Merge pull request #63 from rust-embedded/revert-loom

Revert "Add `loom` support to `std` critical section implementation"

Author: MabezDev

.github/workflows/clippy.yml

@@ -18,10 +18,6 @@ jobs:
             features: ''
           - rust: 1.63
             features: 'std'
-          - rust: 1.73
-            features: 'std'
-            cfgs: "--cfg loom"
-
     steps:
       - uses: actions/checkout@v2
       - name: Install Rust
@@ -31,4 +27,4 @@ jobs:
             components: clippy
             override: true
       - name: Clippy check
-        run: RUSTFLAGS="${{matrix.cfgs}}" cargo clippy --features "${{matrix.features}}"
+        run: cargo clippy --features "${{matrix.features}}"

.github/workflows/test.yml

@@ -18,12 +18,6 @@ jobs:
             features: ''
           - rust: 1.63
             features: 'std'
-          - rust: 1.73
-            features: 'std'
-            cfgs: "--cfg loom"
-            # Lib tests are the only relevant & working ones
-            # for loom.
-            extra_flags: "--lib"
     steps:
       - uses: actions/checkout@v2
       - name: Install Rust
@@ -33,4 +27,4 @@ jobs:
             components: clippy
             override: true
       - name: Test
-        run: RUSTFLAGS="${{matrix.cfgs}}" cargo test --features "${{matrix.features}}" ${{matrix.extra_flags}}
+        run: cargo test --features "${{matrix.features}}"

Cargo.toml

@@ -29,9 +29,3 @@ restore-state-u16 = []
 restore-state-u32 = []
 restore-state-u64 = []
 restore-state-usize = []
-
-[target.'cfg(loom)'.dependencies]
-loom = "0.7.2"
-
-[lints.rust]
-unexpected_cfgs = { level = "allow", check-cfg = ['cfg(loom)'] }

README.md

@@ -99,13 +99,6 @@ provide an implementation based on `std::sync::Mutex`, so you don't have to add
 critical-section = { version = "1.1", features = ["std"]}
 ```
 
-## Usage in [`loom`] tests
-
-`critical-section` supports [`loom`] by enabling the `std` feature and passing `--cfg loom` as `RUSTFLAGS` (either through `.cargo/config.toml`, or through the environment variable).
-This implementation is identical to the normal `std` implementation, but uses `loom` synchronization primitives instead.
-
-[`loom`]: https://docs.rs/loom/latest/loom/#writing-tests
-
 ## Usage in libraries
 
 If you're writing a library intended to be portable across many targets, simply add a dependency on `critical-section`
@@ -226,7 +219,6 @@ This crate is guaranteed to compile on the following Rust versions:
 
 - If the `std` feature is not enabled: stable Rust 1.54 and up.
 - If the `std` feature is enabled: stable Rust 1.63 and up.
-- If the `std` feature and `--cfg loom` are enabled: stable Rust 1.73 and up.
 
 It might compile with older versions but that may change in any new patch release.
 

src/std.rs

@@ -1,31 +1,13 @@
+use std::cell::Cell;
 use std::mem::MaybeUninit;
+use std::sync::{Mutex, MutexGuard};
 
-#[cfg(not(loom))]
-use std::{
-    cell::Cell,
-    sync::{Mutex, MutexGuard},
-    thread_local,
-};
-
-#[cfg(loom)]
-use loom::{
-    cell::Cell,
-    sync::{Mutex, MutexGuard},
-    thread_local,
-};
-
-#[cfg(not(loom))]
 static GLOBAL_MUTEX: Mutex<()> = Mutex::new(());
 
-#[cfg(loom)]
-loom::lazy_static! {
-    static ref GLOBAL_MUTEX: Mutex<()> = Mutex::new(());
-}
-
 // This is initialized if a thread has acquired the CS, uninitialized otherwise.
 static mut GLOBAL_GUARD: MaybeUninit<MutexGuard<'static, ()>> = MaybeUninit::uninit();
 
-thread_local!(static IS_LOCKED: Cell<bool> = Cell::new(false));
+std::thread_local!(static IS_LOCKED: Cell<bool> = Cell::new(false));
 
 struct StdCriticalSection;
 crate::set_impl!(StdCriticalSection);
@@ -82,7 +64,6 @@ unsafe impl crate::Impl for StdCriticalSection {
 }
 
 #[cfg(test)]
-#[cfg(not(loom))]
 mod tests {
     use std::thread;
 
@@ -104,30 +85,3 @@ mod tests {
         })
     }
 }
-
-#[cfg(test)]
-#[cfg(loom)]
-mod tests {
-    use crate as critical_section;
-
-    #[cfg(feature = "std")]
-    #[test]
-    #[should_panic(expected = "Not a PoisonError!")]
-    fn reusable_after_panic_loom() {
-        loom::model(|| {
-            // IMPORTANT: using `std::thread` here because `loom` is effectively
-            // single-threaded, so panicking in `loom::thread` will panic the
-            // entire test.
-            let _ = std::thread::spawn(|| {
-                critical_section::with(|_| {
-                    panic!("Boom!");
-                });
-            })
-            .join();
-
-            critical_section::with(|_| {
-                panic!("Not a PoisonError!");
-            })
-        })
-    }
-}