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1 // SPDX-License-Identifier: GPL-3.0-or-later
2
3 #ifndef NETDATA_API_QUERIES_SES_H
4 #define NETDATA_API_QUERIES_SES_H
5
6 #include "../query.h"
7 #include "../rrdr.h"
8
9 struct tg_ses {
10 NETDATA_DOUBLE alpha;
11 NETDATA_DOUBLE alpha_other;
12 NETDATA_DOUBLE level;
13 size_t count;
14 };
15
16 static size_t tg_ses_max_window_size = 15;
17
18 static inline void tg_ses_init(void) {
19 long long ret = inicfg_get_number(&netdata_config, CONFIG_SECTION_WEB, "ses max tg_des_window", (long long)tg_ses_max_window_size);
20 if(ret <= 1) {
21 inicfg_set_number(&netdata_config, CONFIG_SECTION_WEB, "ses max tg_des_window", (long long)tg_ses_max_window_size);
22 }
23 else {
24 tg_ses_max_window_size = (size_t) ret;
25 }
26 }
27
28 static inline NETDATA_DOUBLE tg_ses_window(RRDR *r, struct tg_ses *g) {
29 (void)g;
30
31 NETDATA_DOUBLE points;
32 if(r->view.group == 1) {
33 // provide a running DES
34 points = (NETDATA_DOUBLE)r->time_grouping.points_wanted;
35 }
36 else {
37 // provide a SES with flush points
38 points = (NETDATA_DOUBLE)r->view.group;
39 }
40
41 return (points > (NETDATA_DOUBLE)tg_ses_max_window_size) ? (NETDATA_DOUBLE)tg_ses_max_window_size : points;
42 }
43
44 static inline void tg_ses_set_alpha(RRDR *r, struct tg_ses *g) {
45 // https://en.wikipedia.org/wiki/Moving_average#Exponential_moving_average
46 // A commonly used value for alpha is 2 / (N + 1)
47 g->alpha = 2.0 / (tg_ses_window(r, g) + 1.0);
48 g->alpha_other = 1.0 - g->alpha;
49 }
50
51 static inline void tg_ses_create(RRDR *r, const char *options __maybe_unused) {
52 struct tg_ses *g = (struct tg_ses *)onewayalloc_callocz(r->internal.owa, 1, sizeof(struct tg_ses));
53 tg_ses_set_alpha(r, g);
54 g->level = 0.0;
55 r->time_grouping.data = g;
56 }
57
58 // resets when switches dimensions
59 // so, clear everything to restart
60 static inline void tg_ses_reset(RRDR *r) {
61 struct tg_ses *g = (struct tg_ses *)r->time_grouping.data;
62 g->level = 0.0;
63 g->count = 0;
64 }
65
66 static inline void tg_ses_free(RRDR *r) {
67 onewayalloc_freez(r->internal.owa, r->time_grouping.data);
68 r->time_grouping.data = NULL;
69 }
70
71 static inline void tg_ses_add(RRDR *r, NETDATA_DOUBLE value) {
72 struct tg_ses *g = (struct tg_ses *)r->time_grouping.data;
73
74 if(unlikely(!g->count))
75 g->level = value;
76
77 g->level = g->alpha * value + g->alpha_other * g->level;
78 g->count++;
79 }
80
81 static inline NETDATA_DOUBLE tg_ses_flush(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr) {
82 struct tg_ses *g = (struct tg_ses *)r->time_grouping.data;
83
84 if(unlikely(!g->count || !netdata_double_isnumber(g->level))) {
85 *rrdr_value_options_ptr |= RRDR_VALUE_EMPTY;
86 return 0.0;
87 }
88
89 return g->level;
90 }
91
92 #endif //NETDATA_API_QUERIES_SES_H