1 files changed, 125 insertions, 0 deletions
diff --git a/library/std/src/sys/windows/thread.rs b/library/std/src/sys/windows/thread.rs
new file mode 100644
index 000000000..c5c9e97e6
--- /dev/null
+++ b/library/std/src/sys/windows/thread.rs
@@ -0,0 +1,125 @@
+use crate::ffi::CStr;
+use crate::io;
+use crate::num::NonZeroUsize;
+use crate::os::windows::io::AsRawHandle;
+use crate::ptr;
+use crate::sys::c;
+use crate::sys::handle::Handle;
+use crate::sys::stack_overflow;
+use crate::sys_common::FromInner;
+use crate::time::Duration;
+
+use libc::c_void;
+
+use super::to_u16s;
+
+pub const DEFAULT_MIN_STACK_SIZE: usize = 2 * 1024 * 1024;
+
+pub struct Thread {
+    handle: Handle,
+}
+
+impl Thread {
+    // unsafe: see thread::Builder::spawn_unchecked for safety requirements
+    pub unsafe fn new(stack: usize, p: Box<dyn FnOnce()>) -> io::Result<Thread> {
+        let p = Box::into_raw(box p);
+
+        // FIXME On UNIX, we guard against stack sizes that are too small but
+        // that's because pthreads enforces that stacks are at least
+        // PTHREAD_STACK_MIN bytes big.  Windows has no such lower limit, it's
+        // just that below a certain threshold you can't do anything useful.
+        // That threshold is application and architecture-specific, however.
+        let ret = c::CreateThread(
+            ptr::null_mut(),
+            stack,
+            thread_start,
+            p as *mut _,
+            c::STACK_SIZE_PARAM_IS_A_RESERVATION,
+            ptr::null_mut(),
+        );
+
+        return if let Ok(handle) = ret.try_into() {
+            Ok(Thread { handle: Handle::from_inner(handle) })
+        } else {
+            // The thread failed to start and as a result p was not consumed. Therefore, it is
+            // safe to reconstruct the box so that it gets deallocated.
+            drop(Box::from_raw(p));
+            Err(io::Error::last_os_error())
+        };
+
+        extern "system" fn thread_start(main: *mut c_void) -> c::DWORD {
+            unsafe {
+                // Next, set up our stack overflow handler which may get triggered if we run
+                // out of stack.
+                let _handler = stack_overflow::Handler::new();
+                // Finally, let's run some code.
+                Box::from_raw(main as *mut Box<dyn FnOnce()>)();
+            }
+            0
+        }
+    }
+
+    pub fn set_name(name: &CStr) {
+        if let Ok(utf8) = name.to_str() {
+            if let Ok(utf16) = to_u16s(utf8) {
+                unsafe {
+                    c::SetThreadDescription(c::GetCurrentThread(), utf16.as_ptr());
+                };
+            };
+        };
+    }
+
+    pub fn join(self) {
+        let rc = unsafe { c::WaitForSingleObject(self.handle.as_raw_handle(), c::INFINITE) };
+        if rc == c::WAIT_FAILED {
+            panic!("failed to join on thread: {}", io::Error::last_os_error());
+        }
+    }
+
+    pub fn yield_now() {
+        // This function will return 0 if there are no other threads to execute,
+        // but this also means that the yield was useless so this isn't really a
+        // case that needs to be worried about.
+        unsafe {
+            c::SwitchToThread();
+        }
+    }
+
+    pub fn sleep(dur: Duration) {
+        unsafe { c::Sleep(super::dur2timeout(dur)) }
+    }
+
+    pub fn handle(&self) -> &Handle {
+        &self.handle
+    }
+
+    pub fn into_handle(self) -> Handle {
+        self.handle
+    }
+}
+
+pub fn available_parallelism() -> io::Result<NonZeroUsize> {
+    let res = unsafe {
+        let mut sysinfo: c::SYSTEM_INFO = crate::mem::zeroed();
+        c::GetSystemInfo(&mut sysinfo);
+        sysinfo.dwNumberOfProcessors as usize
+    };
+    match res {
+        0 => Err(io::const_io_error!(
+            io::ErrorKind::NotFound,
+            "The number of hardware threads is not known for the target platform",
+        )),
+        cpus => Ok(unsafe { NonZeroUsize::new_unchecked(cpus) }),
+    }
+}
+
+#[cfg_attr(test, allow(dead_code))]
+pub mod guard {
+    pub type Guard = !;
+    pub unsafe fn current() -> Option<Guard> {
+        None
+    }
+    pub unsafe fn init() -> Option<Guard> {
+        None
+    }
+}