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) |
int |
drainTo(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()
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() |
E |
poll() |
E |
poll(long timeout,
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(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,
TimeUnit unit)
Transfers the element to a consumer if it is possible to do so
before the timeout elapses.
|
addAll, clear, element, remove
containsAll, removeAll, retainAll, toArray, toArray, toString
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
addAll, clear, containsAll, equals, hashCode, parallelStream, removeAll, removeIf, retainAll, spliterator, stream, toArray, toArray
public 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>
NullPointerException
- if the specified element is nullpublic boolean offer(E e, long timeout, TimeUnit unit)
false
.offer
in interface BlockingQueue<E>
true
(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>
true
(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>
true
(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
false
NullPointerException
- 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 enqueued.public 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
unit
unit
- 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 enqueued.NullPointerException
- if the specified element is nullInterruptedException
- if interrupted while waiting,
in which case the element is not enqueued.public E take() throws InterruptedException
take
in interface BlockingQueue<E>
InterruptedException
public E poll(long timeout, TimeUnit unit) throws InterruptedException
poll
in interface BlockingQueue<E>
InterruptedException
public int drainTo(Collection<? super E> c)
drainTo
in interface BlockingQueue<E>
NullPointerException
IllegalArgumentException
public int drainTo(Collection<? super E> c, int maxElements)
drainTo
in interface BlockingQueue<E>
NullPointerException
IllegalArgumentException
public 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 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()
TransferQueue
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.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()
TransferQueue
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
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
)Copyright © 2015 Oracle Corporation. All rights reserved.