Add contributor-only Shuttle lock tests

.github/workflows/ci.yml

@@ -10,7 +10,15 @@ jobs:
     - name: style
       run: cargo fmt -- --check
     - name: clippy
-      run: cargo clippy --all-targets --all-features -- -D warnings
+      run: cargo clippy --all-targets --features all -- -D warnings
+
+  shuttle:
+    runs-on: ubuntu-22.04
+    steps:
+    - uses: actions/checkout@v2
+    - uses: dtolnay/rust-toolchain@stable
+    - name: test
+      run: RUSTUP_TOOLCHAIN=stable cargo test --features shuttle --test shuttle
 
   test:
     runs-on: ubuntu-22.04

Cargo.toml

@@ -16,12 +16,14 @@ categories = ["concurrency", "algorithms", "data-structures"]
 [features]
 all = ["raw-api", "typesize", "serde", "rayon", "arbitrary"]
 raw-api = []
+shuttle = ["dep:shuttle"]
 typesize = ["dep:typesize"]
 inline-more = ["hashbrown/inline-more"]
 
 [dependencies]
 lock_api = "0.4.12"
 parking_lot_core = "0.9.10"
+shuttle = { version = "0.9.1", optional = true }
 equivalent = "1.0.1"
 hashbrown = { version = "0.15.2", default-features = false }
 serde = { version = "1.0.217", optional = true, features = ["derive"] }
@@ -33,3 +35,8 @@ typesize = { version = "0.1.13", default-features = false, features = ["hashbrow
 
 [package.metadata.docs.rs]
 features = ["all"]
+
+[[test]]
+name = "shuttle"
+path = "tests/shuttle.rs"
+required-features = ["shuttle"]

README.md

@@ -47,6 +47,21 @@ I will take a look as soon as I have time for it.
 That said I do not get paid (yet) to work on open-source. This means
 that my time is limited and my work here comes after my personal life.
 
+### Concurrency Testing
+
+DashMap includes a contributor-only [Shuttle](https://docs.rs/shuttle)-based test mode for
+model checking the internal lock implementation. This is not part of DashMap's supported
+runtime feature surface and is only intended to be run through the dedicated integration
+test target.
+
+Use a current stable toolchain and run:
+
+```bash
+RUSTUP_TOOLCHAIN=stable cargo test --features shuttle --test shuttle
+```
+
+Running the full crate test suite with `--features shuttle` is intentionally unsupported.
+
 ## Performance
 
 A comprehensive benchmark suite including DashMap can be found [here](https://github.com/xacrimon/conc-map-bench).