E - the type of elements held in this collectionpublic class LinkedTransferQueue<E> extends java.util.AbstractQueue<E> implements TransferQueue<E>, java.io.Serializable
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, and so may report
inaccurate results if this collection is modified during traversal.
Additionally, the bulk operations addAll,
removeAll, retainAll, containsAll,
equals, and toArray are not guaranteed
to be performed atomically. For example, an iterator operating
concurrently with an addAll operation might view only some
of the added 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.
| Constructor and Description |
|---|
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. |
| Modifier and Type | Method and Description |
|---|---|
boolean |
add(E e)
Inserts the specified element at the tail of this queue.
|
boolean |
contains(java.lang.Object o)
Returns
true if this queue contains the specified element. |
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
receive elements via
BlockingQueue.take() or timed
poll. |
boolean |
hasWaitingConsumer()
Returns
true if there is at least one consumer waiting
to receive an element via BlockingQueue.take() or
timed poll. |
boolean |
isEmpty()
Returns
true if this queue contains no elements. |
java.util.Iterator<E> |
iterator()
Returns an iterator over the elements in this queue in proper sequence.
|
boolean |
offer(E e)
Inserts the specified element at the tail of this queue.
|
boolean |
offer(E e,
long timeout,
java.util.concurrent.TimeUnit unit)
Inserts the specified element at the tail of this queue.
|
E |
peek() |
E |
poll() |
E |
poll(long timeout,
java.util.concurrent.TimeUnit unit) |
void |
put(E e)
Inserts the specified element at the tail of this queue.
|
int |
remainingCapacity()
Always returns
Integer.MAX_VALUE because a
LinkedTransferQueue is not capacity constrained. |
boolean |
remove(java.lang.Object o)
Removes a single instance of the specified element from this queue,
if it is present.
|
int |
size()
Returns the number of elements in this queue.
|
E |
take() |
void |
transfer(E e)
Transfers the element to a consumer, waiting if necessary to do so.
|
boolean |
tryTransfer(E e)
Transfers the element to a waiting consumer immediately, if possible.
|
boolean |
tryTransfer(E e,
long timeout,
java.util.concurrent.TimeUnit unit)
Transfers the element to a consumer if it is possible to do so
before the timeout elapses.
|
containsAll, removeAll, retainAll, toArray, toArray, toStringpublic LinkedTransferQueue()
LinkedTransferQueue.public LinkedTransferQueue(java.util.Collection<? extends E> c)
LinkedTransferQueue
initially containing the elements of the given collection,
added in traversal order of the collection's iterator.c - the collection of elements to initially containjava.lang.NullPointerException - if the specified collection or any
of its elements are nullpublic void put(E e)
put in interface java.util.concurrent.BlockingQueue<E>java.lang.NullPointerException - if the specified element is nullpublic boolean offer(E e, long timeout, java.util.concurrent.TimeUnit unit)
false.offer in interface java.util.concurrent.BlockingQueue<E>true (as specified by
BlockingQueue.offer)java.lang.NullPointerException - if the specified element is nullpublic boolean offer(E e)
false.public boolean add(E e)
IllegalStateException or return false.add in interface java.util.Collection<E>add in interface java.util.concurrent.BlockingQueue<E>add in interface java.util.Queue<E>add in class java.util.AbstractQueue<E>true (as specified by Collection.add(E))java.lang.NullPointerException - if the specified element is nullpublic boolean tryTransfer(E e)
More precisely, transfers the specified element immediately
if there exists a consumer already waiting to receive it (in
take() or timed poll),
otherwise returning false without enqueuing the element.
tryTransfer in interface TransferQueue<E>e - the element to transfertrue if the element was transferred, else
falsejava.lang.NullPointerException - if the specified element is nullpublic void transfer(E e) throws java.lang.InterruptedException
More precisely, transfers the specified element immediately
if there exists a consumer already waiting to receive it (in
take() or timed poll),
else inserts the specified element at the tail of this queue
and waits until the element is received by a consumer.
transfer in interface TransferQueue<E>e - the element to transferjava.lang.NullPointerException - if the specified element is nulljava.lang.InterruptedException - if interrupted while waiting,
in which case the element is not left enqueuedpublic boolean tryTransfer(E e, long timeout, java.util.concurrent.TimeUnit unit) throws java.lang.InterruptedException
More precisely, transfers the specified element immediately
if there exists a consumer already waiting to receive it (in
take() or timed poll),
else inserts the specified element at the tail of this queue
and waits until the element is received by a consumer,
returning false if the specified wait time elapses
before the element can be transferred.
tryTransfer in interface TransferQueue<E>e - the element to transfertimeout - how long to wait before giving up, in units of
unitunit - a TimeUnit determining how to interpret the
timeout parametertrue if successful, or false if
the specified waiting time elapses before completion,
in which case the element is not left enqueuedjava.lang.NullPointerException - if the specified element is nulljava.lang.InterruptedException - if interrupted while waiting,
in which case the element is not left enqueuedpublic E take() throws java.lang.InterruptedException
take in interface java.util.concurrent.BlockingQueue<E>java.lang.InterruptedExceptionpublic E poll(long timeout, java.util.concurrent.TimeUnit unit) throws java.lang.InterruptedException
poll in interface java.util.concurrent.BlockingQueue<E>java.lang.InterruptedExceptionpublic int drainTo(java.util.Collection<? super E> c)
drainTo in interface java.util.concurrent.BlockingQueue<E>java.lang.NullPointerExceptionjava.lang.IllegalArgumentExceptionpublic int drainTo(java.util.Collection<? super E> c, int maxElements)
drainTo in interface java.util.concurrent.BlockingQueue<E>java.lang.NullPointerExceptionjava.lang.IllegalArgumentExceptionpublic java.util.Iterator<E> iterator()
The returned iterator is a "weakly consistent" iterator that
will never throw ConcurrentModificationException, and guarantees to traverse
elements as they existed upon construction of the iterator, and
may (but is not guaranteed to) reflect any modifications
subsequent to construction.
public boolean isEmpty()
true if this queue contains no elements.public boolean hasWaitingConsumer()
TransferQueuetrue if there is at least one consumer waiting
to receive an element via BlockingQueue.take() or
timed poll.
The return value represents a momentary state of affairs.hasWaitingConsumer in interface TransferQueue<E>true if there is at least one waiting consumerpublic int size()
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.
public int getWaitingConsumerCount()
TransferQueueBlockingQueue.take() or timed
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
TransferQueue.hasWaitingConsumer().getWaitingConsumerCount in interface TransferQueue<E>public boolean remove(java.lang.Object o)
e such
that o.equals(e), if this queue contains one or more such
elements.
Returns true if this queue contained the specified element
(or equivalently, if this queue changed as a result of the call).remove in interface java.util.Collection<E>remove in interface java.util.concurrent.BlockingQueue<E>remove in class java.util.AbstractCollection<E>o - element to be removed from this queue, if presenttrue if this queue changed as a result of the callpublic boolean contains(java.lang.Object o)
true if this queue contains the specified element.
More formally, returns true if and only if this queue contains
at least one element e such that o.equals(e).contains in interface java.util.Collection<E>contains in interface java.util.concurrent.BlockingQueue<E>contains in class java.util.AbstractCollection<E>o - object to be checked for containment in this queuetrue if this queue contains the specified elementpublic int remainingCapacity()
Integer.MAX_VALUE because a
LinkedTransferQueue is not capacity constrained.remainingCapacity in interface java.util.concurrent.BlockingQueue<E>Integer.MAX_VALUE (as specified by
BlockingQueue.remainingCapacity)