Implement rustc_datastructures::RwLock as union over RefCell and parking_lot::RwLock.

compiler/rustc_data_structures/src/sync.rs

@@ -25,29 +25,26 @@
 use std::collections::HashMap;
 use std::hash::{BuildHasher, Hash};
 
-pub use parking_lot::{
-    MappedRwLockReadGuard as MappedReadGuard, MappedRwLockWriteGuard as MappedWriteGuard,
-    RwLockReadGuard as ReadGuard, RwLockWriteGuard as WriteGuard,
-};
-
 pub use self::atomic::AtomicU64;
 pub use self::freeze::{FreezeLock, FreezeReadGuard, FreezeWriteGuard};
 #[doc(no_inline)]
-pub use self::lock::{Lock, LockGuard, Mode};
+pub use self::lock::{Lock, LockGuard};
 pub use self::mode::{
-    FromDyn, check_dyn_thread_safe, is_dyn_thread_safe, set_dyn_thread_safe_mode,
+    FromDyn, Mode, check_dyn_thread_safe, is_dyn_thread_safe, set_dyn_thread_safe_mode,
 };
 pub use self::parallel::{
     broadcast, par_fns, par_for_each_in, par_join, par_map, parallel_guard, spawn,
     try_par_for_each_in,
 };
+pub use self::rw_lock::{MappedReadGuard, MappedWriteGuard, ReadGuard, RwLock, WriteGuard};
 pub use self::vec::{AppendOnlyIndexVec, AppendOnlyVec};
 pub use self::worker_local::{Registry, WorkerLocal};
 pub use crate::marker::*;
 
 mod freeze;
 mod lock;
 mod parallel;
+mod rw_lock;
 mod vec;
 mod worker_local;
 
@@ -68,6 +65,12 @@ mod mode {
 
     use crate::sync::{DynSend, DynSync};
 
+    #[derive(Clone, Copy, PartialEq)]
+    pub enum Mode {
+        NoSync,
+        Sync,
+    }
+
     const UNINITIALIZED: u8 = 0;
     const DYN_NOT_THREAD_SAFE: u8 = 1;
     const DYN_THREAD_SAFE: u8 = 2;
@@ -149,10 +152,6 @@ mod mode {
     }
 }
 
-/// This makes locks panic if they are already held.
-/// It is only useful when you are running in a single thread
-const ERROR_CHECKING: bool = false;
-
 #[derive(Default)]
 #[repr(align(64))]
 pub struct CacheAligned<T>(pub T);
@@ -168,58 +167,3 @@ impl<K: Eq + Hash, V: Eq, S: BuildHasher> HashMapExt<K, V> for HashMap<K, V, S>
         self.entry(key).and_modify(|old| assert!(*old == value)).or_insert(value);
     }
 }
-
-#[derive(Debug, Default)]
-pub struct RwLock<T>(parking_lot::RwLock<T>);
-
-impl<T> RwLock<T> {
-    #[inline(always)]
-    pub fn new(inner: T) -> Self {
-        RwLock(parking_lot::RwLock::new(inner))
-    }
-
-    #[inline(always)]
-    pub fn into_inner(self) -> T {
-        self.0.into_inner()
-    }
-
-    #[inline(always)]
-    pub fn get_mut(&mut self) -> &mut T {
-        self.0.get_mut()
-    }
-
-    #[inline(always)]
-    pub fn read(&self) -> ReadGuard<'_, T> {
-        if ERROR_CHECKING {
-            self.0.try_read().expect("lock was already held")
-        } else {
-            self.0.read()
-        }
-    }
-
-    #[inline(always)]
-    pub fn try_write(&self) -> Result<WriteGuard<'_, T>, ()> {
-        self.0.try_write().ok_or(())
-    }
-
-    #[inline(always)]
-    pub fn write(&self) -> WriteGuard<'_, T> {
-        if ERROR_CHECKING {
-            self.0.try_write().expect("lock was already held")
-        } else {
-            self.0.write()
-        }
-    }
-
-    #[inline(always)]
-    #[track_caller]
-    pub fn borrow(&self) -> ReadGuard<'_, T> {
-        self.read()
-    }
-
-    #[inline(always)]
-    #[track_caller]
-    pub fn borrow_mut(&self) -> WriteGuard<'_, T> {
-        self.write()
-    }
-}

compiler/rustc_data_structures/src/sync/lock.rs

@@ -1,19 +1,13 @@
 //! This module implements a lock which only uses synchronization if `might_be_dyn_thread_safe` is true.
 //! It implements `DynSend` and `DynSync` instead of the typical `Send` and `Sync` traits.
 
-use std::{fmt, hint};
-
-#[derive(Clone, Copy, PartialEq)]
-pub enum Mode {
-    NoSync,
-    Sync,
-}
-
 use std::cell::{Cell, UnsafeCell};
 use std::marker::PhantomData;
 use std::mem::ManuallyDrop;
 use std::ops::{Deref, DerefMut};
+use std::{fmt, hint};
 
+use mode::Mode;
 use parking_lot::RawMutex;
 use parking_lot::lock_api::RawMutex as _;