Docs: document trigger condition and action ownership in 2.13+
[lttng-tools.git] / include / lttng / trigger / trigger.h
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a58c490f 1/*
ab5be9fa 2 * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
a58c490f 3 *
ab5be9fa 4 * SPDX-License-Identifier: LGPL-2.1-only
a58c490f 5 *
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6 */
7
8#ifndef LTTNG_TRIGGER_H
9#define LTTNG_TRIGGER_H
10
64eafdf6 11#include <sys/types.h>
5c504c41 12#include <inttypes.h>
64eafdf6 13
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14struct lttng_action;
15struct lttng_condition;
16struct lttng_trigger;
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17/* A set of triggers. */
18struct lttng_triggers;
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19
20#ifdef __cplusplus
21extern "C" {
22#endif
23
24enum lttng_register_trigger_status {
25 LTTNG_REGISTER_TRIGGER_STATUS_OK = 0,
26 LTTNG_REGISTER_TRIGGER_STATUS_INVALID = -1,
27};
28
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29enum lttng_trigger_status {
30 LTTNG_TRIGGER_STATUS_OK = 0,
31 LTTNG_TRIGGER_STATUS_ERROR = -1,
32 LTTNG_TRIGGER_STATUS_UNKNOWN = -2,
33 LTTNG_TRIGGER_STATUS_INVALID = -3,
34 LTTNG_TRIGGER_STATUS_UNSET = -4,
35 LTTNG_TRIGGER_STATUS_UNSUPPORTED = -5,
36 LTTNG_TRIGGER_STATUS_PERMISSION_DENIED = -6,
37};
38
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39enum lttng_trigger_firing_policy {
40 LTTNG_TRIGGER_FIRING_POLICY_EVERY_N = 0,
41 LTTNG_TRIGGER_FIRING_POLICY_ONCE_AFTER_N = 1,
42};
43
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44/*
45 * Create a trigger object associating a condition and an action.
46 *
47 * A trigger associates a condition and an action to take whenever the
48 * condition evaluates to true. Such actions can, for example, consist
49 * in the emission of a notification to clients listening through
50 * notification channels.
51 *
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52 * Prior to 2.13, the caller had to retain the ownership of both the condition
53 * and action. Both objects had to be kept alive for the lifetime of the trigger
54 * object. This is no longer the case as the condition and action objects are
55 * internally reference counted. It is safe to destroy a condition and an action
56 * after using them to create a trigger. However, they should no longer be used.
75984389 57 *
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58 * If the action is a notification action with capture descriptors,
59 * the condition must be an event rule condition.
60 *
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61 * A trigger must be registered in order to become activate and can
62 * be destroyed after its registration.
63 *
64 * Returns a trigger object on success, NULL on error.
65 * Trigger objects must be destroyed using the lttng_trigger_destroy()
66 * function.
67 */
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68extern struct lttng_trigger *lttng_trigger_create(
69 struct lttng_condition *condition, struct lttng_action *action);
70
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71/*
72 * Set the user identity (uid) of a trigger.
73 *
74 * Only available for the root user (uid 0).
75 *
76 * Returns LTTNG_TRIGGER_STATUS_OK on success,
77 * LTTNG_TRIGGER_STATUS_EPERM if not authorized,
78 * LTTNG_TRIGGER_STATUS_INVALID if invalid parameters are passed.
79 */
80extern enum lttng_trigger_status lttng_trigger_set_owner_uid(
81 struct lttng_trigger *trigger, uid_t uid);
82
83/*
84 * Get the user identity (uid) of a trigger.
85 *
86 * Returns LTTNG_TRIGGER_STATUS_OK on success,
87 * LTTNG_TRIGGER_STATUS_UNSET if unset,
88 * LTTNG_TRIGGER_STATUS_INVALID if invalid parameters are passed.
89 */
90extern enum lttng_trigger_status lttng_trigger_get_owner_uid(
91 const struct lttng_trigger *trigger, uid_t *uid);
92
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93/*
94 * Get the condition of a trigger.
95 *
96 * The caller acquires no ownership of the returned condition.
97 *
98 * Returns a condition on success, NULL on error.
99 */
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100extern struct lttng_condition *lttng_trigger_get_condition(
101 struct lttng_trigger *trigger);
102
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103const struct lttng_condition *lttng_trigger_get_const_condition(
104 const struct lttng_trigger *trigger);
105
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106/*
107 * Get the action of a trigger.
108 *
109 * The caller acquires no ownership of the returned action.
110 *
111 * Returns an action on success, NULL on error.
112 */
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113extern struct lttng_action *lttng_trigger_get_action(
114 struct lttng_trigger *trigger);
115
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116const struct lttng_action *lttng_trigger_get_const_action(
117 const struct lttng_trigger *trigger);
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118
119/*
120 * Get the name of a trigger.
