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       1           1 : /*
       2             :  * Copyright (c) 2024 Mustafa Abdullah Kus, Sparse Technology
       3             :  * Copyright (c) 2024 Nordic Semiconductor
       4             :  *
       5             :  * SPDX-License-Identifier: Apache-2.0
       6             :  */
       7             : 
       8             : #ifndef ZEPHYR_INCLUDE_PROMETHEUS_SUMMARY_H_
       9             : #define ZEPHYR_INCLUDE_PROMETHEUS_SUMMARY_H_
      10             : 
      11             : /**
      12             :  * @file
      13             :  *
      14             :  * @brief Prometheus summary APIs.
      15             :  *
      16             :  * @addtogroup prometheus
      17             :  * @{
      18             :  */
      19             : 
      20             : #include <zephyr/sys/iterable_sections.h>
      21             : #include <zephyr/net/prometheus/metric.h>
      22             : 
      23             : #include <stddef.h>
      24             : 
      25             : /**
      26             :  * @brief Prometheus summary quantile definition.
      27             :  *
      28             :  * This structure defines a Prometheus summary quantile.
      29             :  */
      30           1 : struct prometheus_summary_quantile {
      31             :         /** Quantile of the summary */
      32           1 :         double quantile;
      33             :         /** Value of the quantile */
      34           1 :         double value;
      35             :         /** User data */
      36           1 :         void *user_data;
      37             : };
      38             : 
      39             : /**
      40             :  * @brief Type used to represent a Prometheus summary metric.
      41             :  *
      42             :  * * References
      43             :  * * See https://prometheus.io/docs/concepts/metric_types/#summary
      44             :  */
      45           1 : struct prometheus_summary {
      46             :         /** Base of the Prometheus summary metric */
      47           1 :         struct prometheus_metric base;
      48             :         /** Array of quantiles associated with the Prometheus summary metric */
      49           1 :         struct prometheus_summary_quantile *quantiles;
      50             :         /** Number of quantiles associated with the Prometheus summary metric */
      51           1 :         size_t num_quantiles;
      52             :         /** Sum of all observed values in the summary metric */
      53           1 :         double sum;
      54             :         /** Total count of observations in the summary metric */
      55           1 :         unsigned long count;
      56             :         /** User data */
      57           1 :         void *user_data;
      58             : };
      59             : 
      60             : /**
      61             :  * @brief Prometheus Summary definition.
      62             :  *
      63             :  * This macro defines a Summary metric. If you want to make the summary static,
      64             :  * then add "static" keyword before the PROMETHEUS_SUMMARY_DEFINE.
      65             :  *
      66             :  * @param _name The summary metric name.
      67             :  * @param _desc Summary description
      68             :  * @param _label Label for the metric. Additional labels can be added at runtime.
      69             :  * @param _collector Collector to map this metric. Can be set to NULL if it not yet known.
      70             :  * @param ... Optional user data specific to this metric instance.
      71             :  *
      72             :  *
      73             :  * Example usage:
      74             :  * @code{.c}
      75             :  *
      76             :  * PROMETHEUS_SUMMARY_DEFINE(http_request_summary, "HTTP request summary",
      77             :  *                           ({ .key = "request_latency",
      78             :  *                              .value = "request_latency_seconds" }), NULL);
      79             :  *
      80             :  * @endcode
      81             :  */
      82             : 
      83           1 : #define PROMETHEUS_SUMMARY_DEFINE(_name, _desc, _label, _collector, ...) \
      84             :         STRUCT_SECTION_ITERABLE(prometheus_summary, _name) = {          \
      85             :                 .base.name = STRINGIFY(_name),                          \
      86             :                 .base.type = PROMETHEUS_SUMMARY,                        \
      87             :                 .base.description = _desc,                              \
      88             :                 .base.labels[0] = __DEBRACKET _label,                   \
      89             :                 .base.num_labels = 1,                                   \
      90             :                 .base.collector = _collector,                           \
      91             :                 .quantiles = NULL,                                      \
      92             :                 .num_quantiles = 0,                                     \
      93             :                 .sum = 0.0,                                             \
      94             :                 .count = 0U,                                            \
      95             :                 .user_data = COND_CODE_0(                               \
      96             :                         NUM_VA_ARGS_LESS_1(LIST_DROP_EMPTY(__VA_ARGS__, _)), \
      97             :                         (NULL),                                         \
      98             :                         (GET_ARG_N(1, __VA_ARGS__))),                   \
      99             :         }
     100             : 
     101             : /**
     102             :  * @brief Observes a value in a Prometheus summary metric
     103             :  *
     104             :  * Observes the specified value in the given summary metric.
     105             :  *
     106             :  * @param summary Pointer to the summary metric to observe.
     107             :  * @param value Value to observe in the summary metric.
     108             :  * @return 0 on success, -EINVAL if the value is negative.
     109             :  */
     110           1 : int prometheus_summary_observe(struct prometheus_summary *summary, double value);
     111             : 
     112             : /**
     113             :  * @brief Set the summary value to specific value.
     114             :  * The new value must be higher than the current value. This function can be used
     115             :  * if we cannot add individual increments to the summary but need to periodically
     116             :  * update the counter value. This function will add the difference between the
     117             :  * new value and the old value to the summary fields.
     118             :  * @param summary Pointer to the summary metric to increment.
     119             :  * @param value New value of the summary.
     120             :  * @param count New counter value of the summary.
     121             :  * @return 0 on success, negative errno on error.
     122             :  */
     123           1 : int prometheus_summary_observe_set(struct prometheus_summary *summary,
     124             :                                    double value, unsigned long count);
     125             : 
     126             : /**
     127             :  * @}
     128             :  */
     129             : 
     130             : #endif /* ZEPHYR_INCLUDE_PROMETHEUS_SUMMARY_H_ */