1 use crate::std::ffi::CStr;
2 use crate::std::io;
3 use crate::std::num::NonZeroUsize;
4 use crate::std::os::windows::io::AsRawHandle;
5 use crate::std::os::windows::io::HandleOrNull;
6 use crate::std::ptr;
7 use crate::std::sys::c;
8 use crate::std::sys::handle::Handle;
9 use crate::std::sys::stack_overflow;
10 use crate::std::sys_common::FromInner;
11 use crate::std::time::Duration;
12 use dlibc;
13 use dlibc::c_void;
14
15 use super::to_u16s;
16
17 pub const DEFAULT_MIN_STACK_SIZE: usize = 2 * 1024 * 1024;
18
19 pub struct Thread {
20 handle: Handle,
21 }
22
23 impl Thread {
24 // unsafe: see thread::Builder::spawn_unchecked for safety requirements
new(stack: usize, p: Box<dyn FnOnce()>) -> io::Result<Thread>25 pub unsafe fn new(stack: usize, p: Box<dyn FnOnce()>) -> io::Result<Thread> {
26 let p = Box::into_raw(Box::new(p));
27
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 let ret = c::CreateThread(
34 ptr::null_mut(),
35 stack,
36 Some(thread_start),
37 p as *mut _,
38 c::STACK_SIZE_PARAM_IS_A_RESERVATION,
39 ptr::null_mut(),
40 );
41 let ret = HandleOrNull::from_raw_handle(ret);
42 return if let Ok(handle) = ret.try_into() {
43 Ok(Thread {
44 handle: Handle::from_inner(handle),
45 })
46 } else {
47 // The thread failed to start and as a result p was not consumed. Therefore, it is
48 // safe to reconstruct the box so that it gets deallocated.
49 drop(Box::from_raw(p));
50 Err(io::Error::last_os_error())
51 };
52
53 extern "system" fn thread_start(main: *mut c_void) -> c::DWORD {
54 unsafe {
55 // Next, set up our stack overflow handler which may get triggered if we run
56 // out of stack.
57 let _handler = stack_overflow::Handler::new();
58 // Finally, let's run some code.
59 Box::from_raw(main as *mut Box<dyn FnOnce()>)();
60 }
61 0
62 }
63 }
64
set_name(name: &CStr)65 pub fn set_name(name: &CStr) {
66 if let Ok(utf8) = name.to_str() {
67 if let Ok(utf16) = to_u16s(utf8) {
68 unsafe {
69 c::SetThreadDescription(c::GetCurrentThread(), utf16.as_ptr());
70 };
71 };
72 };
73 }
74
join(self)75 pub fn join(self) {
76 let rc = unsafe { c::WaitForSingleObject(self.handle.as_raw_handle(), c::INFINITE) };
77 if rc == c::WAIT_FAILED {
78 panic!("failed to join on thread: {}", io::Error::last_os_error());
79 }
80 }
81
yield_now()82 pub fn yield_now() {
83 // This function will return 0 if there are no other threads to execute,
84 // but this also means that the yield was useless so this isn't really a
85 // case that needs to be worried about.
86 unsafe {
87 c::SwitchToThread();
88 }
89 }
90
sleep(dur: Duration)91 pub fn sleep(dur: Duration) {
92 unsafe { c::Sleep(super::dur2timeout(dur)) }
93 }
94
handle(&self) -> &Handle95 pub fn handle(&self) -> &Handle {
96 &self.handle
97 }
98
into_handle(self) -> Handle99 pub fn into_handle(self) -> Handle {
100 self.handle
101 }
102 }
103
available_parallelism() -> io::Result<NonZeroUsize>104 pub fn available_parallelism() -> io::Result<NonZeroUsize> {
105 let res = unsafe {
106 let mut sysinfo: c::SYSTEM_INFO = crate::std::mem::zeroed();
107 c::GetSystemInfo(&mut sysinfo);
108 sysinfo.dwNumberOfProcessors as usize
109 };
110 match res {
111 0 => Err(io::const_io_error!(
112 io::ErrorKind::NotFound,
113 "The number of hardware threads is not known for the target platform",
114 )),
115 cpus => Ok(unsafe { NonZeroUsize::new_unchecked(cpus) }),
116 }
117 }
118
119 #[cfg_attr(test, allow(dead_code))]
120 pub mod guard {
121 pub type Guard = !;
current() -> Option<Guard>122 pub unsafe fn current() -> Option<Guard> {
123 None
124 }
init() -> Option<Guard>125 pub unsafe fn init() -> Option<Guard> {
126 None
127 }
128 }
129