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4fb826b1 | 1 | /* |
c0c0989a | 2 | * SPDX-License-Identifier: LGPL-2.1-only |
4fb826b1 | 3 | * |
c0c0989a MJ |
4 | * Copyright (C) 2015 EfficiOS Inc. |
5 | * Copyright (C) 2015 Alexandre Montplaisir <alexmonthy@efficios.com> | |
4fb826b1 AM |
6 | */ |
7 | ||
8 | package org.lttng.ust.agent.filter; | |
9 | ||
10 | import org.lttng.ust.agent.session.EventRule; | |
11 | ||
12 | /** | |
13 | * Filter notification listener interface. | |
14 | * <p> | |
15 | * Applications wanting to be notified of event filtering rule changes should | |
16 | * implement this interface, then register their listener using | |
17 | * {@link FilterChangeNotifier#registerListener}. | |
18 | * </p> | |
19 | * <p> | |
20 | * The callbacks defined in this interface will be called whenever an event rule | |
21 | * is added or removed. The manager will take care of the reference-counting in | |
22 | * case multiple tracing sessions enable the exact same rules. For example, the | |
23 | * {@link #eventRuleRemoved} callback is only called when there are no more | |
24 | * session interested into it. | |
25 | * </p> | |
26 | * <p> | |
27 | * Do not forget to unregister the listener after use, using | |
28 | * {@link FilterChangeNotifier#unregisterListener}. If you do not, or if | |
29 | * you use an anonymous listener for example, these will remain attached until | |
30 | * the complete shutdown of the application. | |
31 | * </p> | |
32 | * <p> | |
33 | * Only one thread is used to dispatch notifications, sequentially. This means | |
34 | * that if a callback hangs it will prevent other listeners from receiving | |
35 | * notifications. Please take care of not blocking inside the listener | |
36 | * callbacks, and use separate threads for potentially long or blocking | |
37 | * operations. | |
38 | * </p> | |
39 | * | |
40 | * @author Alexandre Montplaisir | |
41 | */ | |
42 | public interface IFilterChangeListener { | |
43 | ||
44 | /** | |
45 | * Notification that a new event rule is now enabled in the tracing | |
46 | * sessions. | |
47 | * | |
48 | * @param rule | |
49 | * The event rule that was enabled | |
50 | */ | |
51 | void eventRuleAdded(EventRule rule); | |
52 | ||
53 | /** | |
54 | * Notification that an existing event rule is now disabled in the tracing | |
55 | * sessions. | |
56 | * | |
57 | * @param rule | |
58 | * The event rule that was disabled | |
59 | */ | |
60 | void eventRuleRemoved(EventRule rule); | |
61 | } |