[Fix] Fix stddev calculations

diff --git a/src/libserver/symbols_cache.c b/src/libserver/symbols_cache.c
index 2ffa8e37635d36c1b65473fd84a43e78087c8079..f965798f54eb87221e6dfe8fcf6c5db67af16065 100644 (file)
--- a/src/libserver/symbols_cache.c
+++ b/src/libserver/symbols_cache.c
@@ -328,6 +328,7 @@ cache_logic_cmp (const void *p1, const void *p2, gpointer ud)
 static double
 rspamd_set_counter (struct counter_data *cd, gdouble value)
 {
+       gdouble cerr;
 
        /* Cumulative moving average using per-process counter data */
        if (cd->number == 0) {
@@ -336,7 +337,8 @@ rspamd_set_counter (struct counter_data *cd, gdouble value)
        }
 
        cd->mean += (value - cd->mean) / (gdouble)(++cd->number);
-       cd->stddev += (value - cd->mean) * (value - cd->mean);
+       cerr = (value - cd->mean) * (value - cd->mean);
+       cd->stddev += (cerr - cd->stddev) / (gdouble)(cd->number);
 
        return cd->mean;
 }
@@ -1876,7 +1878,7 @@ rspamd_symbols_cache_call_peak_cb (struct event_base *ev_base,
        rspamd_lua_setclass (L, "rspamd{ev_base}", -1);
        lua_pushstring (L, item->symbol);
        lua_pushnumber (L, item->st->avg_frequency);
-       lua_pushnumber (L, item->st->stddev_frequency);
+       lua_pushnumber (L, sqrt (item->st->stddev_frequency));
        lua_pushnumber (L, cur_value);
        lua_pushnumber (L, cur_err);
 
@@ -1941,7 +1943,7 @@ rspamd_symbols_cache_resort_cb (gint fd, short what, gpointer ud)
                                 * TODO: replace magic number
                                 */
                                if (item->st->frequency_counter.number > 10 &&
-                                               cur_err > item->st->stddev_frequency * 2) {
+                                               cur_err > sqrt (item->st->stddev_frequency) * 3) {
                                        item->frequency_peaks ++;
                                        msg_debug_cache ("peak found for %s is %.2f, avg: %.2f, "
                                                        "stddev: %.2f, error: %.2f, peaks: %d",
@@ -2102,7 +2104,7 @@ rspamd_symbols_cache_stat_symbol (struct symbols_cache *cache,
 
        if (item != NULL) {
                *frequency = item->st->avg_frequency;
-               *freq_stddev = item->st->stddev_frequency;
+               *freq_stddev = sqrt (item->st->stddev_frequency);
                *tm = item->st->time_counter.mean;
 
                return TRUE;