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_COUNTER_H_
9 #define ZEPHYR_INCLUDE_PROMETHEUS_COUNTER_H_
10
11 /**
12 * @file
13 *
14 * @brief Prometheus counter APIs.
15 *
16 * @addtogroup prometheus
17 * @{
18 */
19
20 #include <stdint.h>
21
22 #include <zephyr/sys/iterable_sections.h>
23 #include <zephyr/net/prometheus/metric.h>
24
25 /**
26 * @brief Type used to represent a Prometheus counter metric.
27 *
28 * * References
29 * * See https://prometheus.io/docs/concepts/metric_types/#counter
30 */
31 struct prometheus_counter {
32 /** Base of the Prometheus counter metric */
33 struct prometheus_metric base;
34 /** Value of the Prometheus counter metric */
35 uint64_t value;
36 /** User data */
37 void *user_data;
38 };
39
40 /**
41 * @brief Prometheus Counter definition.
42 *
43 * This macro defines a Counter metric. If you want to make the counter static,
44 * then add "static" keyword before the PROMETHEUS_COUNTER_DEFINE.
45 *
46 * @param _name The counter metric name
47 * @param _desc Counter description
48 * @param _label Label for the metric. Additional labels can be added at runtime.
49 * @param _collector Collector to map this metric. Can be set to NULL if it not yet known.
50 * @param ... Optional user data specific to this metric instance.
51 *
52 * Example usage:
53 * @code{.c}
54 *
55 * PROMETHEUS_COUNTER_DEFINE(http_request_counter, "HTTP request counter",
56 * ({ .key = "http_request", .value = "request_count" }),
57 * NULL);
58 * @endcode
59 */
60 #define PROMETHEUS_COUNTER_DEFINE(_name, _desc, _label, _collector, ...) \
61 STRUCT_SECTION_ITERABLE(prometheus_counter, _name) = { \
62 .base.name = STRINGIFY(_name), \
63 .base.type = PROMETHEUS_COUNTER, \
64 .base.description = _desc, \
65 .base.labels[0] = __DEBRACKET _label, \
66 .base.num_labels = 1, \
67 .base.collector = _collector, \
68 .value = 0ULL, \
69 .user_data = COND_CODE_0( \
70 NUM_VA_ARGS_LESS_1(LIST_DROP_EMPTY(__VA_ARGS__, _)), \
71 (NULL), \
72 (GET_ARG_N(1, __VA_ARGS__))), \
73 }
74
75 /**
76 * @brief Increment the value of a Prometheus counter metric
77 * Increments the value of the specified counter metric by arbitrary amount.
78 * @param counter Pointer to the counter metric to increment.
79 * @param value Amount to increment the counter by.
80 * @return 0 on success, negative errno on error.
81 */
82 int prometheus_counter_add(struct prometheus_counter *counter, uint64_t value);
83
84 /**
85 * @brief Increment the value of a Prometheus counter metric
86 * Increments the value of the specified counter metric by one.
87 * @param counter Pointer to the counter metric to increment.
88 * @return 0 on success, negative errno on error.
89 */
prometheus_counter_inc(struct prometheus_counter * counter)90 static inline int prometheus_counter_inc(struct prometheus_counter *counter)
91 {
92 return prometheus_counter_add(counter, 1ULL);
93 }
94
95 /**
96 * @brief Set the counter value to specific value.
97 * The new value must be higher than the current value. This function can be used
98 * if we cannot add individual increments to the counter but need to periodically
99 * update the counter value. This function will add the difference between the
100 * new value and the old value to the counter.
101 * @param counter Pointer to the counter metric to increment.
102 * @param value New value of the counter.
103 * @return 0 on success, negative errno on error.
104 */
105 int prometheus_counter_set(struct prometheus_counter *counter, uint64_t value);
106
107 /**
108 * @}
109 */
110
111 #endif /* ZEPHYR_INCLUDE_PROMETHEUS_COUNTER_H_ */
112
