Docs: document trigger condition and action ownership in 2.13+

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

diff --git a/include/lttng/trigger/trigger.h b/include/lttng/trigger/trigger.h
index 96e018f248d536eecc6c08e3c0d06f2f5a212dbc..3b1cedda1fb4709457537ded9df978e206d6d3ca 100644 (file)
--- a/include/lttng/trigger/trigger.h
+++ b/include/lttng/trigger/trigger.h
@@ -9,10 +9,13 @@
 #define LTTNG_TRIGGER_H
 
 #include <sys/types.h>
+#include <inttypes.h>
 
 struct lttng_action;
 struct lttng_condition;
 struct lttng_trigger;
+/* A set of triggers. */
+struct lttng_triggers;
 
 #ifdef __cplusplus
 extern "C" {
@@ -33,6 +36,11 @@ enum lttng_trigger_status {
        LTTNG_TRIGGER_STATUS_PERMISSION_DENIED = -6,
 };
 
+enum lttng_trigger_firing_policy {
+       LTTNG_TRIGGER_FIRING_POLICY_EVERY_N = 0,
+       LTTNG_TRIGGER_FIRING_POLICY_ONCE_AFTER_N = 1,
+};
+
 /*
  * Create a trigger object associating a condition and an action.
  *
@@ -41,8 +49,14 @@ enum lttng_trigger_status {
  * 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.
+ * Prior to 2.13, the caller had to retain the ownership of both the condition
+ * and action. Both objects had to be kept alive for the lifetime of the trigger
+ * object. This is no longer the case as the condition and action objects are
+ * internally reference counted. It is safe to destroy a condition and an action
+ * after using them to create a trigger. However, they should no longer be used.
+ *
+ * If the action is a notification action with capture descriptors,
+ * the condition must be an event rule condition.
  *
  * A trigger must be registered in order to become activate and can
  * be destroyed after its registration.
@@ -86,6 +100,9 @@ extern enum lttng_trigger_status lttng_trigger_get_owner_uid(
 extern struct lttng_condition *lttng_trigger_get_condition(
                struct lttng_trigger *trigger);
 
+const struct lttng_condition *lttng_trigger_get_const_condition(
+               const struct lttng_trigger *trigger);
+
 /*
  * Get the action of a trigger.
  *
@@ -96,6 +113,8 @@ extern struct lttng_condition *lttng_trigger_get_condition(
 extern struct lttng_action *lttng_trigger_get_action(
                struct lttng_trigger *trigger);
 
+const struct lttng_action *lttng_trigger_get_const_action(
+               const struct lttng_trigger *trigger);
 
 /*
  * Get the name of a trigger.
@@ -125,6 +144,37 @@ extern enum lttng_trigger_status lttng_trigger_get_name(
 extern enum lttng_trigger_status lttng_trigger_set_name(
                struct lttng_trigger *trigger, const char *name);
 
+/*
+ * Set the trigger firing policy.
+ *
+ * This is optional. By default a trigger is set to fire each time the
+ * associated condition occurs.
+ *
+ * Threshold is the number of times the condition must be hit before the policy
+ * is enacted.
+ *
+ * Return LTTNG_TRIGGER_STATUS_OK on success, LTTNG_TRIGGER_STATUS_INVALID
+ * if invalid parameters are passed.
+ */
+extern enum lttng_trigger_status lttng_trigger_set_firing_policy(
+               struct lttng_trigger *trigger,
+               enum lttng_trigger_firing_policy policy_type,
+               uint64_t threshold);
+
+/*
+ * Get the trigger firing policy.
+ *
+ * Threshold is the number of time the condition must be hit before the policy is
+ * enacted.
+ *
+ * Return LTTNG_TRIGGER_STATUS_OK on success, LTTNG_TRIGGER_STATUS_INVALID
+ * if invalid parameters are passed.
+ */
+extern enum lttng_trigger_status lttng_trigger_get_firing_policy(
+               const struct lttng_trigger *trigger,
+               enum lttng_trigger_firing_policy *policy_type,
+               uint64_t *threshold);
+
 /*
  * Destroy (frees) a trigger object.
  */
@@ -146,7 +196,47 @@ extern int lttng_register_trigger(struct lttng_trigger *trigger);
  *
  * Return 0 on success, a negative LTTng error code on error.
  */
-extern int lttng_unregister_trigger(struct lttng_trigger *trigger);
+extern int lttng_unregister_trigger(const struct lttng_trigger *trigger);
+
+/*
+ * List triggers for the current user.
+ *
+ * On success, a newly-allocated trigger set is returned.
+ *
+ * The trigger set must be destroyed by the caller (see
+ * lttng_triggers_destroy()).
+ *
+ * Returns LTTNG_OK on success, else a suitable LTTng error code.
+ */
+extern enum lttng_error_code lttng_list_triggers(
+               struct lttng_triggers **triggers);
+
+/*
+ * Get a trigger from the set at a given index.
+ *
+ * Note that the trigger set maintains the ownership of the returned trigger.
+ * It must not be destroyed by the user, nor should a reference to it be held
+ * beyond the lifetime of the trigger set.
+ *
+ * Returns a trigger, or NULL on error.
+ */
+extern const struct lttng_trigger *lttng_triggers_get_at_index(
+               const struct lttng_triggers *triggers, unsigned int index);
+
+/*
+ * Get the number of triggers in a trigger set.
+ *
+ * Return LTTNG_TRIGGER_STATUS_OK on success,
+ * LTTNG_TRIGGER_STATUS_INVALID when invalid parameters are passed.
+ */
+extern enum lttng_trigger_status lttng_triggers_get_count(
+               const struct lttng_triggers *triggers, unsigned int *count);
+
+/*
+ * Destroy a trigger set.
+ */
+extern void lttng_triggers_destroy(struct lttng_triggers *triggers);
+
 
 #ifdef __cplusplus
 }