docs(audits): RSS gap from PathBuf and Arc<Path> per FileEntry#3834
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Audit per-entry path overhead in FileEntry vs upstream's pool-allocated file_struct, quantify the RSS gap at 100K entries, and propose five reduction strategies (Box<Path>, basename arena, packed extras, basename interning, bump allocator) with implementation cost and recommended sequencing. Closes task #1048.
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Audit per-entry path overhead in FileEntry vs upstream's pool-allocated file_struct, quantify the RSS gap at 100K entries, and propose five reduction strategies (Box<Path>, basename arena, packed extras, basename interning, bump allocator) with implementation cost and recommended sequencing. Closes task #1048.
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Summary
crates/flist/src/entry.rs,crates/protocol/src/flist/entry/core.rs) and quantify per-entryheap allocations:
PathBufheader + capacity slack,Arc<Path>fat pointer +
ArcInnerheader,Option<Box<FileEntryExtras>>pointer + box body.
flist.c:make_file()pool-allocatedfile_structwith flexible-array basename,lastdir-shareddirname pointer, and
OPT_EXTRA(f, bump)extras packed beforethe header.
Box<Path>overPathBuf, per-flist basename arena with(start, len)indices,packed extras in the same arena allocation, basename interning,
and a
bumpalo-style bump allocator for the wholeFileList.Closes task #1048.
Test plan