Enh: Reuse mutation fast paths#119
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Pull request overview
This PR primarily optimizes CheetahString mutation/concatenation paths by reusing the existing push_str logic in Add/AddAssign and adding fast returns for empty inputs, while expanding the project’s performance tooling (tests/benches) and CI/release automation. It also introduces a new memchr/memmem-based substring search implementation (and a reusable CheetahFinder) plus API changes around fallible UTF-8-checked byte conversions.
Changes:
- Rework mutation fast paths: reuse
push_str_internalforAdd/AddAssign, add empty-input fast returns, and add pointer/capacity preservation tests + mutation benchmark. - Add new substring search module (
memchr/memmem) and exposeCheetahFinder; update docs/README accordingly. - Update packaging/automation: new benches, benchmark scripts/artifact layout, multi-OS CI with layout artifacts, and a new release workflow; also tighten UTF-8 construction APIs (move some constructors to
TryFromand deprecate unchecked safe constructors).
Reviewed changes
Copilot reviewed 20 out of 20 changed files in this pull request and generated 6 comments.
Show a summary per file
| File | Description |
|---|---|
Cargo.toml |
Bumps crate version, adds memchr, makes bytes optional, and registers new benches. |
src/cheetah_string.rs |
Mutation fast paths (empty fast returns, Add/AddAssign reuse), plus fallible UTF-8 byte conversion API changes and deprecations. |
src/search.rs |
New memchr/memmem-based byte substring search + CheetahFinder. |
src/lib.rs |
Wires in search module and re-exports CheetahFinder; updates crate-level docs. |
src/serde.rs |
Simplifies serde to serialize via as_str() and uses checked byte conversions on deserialize. |
src/simd.rs |
Marks now-unused SIMD substring-search helpers as dead-code allowed. |
tests/search.rs |
Adds tests validating find/rfind/contains semantics and CheetahFinder behavior. |
tests/mutation.rs |
Adds mutation tests for pointer reuse and reserve/add fast paths. |
tests/layout_snapshot.rs |
Adds a layout snapshot test that writes a JSON artifact under target/. |
tests/basic.rs |
Updates tests to use fallible try_from_* constructors and adds TryFrom trait coverage. |
benches/mutation.rs |
New Criterion bench for push/add/reserve mutation paths. |
benches/pattern.rs |
New Criterion bench for substring search and reusable finder behavior. |
benches/layout.rs |
New bench that emits a layout JSON artifact for benchmarking builds. |
benches/comprehensive.rs |
Updates bench to use try_from_vec instead of infallible byte conversion. |
scripts/bench-all.sh |
Adds a helper script to run and capture multiple benches/tests into bench-results/. |
scripts/bench-all.ps1 |
PowerShell equivalent for running and capturing benchmark outputs. |
bench-results/README.md |
Documents intended benchmark artifact layout and metadata expectations. |
README.md |
Updates README for new version and default search implementation wording. |
.github/workflows/ci.yaml |
Expands CI to a multi-OS matrix and uploads layout artifacts. |
.github/workflows/release.yml |
Adds a release workflow for tag-based and manual dispatch publishing. |
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| [dependencies] | ||
| bytes = "1.10.0" | ||
| bytes = { version = "1.10.0", optional = true, default-features = false } | ||
| memchr = { version = "2", default-features = false } | ||
| serde = { version = "1.0", optional = true, default-features = false, features = ["alloc"] } |
| impl<'a> TryFrom<&'a [u8]> for CheetahString { | ||
| type Error = Utf8Error; | ||
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||
| #[inline] | ||
| fn from(b: &[u8]) -> Self { | ||
| // SAFETY: This is unsafe and may cause UB if bytes are not valid UTF-8. | ||
| // This will be deprecated in favor of try_from_bytes in the next version. | ||
| CheetahString::from_slice(unsafe { str::from_utf8_unchecked(b) }) | ||
| fn try_from(b: &'a [u8]) -> Result<Self, Self::Error> { |
| - name: Create tag for manual release | ||
| if: github.event_name == 'workflow_dispatch' | ||
| shell: bash | ||
| run: | | ||
| TAG="${{ steps.version.outputs.tag }}" |
| #!/usr/bin/env sh | ||
| set -eu |
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| mod cheetah_string; | ||
| mod error; | ||
| mod search; |
| /// Find the first occurrence of needle in haystack using SIMD when available | ||
| #[allow(dead_code)] | ||
| #[inline] | ||
| pub(crate) fn find_bytes(haystack: &[u8], needle: &[u8]) -> Option<usize> { |
Implements the push_str/Add/reserve fast-path stage.
Scope:
push_strinAddimplementations.Verification completed locally:
cargo test --test mutation --all-featurescargo bench --bench mutation --no-runCloses #111.