121 *
122 * The caller does not assume the ownership of the returned name.
123 * The name shall only only be used for the duration of the trigger's
124 * lifetime, or until a different name is set.
125 *
126 * Returns LTTNG_TRIGGER_STATUS_OK and a pointer to the trigger's name on
127 * success, LTTNG_TRIGGER_STATUS_INVALID if an invalid parameter is passed,
128 * or LTTNG_TRIGGER_STATUS_UNSET if a name was not set prior to this call.
129 */
130extern enum lttng_trigger_status lttng_trigger_get_name(
131 const struct lttng_trigger *trigger, const char **name);
132
133/*
134 * Set the trigger name.
135 *
136 * A name is optional.
137 * A name will be assigned on trigger registration if no name is set.
138 *
139 * The name is copied.
140 *
141 * Return LTTNG_TRIGGER_STATUS_OK on success, LTTNG_TRIGGER_STATUS_INVALID
142 * if invalid parameters are passed.
143 */
144extern enum lttng_trigger_status lttng_trigger_set_name(
145 struct lttng_trigger *trigger, const char *name);
146
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147/*
148 * Set the trigger firing policy.
149 *
150 * This is optional. By default a trigger is set to fire each time the
151 * associated condition occurs.
152 *
153 * Threshold is the number of times the condition must be hit before the policy
154 * is enacted.
155 *
156 * Return LTTNG_TRIGGER_STATUS_OK on success, LTTNG_TRIGGER_STATUS_INVALID
157 * if invalid parameters are passed.
158 */
159extern enum lttng_trigger_status lttng_trigger_set_firing_policy(
160 struct lttng_trigger *trigger,
161 enum lttng_trigger_firing_policy policy_type,
162 uint64_t threshold);
163
164/*
165 * Get the trigger firing policy.
166 *
167 * Threshold is the number of time the condition must be hit before the policy is
168 * enacted.
169 *
170 * Return LTTNG_TRIGGER_STATUS_OK on success, LTTNG_TRIGGER_STATUS_INVALID
171 * if invalid parameters are passed.
172 */
173extern enum lttng_trigger_status lttng_trigger_get_firing_policy(
174 const struct lttng_trigger *trigger,
175 enum lttng_trigger_firing_policy *policy_type,
176 uint64_t *threshold);
177
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178/*
179 * Destroy (frees) a trigger object.
180 */
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181extern void lttng_trigger_destroy(struct lttng_trigger *trigger);
182
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183/*
184 * Register a trigger to the session daemon.
185 *
186 * The trigger can be destroyed after this call.
187 *
188 * Return 0 on success, a negative LTTng error code on error.
189 */
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190extern int lttng_register_trigger(struct lttng_trigger *trigger);
191
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192/*
193 * Unregister a trigger from the session daemon.
194 *
195 * The trigger can be destroyed after this call.
196 *
197 * Return 0 on success, a negative LTTng error code on error.
198 */
b61776fb 199extern int lttng_unregister_trigger(const struct lttng_trigger *trigger);
a58c490f 200
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201/*
202 * List triggers for the current user.
203 *
204 * On success, a newly-allocated trigger set is returned.
205 *
206 * The trigger set must be destroyed by the caller (see
207 * lttng_triggers_destroy()).
208 *
209 * Returns LTTNG_OK on success, else a suitable LTTng error code.
210 */
211extern enum lttng_error_code lttng_list_triggers(
212 struct lttng_triggers **triggers);
213
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214/*
215 * Get a trigger from the set at a given index.
216 *
217 * Note that the trigger set maintains the ownership of the returned trigger.
218 * It must not be destroyed by the user, nor should a reference to it be held
219 * beyond the lifetime of the trigger set.
220 *
221 * Returns a trigger, or NULL on error.
222 */
223extern const struct lttng_trigger *lttng_triggers_get_at_index(
224 const struct lttng_triggers *triggers, unsigned int index);
225
226/*
227 * Get the number of triggers in a trigger set.
228 *
229 * Return LTTNG_TRIGGER_STATUS_OK on success,
230 * LTTNG_TRIGGER_STATUS_INVALID when invalid parameters are passed.
231 */
232extern enum lttng_trigger_status lttng_triggers_get_count(
233 const struct lttng_triggers *triggers, unsigned int *count);
234
235/*
236 * Destroy a trigger set.
237 */
238extern void lttng_triggers_destroy(struct lttng_triggers *triggers);
239
240
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241#ifdef __cplusplus
242}
243#endif
244
245#endif /* LTTNG_TRIGGER_H */
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