From 4d9ed86ed569cd0eaf4fe4211b84b41c241dd5a9 Mon Sep 17 00:00:00 2001
From: Michael Tremer <michael.tremer@ipfire.org>
Date: Mon, 14 Dec 2015 23:50:19 +0100
Subject: [PATCH] Allow getting the standard deviation of the plotted values

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
---
 src/collecty/constants.py    |  9 +++++++++
 src/collecty/plugins/base.py | 32 +++++++++++++++++---------------
 src/collecty/util.py         |  6 ++++++
 3 files changed, 32 insertions(+), 15 deletions(-)

diff --git a/src/collecty/constants.py b/src/collecty/constants.py
index bae6ed4..082203e 100644
--- a/src/collecty/constants.py
+++ b/src/collecty/constants.py
@@ -55,6 +55,15 @@ GRAPH_DEFAULT_ARGUMENTS = (
 	"--watermark", _("Created by collecty"),
 )
 
+INTERVALS = {
+	None   : "-3h",
+	"hour" : "-1h",
+	"day"  : "-25h",
+	"month": "-30d",
+	"week" : "-360h",
+	"year" : "-365d",
+}
+
 GRAPH_DEFAULT_WIDTH = 768
 GRAPH_DEFAULT_HEIGHT = 480
 
diff --git a/src/collecty/plugins/base.py b/src/collecty/plugins/base.py
index dd7f0d9..c1666b6 100644
--- a/src/collecty/plugins/base.py
+++ b/src/collecty/plugins/base.py
@@ -31,6 +31,7 @@ import time
 import unicodedata
 
 from .. import locales
+from .. import util
 from ..constants import *
 from ..i18n import _
 
@@ -465,6 +466,21 @@ class Object(object):
 
 		return defs
 
+	def get_stddev(self, interval=None):
+		args = self.make_rrd_defs()
+
+		# Add the correct interval
+		args += ["--start", util.make_interval(interval)]
+
+		for name in self.rrd_schema_names:
+			args += [
+				"VDEF:%s_stddev=%s,STDEV" % (name, name),
+				"PRINT:%s_stddev:%%lf" % name,
+			]
+
+		x, y, vals = rrdtool.graph("/dev/null", *args)
+		return dict(zip(self.rrd_schema_names, vals))
+
 	def execute(self):
 		if self.collected:
 			raise RuntimeError("This object has already collected its data")
@@ -506,15 +522,6 @@ class GraphTemplate(object):
 	# Extra arguments passed to rrdgraph.
 	rrd_graph_args = []
 
-	intervals = {
-		None   : "-3h",
-		"hour" : "-1h",
-		"day"  : "-25h",
-		"month": "-30d",
-		"week" : "-360h",
-		"year" : "-365d",
-	}
-
 	# Default dimensions for this graph
 	height = GRAPH_DEFAULT_HEIGHT
 	width  = GRAPH_DEFAULT_WIDTH
@@ -583,13 +590,8 @@ class GraphTemplate(object):
 			if self.upper_limit is not None:
 				args += ["--upper-limit", self.upper_limit]
 
-		try:
-			interval = self.intervals[interval]
-		except KeyError:
-			interval = "end-%s" % interval
-
 		# Add interval
-		args += ["--start", interval]
+		args += ["--start", util.make_interval(interval)]
 
 		return args
 
diff --git a/src/collecty/util.py b/src/collecty/util.py
index fdde126..72fc0c1 100644
--- a/src/collecty/util.py
+++ b/src/collecty/util.py
@@ -72,6 +72,12 @@ def get_network_interfaces():
 
 		yield interface
 
+def make_interval(interval):
+	try:
+		return INTERVALS[interval]
+	except KeyError:
+		return "end-%s" % interval
+
 class ProcNetSnmpParser(object):
 	"""
 		This class parses /proc/net/snmp{,6} and allows
-- 
2.39.2