diff options
Diffstat (limited to 'web/api/queries/ses/ses.c')
-rw-r--r-- | web/api/queries/ses/ses.c | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/web/api/queries/ses/ses.c b/web/api/queries/ses/ses.c new file mode 100644 index 0000000..5e94002 --- /dev/null +++ b/web/api/queries/ses/ses.c @@ -0,0 +1,90 @@ +// SPDX-License-Identifier: GPL-3.0-or-later + +#include "ses.h" + + +// ---------------------------------------------------------------------------- +// single exponential smoothing + +struct grouping_ses { + NETDATA_DOUBLE alpha; + NETDATA_DOUBLE alpha_other; + NETDATA_DOUBLE level; + size_t count; +}; + +static size_t max_window_size = 15; + +void grouping_init_ses(void) { + long long ret = config_get_number(CONFIG_SECTION_WEB, "ses max window", (long long)max_window_size); + if(ret <= 1) { + config_set_number(CONFIG_SECTION_WEB, "ses max window", (long long)max_window_size); + } + else { + max_window_size = (size_t) ret; + } +} + +static inline NETDATA_DOUBLE window(RRDR *r, struct grouping_ses *g) { + (void)g; + + NETDATA_DOUBLE points; + if(r->group == 1) { + // provide a running DES + points = (NETDATA_DOUBLE)r->internal.points_wanted; + } + else { + // provide a SES with flush points + points = (NETDATA_DOUBLE)r->group; + } + + return (points > (NETDATA_DOUBLE)max_window_size) ? (NETDATA_DOUBLE)max_window_size : points; +} + +static inline void set_alpha(RRDR *r, struct grouping_ses *g) { + // https://en.wikipedia.org/wiki/Moving_average#Exponential_moving_average + // A commonly used value for alpha is 2 / (N + 1) + g->alpha = 2.0 / (window(r, g) + 1.0); + g->alpha_other = 1.0 - g->alpha; +} + +void grouping_create_ses(RRDR *r, const char *options __maybe_unused) { + struct grouping_ses *g = (struct grouping_ses *)onewayalloc_callocz(r->internal.owa, 1, sizeof(struct grouping_ses)); + set_alpha(r, g); + g->level = 0.0; + r->internal.grouping_data = g; +} + +// resets when switches dimensions +// so, clear everything to restart +void grouping_reset_ses(RRDR *r) { + struct grouping_ses *g = (struct grouping_ses *)r->internal.grouping_data; + g->level = 0.0; + g->count = 0; +} + +void grouping_free_ses(RRDR *r) { + onewayalloc_freez(r->internal.owa, r->internal.grouping_data); + r->internal.grouping_data = NULL; +} + +void grouping_add_ses(RRDR *r, NETDATA_DOUBLE value) { + struct grouping_ses *g = (struct grouping_ses *)r->internal.grouping_data; + + if(unlikely(!g->count)) + g->level = value; + + g->level = g->alpha * value + g->alpha_other * g->level; + g->count++; +} + +NETDATA_DOUBLE grouping_flush_ses(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr) { + struct grouping_ses *g = (struct grouping_ses *)r->internal.grouping_data; + + if(unlikely(!g->count || !netdata_double_isnumber(g->level))) { + *rrdr_value_options_ptr |= RRDR_VALUE_EMPTY; + return 0.0; + } + + return g->level; +} |