23 |
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* peek} operation. |
24 |
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* |
25 |
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* <p>Like other blocking queues, a {@code TransferQueue} may be |
26 |
< |
* capacity bounded. If so, an attempted {@code transfer} operation |
27 |
< |
* may initially block waiting for available space, and/or |
28 |
< |
* subsequently block waiting for reception by a consumer. Note that |
29 |
< |
* in a queue with zero capacity, such as {@link SynchronousQueue}, |
30 |
< |
* {@code put} and {@code transfer} are effectively synonymous. |
26 |
> |
* capacity bounded. If so, an attempted transfer operation may |
27 |
> |
* initially block waiting for available space, and/or subsequently |
28 |
> |
* block waiting for reception by a consumer. Note that in a queue |
29 |
> |
* with zero capacity, such as {@link SynchronousQueue}, {@code put} |
30 |
> |
* and {@code transfer} are effectively synonymous. |
31 |
|
* |
32 |
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* <p>This interface is a member of the |
33 |
|
* <a href="{@docRoot}/../technotes/guides/collections/index.html"> |
39 |
|
*/ |
40 |
|
public interface TransferQueue<E> extends BlockingQueue<E> { |
41 |
|
/** |
42 |
< |
* Transfers the specified element immediately if there exists a |
43 |
< |
* consumer already waiting to receive it (in {@link #take} or |
44 |
< |
* timed {@link #poll(Object,long,TimeUnit) poll}), otherwise |
45 |
< |
* returning {@code false} without enqueuing the element. |
42 |
> |
* Transfers the element to a waiting consumer immediately, if possible. |
43 |
> |
* |
44 |
> |
* <p>More precisely, transfers the specified element immediately |
45 |
> |
* if there exists a consumer already waiting to receive it (in |
46 |
> |
* {@link #take} or timed {@link #poll(long,TimeUnit) poll}), |
47 |
> |
* otherwise returning {@code false} without enqueuing the element. |
48 |
|
* |
49 |
|
* @param e the element to transfer |
50 |
|
* @return {@code true} if the element was transferred, else |
58 |
|
boolean tryTransfer(E e); |
59 |
|
|
60 |
|
/** |
61 |
< |
* Inserts the specified element into this queue, waiting if |
62 |
< |
* necessary for space to become available and the element to be |
63 |
< |
* received by a consumer invoking {@code take} or {@code poll}. |
61 |
> |
* Transfers the element to a consumer, waiting if necessary to do so. |
62 |
> |
* |
63 |
> |
* <p>More precisely, transfers the specified element immediately |
64 |
> |
* if there exists a consumer already waiting to receive it (in |
65 |
> |
* {@link #take} or timed {@link #poll(long,TimeUnit) poll}), |
66 |
> |
* else waits until the element is received by a consumer. |
67 |
|
* |
68 |
|
* @param e the element to transfer |
69 |
|
* @throws InterruptedException if interrupted while waiting, |
70 |
< |
* in which case the element is not enqueued |
70 |
> |
* in which case the element is not left enqueued |
71 |
|
* @throws ClassCastException if the class of the specified element |
72 |
|
* prevents it from being added to this queue |
73 |
|
* @throws NullPointerException if the specified element is null |
77 |
|
void transfer(E e) throws InterruptedException; |
78 |
|
|
79 |
|
/** |
80 |
< |
* Inserts the specified element into this queue, waiting up to |
81 |
< |
* the specified wait time if necessary for space to become |
82 |
< |
* available and the element to be received by a consumer invoking |
83 |
< |
* {@code take} or {@code poll}. |
80 |
> |
* Transfers the element to a consumer if it is possible to do so |
81 |
> |
* before the timeout elapses. |
82 |
> |
* |
83 |
> |
* <p>More precisely, transfers the specified element immediately |
84 |
> |
* if there exists a consumer already waiting to receive it (in |
85 |
> |
* {@link #take} or timed {@link #poll(long,TimeUnit) poll}), |
86 |
> |
* else waits until the element is received by a consumer, |
87 |
> |
* returning {@code false} if the specified wait time elapses |
88 |
> |
* before the element can be transferred. |
89 |
|
* |
90 |
|
* @param e the element to transfer |
91 |
|
* @param timeout how long to wait before giving up, in units of |
94 |
|
* {@code timeout} parameter |
95 |
|
* @return {@code true} if successful, or {@code false} if |
96 |
|
* the specified waiting time elapses before completion, |
97 |
< |
* in which case the element is not enqueued |
97 |
> |
* in which case the element is not left enqueued |
98 |
|
* @throws InterruptedException if interrupted while waiting, |
99 |
< |
* in which case the element is not enqueued |
99 |
> |
* in which case the element is not left enqueued |
100 |
|
* @throws ClassCastException if the class of the specified element |
101 |
|
* prevents it from being added to this queue |
102 |
|
* @throws NullPointerException if the specified element is null |
109 |
|
/** |
110 |
|
* Returns {@code true} if there is at least one consumer waiting |
111 |
|
* to receive an element via {@link #take} or |
112 |
< |
* timed {@link #poll(Object,long,TimeUnit) poll}. |
112 |
> |
* timed {@link #poll(long,TimeUnit) poll}. |
113 |
|
* The return value represents a momentary state of affairs. |
114 |
|
* |
115 |
|
* @return {@code true} if there is at least one waiting consumer |
118 |
|
|
119 |
|
/** |
120 |
|
* Returns an estimate of the number of consumers waiting to |
121 |
< |
* receive elements via {@link #take} or |
122 |
< |
* timed {@link #poll(Object,long,TimeUnit) poll}. The return |
123 |
< |
* value is an approximation of a momentary state of affairs, that |
124 |
< |
* may be inaccurate if consumers have completed or given up |
125 |
< |
* waiting. The value may be useful for monitoring and heuristics, |
126 |
< |
* but not for synchronization control. Implementations of this |
121 |
> |
* receive elements via {@link #take} or timed |
122 |
> |
* {@link #poll(long,TimeUnit) poll}. The return value is an |
123 |
> |
* approximation of a momentary state of affairs, that may be |
124 |
> |
* inaccurate if consumers have completed or given up waiting. |
125 |
> |
* The value may be useful for monitoring and heuristics, but |
126 |
> |
* not for synchronization control. Implementations of this |
127 |
|
* method are likely to be noticeably slower than those for |
128 |
|
* {@link #hasWaitingConsumer}. |
129 |
|
* |