Always use WaitOnAddress on Win10+

Author: ChrisDenton

library/std/src/sys/pal/windows/c.rs

@@ -28,17 +28,14 @@ pub type SIZE_T = usize;
 pub type WORD = u16;
 pub type CHAR = c_char;
 pub type ULONG = c_ulong;
-pub type ACCESS_MASK = DWORD;
 
 pub type LPCVOID = *const c_void;
-pub type LPHANDLE = *mut HANDLE;
 pub type LPOVERLAPPED = *mut OVERLAPPED;
 pub type LPSECURITY_ATTRIBUTES = *mut SECURITY_ATTRIBUTES;
 pub type LPVOID = *mut c_void;
 pub type LPWCH = *mut WCHAR;
 pub type LPWSTR = *mut WCHAR;
 
-pub type PLARGE_INTEGER = *mut c_longlong;
 pub type PSRWLOCK = *mut SRWLOCK;
 
 pub type socklen_t = c_int;
@@ -345,6 +342,19 @@ compat_fn_with_fallback! {
     }
 }
 
+#[cfg(not(target_vendor = "win7"))]
+#[link(name = "synchronization")]
+extern "system" {
+    pub fn WaitOnAddress(
+        address: *const c_void,
+        compareaddress: *const c_void,
+        addresssize: usize,
+        dwmilliseconds: u32,
+    ) -> BOOL;
+    pub fn WakeByAddressSingle(address: *const c_void);
+}
+
+#[cfg(target_vendor = "win7")]
 compat_fn_optional! {
     crate::sys::compat::load_synch_functions();
     pub fn WaitOnAddress(
@@ -356,30 +366,34 @@ compat_fn_optional! {
     pub fn WakeByAddressSingle(address: *const ::core::ffi::c_void);
 }
 
+#[cfg(any(target_vendor = "win7", target_vendor = "uwp"))]
 compat_fn_with_fallback! {
     pub static NTDLL: &CStr = c"ntdll";
 
+    #[cfg(target_vendor = "win7")]
     pub fn NtCreateKeyedEvent(
-        KeyedEventHandle: LPHANDLE,
-        DesiredAccess: ACCESS_MASK,
+        KeyedEventHandle: *mut HANDLE,
+        DesiredAccess: DWORD,
         ObjectAttributes: LPVOID,
         Flags: ULONG
     ) -> NTSTATUS {
         panic!("keyed events not available")
     }
+    #[cfg(target_vendor = "win7")]
     pub fn NtReleaseKeyedEvent(
         EventHandle: HANDLE,
         Key: LPVOID,
         Alertable: BOOLEAN,
-        Timeout: PLARGE_INTEGER
+        Timeout: *mut c_longlong
     ) -> NTSTATUS {
         panic!("keyed events not available")
     }
+    #[cfg(target_vendor = "win7")]
     pub fn NtWaitForKeyedEvent(
         EventHandle: HANDLE,
         Key: LPVOID,
         Alertable: BOOLEAN,
-        Timeout: PLARGE_INTEGER
+        Timeout: *mut c_longlong
     ) -> NTSTATUS {
         panic!("keyed events not available")
     }

library/std/src/sys/pal/windows/compat.rs

@@ -21,7 +21,6 @@
 
 use crate::ffi::{c_void, CStr};
 use crate::ptr::NonNull;
-use crate::sync::atomic::Ordering;
 use crate::sys::c;
 
 // This uses a static initializer to preload some imported functions.
@@ -38,6 +37,7 @@ use crate::sys::c;
 // file an issue for discussion; currently we don't guarantee any functionality
 // before main.
 // See https://docs.microsoft.com/en-us/cpp/c-runtime-library/crt-initialization?view=msvc-170
+#[cfg(target_vendor = "win7")]
 #[used]
 #[link_section = ".CRT$XCT"]
 static INIT_TABLE_ENTRY: unsafe extern "C" fn() = init;
@@ -52,6 +52,7 @@ static INIT_TABLE_ENTRY: unsafe extern "C" fn() = init;
 /// negative performance impact in practical situations.
 ///
 /// Currently we only preload `WaitOnAddress` and `WakeByAddressSingle`.
+#[cfg(target_vendor = "win7")]
 unsafe extern "C" fn init() {
     // In an exe this code is executed before main() so is single threaded.
     // In a DLL the system's loader lock will be held thereby synchronizing
@@ -183,6 +184,7 @@ macro_rules! compat_fn_with_fallback {
                 func($($argname),*)
             }
         }
+        #[allow(unused)]
         $(#[$meta])*
         $vis use $symbol::call as $symbol;
     )*)
@@ -191,6 +193,7 @@ macro_rules! compat_fn_with_fallback {
 /// Optionally loaded functions.
 ///
 /// Actual loading of the function defers to $load_functions.
+#[cfg(target_vendor = "win7")]
 macro_rules! compat_fn_optional {
     ($load_functions:expr;
     $(
@@ -218,13 +221,19 @@ macro_rules! compat_fn_optional {
                     NonNull::new(PTR.load(Ordering::Relaxed)).map(|f| unsafe { mem::transmute(f) })
                 }
             }
+            #[inline]
+            pub unsafe extern "system" fn $symbol($($argname: $argtype),*) $(-> $rettype)? {
+                $symbol::option().unwrap()($($argname),*)
+            }
         )+
     )
 }
 
 /// Load all needed functions from "api-ms-win-core-synch-l1-2-0".
+#[cfg(target_vendor = "win7")]
 pub(super) fn load_synch_functions() {
     fn try_load() -> Option<()> {
+        use crate::sync::atomic::Ordering;
         const MODULE_NAME: &CStr = c"api-ms-win-core-synch-l1-2-0";
         const WAIT_ON_ADDRESS: &CStr = c"WaitOnAddress";
         const WAKE_BY_ADDRESS_SINGLE: &CStr = c"WakeByAddressSingle";