so in v2, we will almost certainly move away from ...
# developmentw
witty-crayon-22786
10/17/2019, 7:24 PMso in v2, we will almost certainly move away from "i tell you what has changed", and towards, "the Graph can quickly recompute some value for you."
witty-crayon-22786
10/17/2019, 7:25 PMwhat this might look like concretely is something similar to the watchman model:
witty-crayon-22786
10/17/2019, 7:26 PMi connected and ran
./pants listwitty-crayon-22786
10/17/2019, 7:26 PMso it might be emitting a token that identifies the root node
witty-crayon-22786
10/17/2019, 7:27 PMand then very quickly being able to say "has that root changed"?
witty-crayon-22786
10/17/2019, 7:28 PMftr, i think that an API like this one might be possible and even easy today.
a
aloof-angle-91616
10/17/2019, 7:29 PMok. that might be really useful for Metals or any IDE which might want to auto-import when a target has changed
aloof-angle-91616
10/17/2019, 7:29 PMand would allow the IDE to avoid using its own file watching heuristics, more importantly
w
witty-crayon-22786
10/17/2019, 7:30 PMand the equivalent for building a pex is rebuilding it, and digesting the pex
witty-crayon-22786
10/17/2019, 7:30 PMand then optionally using this API for low latency if you're doing it in a loop.
a
aloof-angle-91616
10/17/2019, 7:37 PMyes
aloof-angle-91616
10/17/2019, 7:38 PMthe user mentioned that they’d prefer to use the target fingerprint or something since they can’t rely on pexes being built reproducibly if the sources haven’t changed
aloof-angle-91616
10/17/2019, 7:38 PMwill link the issue
aloof-angle-91616
10/17/2019, 7:39 PMi mentioned to the user that reproducible pex building is i believe also possible
aloof-angle-91616
10/17/2019, 7:40 PMhere’s the original issue: https://github.com/pantsbuild/pants/issues/8445
aloof-angle-91616
10/17/2019, 7:40 PMWe could hash the PEX file, but then we're at the mercy of pants to produce exactly (bit for bit) the same PEX file with each build. Admittedly, a shared cache probably makes this mostly an academic concern.
w
witty-crayon-22786
10/18/2019, 2:46 AMwe did actually spend time to make pex reproducible. it's not perfect, but.
witty-crayon-22786
10/18/2019, 2:46 AMwe/Eric
a
aloof-angle-91616
10/18/2019, 2:46 AMyeah
aloof-angle-91616
10/18/2019, 2:47 AMi was wondering whether it was sufficient for their needs here