Apache CouchDB

Clone this repo:
  1. 7895d4d Merge branch 'use-notify-existing-metric' by Russell Branca · 2 years, 2 months ago master
  2. 9ba5201 We already know the metric type, so supply it directly by Russell Branca · 2 years, 2 months ago use-notify-existing-metric
  3. a842f3b Use `chttpd:qs` instead of `couch_httpd:qs` by ILYA Khlopotov · 2 years, 3 months ago
  4. c4039dd export functions for use in chttpd_misc by Robert Newson · 2 years, 4 months ago
  5. a060a75 Fix compilation warning by Alexander Shorin · 2 years, 8 months ago

couch_stats

couch_stats is a simple statistics collection app for Erlang applications. Its core API is a thin wrapper around a stat storage library (currently Folsom,) but abstracting over that library provides several benefits:

  • All references to stat storage are in one place, so it's easy to swap the module out.

  • Some common patterns, such as tying a process's lifetime to a counter value, are straightforward to support.

  • Configuration can be managed in a single place - for example, it's much easier to ensure that all histogram metrics use a 10-second sliding window if those metrics are instantiated/configured centrally.

Adding a metric

  1. Write a stat description file. See `priv/descriptions.cfg for an example.
  • The metric name should be of type [atom()].
  • The type should be one of counter, gauge, or histogram.

If you don‘t add your metric to a description file, your metric will be accessible via couch_stats:sample/1, but it won’t be read by the stats collector and therefore won't be available to HTTP _stats requests, etc.

  1. Tell couch_stats to use your description file via application configuration.

  2. Instrument your code with the helper functions in couch_stats.erl.