[Buildbot-devel] problem in the waterfall display

[Brian Warner]

From: Alexander Lorenz <lorenz at testingtech.de>
> 
> btw: what does the "expectations" line with "outpit"and "target" for 
> every buildstep mean?

Those are related to the ETA tracking feature. Each BuildStep registers a
number of named "metrics" along which progress can be made. While the step is
running, each metric has a particular value (the "output" metric counts how
many characters have been emitted to stdout/stderr). When the step is
finished, the value of each metric is combined in a weighted average with
previous runs to compute the "expectation", which is used in later builds to
guess how close we are to finishing that step. The idea is that if your step
is running and so far you've emitted 75% of the total text that you created
last time, then you've probably got 25% of the step's time left to go.

The intention is that steps can provide more accurate metrics, like a count
of how many files have been compiled, or how many test cases have been run.
But at the moment none of them do, they only produce the default "output"
metric.

This code really needs overhaul, and I'm pretty sure I've done a braindump of
how it should work to the list a while back. We need smarter buildsteps which
count more useful things than characters, and the ETA calculation needs to
stop assuming linear progress along each metric. Not exactly rocket science,
but so far it hasn't crawled its way up the priority ladder to get finished.


hope that's useful,
 -Brian