feat: BigramQuery trait + FileRecord/FileListView for zero-copy index support#341
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magnusmalm wants to merge 3 commits intodmtrKovalenko:mainfrom
Open
feat: BigramQuery trait + FileRecord/FileListView for zero-copy index support#341magnusmalm wants to merge 3 commits intodmtrKovalenko:mainfrom
magnusmalm wants to merge 3 commits intodmtrKovalenko:mainfrom
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Extract query() and is_ready() into a BigramQuery trait that BigramFilter implements. grep_search() now accepts Option<&dyn BigramQuery>, allowing external consumers to provide alternative implementations (e.g. a zero-copy mmap-backed view) without changing the grep pipeline. Static helpers (is_candidate, count_candidates) remain on BigramFilter since they operate on the returned Vec<u64> directly.
Add building blocks for mmap-friendly file list storage: - FileRecord: 24-byte repr(C) struct with path offset, lengths, size, modified time, and is_binary flag packed into the high bit - FileListView: borrows records + string table from an mmap, provides indexed access to paths and metadata without heap allocation - build_file_records(): convert &[FileItem] to records + string table - to_file_items(): convert back to owned FileItems for the search pipeline Tests for record layout, flags, and FileItem round-trip included.
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Summary
Two changes toward zero-copy index support, following up on the discussion in #330.
Commit 1: BigramQuery trait
Extracts
query()andis_ready()into aBigramQuerytrait thatBigramFilterimplements.grep_search()now acceptsOption<&dyn BigramQuery>, so external consumers can provide alternative implementations (e.g. an mmap-backed view) without changing the grep pipeline.Static helpers (
is_candidate,count_candidates) stay onBigramFiltersince they operate on the returnedVec<u64>, not the index itself.Commit 2: FileRecord + FileListView
Adds building blocks for mmap-friendly file list storage:
FileRecord: 24-byterepr(C)struct storing path offset, lengths, size, modified, and is_binary flagFileListView<'a>: borrows records + string table from an mmap, provides indexed access without heap allocationbuild_file_records(): convert&[FileItem]to records + string tableto_file_items(): convert back when the search pipeline needs ownedFileItemsWiring
FileListViewdirectly intomatch_and_score_files/grep_searchwould require aFileEntrytrait that changes field access to method calls throughoutscore.rsandgrep.rs. That felt too invasive for this PR. Happy to do it as a follow-up if you want to go that direction.Benchmarked with fff-cli on buildroot (13k files). The
dyn BigramQueryvtable dispatch adds no measurable overhead to grep or search.