1 files changed, 30 insertions, 0 deletions
diff --git a/munin/ipmi_sensor_ b/munin/ipmi_sensor_
index 11a66fd..148f1d3 100755
--- a/munin/ipmi_sensor_
+++ b/munin/ipmi_sensor_
@@ -19,6 +19,10 @@ require 'yaml';
 
 VALID_UNITS = %w{volts degrees_c rpm}
 
+CACHEDIR = "/var/lib/munin/plugin-state"
+CACHEFILE = "plugin-ipmi_sensor.cache"
+CACHE_AGE = 290
+
 def bail_out(m)
 	STDERR.puts "#{$0}: #{m}"
 	exit 1
@@ -32,7 +36,32 @@ end
 def normalize_unit(s)
 	s.downcase.tr('^a-z0-9', '_')
 end
+def fetch_cache
+	fn = CACHEDIR+"/"+CACHEFILE
+	return nil unless FileTest.exists? fn
+	cache = YAML::load( File.open(fn) )
+	return nil unless cache
+	return nil unless cache[:version] == 1
+	return nil if Time.now - cache[:timestamp] > CACHE_AGE
+	return cache[:data]
+end
+def write_cache(data)
+	fn = CACHEDIR+"/"+CACHEFILE
+	return unless FileTest.directory? CACHEDIR
+	return unless FileTest.writable? CACHEDIR or FileTest.writable? fn
+	File.open(fn, "w", 0600) { |f|
+		cache = {
+				:version => 1,
+				:timestamp => Time.now,
+				:data => data
+			}
+		f.puts cache.to_yaml
+	}
+end
 def get_sensor_data
+	data = fetch_cache
+	return data if data
+
 	data = []
 	names = {}
 	IO.popen("ipmitool -I open sensor") do |f|
@@ -65,6 +94,7 @@ def get_sensor_data
 			}
 		end
 	end
+	write_cache data
 	data
 end