[vim/vim] Speed up executable() on MS-Windows with a prefix search (PR #21416)
mattn
On MS-Windows, executable() queries every $PATHEXT extension in every $PATH directory, although most directories do not contain the command at all. This patch first does a single FindFirstFileExW() search for "name*" in each directory and skips it when nothing matches. When the search is inconclusive, or the path or extensions are unusual (".", wildcards, ":", trailing dot/space, non-alphanumeric extensions, fewer than 3 extensions), the existing per-extension checks are used as before.
Benchmark (54 $PATH entries, 11 $PATHEXT entries, 'shell' is cmd.exe, average per call):
| case | before | after |
|---|---|---|
| full $PATH, command not found | 5.0 ms | 1.5 ms |
| full $PATH, found in System32 | 1.6 ms | 0.75 ms |
| full $PATH, found (git) | 130 us | 85 us |
| full $PATH, name with extension (git.exe) | 129 us | 126 us |
| $PATH=System32 only, not found | 111 us | 42 us |
| $PATH=System32 only, found | 39 us | 73 us |
The last row is the worst case: when the command is in the first, large directory, the extra prefix search adds a few tens of microseconds. In normal setups the skipped directories outweigh this.
You can view, comment on, or merge this pull request online at:
https://github.com/vim/vim/pull/21416
Commit Summary
- 80bb9a2 Speed up executable() on MS-Windows with a prefix search
File Changes
(2 files)
- M src/os_win32.c (63)
- M src/testdir/test_functions.vim (120)
Patch Links:
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