feat: Introduce the `multitude` crate. by geeknoid · Pull Request #402 · microsoft/oxidizer

geeknoid · 2026-05-04T22:50:39Z

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Pull request overview

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Introduces the new multitude arena allocator crate and expands the repo’s verification tooling with Loom model checking and Bolero fuzz/property tests.

Changes:

Adds the multitude crate (core implementation, integrations, examples, benches, docs, and tests).
Adds just recipes and CI jobs for Loom (just loom) and Bolero (just bolero) auto-discovered testing.
Updates workspace metadata/dependencies, docs, spelling allowlist, and changelogs to include the new crate.

Reviewed changes

Copilot reviewed 68 out of 70 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
justfiles/extended.just	Adds `just` scripts for Loom and Bolero discovery/execution.
justfile	Imports the new extended `just` recipes.
crates/multitude/tests/loom_arc.rs	Adds Loom model-checked tests for cross-thread refcounting invariants.
crates/multitude/tests/bolero_lifecycle.rs	Adds Bolero property tests for arena lifecycle/drop invariants.
crates/multitude/src/zerocopy.rs	Adds `zerocopy` integration allocation helpers.
crates/multitude/src/sync.rs	Adds an atomic facade switching between `core` and `loom` atomics.
crates/multitude/src/rc_utf16_str.rs	Introduces arena-backed `RcUtf16Str`.
crates/multitude/src/rc_str.rs	Introduces arena-backed `RcStr`.
crates/multitude/src/rc.rs	Introduces arena-backed `Rc<T>` smart pointer.
crates/multitude/src/raw_handle.rs	Adds shared handle plumbing for refcounted smart pointers and init rewriting.
crates/multitude/src/owned_chunk.rs	Adds RAII wrappers and slot management for owned/retired chunks.
crates/multitude/src/flavor.rs	Adds `Local`/`Shared` refcount flavor abstraction.
crates/multitude/src/entry_layout.rs	Adds layout math utilities and unit tests for entry/value placement.
crates/multitude/src/dst/mod.rs	Adds DST support and `ptr_meta` re-exports.
crates/multitude/src/drop_entry.rs	Adds drop-list node representation and helpers with tests.
crates/multitude/src/constants.rs	Introduces allocator constants and low-level alignment helpers with tests.
crates/multitude/src/chunk_size_class.rs	Adds chunk sizing classification (normal vs oversized).
crates/multitude/src/chunk_sharing.rs	Adds chunk sharing mode enum (local vs shared).
crates/multitude/src/bytesbuf.rs	Adds `bytesbuf::mem::Memory` implementation for `Arena`.
crates/multitude/src/bytes.rs	Adds zero-copy conversions into `bytes::Bytes`.
crates/multitude/src/bytemuck.rs	Adds safe zero-initialized allocation for `bytemuck::Zeroable` types.
crates/multitude/src/builders/vec_macro.rs	Adds `builders::vec!` macro for arena-resident builders.
crates/multitude/src/builders/mod.rs	Exposes builder types and re-exports builder macros.
crates/multitude/src/builders/from_iterator_in.rs	Adds `FromIteratorIn` trait for arena-aware collection building.
crates/multitude/src/builders/format_utf16_macro.rs	Adds UTF-16 formatting macro and `fmt::Write` impl.
crates/multitude/src/builders/format_macro.rs	Adds formatting macro and `fmt::Write` impl for arena string builder.
crates/multitude/src/builders/collect_in.rs	Adds `CollectIn` iterator extension trait.
crates/multitude/src/box_utf16_str.rs	Adds mutable `BoxUtf16Str` with freeze-to-`RcUtf16Str`.
crates/multitude/src/box_str.rs	Adds mutable `BoxStr` with freeze-to-`RcStr`.
crates/multitude/src/box.rs	Adds arena-backed owned `Box<T>` with immediate drop semantics.
crates/multitude/src/arena_str_helpers.rs	Adds shared helpers for arena-backed string allocation and prefix reading.
crates/multitude/src/arena_stats.rs	Adds arena statistics snapshot and internal counters (feature-gated).
crates/multitude/src/arena_inner.rs	Adds cross-thread arena state with encoded liveness counter + cache.
crates/multitude/src/arena_handle_macros.rs	Adds macros for common smart-pointer trait impls.
crates/multitude/src/arena_builder.rs	Adds `ArenaBuilder` + validation and preallocation support.
crates/multitude/src/arc_utf16_str.rs	Introduces arena-backed `ArcUtf16Str`.
crates/multitude/src/arc_str.rs	Introduces arena-backed `ArcStr`.
crates/multitude/src/arc.rs	Introduces arena-backed `Arc<T>` smart pointer.
crates/multitude/src/allocator_impl.rs	Implements `Allocator` for `&Arena<A>` for allocator-API interop.
crates/multitude/scripts/perf_report.sh	Adds perf report runner for criterion + gungraun.
crates/multitude/scripts/build_perf_report.py	Adds PERF.md generator from benchmark logs.
crates/multitude/logo.png	Adds crate logo asset via Git LFS.
crates/multitude/favicon.ico	Adds crate favicon asset via Git LFS.
crates/multitude/examples/strings.rs	Adds example showcasing arena string flavors and builders.
crates/multitude/examples/custom_allocator.rs	Adds example for custom allocator integration.
crates/multitude/examples/basic.rs	Adds basic usage example covering multiple APIs.
crates/multitude/examples/alloc_ref.rs	Adds example for simple-reference (`&mut`) allocations.
crates/multitude/benches/gungraun_drop.rs	Adds callgrind-based drop benchmarks.
crates/multitude/benches/criterion_drop.rs	Adds criterion-based drop benchmarks.
crates/multitude/PERF.md	Adds a generated performance report artifact.
crates/multitude/Cargo.toml	Adds new crate manifest with features, deps, benches, examples, loom cfg deps.
crates/multitude/CHANGELOG.md	Adds crate changelog stub.
constants.env	Adds cargo tool version pinning for `cargo-bolero`.
README.md	Adds `multitude` to crate list; documents loom/bolero verification.
Cargo.toml	Adds `multitude` to workspace deps and declares new shared third-party deps.
CHANGELOG.md	Adds `multitude` to top-level changelog index.
.spelling	Extends spelling allowlist for new terminology and symbols.
.github/workflows/main.yml	Expands Miri matrix and adds Loom + Bolero jobs on PRs.

