Specified by:

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

Throws:

java.lang.InterruptedException

poll

public E poll()

Specified by:

poll in interface java.util.Queue<E>

drainTo

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

Specified by:

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

drainTo

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

Specified by:

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

iterator

public java.util.Iterator<E> iterator()

Specified by:

iterator in interface java.lang.Iterable<E>

Specified by:

iterator in interface java.util.Collection<E>

Specified by:

iterator in class java.util.AbstractCollection<E>

peek

public E peek()

Specified by:

peek in interface java.util.Queue<E>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface java.util.Collection<E>

Overrides:

isEmpty in class java.util.AbstractCollection<E>

hasWaitingConsumer

public boolean hasWaitingConsumer()

Description copied from interface: TransferQueue

Returns true if there is at least one consumer waiting to dequeue an element via take or poll. The return value represents a momentary state of affairs.

Specified by:

hasWaitingConsumer in interface TransferQueue<E>

Returns:

true if there is at least one waiting consumer.

size

public int size()

Returns the number of elements in this queue. If this queue contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.

Beware that, unlike in most collections, this method is NOT a constant-time operation. Because of the asynchronous nature of these queues, determining the current number of elements requires an O(n) traversal.

Specified by:

size in interface java.util.Collection<E>

Specified by:

size in class java.util.AbstractCollection<E>

Returns:

the number of elements in this queue

getWaitingConsumerCount

public int getWaitingConsumerCount()

Description copied from interface: TransferQueue

Returns an estimate of the number of consumers waiting to dequeue elements via take or poll. The return value is an approximation of a momentary state of affairs, that may be inaccurate if consumers have completed or given up waiting. The value may be useful for monitoring and heuristics, but not for synchronization control. Implementations of this method are likely to be noticeably slower than those for hasWaitingConsumer.

Specified by:

getWaitingConsumerCount in interface TransferQueue<E>

Returns:

the number of consumers waiting to dequeue elements

remainingCapacity

public int remainingCapacity()

Specified by:

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