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 enum lttng_evaluation_on_event_status {
  23         LTTNG_EVALUATION_ON_EVENT_STATUS_NONE = 1,
  24         LTTNG_EVALUATION_ON_EVENT_STATUS_OK = 0,
  25         LTTNG_EVALUATION_ON_EVENT_STATUS_INVALID = -1,
  26 };
  27
  28 /**
  29  * On event conditions allows an action to be taken whenever an event matching
  30  * the on event is hit by the tracers.
  31  *
  32  * An on event condition can also specify a payload to be captured at runtime.
  33  * This is done via the capture descriptor.
  34  *
  35  * Note: the dynamic runtime capture of payload is only available for the
  36  *       trigger notification subsystem.
  37  */
  38
  39 /*
  40  * Create a newly allocated on event condition.
  41  *
  42  * Returns a new condition on success, NULL on failure. This condition must be
  43  * destroyed using lttng_condition_destroy().
  44  */
  45 extern struct lttng_condition *lttng_condition_on_event_create(
  46                 struct lttng_event_rule *rule);
  47
  48 /*
  49  * Get the rule property of a on event condition.
  50  *
  51  * The caller does not assume the ownership of the returned rule. The
  52  * rule shall only be used for the duration of the condition's
  53  * lifetime.
  54  *
  55  * Returns LTTNG_CONDITION_STATUS_OK and a pointer to the condition's rule
  56  * on success, LTTNG_CONDITION_STATUS_INVALID if an invalid
  57  * parameter is passed. */
  58 extern enum lttng_condition_status lttng_condition_on_event_get_rule(
  59                 const struct lttng_condition *condition,
  60                 const struct lttng_event_rule **rule);
  61
  62 /**
  63  * lttng_evaluation_on_event_hit are specialised lttng_evaluations which
  64  * allow users to query a number of properties resulting from the evaluation
  65  * of a condition which evaluated to true.
  66  *
  67  * The evaluation of an on event condition contains the captured event
  68  * payload fields that were specified by the condition.
  69  */
  70
  71 /*
  72  * Sets `*field_val` to the array event field value of the on event
  73  * condition evaluation `evaluation` which contains its captured values.
  74  *
  75  * Returns:
  76  *
  77  * `LTTNG_EVALUATION_ON_EVENT_STATUS_OK`:
  78  *     Success.
  79  *
  80  *     `*field_val` is an array event field value with a length of at
  81  *     least one.
  82  *
  83  * `LTTNG_EVALUATION_ON_EVENT_STATUS_INVALID`:
  84  *     * `evaluation` is `NULL`.
  85  *     * The type of the condition of `evaluation` is not
  86  *       `LTTNG_CONDITION_TYPE_ON_EVENT`.
  87  *     * `field_val` is `NULL`.
  88  *
  89  * `LTTNG_EVALUATION_ON_EVENT_STATUS_NONE`:
  90  *     * The condition of `evaluation` has no capture descriptors.
  91  */
  92 extern enum lttng_evaluation_on_event_status
  93 lttng_evaluation_on_event_get_captured_values(
  94                 const struct lttng_evaluation *evaluation,
  95                 const struct lttng_event_field_value **field_val);
  96
  97 /*
  98  * Appends (transfering the ownership) the capture descriptor `expr` to
  99  * the on event condition `condition`.
 100  *
 101  * Returns:
 102  *
 103  * `LTTNG_CONDITION_STATUS_OK`:
 104  *     Success.
 105  *
 106  * `LTTNG_CONDITION_STATUS_ERROR`:
 107  *     Memory error.
 108  *
 109  * `LTTNG_CONDITION_STATUS_INVALID`:
 110  *     * `condition` is `NULL`.
 111  *     * The type of `condition` is not
 112  *       `LTTNG_CONDITION_TYPE_ON_EVENT`.
 113  *     * `expr` is `NULL`.
 114  *     * `expr` is not a locator expression, that is, its type is not
 115  *       one of:
 116  *
 117  *       * `LTTNG_EVENT_EXPR_TYPE_EVENT_PAYLOAD_FIELD`
 118  *       * `LTTNG_EVENT_EXPR_TYPE_CHANNEL_CONTEXT_FIELD`
 119  *       * `LTTNG_EVENT_EXPR_TYPE_APP_SPECIFIC_CONTEXT_FIELD`
 120  *       * `LTTNG_EVENT_EXPR_TYPE_ARRAY_FIELD_ELEMENT`
 121  *
 122  * `LTTNG_CONDITION_STATUS_UNSUPPORTED`:
 123  *     * The associated event-rule does not support runtime capture.
 124  */
 125 extern enum lttng_condition_status
 126 lttng_condition_on_event_append_capture_descriptor(
 127                 struct lttng_condition *condition,
 128                 struct lttng_event_expr *expr);
 129
 130 /*
 131  * Sets `*count` to the number of capture descriptors in the on event
 132  * condition `condition`.
 133  *
 134  * Returns:
 135  *
 136  * `LTTNG_CONDITION_STATUS_OK`:
 137  *     Success.
 138  *
 139  * `LTTNG_CONDITION_STATUS_INVALID`:
 140  *     * `condition` is `NULL`.
 141  *     * The type of `condition` is not
 142  *       `LTTNG_CONDITION_TYPE_ON_EVENT`.
 143  *     * `count` is `NULL`.
 144  */
 145 extern enum lttng_condition_status
 146 lttng_condition_on_event_get_capture_descriptor_count(
 147                 const struct lttng_condition *condition, unsigned int *count);
 148
 149 /*
 150  * Returns the capture descriptor (borrowed) of the on event condition
 151  * `condition` at the index `index`, or `NULL` if:
 152  *
 153  * * `condition` is `NULL`.
 154  * * The type of `condition` is not
 155  *   `LTTNG_CONDITION_TYPE_ON_EVENT`.
 156  * * `index` is greater than or equal to the number of capture
 157  *   descriptors in `condition` (as returned by
 158  *   lttng_condition_on_event_get_capture_descriptor_count()).
 159  */
 160 extern const struct lttng_event_expr *
 161 lttng_condition_on_event_get_capture_descriptor_at_index(
 162                 const struct lttng_condition *condition, unsigned int index);
 163
 164 #ifdef __cplusplus
 165 }
 166 #endif
 167
 168 #endif /* LTTNG_CONDITION_ON_EVENT_H */