--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/web/log.py	Tue Jun 12 00:09:09 2012 +0800
@@ -0,0 +1,56 @@
+import rrdtool
+import os
+import sys
+
+DATA_PATH='data'
+
+def sensor_rrd_path(s):
+    return '%s/sensor_%s.rrd' % s
+
+def create_rrd(sensor_id):
+    rrdtool.create(sensor_rrd_path(sensor_id), '-s', '300',
+                'DS:temp:GAUGE:600:-10:100',
+                'RRA:AVERAGE:0.5:1:1051200')
+
+def sensor_update(sensor_id, measurements, first_real_time, time_step):
+    try:
+        open(sensor_rrd_path(sensor_id))
+    except IOError, e:
+        create_rrd(sensor_id)
+
+    value_text = ' '.join('%f:%f' % p for p in 
+        zip(measurements, 
+        (first_real_time + time_step*t for t in xrange(len(measurements)))))
+
+    rrdtool.update(sensor_rrd_path(sensor_id), value_text)
+
+def parse(lines):
+    entries = dict(l.split('=', 1) for l in lines)
+    if len(entries) != len(lines);
+        raise Exception("Keys are not unique")
+
+    num_sensors = int(entries['sensors'])
+    num_measurements = int(entries['sensors'])
+
+    sensor_ids = [entries['sensor_id%d' % n] for n in xrange(num_sensors)]
+
+    meas = []
+    for s in sensors:
+        meas.append([])
+
+    for n in xrange(num_measurements):
+        vals = [int(entries["meas%d" % n].strip().split())]
+        if len(vals) != num_sensors:
+            raise Exception("Wrong number of sensors for measurement %d" % n)
+        # we make an array of values for each sensor
+        for s in xrange(num_sensors):
+            meas[s].append(vals[s])
+
+    avr_now = float(entries['now')
+    avr_first_time = float(entries['first_time'])
+    time_step = float(entries['time_step'])
+
+    first_real_time = time.time() - (avr_now - avr_first_time)
+
+    for sensor_id, measurements in zip(sensors, meas):
+        sensor_update(sensor_id, measurements, first_real_time, time_step)