Docs: document the trigger API

[lttng-tools.git] / include / lttng / trigger / trigger.h

diff --git a/include/lttng/trigger/trigger.h b/include/lttng/trigger/trigger.h
index b2eab0e3da9fa10192b2f6a05da110c0178523c9..0c67abb0b03646ccbd287a162b8fb0884a8eec4d 100644 (file)
--- a/include/lttng/trigger/trigger.h
+++ b/include/lttng/trigger/trigger.h
@@ -31,20 +31,68 @@ enum lttng_register_trigger_status {
        LTTNG_REGISTER_TRIGGER_STATUS_INVALID = -1,
 };
 
-/* The caller retains the ownership of both condition and action. */
+/*
+ * Create a trigger object associating a condition and an action.
+ *
+ * A trigger associates a condition and an action to take whenever the
+ * condition evaluates to true. Such actions can, for example, consist
+ * in the emission of a notification to clients listening through
+ * notification channels.
+ *
+ * The caller retains the ownership of both the condition and action
+ * and both must be kept alive for the lifetime of the trigger object.
+ *
+ * A trigger must be registered in order to become activate and can
+ * be destroyed after its registration.
+ *
+ * Returns a trigger object on success, NULL on error.
+ * Trigger objects must be destroyed using the lttng_trigger_destroy()
+ * function.
+ */
 extern struct lttng_trigger *lttng_trigger_create(
                struct lttng_condition *condition, struct lttng_action *action);
 
+/*
+ * Get the condition of a trigger.
+ *
+ * The caller acquires no ownership of the returned condition.
+ *
+ * Returns a condition on success, NULL on error.
+ */
 extern struct lttng_condition *lttng_trigger_get_condition(
                struct lttng_trigger *trigger);
 
+/*
+ * Get the action of a trigger.
+ *
+ * The caller acquires no ownership of the returned action.
+ *
+ * Returns an action on success, NULL on error.
+ */
 extern struct lttng_action *lttng_trigger_get_action(
                struct lttng_trigger *trigger);
 
+/*
+ * Destroy (frees) a trigger object.
+ */
 extern void lttng_trigger_destroy(struct lttng_trigger *trigger);
 
+/*
+ * Register a trigger to the session daemon.
+ *
+ * The trigger can be destroyed after this call.
+ *
+ * Return 0 on success, a negative LTTng error code on error.
+ */
 extern int lttng_register_trigger(struct lttng_trigger *trigger);
 
+/*
+ * Unregister a trigger from the session daemon.
+ *
+ * The trigger can be destroyed after this call.
+ *
+ * Return 0 on success, a negative LTTng error code on error.
+ */
 extern int lttng_unregister_trigger(struct lttng_trigger *trigger);
 
 #ifdef __cplusplus