fix bug and add guess for instrument

influx.py

@@ -403,7 +403,7 @@ class InfluxDBWrapper:
         except StopIteration:
             return
         converters = key_dict = table_properties = None  # make IDE happy
-        for i in range(5):
+        while 1:
             header = {}
             if row[0]:  # this is a header
                 header[row[0]] = row
@@ -647,17 +647,23 @@ class InfluxDBWrapper:
                 result[stream] = entry.tags.get('instrument', '0')
         return result
 
-    def set_instrument(self, stream, value, ts=None, **tags):
+    def set_instrument(self, stream, value, ts=None, guess=True, **tags):
         """set stream and instrument on or off
 
         :param stream: the uri of the stream
         :param value: instrument, "0" when unknown or None when switching to off
         :param ts: the time or None when now
+        :param guess: when instrument is undefined, take from previous
         """
-        prev, row = self.get_instrument(stream, ts, **tags)
-        if row is not None:
-            if prev in (None, '0') or ts < row[0]:
+        prev, prevts = self.get_instrument(stream, ts, **tags)
+        if prevts is not None:
+            if prev in (None, '0'):
                 ts = prevts + 0.001
+            else:
+                if value == '0' and guess:
+                    value = prev
+                if ts < prevts:
+                    ts = prevts + 0.001
         tags['stream'] = stream
         if value:
             tags['instrument'] = value