diff --git a/synapse/metrics/metric.py b/synapse/metrics/metric.py
index ff5aa8c0e1..fbba94e633 100644
--- a/synapse/metrics/metric.py
+++ b/synapse/metrics/metric.py
@@ -16,6 +16,7 @@
from itertools import chain
import logging
+import re
logger = logging.getLogger(__name__)
@@ -56,8 +57,7 @@ class BaseMetric(object):
return not len(self.labels)
def _render_labelvalue(self, value):
- # TODO: escape backslashes, quotes and newlines
- return '"%s"' % (value)
+ return '"%s"' % (_escape_label_value(value),)
def _render_key(self, values):
if self.is_scalar():
@@ -115,7 +115,7 @@ class CounterMetric(BaseMetric):
# 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).
+ # (if the metric is a scalar, the (single) key is the empty tuple).
self.counts = {}
# Scalar metrics are never empty
@@ -145,6 +145,36 @@ class CounterMetric(BaseMetric):
)
+class GaugeMetric(BaseMetric):
+ """A metric that can go up or down
+ """
+
+ def __init__(self, *args, **kwargs):
+ super(GaugeMetric, 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 tuple).
+ self.guages = {}
+
+ def set(self, v, *values):
+ if len(values) != self.dimension():
+ raise ValueError(
+ "Expected as many values to inc() as labels (%d)" % (self.dimension())
+ )
+
+ # TODO: should assert that the tag values are all strings
+
+ self.guages[values] = v
+
+ def render(self):
+ return flatten(
+ self._render_for_labels(k, self.guages[k])
+ for k in sorted(self.guages.keys())
+ )
+
+
class CallbackMetric(BaseMetric):
"""A metric that returns the numeric value returned by a callback whenever
it is rendered. Typically this is used to implement gauges that yield the
@@ -269,3 +299,29 @@ class MemoryUsageMetric(object):
"process_psutil_rss:total %d" % sum_rss,
"process_psutil_rss:count %d" % len_rss,
]
+
+
+def _escape_character(m):
+ """Replaces a single character with its escape sequence.
+
+ Args:
+ m (re.MatchObject): A match object whose first group is the single
+ character to replace
+
+ Returns:
+ str
+ """
+ c = m.group(1)
+ if c == "\\":
+ return "\\\\"
+ elif c == "\"":
+ return "\\\""
+ elif c == "\n":
+ return "\\n"
+ return c
+
+
+def _escape_label_value(value):
+ """Takes a label value and escapes quotes, newlines and backslashes
+ """
+ return re.sub(r"([\n\"\\])", _escape_character, value)
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