[Minor] Place moving average function is generic utilities

2 files changed, 67 insertions, 1 deletions

diff --git a/src/libutil/util.c b/src/libutil/util.c
index 93f449791..6554da63b 100644
--- a/src/libutil/util.c
+++ b/src/libutil/util.c
@@ -2973,4 +2973,44 @@ rspamd_glob_path (const gchar *dir,
 	}
 
 	return res;
-}
\ No newline at end of file
+}
+
+double
+rspamd_set_counter (struct rspamd_counter_data *cd, gdouble value)
+{
+	gdouble cerr;
+
+	/* Cumulative moving average using per-process counter data */
+	if (cd->number == 0) {
+		cd->mean = 0;
+		cd->stddev = 0;
+	}
+
+	cd->mean += (value - cd->mean) / (gdouble)(++cd->number);
+	cerr = (value - cd->mean) * (value - cd->mean);
+	cd->stddev += (cerr - cd->stddev) / (gdouble)(cd->number);
+
+	return cd->mean;
+}
+
+double
+rspamd_set_counter_ema (struct rspamd_counter_data *cd,
+		gdouble value,
+		gdouble alpha)
+{
+	gdouble diff, incr;
+
+	/* Cumulative moving average using per-process counter data */
+	if (cd->number == 0) {
+		cd->mean = 0;
+		cd->stddev = 0;
+	}
+
+	diff = value - cd->mean;
+	incr = diff * alpha;
+	cd->mean += incr;
+	cd->stddev = (1 - alpha) * (cd->stddev + diff * incr);
+	cd->number ++;
+
+	return cd->mean;
+}
diff --git a/src/libutil/util.h b/src/libutil/util.h
index 5968094a9..4338d5557 100644
--- a/src/libutil/util.h
+++ b/src/libutil/util.h
@@ -511,4 +511,30 @@ GPtrArray *rspamd_glob_path (const gchar *dir,
 							 gboolean recursive,
 							 GError **err);
 
+struct rspamd_counter_data {
+	gdouble mean;
+	gdouble stddev;
+	guint64 number;
+};
+
+/**
+ * Sets counter's data using exponential moving average
+ * @param cd counter
+ * @param value new counter value
+ * @param alpha decay coefficient (0..1)
+ * @return new counter value
+ */
+double rspamd_set_counter_ema (struct rspamd_counter_data *cd,
+							   gdouble value,
+							   gdouble alpha);
+
+/**
+ * Sets counter's data using flat moving average
+ * @param cd counter
+ * @param value new counter value
+ * @return new counter value
+ */
+double rspamd_set_counter (struct rspamd_counter_data *cd,
+						   gdouble value);
+
 #endif