Comments suppressed due to low confidence (5)

justfiles/extended.just:1

This overwrites RUSTFLAGS and then unconditionally removes it, which will drop any pre-existing user RUSTFLAGS value. Preserve the prior value (e.g., save it before mutation) and restore it in finally instead of deleting the variable.
justfiles/extended.just:1
This overwrites RUSTFLAGS and then unconditionally removes it, which will drop any pre-existing user RUSTFLAGS value. Preserve the prior value (e.g., save it before mutation) and restore it in finally instead of deleting the variable.
crates/multitude/src/arena_inner.rs:1
This paragraph is duplicated verbatim (lines 30–39 repeat 30–34). Remove the duplicate block to keep the doc comment concise and avoid confusion during maintenance.
crates/multitude/src/bytemuck.rs:1
The panic docs say “alignment greater than 64 KiB” while the error docs say “alignment >= 64 KiB”. Since the implementation rejects align() >= 64 KiB, align the wording (recommended: use >= 64 KiB) for consistency. (Same inconsistency also appears in the zerocopy integration module.)
crates/multitude/src/bytemuck.rs:1
The panic docs say “alignment greater than 64 KiB” while the error docs say “alignment >= 64 KiB”. Since the implementation rejects align() >= 64 KiB, align the wording (recommended: use >= 64 KiB) for consistency. (Same inconsistency also appears in the zerocopy integration module.)

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github-actions · 2026-05-04T23:05:42Z

⚠️ Breaking Changes Detected

error: failed to retrieve local crate data from git revision

Caused by:
    0: failed to retrieve manifest file from git revision source
    1: possibly due to errors: [
         failed when reading /home/runner/work/oxidizer/oxidizer/target/semver-checks/git-origin_main/8fcbf34ab8d7a92fef6755c91cd0e6750ce32375/scripts/crate-template/Cargo.toml: TOML parse error at line 9, column 26
         |
       9 | keywords = ["oxidizer", {{CRATE_KEYWORDS}}]
         |                          ^
       missing key for inline table element, expected key
       : TOML parse error at line 9, column 26
         |
       9 | keywords = ["oxidizer", {{CRATE_KEYWORDS}}]
         |                          ^
       missing key for inline table element, expected key
       ,
         failed to parse /home/runner/work/oxidizer/oxidizer/target/semver-checks/git-origin_main/8fcbf34ab8d7a92fef6755c91cd0e6750ce32375/Cargo.toml: no `package` table,
       ]
    2: package `multitude` not found in /home/runner/work/oxidizer/oxidizer/target/semver-checks/git-origin_main/8fcbf34ab8d7a92fef6755c91cd0e6750ce32375

Stack backtrace:
   0: anyhow::error::<impl anyhow::Error>::msg
   1: cargo_semver_checks::rustdoc_gen::RustdocFromProjectRoot::get_crate_source
   2: cargo_semver_checks::rustdoc_gen::StatefulRustdocGenerator<cargo_semver_checks::rustdoc_gen::CoupledState>::prepare_generator
   3: cargo_semver_checks::Check::check_release::{{closure}}
   4: cargo_semver_checks::Check::check_release
   5: cargo_semver_checks::exit_on_error
   6: cargo_semver_checks::main
   7: std::sys::backtrace::__rust_begin_short_backtrace
   8: main
   9: <unknown>
  10: __libc_start_main
  11: _start

If the breaking changes are intentional then everything is fine - this message is merely informative.

Remember to apply a version number bump with the correct severity when publishing a version with breaking changes (1.x.x -> 2.x.x or 0.1.x -> 0.2.x).

codecov · 2026-05-05T00:06:26Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.0%. Comparing base (9bbe9d7) to head (563c116).

Additional details and impacted files

@@            Coverage Diff            @@
##             main     #402     +/-   ##
=========================================
  Coverage   100.0%   100.0%             
=========================================
  Files         227      261     +34     
  Lines       16740    21473   +4733     
=========================================
+ Hits        16740    21473   +4733

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