3 use crate::num::NonZeroUsize;
4 use crate::os::windows::io::{AsRawHandle, FromRawHandle};
7 use crate::sys::handle::Handle;
8 use crate::sys::stack_overflow;
9 use crate::time::Duration;
15 pub const DEFAULT_MIN_STACK_SIZE: usize = 2 * 1024 * 1024;
22 // unsafe: see thread::Builder::spawn_unchecked for safety requirements
23 pub unsafe fn new(stack: usize, p: Box<dyn FnOnce()>) -> io::Result<Thread> {
24 let p = Box::into_raw(box p);
26 // FIXME On UNIX, we guard against stack sizes that are too small but
27 // that's because pthreads enforces that stacks are at least
28 // PTHREAD_STACK_MIN bytes big. Windows has no such lower limit, it's
29 // just that below a certain threshold you can't do anything useful.
30 // That threshold is application and architecture-specific, however.
31 // Round up to the next 64 kB because that's what the NT kernel does,
32 // might as well make it explicit.
33 let stack_size = (stack + 0xfffe) & (!0xfffe);
34 let ret = c::CreateThread(
39 c::STACK_SIZE_PARAM_IS_A_RESERVATION,
43 return if ret as usize == 0 {
44 // The thread failed to start and as a result p was not consumed. Therefore, it is
45 // safe to reconstruct the box so that it gets deallocated.
46 drop(Box::from_raw(p));
47 Err(io::Error::last_os_error())
49 Ok(Thread { handle: Handle::from_raw_handle(ret) })
52 extern "system" fn thread_start(main: *mut c_void) -> c::DWORD {
54 // Next, set up our stack overflow handler which may get triggered if we run
56 let _handler = stack_overflow::Handler::new();
57 // Finally, let's run some code.
58 Box::from_raw(main as *mut Box<dyn FnOnce()>)();
64 pub fn set_name(name: &CStr) {
65 if let Ok(utf8) = name.to_str() {
66 if let Ok(utf16) = to_u16s(utf8) {
68 c::SetThreadDescription(c::GetCurrentThread(), utf16.as_ptr());
75 let rc = unsafe { c::WaitForSingleObject(self.handle.as_raw_handle(), c::INFINITE) };
76 if rc == c::WAIT_FAILED {
77 panic!("failed to join on thread: {}", io::Error::last_os_error());
82 // This function will return 0 if there are no other threads to execute,
83 // but this also means that the yield was useless so this isn't really a
84 // case that needs to be worried about.
90 pub fn sleep(dur: Duration) {
91 unsafe { c::Sleep(super::dur2timeout(dur)) }
94 pub fn handle(&self) -> &Handle {
98 pub fn into_handle(self) -> Handle {
103 pub fn available_parallelism() -> io::Result<NonZeroUsize> {
105 let mut sysinfo: c::SYSTEM_INFO = crate::mem::zeroed();
106 c::GetSystemInfo(&mut sysinfo);
107 sysinfo.dwNumberOfProcessors as usize
110 0 => Err(io::Error::new_const(
111 io::ErrorKind::NotFound,
112 &"The number of hardware threads is not known for the target platform",
114 cpus => Ok(unsafe { NonZeroUsize::new_unchecked(cpus) }),
118 #[cfg_attr(test, allow(dead_code))]
121 pub unsafe fn current() -> Option<Guard> {
124 pub unsafe fn init() -> Option<Guard> {