diff options
Diffstat (limited to 'web/api/queries/des/des.h')
-rw-r--r-- | web/api/queries/des/des.h | 133 |
1 files changed, 127 insertions, 6 deletions
diff --git a/web/api/queries/des/des.h b/web/api/queries/des/des.h index 05fa01b349..3153d497cb 100644 --- a/web/api/queries/des/des.h +++ b/web/api/queries/des/des.h @@ -6,12 +6,133 @@ #include "../query.h" #include "../rrdr.h" -void grouping_init_des(void); +struct tg_des { + NETDATA_DOUBLE alpha; + NETDATA_DOUBLE alpha_other; + NETDATA_DOUBLE beta; + NETDATA_DOUBLE beta_other; -void grouping_create_des(RRDR *r, const char *options __maybe_unused); -void grouping_reset_des(RRDR *r); -void grouping_free_des(RRDR *r); -void grouping_add_des(RRDR *r, NETDATA_DOUBLE value); -NETDATA_DOUBLE grouping_flush_des(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr); + NETDATA_DOUBLE level; + NETDATA_DOUBLE trend; + + size_t count; +}; + +static size_t tg_des_max_window_size = 15; + +static inline void tg_des_init(void) { + long long ret = config_get_number(CONFIG_SECTION_WEB, "des max tg_des_window", (long long)tg_des_max_window_size); + if(ret <= 1) { + config_set_number(CONFIG_SECTION_WEB, "des max tg_des_window", (long long)tg_des_max_window_size); + } + else { + tg_des_max_window_size = (size_t) ret; + } +} + +static inline NETDATA_DOUBLE tg_des_window(RRDR *r, struct tg_des *g) { + (void)g; + + NETDATA_DOUBLE points; + if(r->view.group == 1) { + // provide a running DES + points = (NETDATA_DOUBLE)r->time_grouping.points_wanted; + } + else { + // provide a SES with flush points + points = (NETDATA_DOUBLE)r->view.group; + } + + // https://en.wikipedia.org/wiki/Moving_average#Exponential_moving_average + // A commonly used value for alpha is 2 / (N + 1) + return (points > (NETDATA_DOUBLE)tg_des_max_window_size) ? (NETDATA_DOUBLE)tg_des_max_window_size : points; +} + +static inline void tg_des_set_alpha(RRDR *r, struct tg_des *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 / (tg_des_window(r, g) + 1.0); + g->alpha_other = 1.0 - g->alpha; + + //info("alpha for chart '%s' is " CALCULATED_NUMBER_FORMAT, r->st->name, g->alpha); +} + +static inline void tg_des_set_beta(RRDR *r, struct tg_des *g) { + // https://en.wikipedia.org/wiki/Moving_average#Exponential_moving_average + // A commonly used value for alpha is 2 / (N + 1) + + g->beta = 2.0 / (tg_des_window(r, g) + 1.0); + g->beta_other = 1.0 - g->beta; + + //info("beta for chart '%s' is " CALCULATED_NUMBER_FORMAT, r->st->name, g->beta); +} + +static inline void tg_des_create(RRDR *r, const char *options __maybe_unused) { + struct tg_des *g = (struct tg_des *)onewayalloc_mallocz(r->internal.owa, sizeof(struct tg_des)); + tg_des_set_alpha(r, g); + tg_des_set_beta(r, g); + g->level = 0.0; + g->trend = 0.0; + g->count = 0; + r->time_grouping.data = g; +} + +// resets when switches dimensions +// so, clear everything to restart +static inline void tg_des_reset(RRDR *r) { + struct tg_des *g = (struct tg_des *)r->time_grouping.data; + g->level = 0.0; + g->trend = 0.0; + g->count = 0; + + // fprintf(stderr, "\nDES: "); + +} + +static inline void tg_des_free(RRDR *r) { + onewayalloc_freez(r->internal.owa, r->time_grouping.data); + r->time_grouping.data = NULL; +} + +static inline void tg_des_add(RRDR *r, NETDATA_DOUBLE value) { + struct tg_des *g = (struct tg_des *)r->time_grouping.data; + + if(likely(g->count > 0)) { + // we have at least a number so far + + if(unlikely(g->count == 1)) { + // the second value we got + g->trend = value - g->trend; + g->level = value; + } + + // for the values, except the first + NETDATA_DOUBLE last_level = g->level; + g->level = (g->alpha * value) + (g->alpha_other * (g->level + g->trend)); + g->trend = (g->beta * (g->level - last_level)) + (g->beta_other * g->trend); + } + else { + // the first value we got + g->level = g->trend = value; + } + + g->count++; + + //fprintf(stderr, "value: " CALCULATED_NUMBER_FORMAT ", level: " CALCULATED_NUMBER_FORMAT ", trend: " CALCULATED_NUMBER_FORMAT "\n", value, g->level, g->trend); +} + +static inline NETDATA_DOUBLE tg_des_flush(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr) { + struct tg_des *g = (struct tg_des *)r->time_grouping.data; + + if(unlikely(!g->count || !netdata_double_isnumber(g->level))) { + *rrdr_value_options_ptr |= RRDR_VALUE_EMPTY; + return 0.0; + } + + //fprintf(stderr, " RESULT for %zu values = " CALCULATED_NUMBER_FORMAT " \n", g->count, g->level); + + return g->level; +} #endif //NETDATA_API_QUERIES_DES_H |