include/lttng/condition/on-event.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_ON_EVENT_H
   9 #define LTTNG_CONDITION_ON_EVENT_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  * On event conditions allows an action to be taken whenever an event matching
  24  * the on event is hit by the tracers.
  25  *
  26  * An on event condition can also specify a 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 on event 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_on_event_create(
  40                 struct lttng_event_rule *rule);
  41
  42 /*
  43  * Get the rule property of a on event 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_on_event_get_rule(
  53                 const struct lttng_condition *condition,
  54                 const struct lttng_event_rule **rule);
  55
  56 /**
  57  * lttng_evaluation_on_event_hit are specialised lttng_evaluations which
  58  * allow users to query a number of properties resulting from the evaluation
  59  * of a condition which evaluated to true.
  60  *
  61  * The evaluation of a on event hit yields two different results:
  62  *    TEMPORARY - The name of the triggers associated with the condition.
  63  *    TODO - The captured event payload if any
  64  */
  65
  66 /*
  67  * Get the trigger name property of a on event hit evaluation.
  68  *
  69  * Returns LTTNG_EVALUATION_STATUS_OK on success and a trigger name
  70  * or LTTNG_EVALUATION_STATUS_INVALID if
  71  * an invalid parameter is passed.
  72  */
  73 extern enum lttng_evaluation_status
  74 lttng_evaluation_on_event_get_trigger_name(
  75                 const struct lttng_evaluation *evaluation,
  76                 const char **name);
  77
  78 /*
  79  * Sets `*field_val` to the array event field value of the on event
  80  * condition evaluation `evaluation` which contains its captured values.
  81  *
  82  * Returns:
  83  *
  84  * `LTTNG_EVALUATION_STATUS_OK`:
  85  *     Success.
  86  *
  87  *     `*field_val` is an array event field value with a length of at
  88  *     least one.
  89  *
  90  * `LTTNG_EVALUATION_STATUS_INVALID`:
  91  *     * `evaluation` is `NULL`.
  92  *     * The type of the condition of `evaluation` is not
  93  *       `LTTNG_CONDITION_TYPE_ON_EVENT`.
  94  *     * The condition of `evaluation` has no capture descriptors.
  95  *     * `field_val` is `NULL`.
  96  */
  97 extern enum lttng_evaluation_status
  98 lttng_evaluation_on_event_get_captured_values(
  99                 const struct lttng_evaluation *evaluation,
 100                 const struct lttng_event_field_value **field_val);
 101
 102 /*
 103  * Appends (transfering the ownership) the capture descriptor `expr` to
 104  * the on event condition `condition`.
 105  *
 106  * Returns:
 107  *
 108  * `LTTNG_CONDITION_STATUS_OK`:
 109  *     Success.
 110  *
 111  * `LTTNG_CONDITION_STATUS_ERROR`:
 112  *     Memory error.
 113  *
 114  * `LTTNG_CONDITION_STATUS_INVALID`:
 115  *     * `condition` is `NULL`.
 116  *     * The type of `condition` is not
 117  *       `LTTNG_CONDITION_TYPE_ON_EVENT`.
 118  *     * `expr` is `NULL`.
 119  *     * `expr` is not a locator expression, that is, its type is not
 120  *       one of:
 121  *
 122  *       * `LTTNG_EVENT_EXPR_TYPE_EVENT_PAYLOAD_FIELD`
 123  *       * `LTTNG_EVENT_EXPR_TYPE_CHANNEL_CONTEXT_FIELD`
 124  *       * `LTTNG_EVENT_EXPR_TYPE_APP_SPECIFIC_CONTEXT_FIELD`
 125  *       * `LTTNG_EVENT_EXPR_TYPE_ARRAY_FIELD_ELEMENT`
 126  *
 127  * `LTTNG_CONDITION_STATUS_UNSUPPORTED`:
 128  *     * The associated event-rule does not support runtime capture.
 129  */
 130 extern enum lttng_condition_status
 131 lttng_condition_on_event_append_capture_descriptor(
 132                 struct lttng_condition *condition,
 133                 struct lttng_event_expr *expr);
 134
 135 /*
 136  * Sets `*count` to the number of capture descriptors in the on event
 137  * condition `condition`.
 138  *
 139  * Returns:
 140  *
 141  * `LTTNG_CONDITION_STATUS_OK`:
 142  *     Success.
 143  *
 144  * `LTTNG_CONDITION_STATUS_INVALID`:
 145  *     * `condition` is `NULL`.
 146  *     * The type of `condition` is not
 147  *       `LTTNG_CONDITION_TYPE_ON_EVENT`.
 148  *     * `count` is `NULL`.
 149  */
 150 extern enum lttng_condition_status
 151 lttng_condition_on_event_get_capture_descriptor_count(
 152                 const struct lttng_condition *condition, unsigned int *count);
 153
 154 /*
 155  * Returns the capture descriptor (borrowed) of the on event condition
 156  * `condition` at the index `index`, or `NULL` if:
 157  *
 158  * * `condition` is `NULL`.
 159  * * The type of `condition` is not
 160  *   `LTTNG_CONDITION_TYPE_ON_EVENT`.
 161  * * `index` is greater than or equal to the number of capture
 162  *   descriptors in `condition` (as returned by
 163  *   lttng_condition_on_event_get_capture_descriptor_count()).
 164  */
 165 extern const struct lttng_event_expr *
 166 lttng_condition_on_event_get_capture_descriptor_at_index(
 167                 const struct lttng_condition *condition, unsigned int index);
 168
 169 #ifdef __cplusplus
 170 }
 171 #endif
 172
 173 #endif /* LTTNG_CONDITION_ON_EVENT_H */