From 80fa610f9c8702d6b7256be9d97668de29ba2e06 Mon Sep 17 00:00:00 2001 From: Richard van der Hoff Date: Mon, 15 Jan 2018 16:52:52 +0000 Subject: [PATCH] Add some comments to metrics classes --- synapse/metrics/metric.py | 28 +++++++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-) diff --git a/synapse/metrics/metric.py b/synapse/metrics/metric.py index 1d054dd557..c5f0bcbc15 100644 --- a/synapse/metrics/metric.py +++ b/synapse/metrics/metric.py @@ -24,8 +24,16 @@ def map_concat(func, items): class BaseMetric(object): + """Base class for metrics which report a single value per label set + """ def __init__(self, name, labels=[]): + """ + Args: + name (str): principal name for this metric + labels (list(str)): names of the labels which will be reported + for this metric + """ self.name = name self.labels = labels # OK not to clone as we never write it @@ -36,7 +44,7 @@ class BaseMetric(object): return not len(self.labels) def _render_labelvalue(self, value): - # TODO: some kind of value escape + # TODO: escape backslashes, quotes and newlines return '"%s"' % (value) def _render_key(self, values): @@ -47,6 +55,20 @@ class BaseMetric(object): for k, v in zip(self.labels, values)]) ) + def render(self): + """Render this metric + + Each metric is rendered as: + + name{label1="val1",label2="val2"} value + + https://prometheus.io/docs/instrumenting/exposition_formats/#text-format-details + + Returns: + iterable[str]: rendered metrics + """ + raise NotImplementedError() + class CounterMetric(BaseMetric): """The simplest kind of metric; one that stores a monotonically-increasing @@ -62,6 +84,10 @@ class CounterMetric(BaseMetric): def __init__(self, *args, **kwargs): super(CounterMetric, self).__init__(*args, **kwargs) + # dict[list[str]]: value for each set of label values. the keys are the + # label values, in the same order as the labels in self.labels. + # + # (if the metric is a scalar, the (single) key is the empty list). self.counts = {} # Scalar metrics are never empty