optimise: reduce lstat and use correct inode#15831
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Why does it matter? It's the same inode either way. |
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In case of a race that another optimise got there first. I guess it would be rare. (i was thinking multiple could run at once) Remove that change to make it minimal? (and remove that extra lstat) |
Before this change, optimisePath_ would lstat the .links entry up to 4 times per file: - pathExists(linkPath) does an lstat - lstat(linkPath) to check for corruption - pathExists(linkPath) again to check if link needs creation - lstat(linkPath) again after the checks This changes the code to lstat once via maybeLstat() and reuse the result throughout the function, reducing syscalls by 50-75% during optimization. Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
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Motivation
Make
nix store optimisefaster. Noticed 4 lstat's taking place per operation in an strace. These come from lstate and pathExists calls.Claude helped. Also found/fixed the issue of saving the inode of the link, rather than the original file.