diff --git a/synapse/metrics/metric.py b/synapse/metrics/metric.py
index e87b2b80a7..1d054dd557 100644
--- a/synapse/metrics/metric.py
+++ b/synapse/metrics/metric.py
@@ -50,7 +50,14 @@ class BaseMetric(object):
class CounterMetric(BaseMetric):
"""The simplest kind of metric; one that stores a monotonically-increasing
- integer that counts events."""
+ value that counts events or running totals.
+
+ Example use cases for Counters:
+ - Number of requests processed
+ - Number of items that were inserted into a queue
+ - Total amount of data that a system has processed
+ Counters can only go up (and be reset when the process restarts).
+ """
def __init__(self, *args, **kwargs):
super(CounterMetric, self).__init__(*args, **kwargs)
@@ -59,7 +66,7 @@ class CounterMetric(BaseMetric):
# Scalar metrics are never empty
if self.is_scalar():
- self.counts[()] = 0
+ self.counts[()] = 0.
def inc_by(self, incr, *values):
if len(values) != self.dimension():
@@ -78,7 +85,7 @@ class CounterMetric(BaseMetric):
self.inc_by(1, *values)
def render_item(self, k):
- return ["%s%s %d" % (self.name, self._render_key(k), self.counts[k])]
+ return ["%s%s %.12g" % (self.name, self._render_key(k), self.counts[k])]
def render(self):
return map_concat(self.render_item, sorted(self.counts.keys()))
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