pantsbuild / pants / 41268032730

93%

Build Type

push

github

Committed by web-flow

Commit Message

perf(engine): Parse Each BUILD Directory Once (#23741)

`parse_address_family` is requested for a directory's own targets, and
again by each of its subdirectories, which inherit the directory's
`__defaults__` and dependency rules. Two of those lookups passed
`AddressFamilyDir` positionally: the parent-directory lookup in
`parse_address_family` itself, and the lookup of the BUILD files that
declare dependency rules. Every other caller passes it through
`**implicitly(...)`.

A `Task` node's identity is its params plus its positional arguments
(`src/rust/engine/src/nodes/task.rs`), so the two forms were separate
memo entries for the same directory, and most directories were parsed
twice. The engine can't merge them in general, because a param also
reaches the rules the callee calls, while a positional argument doesn't.
Both call sites now use `**implicitly(...)`.

The root's BUILD files are still parsed twice, because the parent lookup
spells the root `.` while `Address.spec_path` spells it `""`. The parent
lookup can't use `""`, because that's
`SyntheticTargetsRequest.SINGLE_REQUEST_FOR_ALL_TARGETS`.

Disclosure: investigated and implemented with Claude.

Coverage Stats

10 of 10 new or added lines in 1 file covered. (100.0%)

1 existing line in 1 file now uncovered.

97902 of 105193 relevant lines covered (93.07%)

3.65 hits per line