tree 13b6a5d5ddb79a90070397cf43cd6213a4ccfcdb
parent 3007f57168dbe495a6a0a206c4ac54aca9a0d56f
author David 'Digit' Turner <digit@google.com> 1774259369 +0000
committer GN LUCI <gn-scoped@luci-project-accounts.iam.gserviceaccount.com> 1774282716 -0700

Only run target checks in background threads during resolution.

Before this CL, Target::OnResolved() did propagate information
from dependencies to finalize the instance's state, and would
also run several checks to report errors.

The CL separates these into Target::OnResolvedWithoutChecks()
and Target::RunChecksAfterResolution(), then modifies the
Builder::ResolveItem() implementation to only call the latter
in background threads, while keeping the call to the former
in the main thread.

This ensures that the result of resolution is deterministic,
thus removing a source of data races that masked the problems
described in the associated bug.

This CL does *not* fix the issue though, this will happen
in a future CL. Benchmarking shows no statistical difference
in `gn gen` and `gn gen --check` times for a Chrome/Android
build configuration.

Bug: 494481832
Change-Id: I3947709fbda2fb39ccc75c620f8b9d535e0d3d26
Reviewed-on: https://gn-review.googlesource.com/c/gn/+/21720
Reviewed-by: Takuto Ikuta <tikuta@google.com>
Commit-Queue: David Turner <digit@google.com>
Reviewed-by: Andrew Grieve <agrieve@google.com>