Line data    Source code

       1           1 : /*
       2             :  * Copyright (c) 2024 Mustafa Abdullah Kus, Sparse Technology
       3             :  *
       4             :  * SPDX-License-Identifier: Apache-2.0
       5             :  */
       6             : 
       7             : #ifndef ZEPHYR_INCLUDE_PROMETHEUS_HISTOGRAM_H_
       8             : #define ZEPHYR_INCLUDE_PROMETHEUS_HISTOGRAM_H_
       9             : 
      10             : /**
      11             :  * @file
      12             :  *
      13             :  * @brief Prometheus histogram APIs.
      14             :  *
      15             :  * @addtogroup prometheus
      16             :  * @{
      17             :  */
      18             : 
      19             : #include <zephyr/sys/iterable_sections.h>
      20             : #include <zephyr/net/prometheus/metric.h>
      21             : 
      22             : #include <stddef.h>
      23             : 
      24             : /**
      25             :  * @brief Prometheus histogram bucket definition.
      26             :  *
      27             :  * This structure defines a Prometheus histogram bucket.
      28             :  */
      29           1 : struct prometheus_histogram_bucket {
      30             :         /** Upper bound value of bucket */
      31           1 :         double upper_bound;
      32             :         /** Cumulative count of observations in the bucket */
      33           1 :         unsigned long count;
      34             : };
      35             : 
      36             : /**
      37             :  * @brief Type used to represent a Prometheus histogram metric.
      38             :  *
      39             :  * * References
      40             :  * * See https://prometheus.io/docs/concepts/metric_types/#histogram
      41             :  */
      42           1 : struct prometheus_histogram {
      43             :         /** Base of the Prometheus histogram metric */
      44           1 :         struct prometheus_metric *base;
      45             :         /** Array of buckets in the histogram */
      46           1 :         struct prometheus_histogram_bucket *buckets;
      47             :         /** Number of buckets in the histogram */
      48           1 :         size_t num_buckets;
      49             :         /** Sum of all observed values in the histogram */
      50           1 :         double sum;
      51             :         /** Total count of observations in the histogram */
      52           1 :         unsigned long count;
      53             : };
      54             : 
      55             : /**
      56             :  * @brief Prometheus Histogram definition.
      57             :  *
      58             :  * This macro defines a Histogram metric.
      59             :  *
      60             :  * @param _name The channel's name.
      61             :  * @param _detail The metric base.
      62             :  *
      63             :  * Example usage:
      64             :  * @code{.c}
      65             :  *
      66             :  * struct prometheus_metric http_request_gauge = {
      67             :  *      .type = PROMETHEUS_HISTOGRAM,
      68             :  *      .name = "http_request_histograms",
      69             :  *      .description = "HTTP request histogram",
      70             :  *      .num_labels = 1,
      71             :  *      .labels = {
      72             :  *              { .key = "request_latency", .value = "request_latency_seconds",}
      73             :  *      },
      74             :  * };
      75             :  *
      76             :  * PROMETHEUS_HISTOGRAM_DEFINE(test_histogram, &test_histogram_metric);
      77             :  *
      78             :  * @endcode
      79             :  */
      80           1 : #define PROMETHEUS_HISTOGRAM_DEFINE(_name, _detail)                                                \
      81             :         static STRUCT_SECTION_ITERABLE(prometheus_histogram, _name) = {.base = (void *)(_detail),  \
      82             :                                                                        .buckets = NULL,            \
      83             :                                                                        .num_buckets = 0,           \
      84             :                                                                        .sum = 0,                   \
      85             :                                                                        .count = 0}
      86             : 
      87             : /**
      88             :  * @brief Observe a value in a Prometheus histogram metric
      89             :  *
      90             :  * Observes the specified value in the given histogram metric.
      91             :  *
      92             :  * @param histogram Pointer to the histogram metric to observe.
      93             :  * @param value Value to observe in the histogram metric.
      94             :  * @return 0 on success, -EINVAL if the value is negative.
      95             :  */
      96           1 : int prometheus_histogram_observe(struct prometheus_histogram *histogram, double value);
      97             : 
      98             : /**
      99             :  * @}
     100             :  */
     101             : 
     102             : #endif /* ZEPHYR_INCLUDE_PROMETHEUS_HISTOGRAM_H_ */