Prometheus.ex v1.0.0-alpha3 Prometheus.Metric.Gauge

Gauge metric, to report instantaneous values.

Gauge is a metric that represents a single numerical value that can arbitrarily go up and down.

A Gauge is typically used for measured values like temperatures or current memory usage, but also “counts” that can go up and down, like the number of running processes.

Example use cases for Gauges:

Inprogress requests;
Number of items in a queue;
Free memory;
Total memory;
Temperature.

Example:

defmodule MyPoolInstrumenter do

  use Prometheus.Metric

  ## to be called at app/supervisor startup.
  ## to tolerate restarts use declare.
  def setup() do
    Gauge.declare([name: :my_pool_size,
                   help: "Pool size."])

    Gauge.declare([name: :my_pool_checked_out,
                   help: "Number of sockets checked out from the pool"])
  end

  def set_size(size) do
    Gauge.set([name: :my_pool_size], size)
  end

  def track_checked_out_sockets(checkout_fun) do
    Gauge.track_inprogress([name: :my_pool_checked_out], checkout_fun)
  end

end

Summary

Macros

declare(spec)

Creates a gauge using spec. If a gauge with the same spec exists returns false

new(spec)

Creates a gauge using spec

reset(spec)

Resets the value of the gauge identified by spec

set(spec, value)

Sets the gauge identified by spec to value

set_to_current_time(spec)

Sets the gauge identified by spec to the current unixtime

track_inprogress(spec, fun)

Track inprogress functions

value(spec)

Returns the value of the gauge identified by spec

Macros

declare(spec)

Creates a gauge using spec. If a gauge with the same spec exists returns false.

Raises Prometheus.Error.MissingMetricSpecKey if required spec key is missing.
Raises Prometheus.Error.InvalidMetricName if metric name is invalid.
Raises Prometheus.Error.InvalidMetricHelp if help is invalid.
Raises Prometheus.Error.InvalidMetricLabels if labels isn’t a list.
Raises Prometheus.Error.InvalidMetricName if label name is invalid.

new(spec)

Creates a gauge using spec.

reset(spec)

Resets the value of the gauge identified by spec.

Raises Prometheus.Error.UnknownMetric exception if a gauge for spec can’t be found.
Raises Prometheus.Error.InvalidMetricArity exception if labels count mismatch.

set(spec, value)

Sets the gauge identified by spec to value.

Raises Prometheus.Error.InvalidValue exception if value isn’t a number.
Raises Prometheus.Error.UnknownMetric exception if a gauge for spec can’t be found.
Raises Prometheus.Error.InvalidMetricArity exception if labels count mismatch.

set_to_current_time(spec)

Sets the gauge identified by spec to the current unixtime.

Raises Prometheus.Error.UnknownMetric exception if a gauge for spec can’t be found.
Raises Prometheus.Error.InvalidMetricArity exception if labels count mismatch.

track_inprogress(spec, fun)

Track inprogress functions.

Raises Prometheus.Error.UnknownMetric exception if a gauge for spec can’t be found.
Raises Prometheus.Error.InvalidMetricArity exception if labels count mismatch.

value(spec)

Returns the value of the gauge identified by spec.

Raises Prometheus.Error.UnknownMetric exception if a gauge for spec can’t be found.
Raises Prometheus.Error.InvalidMetricArity exception if labels count mismatch.