include/lttng/condition/event-rule.h

   1 /*
   2  * Copyright (C) 2019 Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
   3  *
   4  * SPDX-License-Identifier: LGPL-2.1-only
   5  *
   6  */
   7
   8 #ifndef LTTNG_CONDITION_EVENT_RULE_H
   9 #define LTTNG_CONDITION_EVENT_RULE_H
  10
  11 #include <lttng/event-rule/event-rule.h>
  12 #include <lttng/condition/condition.h>
  13 #include <lttng/condition/evaluation.h>
  14
  15 #ifdef __cplusplus
  16 extern "C" {
  17 #endif
  18
  19 struct lttng_event_expr;
  20 struct lttng_event_field_value;
  21
  22 /**
  23  * Event rule conditions allows an action to be taken whenever an event matching
  24  * the event rule is hit by the tracers.
  25  *
  26  * An event rule condition can also specify payload to be captured at runtime.
  27  * This is done via the capture descriptor.
  28  *
  29  * Note: the dynamic runtime capture of payload is only available for the
  30  *       trigger notification subsystem.
  31  */
  32
  33 /*
  34  * Create a newly allocated event rule condition.
  35  *
  36  * Returns a new condition on success, NULL on failure. This condition must be
  37  * destroyed using lttng_condition_destroy().
  38  */
  39 extern struct lttng_condition *lttng_condition_event_rule_create(
  40                 struct lttng_event_rule *rule);
  41
  42 /*
  43  * Get the rule property of a event rule condition.
  44  *
  45  * The caller does not assume the ownership of the returned rule. The
  46  * rule shall only be used for the duration of the condition's
  47  * lifetime.
  48  *
  49  * Returns LTTNG_CONDITION_STATUS_OK and a pointer to the condition's rule
  50  * on success, LTTNG_CONDITION_STATUS_INVALID if an invalid
  51  * parameter is passed. */
  52 extern enum lttng_condition_status lttng_condition_event_rule_get_rule(
  53                 const struct lttng_condition *condition, const struct lttng_event_rule **rule);
  54
  55 /**
  56  * lttng_evaluation_event_rule_hit are specialised lttng_evaluations which
  57  * allow users to query a number of properties resulting from the evaluation
  58  * of a condition which evaluated to true.
  59  *
  60  * The evaluation of a event rule hit yields two different results:
  61  *    TEMPORARY - The name of the triggers associated with the condition.
  62  *    TODO - The captured event payload if any
  63  */
  64
  65 /*
  66  * Get the trigger name property of a event rule hit evaluation.
  67  *
  68  * Returns LTTNG_EVALUATION_STATUS_OK on success and a trigger name
  69  * or LTTNG_EVALUATION_STATUS_INVALID if
  70  * an invalid parameter is passed.
  71  */
  72 extern enum lttng_evaluation_status
  73 lttng_evaluation_event_rule_get_trigger_name(
  74                 const struct lttng_evaluation *evaluation,
  75                 const char **name);
  76
  77 /*
  78  * Sets `*field_val` to the array event field value of the event rule
  79  * condition evaluation `evaluation` which contains its captured values.
  80  *
  81  * Returns:
  82  *
  83  * `LTTNG_EVALUATION_STATUS_OK`:
  84  *     Success.
  85  *
  86  *     `*field_val` is an array event field value with a length of at
  87  *     least one.
  88  *
  89  * `LTTNG_EVALUATION_STATUS_INVALID`:
  90  *     * `evaluation` is `NULL`.
  91  *     * The type of the condition of `evaluation` is not
  92  *       `LTTNG_CONDITION_TYPE_EVENT_RULE_HIT`.
  93  *     * The condition of `evaluation` has no capture descriptors.
  94  *     * `field_val` is `NULL`.
  95  */
  96 extern enum lttng_evaluation_status
  97 lttng_evaluation_get_captured_values(
  98                 const struct lttng_evaluation *evaluation,
  99                 const struct lttng_event_field_value **field_val);
 100
 101 /*
 102  * Appends (transfering the ownership) the capture descriptor `expr` to
 103  * the event rule condition `condition`.
 104  *
 105  * Returns:
 106  *
 107  * `LTTNG_CONDITION_STATUS_OK`:
 108  *     Success.
 109  *
 110  * `LTTNG_CONDITION_STATUS_ERROR`:
 111  *     Memory error.
 112  *
 113  * `LTTNG_CONDITION_STATUS_INVALID`:
 114  *     * `condition` is `NULL`.
 115  *     * The type of `condition` is not
 116  *       `LTTNG_CONDITION_TYPE_EVENT_RULE_HIT`.
 117  *     * `expr` is `NULL`.
 118  *     * `expr` is not a locator expression, that is, its type is not
 119  *       one of:
 120  *
 121  *       * `LTTNG_EVENT_EXPR_TYPE_EVENT_PAYLOAD_FIELD`
 122  *       * `LTTNG_EVENT_EXPR_TYPE_CHANNEL_CONTEXT_FIELD`
 123  *       * `LTTNG_EVENT_EXPR_TYPE_APP_SPECIFIC_CONTEXT_FIELD`
 124  *       * `LTTNG_EVENT_EXPR_TYPE_ARRAY_FIELD_ELEMENT`
 125  * `LTTNG_CONDITION_STATUS_UNSUPPORTED`:
 126  *     * The associated event-rule does not support runtime capture.
 127  */
 128 extern enum lttng_condition_status
 129 lttng_condition_event_rule_append_capture_descriptor(
 130                 struct lttng_condition *condition,
 131                 struct lttng_event_expr *expr);
 132
 133 /*
 134  * Sets `*count` to the number of capture descriptors in the event rule
 135  * condition `condition`.
 136  *
 137  * Returns:
 138  *
 139  * `LTTNG_CONDITION_STATUS_OK`:
 140  *     Success.
 141  *
 142  * `LTTNG_CONDITION_STATUS_INVALID`:
 143  *     * `condition` is `NULL`.
 144  *     * The type of `condition` is not
 145  *       `LTTNG_CONDITION_TYPE_EVENT_RULE_HIT`.
 146  *     * `count` is `NULL`.
 147  */
 148 extern enum lttng_condition_status
 149 lttng_condition_event_rule_get_capture_descriptor_count(
 150                 const struct lttng_condition *condition, unsigned int *count);
 151
 152 /*
 153  * Returns the capture descriptor (borrowed) of the event rule condition
 154  * `condition` at the index `index`, or `NULL` if:
 155  *
 156  * * `condition` is `NULL`.
 157  * * The type of `condition` is not
 158  *   `LTTNG_CONDITION_TYPE_EVENT_RULE_HIT`.
 159  * * `index` is greater than or equal to the number of capture
 160  *   descriptors in `condition` (as returned by
 161  *   lttng_condition_event_rule_get_capture_descriptor_count()).
 162  */
 163 extern const struct lttng_event_expr *
 164 lttng_condition_event_rule_get_capture_descriptor_at_index(
 165                 const struct lttng_condition *condition, unsigned int index);
 166
 167 #ifdef __cplusplus
 168 }
 169 #endif
 170
 171 #endif /* LTTNG_CONDITION_EVENT_RULE_H */