E
- the type of elements held in this collection@Deprecated public interface TransferQueue<E> extends BlockingQueue<E>
BlockingQueue
in which producers may wait for consumers
to receive elements. A TransferQueue
may be useful for
example in message passing applications in which producers
sometimes (using method transfer
) await receipt of
elements by consumers invoking take
or poll
,
while at other times enqueue elements (via method put
)
without waiting for receipt. Non-blocking and time-out versions of
tryTransfer
are also available. A TransferQueue may also
be queried via hasWaitingConsumer
whether there are any
threads waiting for items, which is a converse analogy to a
peek
operation.
Like any BlockingQueue
, a TransferQueue
may be
capacity bounded. If so, an attempted transfer
operation
may initially block waiting for available space, and/or
subsequently block waiting for reception by a consumer. Note that
in a queue with zero capacity, such as SynchronousQueue
,
put
and transfer
are effectively synonymous.
This interface is a member of the Java Collections Framework.
Modifier and Type | Method and Description |
---|---|
int |
getWaitingConsumerCount()
Deprecated.
Returns an estimate of the number of consumers waiting to
dequeue elements via
take or poll . |
boolean |
hasWaitingConsumer()
Deprecated.
Returns
true if there is at least one consumer waiting
to dequeue an element via take or poll . |
void |
transfer(E e)
Deprecated.
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)
Deprecated.
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,
TimeUnit unit)
Deprecated.
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 . |
add, contains, drainTo, drainTo, offer, offer, poll, put, remainingCapacity, remove, take
addAll, clear, containsAll, equals, hashCode, isEmpty, iterator, parallelStream, removeAll, removeIf, retainAll, size, spliterator, stream, toArray, toArray
boolean tryTransfer(E e)
false
without enqueuing the element.e
- the element to transfertrue
if the element was transferred, else
false
ClassCastException
- if the class of the specified element
prevents it from being added to this queueNullPointerException
- if the specified element is nullIllegalArgumentException
- if some property of the specified
element prevents it from being added to this queuevoid transfer(E e) throws InterruptedException
take
or poll
.e
- the element to transferInterruptedException
- if interrupted while waiting,
in which case the element is not enqueued.ClassCastException
- if the class of the specified element
prevents it from being added to this queueNullPointerException
- if the specified element is nullIllegalArgumentException
- if some property of the specified
element prevents it from being added to this queueboolean tryTransfer(E e, long timeout, TimeUnit unit) throws InterruptedException
take
or poll
.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.InterruptedException
- if interrupted while waiting,
in which case the element is not enqueued.ClassCastException
- if the class of the specified element
prevents it from being added to this queueNullPointerException
- if the specified element is nullIllegalArgumentException
- if some property of the specified
element prevents it from being added to this queueboolean hasWaitingConsumer()
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.true
if there is at least one waiting consumerint getWaitingConsumerCount()
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()
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