E - the type of elements held in this collectionpublic class LinkedTransferQueue<E> extends AbstractQueue<E> implements TransferQueue<E>, 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(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(Object o)
Returns
true if this queue contains the specified element. |
int |
drainTo(Collection<? super E> c)
Removes all available elements from this queue and adds them
to the given collection.
|
int |
drainTo(Collection<? super E> c,
int maxElements)
Removes at most the given number of available elements from
this queue and adds them to the given collection.
|
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. |
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,
TimeUnit unit)
Inserts the specified element at the tail of this queue.
|
E |
peek()
Retrieves, but does not remove, the head of this queue,
or returns null if this queue is empty.
|
E |
poll()
Retrieves and removes the head of this queue,
or returns null if this queue is empty.
|
E |
poll(long timeout,
TimeUnit unit)
Retrieves and removes the head of this queue, waiting up to the
specified wait time if necessary for an element to become available.
|
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(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()
Retrieves and removes the head of this queue, waiting if necessary
until an element becomes available.
|
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,
TimeUnit unit)
Transfers the element to a consumer if it is possible to do so
before the timeout elapses.
|
addAll, clear, element, removecontainsAll, removeAll, retainAll, toArray, toArray, toStringclone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, waitaddAll, clear, containsAll, equals, hashCode, removeAll, retainAll, toArray, toArraypublic LinkedTransferQueue()
LinkedTransferQueue.public LinkedTransferQueue(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 containNullPointerException - if the specified collection or any
of its elements are nullpublic void put(E e)
put in interface BlockingQueue<E>e - the element to addNullPointerException - if the specified element is nullpublic boolean offer(E e, long timeout, TimeUnit unit)
false.offer in interface BlockingQueue<E>e - the element to addtimeout - how long to wait before giving up, in units of
unitunit - a TimeUnit determining how to interpret the
timeout parametertrue (as specified by
BlockingQueue.offer)NullPointerException - if the specified element is nullpublic boolean offer(E e)
false.offer in interface BlockingQueue<E>offer in interface Queue<E>e - the element to addtrue (as specified by Queue.offer(E))NullPointerException - if the specified element is nullpublic boolean add(E e)
IllegalStateException or return false.add in interface Collection<E>add in interface BlockingQueue<E>add in interface Queue<E>add in class AbstractQueue<E>e - the element to addtrue (as specified by Collection.add(E))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
falseNullPointerException - if the specified element is nullpublic void transfer(E e) throws 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 transferNullPointerException - if the specified element is nullInterruptedException - if interrupted while waiting,
in which case the element is not left enqueuedpublic boolean tryTransfer(E e, long timeout, TimeUnit unit) throws 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 enqueuedNullPointerException - if the specified element is nullInterruptedException - if interrupted while waiting,
in which case the element is not left enqueuedpublic E take() throws InterruptedException
BlockingQueuetake in interface BlockingQueue<E>InterruptedException - if interrupted while waitingpublic E poll(long timeout, TimeUnit unit) throws InterruptedException
BlockingQueuepoll in interface BlockingQueue<E>timeout - how long to wait before giving up, in units of
unitunit - a TimeUnit determining how to interpret the
timeout parameterInterruptedException - if interrupted while waitingpublic E poll()
Queuepublic int drainTo(Collection<? super E> c)
BlockingQueuedrainTo in interface BlockingQueue<E>c - the collection to transfer elements intoNullPointerException - if the specified collection is nullIllegalArgumentException - if the specified collection is this
queue, or some property of an element of this queue prevents
it from being added to the specified collectionpublic int drainTo(Collection<? super E> c, int maxElements)
BlockingQueuedrainTo in interface BlockingQueue<E>c - the collection to transfer elements intomaxElements - the maximum number of elements to transferNullPointerException - if the specified collection is nullIllegalArgumentException - if the specified collection is this
queue, or some property of an element of this queue prevents
it from being added to the specified collectionpublic 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.
iterator in interface Iterable<E>iterator in interface Collection<E>iterator in class AbstractCollection<E>public E peek()
Queuepublic boolean isEmpty()
true if this queue contains no elements.isEmpty in interface Collection<E>isEmpty in class AbstractCollection<E>true if this queue contains no elementspublic 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.
size in interface Collection<E>size in class AbstractCollection<E>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(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 Collection<E>remove in interface BlockingQueue<E>remove in class AbstractCollection<E>o - element to be removed from this queue, if presenttrue if this queue changed as a result of the callpublic boolean contains(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 Collection<E>contains in interface BlockingQueue<E>contains in class 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 BlockingQueue<E>Integer.MAX_VALUE (as specified by
BlockingQueue.remainingCapacity())