perf(tspath): optimize hasRelativePathSegment
#1569
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│ old.txt │ new.txt │
│ sec/op │ sec/op vs base │
HasRelativePathSegment/foo/bar/baz-12 29.10n ± 2% 14.79n ± 1% -49.16% (p=0.000 n=10)
HasRelativePathSegment/./some/path-12 2.065n ± 0% 2.039n ± 2% -1.26% (p=0.022 n=10)
HasRelativePathSegment//foo/./bar/../../.-12 7.030n ± 0% 2.025n ± 0% -71.20% (p=0.000 n=10)
HasRelativePathSegment/foo/foo/foo/foo/foo/...etc-12 9.076n ± 1% 2.308n ± 1% -74.56% (p=0.000 n=10)
geomean 7.869n 3.446n -56.21%
jakebailey
approved these changes
Aug 12, 2025
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Ran with go test -fuzz=FuzzToFileNameLowerCase ./internal/tspath for a while and nothing broke.
Thanks for this; when I improved this the first time, it was way better than the original one, but I always meant to come back and improve it further. It's just never been a bottleneck for anything we see in tsc/LSP.
jakebailey
requested changes
Aug 12, 2025
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Oops, I ran the wrong one. This PR is FuzzHasRelativePathSegment.
go test -fuzz=FuzzHasRelativePathSegment ./internal/tspath immediately fails with:
fuzz: elapsed: 0s, gathering baseline coverage: 0/9 completed
fuzz: elapsed: 0s, gathering baseline coverage: 9/9 completed, now fuzzing with 20 workers
fuzz: minimizing 37-byte failing input file
fuzz: elapsed: 0s, minimizing
--- FAIL: FuzzHasRelativePathSegment (0.11s)
--- FAIL: FuzzHasRelativePathSegment (0.00s)
path_test.go:616: assertion failed: false (bool) != true (bool)
Failing input written to testdata/fuzz/FuzzHasRelativePathSegment/9cd9b70960b4a733
To re-run:
go test -run=FuzzHasRelativePathSegment/9cd9b70960b4a733
FAIL
exit status 1
FAIL github.com/microsoft/typescript-go/internal/tspath 0.129s
Which tests the string /.
🫣 oops, thanks for testing, should be fixed now: |
jakebailey
approved these changes
Aug 12, 2025
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This pull request optimises
hasRelativePathSegment, delivering a ~56% perf improvement.This function is Called
27_628_418times via tsgolint when linting vscode repo.this function has tests here to ensure we don't regress vs the old version:
typescript-go/internal/tspath/path_test.go
Lines 610 to 618 in d6c0867