From 2f08ce28937ba7755da12aa47a4a520ad39694a8 Mon Sep 17 00:00:00 2001
From: Sebastian Harl <sh@tokkee.org>
Date: Wed, 2 Apr 2014 12:37:10 +0200
Subject: [PATCH] store: Calculate and store each objects update interval.

The interval is calculated as the moving average of the incoming update
intervals. This should also work fine for out-of-order updates or updates from
multiple sources.
---
 src/core/store-private.h | 2 ++
 src/core/store.c         | 7 +++++++
 2 files changed, 9 insertions(+)

diff --git a/src/core/store-private.h b/src/core/store-private.h
index abd94c2..a5bf026 100644
--- a/src/core/store-private.h
+++ b/src/core/store-private.h
@@ -46,6 +46,7 @@ struct sdb_store_base {
 
 	/* common meta information */
 	sdb_time_t last_update;
+	sdb_time_t interval; /* moving average */
 	sdb_store_base_t *parent;
 };
 #define STORE_BASE(obj) ((sdb_store_base_t *)(obj))
@@ -81,6 +82,7 @@ enum {
 /* shortcuts for accessing the sdb_store_obj_t attributes
  * of inheriting objects */
 #define _last_update super.last_update
+#define _interval super.interval
 
 #ifdef __cplusplus
 } /* extern "C" */
diff --git a/src/core/store.c b/src/core/store.c
index b2fb0f6..6420190 100644
--- a/src/core/store.c
+++ b/src/core/store.c
@@ -67,6 +67,7 @@ store_base_init(sdb_object_t *obj, va_list ap)
 	sobj->type = va_arg(ap, int);
 
 	sobj->last_update = va_arg(ap, sdb_time_t);
+	sobj->interval = 0;
 	sobj->parent = NULL;
 	return 0;
 } /* store_base_init */
@@ -292,7 +293,13 @@ store_obj(int parent_type, const char *parent_name,
 			status = 1;
 		}
 		else {
+			sdb_time_t interval = last_update - old->last_update;
 			old->last_update = last_update;
+			if (old->interval)
+				old->interval = (sdb_time_t)((0.9 * (double)old->interval)
+						+ (0.1 * interval));
+			else
+				old->interval = interval;
 		}
 
 		if (updated_obj)
-- 
2.30.2