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[lttng-tools.git] / include / lttng / trigger / trigger.h
1 /*
2 * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
3 *
4 * SPDX-License-Identifier: LGPL-2.1-only
5 *
6 */
7
8 #ifndef LTTNG_TRIGGER_H
9 #define LTTNG_TRIGGER_H
10
11 struct lttng_action;
12 struct lttng_condition;
13 struct lttng_trigger;
14
15 #ifdef __cplusplus
16 extern "C" {
17 #endif
18
19 enum lttng_register_trigger_status {
20 LTTNG_REGISTER_TRIGGER_STATUS_OK = 0,
21 LTTNG_REGISTER_TRIGGER_STATUS_INVALID = -1,
22 };
23
24 /*
25 * Create a trigger object associating a condition and an action.
26 *
27 * A trigger associates a condition and an action to take whenever the
28 * condition evaluates to true. Such actions can, for example, consist
29 * in the emission of a notification to clients listening through
30 * notification channels.
31 *
32 * The caller retains the ownership of both the condition and action
33 * and both must be kept alive for the lifetime of the trigger object.
34 *
35 * A trigger must be registered in order to become activate and can
36 * be destroyed after its registration.
37 *
38 * Returns a trigger object on success, NULL on error.
39 * Trigger objects must be destroyed using the lttng_trigger_destroy()
40 * function.
41 */
42 extern struct lttng_trigger *lttng_trigger_create(
43 struct lttng_condition *condition, struct lttng_action *action);
44
45 /*
46 * Get the condition of a trigger.
47 *
48 * The caller acquires no ownership of the returned condition.
49 *
50 * Returns a condition on success, NULL on error.
51 */
52 extern struct lttng_condition *lttng_trigger_get_condition(
53 struct lttng_trigger *trigger);
54
55 /*
56 * Get the action of a trigger.
57 *
58 * The caller acquires no ownership of the returned action.
59 *
60 * Returns an action on success, NULL on error.
61 */
62 extern struct lttng_action *lttng_trigger_get_action(
63 struct lttng_trigger *trigger);
64
65 /*
66 * Destroy (frees) a trigger object.
67 */
68 extern void lttng_trigger_destroy(struct lttng_trigger *trigger);
69
70 /*
71 * Register a trigger to the session daemon.
72 *
73 * The trigger can be destroyed after this call.
74 *
75 * Return 0 on success, a negative LTTng error code on error.
76 */
77 extern int lttng_register_trigger(struct lttng_trigger *trigger);
78
79 /*
80 * Unregister a trigger from the session daemon.
81 *
82 * The trigger can be destroyed after this call.
83 *
84 * Return 0 on success, a negative LTTng error code on error.
85 */
86 extern int lttng_unregister_trigger(struct lttng_trigger *trigger);
87
88 #ifdef __cplusplus
89 }
90 #endif
91
92 #endif /* LTTNG_TRIGGER_H */
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