1 files changed, 72 insertions, 0 deletions
diff --git a/library/std/src/sys/wasi/thread.rs b/library/std/src/sys/wasi/thread.rs
new file mode 100644
index 00000000000..0d39b1cec32
--- /dev/null
+++ b/library/std/src/sys/wasi/thread.rs
@@ -0,0 +1,72 @@
+use crate::ffi::CStr;
+use crate::io;
+use crate::mem;
+use crate::sys::{unsupported, Void};
+use crate::time::Duration;
+
+pub struct Thread(Void);
+
+pub const DEFAULT_MIN_STACK_SIZE: usize = 4096;
+
+impl Thread {
+    // unsafe: see thread::Builder::spawn_unchecked for safety requirements
+    pub unsafe fn new(_stack: usize, _p: Box<dyn FnOnce()>) -> io::Result<Thread> {
+        unsupported()
+    }
+
+    pub fn yield_now() {
+        let ret = unsafe { wasi::sched_yield() };
+        debug_assert_eq!(ret, Ok(()));
+    }
+
+    pub fn set_name(_name: &CStr) {
+        // nope
+    }
+
+    pub fn sleep(dur: Duration) {
+        let nanos = dur.as_nanos();
+        assert!(nanos <= u64::MAX as u128);
+
+        const USERDATA: wasi::Userdata = 0x0123_45678;
+
+        let clock = wasi::SubscriptionClock {
+            id: wasi::CLOCKID_MONOTONIC,
+            timeout: nanos as u64,
+            precision: 0,
+            flags: 0,
+        };
+
+        let in_ = wasi::Subscription {
+            userdata: USERDATA,
+            r#type: wasi::EVENTTYPE_CLOCK,
+            u: wasi::SubscriptionU { clock },
+        };
+        unsafe {
+            let mut event: wasi::Event = mem::zeroed();
+            let res = wasi::poll_oneoff(&in_, &mut event, 1);
+            match (res, event) {
+                (
+                    Ok(1),
+                    wasi::Event {
+                        userdata: USERDATA, error: 0, r#type: wasi::EVENTTYPE_CLOCK, ..
+                    },
+                ) => {}
+                _ => panic!("thread::sleep(): unexpected result of poll_oneoff"),
+            }
+        }
+    }
+
+    pub fn join(self) {
+        match self.0 {}
+    }
+}
+
+pub mod guard {
+    pub type Guard = !;
+    pub unsafe fn current() -> Option<Guard> {
+        None
+    }
+    pub unsafe fn init() -> Option<Guard> {
+        None
+    }
+}