1 use crate::ffi::CStr;
2 use crate::io;
3 use crate::num::NonZeroUsize;
4 use crate::os::windows::io::{AsRawHandle, FromRawHandle};
5 use crate::ptr;
6 use crate::sys::c;
7 use crate::sys::handle::Handle;
8 use crate::sys::stack_overflow;
9 use crate::time::Duration;
10
11 use libc::c_void;
12
13 use super::to_u16s;
14
15 pub const DEFAULT_MIN_STACK_SIZE: usize = 2 * 1024 * 1024;
16
17 pub struct Thread {
18 handle: Handle,
19 }
20
21 impl Thread {
22 // unsafe: see thread::Builder::spawn_unchecked for safety requirements
new(stack: usize, p: Box<dyn FnOnce()>) -> io::Result<Thread>23 pub unsafe fn new(stack: usize, p: Box<dyn FnOnce()>) -> io::Result<Thread> {
24 let p = Box::into_raw(box p);
25
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(
35 ptr::null_mut(),
36 stack_size,
37 thread_start,
38 p as *mut _,
39 c::STACK_SIZE_PARAM_IS_A_RESERVATION,
40 ptr::null_mut(),
41 );
42
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())
48 } else {
49 Ok(Thread { handle: Handle::from_raw_handle(ret) })
50 };
51
52 extern "system" fn thread_start(main: *mut c_void) -> c::DWORD {
53 unsafe {
54 // Next, set up our stack overflow handler which may get triggered if we run
55 // out of stack.
56 let _handler = stack_overflow::Handler::new();
57 // Finally, let's run some code.
58 Box::from_raw(main as *mut Box<dyn FnOnce()>)();
59 }
60 0
61 }
62 }
63
set_name(name: &CStr)64 pub fn set_name(name: &CStr) {
65 if let Ok(utf8) = name.to_str() {
66 if let Ok(utf16) = to_u16s(utf8) {
67 unsafe {
68 c::SetThreadDescription(c::GetCurrentThread(), utf16.as_ptr());
69 };
70 };
71 };
72 }
73
join(self)74 pub fn join(self) {
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());
78 }
79 }
80
yield_now()81 pub fn yield_now() {
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.
85 unsafe {
86 c::SwitchToThread();
87 }
88 }
89
sleep(dur: Duration)90 pub fn sleep(dur: Duration) {
91 unsafe { c::Sleep(super::dur2timeout(dur)) }
92 }
93
handle(&self) -> &Handle94 pub fn handle(&self) -> &Handle {
95 &self.handle
96 }
97
into_handle(self) -> Handle98 pub fn into_handle(self) -> Handle {
99 self.handle
100 }
101 }
102
available_parallelism() -> io::Result<NonZeroUsize>103 pub fn available_parallelism() -> io::Result<NonZeroUsize> {
104 let res = unsafe {
105 let mut sysinfo: c::SYSTEM_INFO = crate::mem::zeroed();
106 c::GetSystemInfo(&mut sysinfo);
107 sysinfo.dwNumberOfProcessors as usize
108 };
109 match res {
110 0 => Err(io::Error::new_const(
111 io::ErrorKind::NotFound,
112 &"The number of hardware threads is not known for the target platform",
113 )),
114 cpus => Ok(unsafe { NonZeroUsize::new_unchecked(cpus) }),
115 }
116 }
117
118 #[cfg_attr(test, allow(dead_code))]
119 pub mod guard {
120 pub type Guard = !;
current() -> Option<Guard>121 pub unsafe fn current() -> Option<Guard> {
122 None
123 }
init() -> Option<Guard>124 pub unsafe fn init() -> Option<Guard> {
125 None
126 }
127 }
128