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Java > Open Source Codes > org > apache > avalon > excalibur > event > Sink


1 /*
2  * Copyright (C) The Apache Software Foundation. All rights reserved.
3  *
4  * This software is published under the terms of the Apache Software License
5  * version 1.1, a copy of which has been included with this distribution in
6  * the LICENSE.txt file.
7  */
8 package org.apache.avalon.excalibur.event;
9
10 /**
11  * A Sink implements the side of an event queue where QueueElements are
12  * dequeued operations only.
13  *
14  * @author <a HREF="mailto:bloritsch@apache.org">Berin Loritsch</a>
15  */
16 public interface Sink {
17     /**
18      * Sets the timeout on a blocking Sink. Values above <code>1</code> will
19      * force all <code>dequeue</code> operations to block for up to that number
20      * of milliseconds waiting for new elements. Values below <code>1</code>
21      * will turn off blocking for Sink. This is intentional because a Sink should
22      * never block indefinitely.
23      */
24     void setTimeout( long millis );
25
26     /**
27      * Dequeues the next element, or returns <code>null</code> if there is
28      * nothing left on the queue.
29      *
30      * @return the next <code>QueueElement</code> on the queue
31      */
32     QueueElement dequeue();
33
34     /**
35      * Dequeues all available elements, or returns <code>null</code> if there is
36      * nothing left on the queue.
37      *
38      * @return all pending <code>QueueElement</code>s on the queue
39      */
40     QueueElement[] dequeueAll();
41
42     /**
43      * Dequeues at most <code>num</code> available elements, or returns
44      * <code>null</code> if there is nothing left on the queue.
45      *
46      * @return At most <code>num</code> <code>QueueElement</code>s on the queue
47      */
48     QueueElement[] dequeue(int num);
49
50     /**
51      * Returns the number of elements waiting in this queue.
52      */
53     int size();
54
55 }
56
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