3 use crate::num::NonZeroUsize;
4 use crate::os::windows::io::AsRawHandle;
7 use crate::sys::handle::Handle;
8 use crate::sys::stack_overflow;
9 use crate::sys_common::FromInner;
10 use crate::time::Duration;
16 pub const DEFAULT_MIN_STACK_SIZE: usize = 2 * 1024 * 1024;
23 // unsafe: see thread::Builder::spawn_unchecked for safety requirements
24 pub unsafe fn new(stack: usize, p: Box<dyn FnOnce()>) -> io::Result<Thread> {
25 let p = Box::into_raw(Box::new(p));
27 // FIXME On UNIX, we guard against stack sizes that are too small but
28 // that's because pthreads enforces that stacks are at least
29 // PTHREAD_STACK_MIN bytes big. Windows has no such lower limit, it's
30 // just that below a certain threshold you can't do anything useful.
31 // That threshold is application and architecture-specific, however.
32 let ret = c::CreateThread(
37 c::STACK_SIZE_PARAM_IS_A_RESERVATION,
41 return if let Ok(handle) = ret.try_into() {
42 Ok(Thread { handle: Handle::from_inner(handle) })
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())
50 extern "system" fn thread_start(main: *mut c_void) -> c::DWORD {
52 // Next, set up our stack overflow handler which may get triggered if we run
54 let _handler = stack_overflow::Handler::new();
55 // Finally, let's run some code.
56 Box::from_raw(main as *mut Box<dyn FnOnce()>)();
62 pub fn set_name(name: &CStr) {
63 if let Ok(utf8) = name.to_str() {
64 if let Ok(utf16) = to_u16s(utf8) {
66 c::SetThreadDescription(c::GetCurrentThread(), utf16.as_ptr());
73 let rc = unsafe { c::WaitForSingleObject(self.handle.as_raw_handle(), c::INFINITE) };
74 if rc == c::WAIT_FAILED {
75 panic!("failed to join on thread: {}", io::Error::last_os_error());
80 // This function will return 0 if there are no other threads to execute,
81 // but this also means that the yield was useless so this isn't really a
82 // case that needs to be worried about.
88 pub fn sleep(dur: Duration) {
89 unsafe { c::Sleep(super::dur2timeout(dur)) }
92 pub fn handle(&self) -> &Handle {
96 pub fn into_handle(self) -> Handle {
101 pub fn available_parallelism() -> io::Result<NonZeroUsize> {
103 let mut sysinfo: c::SYSTEM_INFO = crate::mem::zeroed();
104 c::GetSystemInfo(&mut sysinfo);
105 sysinfo.dwNumberOfProcessors as usize
108 0 => Err(io::const_io_error!(
109 io::ErrorKind::NotFound,
110 "The number of hardware threads is not known for the target platform",
112 cpus => Ok(unsafe { NonZeroUsize::new_unchecked(cpus) }),
116 #[cfg_attr(test, allow(dead_code))]
119 pub unsafe fn current() -> Option<Guard> {
122 pub unsafe fn init() -> Option<Guard> {