java.util.concurrent.TransferQueue<E> |
Known Indirect Subclasses |
A 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(E)
) 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 other blocking queues, 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.
Public Methods | |||||||||||
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Transfers the element to a consumer, waiting if necessary to do so.
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Transfers the element to a waiting consumer immediately, if possible.
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Transfers the element to a consumer if it is possible to do so
before the timeout elapses.
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Inherited Methods | |||||||||||
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From interface
java.lang.Iterable
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From interface
java.util.Collection
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From interface
java.util.Queue
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From interface
java.util.concurrent.BlockingQueue
|
Returns an estimate of the number of consumers waiting to
receive elements via 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
hasWaitingConsumer()
.
Transfers the element to a consumer, waiting if necessary to do so.
More precisely, transfers the specified element immediately
if there exists a consumer already waiting to receive it (in
take()
or timed poll
),
else waits until the element is received by a consumer.
e | the element to transfer |
---|
InterruptedException | if interrupted while waiting, in which case the element is not left enqueued |
---|---|
ClassCastException | if the class of the specified element prevents it from being added to this queue |
NullPointerException | if the specified element is null |
IllegalArgumentException | if some property of the specified element prevents it from being added to this queue |
Transfers the element to a waiting consumer immediately, if possible.
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.
e | the element to transfer |
---|
true
if the element was transferred, else
false
ClassCastException | if the class of the specified element prevents it from being added to this queue |
---|---|
NullPointerException | if the specified element is null |
IllegalArgumentException | if some property of the specified element prevents it from being added to this queue |
Transfers the element to a consumer if it is possible to do so before the timeout elapses.
More precisely, transfers the specified element immediately
if there exists a consumer already waiting to receive it (in
take()
or timed poll
),
else waits until the element is received by a consumer,
returning false
if the specified wait time elapses
before the element can be transferred.
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 |
true
if successful, or false
if
the specified waiting time elapses before completion,
in which case the element is not left enqueuedInterruptedException | if interrupted while waiting, in which case the element is not left enqueued |
---|---|
ClassCastException | if the class of the specified element prevents it from being added to this queue |
NullPointerException | if the specified element is null |
IllegalArgumentException | if some property of the specified element prevents it from being added to this queue |