corProm — Prometheus Metrics

Counters, gauges and histograms for a server whose metrics path must not allocate, block or take a lock: every update is an atomic on a fixed-point int64_t. Rendering happens only when the metrics are asked for — as Prometheus text, or as a corTree.

• Version: 0.1.0
• Language: C
• License: Apache License 2.0

The only dependency is corTree (for corPromMetrics).

It is kprom under new names, moved onto corTree so that the coraine stack links one tree library rather than two.

API

CorPromMetric* reqs = corPromCounterCreate("requests_total", "Requests served");
CorPromMetric* conn = corPromGaugeCreate("connections", "Open connections");
double         b[]  = { 0.001, 0.01, 0.1, 1 };
CorPromMetric* lat  = corPromHistogramCreate("latency_seconds", "Latency", b, 4);

corPromCounterInc(reqs);
corPromGaugeAdd(conn, 1);
corPromHistogramObserve(lat, 0.004);

int   size = corPromRenderSize();
char* text = malloc(size);
corPromRender(text, size);                 // Prometheus text exposition format

CorNode* treeP = corPromMetrics(kaP);      // the same, as a tree (NULL: malloc)

Build

make di