Calculate Delta Middleware Source

telem.middleware.calcDelta (windowSize?: integer)

Measures the delta and rate of each metric in a collection, in both instant and ranged variants. Each measurement is appended to the collection as a new metric, with a suffix appended to the name, and the source set to middleware.

The instant delta is calculated as the difference between the current and previous values, and the instant rate is calculated as the delta divided by the observed time between cycles. The ranged delta and rate are similar, but the previous value is taken from windowSize cycles ago.

Name	Type	Default
windowSize	integer	50
Number of cycles to include when calculating the delta and rate.

Methods

force

CalcDeltaMiddleware:force (): self

Force the middleware to process metrics from other middleware (source = 'middleware'), default is to ignore metrics from other middleware.

interval

CalcDeltaMiddleware:interval (interval: string): self

Set the interval used to calculate the rate. The default is 1s, which will result in the rate being calculated in units per second.

The format is (unitScale)(unit), where unitScale is an integer greater than 0, and unit is one of: s (second), m (minute), h (hour), d (day). Note that "day" is a 24-hour day, not an in-game day.

Usage

local telem = require 'telem'
local mw = telem.middleware

local state = 0

local backplane = telem.backplane()
  :addInput('increments', telem.input.custom(function ()
    state = state + 1

    return { inc = state }
  end))
  :middleware(mw.calcDelta():interval('1m'))
  :cycleEvery(0.1)()

This will result in the following collection:

Name	Value	Unit	Adapter	Source
inc	0 - inf		increments
inc_idelta	1			middleware
inc_delta	~ 49			middleware
inc_irate	~ 600			middleware
inc_rate	~ 600			middleware

Observing the value over time looks something like this: