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perf(coverage): normalize a path with one fork instead of four - #1105
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normalize_path is what the DEBUG trap calls on every cache miss -- 494 times in a single run of one test file, because the caches live in shell variables and each test body is a subshell. Its body was echo "$(cd "$(dirname "$file")" && pwd)/$(basename "$file")" which is four command substitutions. Doing the dirname and basename with parameter expansion leaves one: 2081ms to 424ms per 500 calls, and a --coverage run of tests/unit/assert/basic_test.sh from 6.4s to 4.7s, with the same hit count. The cd and pwd stay. They resolve symlinks, so /tmp/x normalizes to /private/tmp/x on macOS the way the tracked roots expect; pure string manipulation would be faster still and would quietly stop matching them. builtin printf rather than printf, so a test spying printf cannot shadow a path the engine depends on -- the #724 test caught exactly that. Closes #1102
This was referenced Aug 13, 2026
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🤔 Background
Related #1102
normalize_pathis what the DEBUG trap calls on every cache miss — 494 timesin a single run of one test file, because the caches live in shell variables
and each test body is a subshell. Its body was
four command substitutions per call.
💡 Changes
dirname/basenamebecome parameter expansions, leaving one fork: 2081 ms → 424 ms per 500 calls, and a--coveragerun ofbasic_test.sh6.4 s → 4.7 s with the same hit countcd+pwdstays deliberately: it resolves symlinks, so/tmp/xnormalizes to/private/tmp/xon macOS the way the tracked roots expect. Pure string manipulation is faster still and would quietly stop matching thembuiltin printf, notprintf, so a test spyingprintfcannot shadow a path the engine depends on — the Spying on printf breaks coverage collection #724 test caught exactly that during developmentNote the issue's original premise (path mangling dominates) was wrong and is
corrected in the thread: the memo it proposed bought 4%, this buys 27%.