Merge lp:~sidnei/txstatsd/preserve-last-gauge into lp:txstatsd

[Sidnei da Silva]

[a=bicycleday] Preserve gauges after each flush.

If the gauge is not updated at the next flush, it will send the
previous value. This is the definition of a gauge as per Etsy StatsD.
Also updated test_flush_gauge_metric in test_processor.py.

Preserve gauges after each flush.

If the gauge is not updated at the next flush, it will send the
previous value. This is the definition of a gauge as per Etsy StatsD.
Also updated test_flush_gauge_metric in test_processor.py.

[Sidnei da Silva (sidnei)]

review: Approve

=== modified file 'txstatsd/server/processor.py'
--- txstatsd/server/processor.py	2013-06-07 21:25:55 +0000
+++ txstatsd/server/processor.py	2013-10-15 20:59:48 +0000
@@ -25,7 +25,6 @@
 import logging
 
 from twisted.python import log
-from twisted.internet.task import Cooperator
 
 from txstatsd.metrics.metermetric import MeterMetricReporter
 
@@ -331,8 +330,6 @@
 
             yield ((self.gauge_prefix + key + ".value", value, timestamp),)
 
-        self.gauge_metrics.clear()
-
     def flush_meter_metrics(self, timestamp):
         for metric in self.meter_metrics.itervalues():
             messages = metric.report(timestamp)
 
=== modified file 'txstatsd/tests/test_processor.py'
--- txstatsd/tests/test_processor.py	2013-06-07 21:25:55 +0000
+++ txstatsd/tests/test_processor.py	2013-10-15 20:59:48 +0000
@@ -339,7 +339,16 @@
             ("stats.gauge.gorets.value", 9.6, 42), messages[0])
         self.assertEqual(
             ("statsd.numStats", 1, 42), messages[1])
-        self.assertEqual(0, len(self.processor.gauge_metrics))
+
+        # ensure the gauge value remains after the flush.
+        self.assertEqual(1, len(self.processor.gauge_metrics))
+
+        # ensure that subsequent flushes continue to report the gauge value
+        messages = list(self.processor.flush())
+        self.assertEqual(
+            ("stats.gauge.gorets.value", 9.6, 42), messages[0])
+        self.assertEqual(
+            ("statsd.numStats", 1, 42), messages[1])
 
     def test_flush_distinct_metric(self):
         """