sync: add OnceCell::wait_initialized method

spellcheck.dic

@@ -1,4 +1,4 @@
-300
+302
 &
 +
 <
@@ -139,6 +139,7 @@ implementers
 implementor
 implementors
 incrementing
+initializer
 inlining
 interoperate
 invariants
@@ -299,3 +300,4 @@ Wakers
 wakeup
 wakeups
 workstealing
+ZSTs

tokio/Cargo.toml

@@ -27,18 +27,18 @@ default = []
 
 # enable everything
 full = [
-  "fs",
-  "io-util",
-  "io-std",
-  "macros",
-  "net",
-  "parking_lot",
-  "process",
-  "rt",
-  "rt-multi-thread",
-  "signal",
-  "sync",
-  "time",
+    "fs",
+    "io-util",
+    "io-std",
+    "macros",
+    "net",
+    "parking_lot",
+    "process",
+    "rt",
+    "rt-multi-thread",
+    "signal",
+    "sync",
+    "time",
 ]
 
 fs = []
@@ -47,39 +47,39 @@ io-util = ["bytes"]
 io-std = []
 macros = ["tokio-macros"]
 net = [
-  "libc",
-  "mio/os-poll",
-  "mio/os-ext",
-  "mio/net",
-  "socket2",
-  "windows-sys/Win32_Foundation",
-  "windows-sys/Win32_Security",
-  "windows-sys/Win32_Storage_FileSystem",
-  "windows-sys/Win32_System_Pipes",
-  "windows-sys/Win32_System_SystemServices",
+    "libc",
+    "mio/os-poll",
+    "mio/os-ext",
+    "mio/net",
+    "socket2",
+    "windows-sys/Win32_Foundation",
+    "windows-sys/Win32_Security",
+    "windows-sys/Win32_Storage_FileSystem",
+    "windows-sys/Win32_System_Pipes",
+    "windows-sys/Win32_System_SystemServices",
 ]
 process = [
-  "bytes",
-  "libc",
-  "mio/os-poll",
-  "mio/os-ext",
-  "mio/net",
-  "signal-hook-registry",
-  "windows-sys/Win32_Foundation",
-  "windows-sys/Win32_System_Threading",
-  "windows-sys/Win32_System_WindowsProgramming",
+    "bytes",
+    "libc",
+    "mio/os-poll",
+    "mio/os-ext",
+    "mio/net",
+    "signal-hook-registry",
+    "windows-sys/Win32_Foundation",
+    "windows-sys/Win32_System_Threading",
+    "windows-sys/Win32_System_WindowsProgramming",
 ]
 # Includes basic task execution capabilities
 rt = []
 rt-multi-thread = ["rt"]
 signal = [
-  "libc",
-  "mio/os-poll",
-  "mio/net",
-  "mio/os-ext",
-  "signal-hook-registry",
-  "windows-sys/Win32_Foundation",
-  "windows-sys/Win32_System_Console",
+    "libc",
+    "mio/os-poll",
+    "mio/net",
+    "mio/os-ext",
+    "signal-hook-registry",
+    "windows-sys/Win32_Foundation",
+    "windows-sys/Win32_System_Console",
 ]
 sync = []
 test-util = ["rt", "sync", "time"]
@@ -123,8 +123,8 @@ optional = true
 [target.'cfg(windows)'.dev-dependencies.windows-sys]
 version = "0.52"
 features = [
-  "Win32_Foundation",
-  "Win32_Security_Authorization",
+    "Win32_Foundation",
+    "Win32_Security_Authorization",
 ]
 
 [dev-dependencies]
@@ -169,9 +169,9 @@ features = ["full", "test-util"]
 # The following are types that are allowed to be exposed in Tokio's public API.
 # The standard library is allowed by default.
 allowed_external_types = [
-  "bytes::buf::buf_impl::Buf",
-  "bytes::buf::buf_mut::BufMut",
-  "tokio_macros::*",
+    "bytes::buf::buf_impl::Buf",
+    "bytes::buf::buf_mut::BufMut",
+    "tokio_macros::*",
 ]
 
