chore: unify all mocked `loom` files (#1732)

When the crates were merged, each component kept its own `loom` file
containing mocked types it needed. This patch unifies them all in one
location.

9 files changed, 13 insertions, 67 deletions

diff --git a/tokio/src/sync/loom.rs b/tokio/src/sync/loom.rs
deleted file mode 100644
index 1b5a5c9d..00000000
--- a/tokio/src/sync/loom.rs
+++ /dev/null
@@ -1,48 +0,0 @@
-#[cfg(not(all(test, loom)))]
-mod imp {
-    pub(crate) mod future {
-        pub(crate) use crate::sync::task::AtomicWaker;
-    }
-
-    pub(crate) mod sync {
-        pub(crate) use std::sync::atomic;
-        pub(crate) use std::sync::Arc;
-
-        use std::cell::UnsafeCell;
-
-        pub(crate) struct CausalCell<T>(UnsafeCell<T>);
-
-        impl<T> CausalCell<T> {
-            pub(crate) fn new(data: T) -> CausalCell<T> {
-                CausalCell(UnsafeCell::new(data))
-            }
-
-            pub(crate) fn with<F, R>(&self, f: F) -> R
-            where
-                F: FnOnce(*const T) -> R,
-            {
-                f(self.0.get())
-            }
-
-            pub(crate) fn with_mut<F, R>(&self, f: F) -> R
-            where
-                F: FnOnce(*mut T) -> R,
-            {
-                f(self.0.get())
-            }
-        }
-    }
-
-    pub(crate) mod thread {
-        pub(crate) fn yield_now() {
-            ::std::sync::atomic::spin_loop_hint();
-        }
-    }
-}
-
-#[cfg(all(test, loom))]
-mod imp {
-    pub(crate) use loom::*;
-}
-
-pub(crate) use self::imp::*;
diff --git a/tokio/src/sync/mod.rs b/tokio/src/sync/mod.rs
index 84f6bd98..25f58ffd 100644
--- a/tokio/src/sync/mod.rs
+++ b/tokio/src/sync/mod.rs
@@ -37,8 +37,6 @@ macro_rules! if_loom {
 mod barrier;
 pub use barrier::{Barrier, BarrierWaitResult};
 
-mod loom;
-
 pub mod mpsc;
 
 mod mutex;
diff --git a/tokio/src/sync/mpsc/block.rs b/tokio/src/sync/mpsc/block.rs
index aea69384..f03648ba 100644
--- a/tokio/src/sync/mpsc/block.rs
+++ b/tokio/src/sync/mpsc/block.rs
@@ -1,6 +1,6 @@
-use crate::sync::loom::{
+use crate::loom::{
+    cell::CausalCell,
     sync::atomic::{AtomicPtr, AtomicUsize},
-    sync::CausalCell,
     thread,
 };
 
diff --git a/tokio/src/sync/mpsc/chan.rs b/tokio/src/sync/mpsc/chan.rs
index fe5ff904..ad0d99a8 100644
--- a/tokio/src/sync/mpsc/chan.rs
+++ b/tokio/src/sync/mpsc/chan.rs
@@ -1,8 +1,4 @@
-use crate::sync::loom::{
-    future::AtomicWaker,
-    sync::atomic::AtomicUsize,
-    sync::{Arc, CausalCell},
-};
+use crate::loom::{cell::CausalCell, future::AtomicWaker, sync::atomic::AtomicUsize, sync::Arc};
 use crate::sync::mpsc::list;
 
 use std::fmt;
diff --git a/tokio/src/sync/mpsc/list.rs b/tokio/src/sync/mpsc/list.rs
index a1295bb0..eecc4da3 100644
--- a/tokio/src/sync/mpsc/list.rs
+++ b/tokio/src/sync/mpsc/list.rs
@@ -1,6 +1,6 @@
 //! A concurrent, lock-free, FIFO list.
 
-use crate::sync::loom::{
+use crate::loom::{
     sync::atomic::{AtomicPtr, AtomicUsize},
     thread,
 };
diff --git a/tokio/src/sync/mpsc/unbounded.rs b/tokio/src/sync/mpsc/unbounded.rs
index 5a73771e..4eb750ef 100644
--- a/tokio/src/sync/mpsc/unbounded.rs
+++ b/tokio/src/sync/mpsc/unbounded.rs
@@ -1,4 +1,4 @@
-use crate::sync::loom::sync::atomic::AtomicUsize;
+use crate::loom::sync::atomic::AtomicUsize;
 use crate::sync::mpsc::chan;
 
 use std::fmt;
diff --git a/tokio/src/sync/oneshot.rs b/tokio/src/sync/oneshot.rs
index 7cf4eb8f..3c757e9e 100644
--- a/tokio/src/sync/oneshot.rs
+++ b/tokio/src/sync/oneshot.rs
@@ -1,6 +1,8 @@
 //! A channel for sending a single message between asynchronous tasks.
 
-use crate::sync::loom::sync::{atomic::AtomicUsize, Arc, CausalCell};
+use crate::loom::cell::CausalCell;
+use crate::loom::sync::atomic::AtomicUsize;
+use crate::loom::sync::Arc;
 
 use futures_core::ready;
 use std::fmt;
diff --git a/tokio/src/sync/semaphore.rs b/tokio/src/sync/semaphore.rs
index 1120be07..b4a093f8 100644
--- a/tokio/src/sync/semaphore.rs
+++ b/tokio/src/sync/semaphore.rs
@@ -8,12 +8,10 @@
 //! section. If no permits are available, then acquiring the semaphore returns
 //! `Pending`. The task is woken once a permit becomes available.
 
-use crate::sync::loom::{
+use crate::loom::{
+    cell::CausalCell,
     future::AtomicWaker,
-    sync::{
-        atomic::{AtomicPtr, AtomicUsize},
-        CausalCell,
-    },
+    sync::atomic::{AtomicPtr, AtomicUsize},
     thread,
 };
 
diff --git a/tokio/src/sync/task/atomic_waker.rs b/tokio/src/sync/task/atomic_waker.rs
index ff952a18..88d083d6 100644
--- a/tokio/src/sync/task/atomic_waker.rs
+++ b/tokio/src/sync/task/atomic_waker.rs
@@ -1,5 +1,5 @@
-use crate::sync::loom::sync::atomic::{self, AtomicUsize};
-use crate::sync::loom::sync::CausalCell;
+use crate::loom::cell::CausalCell;
+use crate::loom::sync::atomic::{self, AtomicUsize};
 
 use std::fmt;
 use std::sync::atomic::Ordering::{AcqRel, Acquire, Release};