1 use crate::convert::TryInto;
4 use crate::num::NonZeroUsize;
5 use crate::os::windows::io::AsRawHandle;
8 use crate::sys::handle::Handle;
9 use crate::sys::stack_overflow;
10 use crate::sys_common::FromInner;
11 use crate::time::Duration;
17 pub const DEFAULT_MIN_STACK_SIZE: usize = 2 * 1024 * 1024;
24 // unsafe: see thread::Builder::spawn_unchecked for safety requirements
25 pub unsafe fn new(stack: usize, p: Box<dyn FnOnce()>) -> io::Result<Thread> {
26 let p = Box::into_raw(box p);
28 // FIXME On UNIX, we guard against stack sizes that are too small but
29 // that's because pthreads enforces that stacks are at least
30 // PTHREAD_STACK_MIN bytes big. Windows has no such lower limit, it's
31 // just that below a certain threshold you can't do anything useful.
32 // That threshold is application and architecture-specific, however.
33 // Round up to the next 64 kB because that's what the NT kernel does,
34 // might as well make it explicit.
35 let stack_size = (stack + 0xfffe) & (!0xfffe);
36 let ret = c::CreateThread(
41 c::STACK_SIZE_PARAM_IS_A_RESERVATION,
45 return if let Ok(handle) = ret.try_into() {
46 Ok(Thread { handle: Handle::from_inner(handle) })
48 // The thread failed to start and as a result p was not consumed. Therefore, it is
49 // safe to reconstruct the box so that it gets deallocated.
50 drop(Box::from_raw(p));
51 Err(io::Error::last_os_error())
54 extern "system" fn thread_start(main: *mut c_void) -> c::DWORD {
56 // Next, set up our stack overflow handler which may get triggered if we run
58 let _handler = stack_overflow::Handler::new();
59 // Finally, let's run some code.
60 Box::from_raw(main as *mut Box<dyn FnOnce()>)();
66 pub fn set_name(name: &CStr) {
67 if let Ok(utf8) = name.to_str() {
68 if let Ok(utf16) = to_u16s(utf8) {
70 c::SetThreadDescription(c::GetCurrentThread(), utf16.as_ptr());
77 let rc = unsafe { c::WaitForSingleObject(self.handle.as_raw_handle(), c::INFINITE) };
78 if rc == c::WAIT_FAILED {
79 panic!("failed to join on thread: {}", io::Error::last_os_error());
84 // This function will return 0 if there are no other threads to execute,
85 // but this also means that the yield was useless so this isn't really a
86 // case that needs to be worried about.
92 pub fn sleep(dur: Duration) {
93 unsafe { c::Sleep(super::dur2timeout(dur)) }
96 pub fn handle(&self) -> &Handle {
100 pub fn into_handle(self) -> Handle {
105 pub fn available_parallelism() -> io::Result<NonZeroUsize> {
107 let mut sysinfo: c::SYSTEM_INFO = crate::mem::zeroed();
108 c::GetSystemInfo(&mut sysinfo);
109 sysinfo.dwNumberOfProcessors as usize
112 0 => Err(io::const_io_error!(
113 io::ErrorKind::NotFound,
114 "The number of hardware threads is not known for the target platform",
116 cpus => Ok(unsafe { NonZeroUsize::new_unchecked(cpus) }),
120 #[cfg_attr(test, allow(dead_code))]
123 pub unsafe fn current() -> Option<Guard> {
126 pub unsafe fn init() -> Option<Guard> {