 [lints]

tokio/src/loom/std/atomic_u8.rs

@@ -0,0 +1,35 @@
+use std::cell::UnsafeCell;
+use std::fmt;
+use std::ops::Deref;
+use std::panic;
+
+/// `AtomicU8` providing an additional `with_mut` function.
+pub(crate) struct AtomicU8 {
+    inner: std::sync::atomic::AtomicU8,
+}
+
+impl AtomicU8 {
+    pub(crate) const fn new(val: u8) -> AtomicU8 {
+        let inner = std::sync::atomic::AtomicU8::new(val);
+        AtomicU8 { inner }
+    }
+
+    /// Get access to a mutable reference to the inner value.
+    pub(crate) fn with_mut<R>(&mut self, f: impl FnOnce(&mut u8) -> R) -> R {
+        f(self.inner.get_mut())
+    }
+}
+
+impl Deref for AtomicU8 {
+    type Target = std::sync::atomic::AtomicU8;
+
+    fn deref(&self) -> &Self::Target {
+        &self.inner
+    }
+}
+
+impl fmt::Debug for AtomicU8 {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.deref().fmt(fmt)
+    }
+}

tokio/src/loom/std/mod.rs

@@ -3,6 +3,7 @@
 mod atomic_u16;
 mod atomic_u32;
 mod atomic_u64;
+mod atomic_u8;
 mod atomic_usize;
 mod barrier;
 mod mutex;
@@ -77,9 +78,10 @@ pub(crate) mod sync {
         pub(crate) use crate::loom::std::atomic_u16::AtomicU16;
         pub(crate) use crate::loom::std::atomic_u32::AtomicU32;
         pub(crate) use crate::loom::std::atomic_u64::{AtomicU64, StaticAtomicU64};
+        pub(crate) use crate::loom::std::atomic_u8::AtomicU8;
         pub(crate) use crate::loom::std::atomic_usize::AtomicUsize;
 
-        pub(crate) use std::sync::atomic::{fence, AtomicBool, AtomicPtr, AtomicU8, Ordering};
+        pub(crate) use std::sync::atomic::{fence, AtomicBool, AtomicPtr, Ordering};
     }
 
     pub(crate) use super::barrier::Barrier;

tokio/src/macros/cfg.rs

@@ -144,6 +144,20 @@ macro_rules! cfg_io_driver_impl {
     }
 }
 
+macro_rules! cfg_io_driver_or_sync {
+    ( $( $item:item )* ) => {
+        $(
+            #[cfg(any(
+                feature = "net",
+                all(unix, feature = "process"),
+                all(unix, feature = "signal"),
+                feature = "sync",
+            ))]
+            $item
+        )*
+    }
+}
+
 macro_rules! cfg_not_io_driver {
     ($($item:item)*) => {
         $(

tokio/src/sync/batch_semaphore.rs

@@ -193,33 +193,6 @@ impl Semaphore {
         }
     }
 
-    /// Creates a new closed semaphore with 0 permits.
-    pub(crate) fn new_closed() -> Self {
-        Self {
-            permits: AtomicUsize::new(Self::CLOSED),
-            waiters: Mutex::new(Waitlist {
-                queue: LinkedList::new(),
-                closed: true,
-            }),
-            #[cfg(all(tokio_unstable, feature = "tracing"))]
-            resource_span: tracing::Span::none(),
-        }
-    }
-
-    /// Creates a new closed semaphore with 0 permits.
-    #[cfg(not(all(loom, test)))]
-    pub(crate) const fn const_new_closed() -> Self {
-        Self {
-            permits: AtomicUsize::new(Self::CLOSED),
-            waiters: Mutex::const_new(Waitlist {
-                queue: LinkedList::new(),
-                closed: true,
-            }),
-            #[cfg(all(tokio_unstable, feature = "tracing"))]
-            resource_span: tracing::Span::none(),
-        }
-    }
-
     /// Returns the current number of available permits.
     pub(crate) fn available_permits(&self) -> usize {
         self.permits.load(Acquire) >> Self::PERMIT_SHIFT