1 files changed, 152 insertions, 0 deletions
diff --git a/library/std/src/sys/cloudabi/condvar.rs b/library/std/src/sys/cloudabi/condvar.rs
new file mode 100644
index 00000000000..dabdc0c9b51
--- /dev/null
+++ b/library/std/src/sys/cloudabi/condvar.rs
@@ -0,0 +1,152 @@
+use crate::cell::UnsafeCell;
+use crate::mem;
+use crate::sync::atomic::{AtomicU32, Ordering};
+use crate::sys::cloudabi::abi;
+use crate::sys::mutex::{self, Mutex};
+use crate::sys::time::checked_dur2intervals;
+use crate::time::Duration;
+
+extern "C" {
+    #[thread_local]
+    static __pthread_thread_id: abi::tid;
+}
+
+pub struct Condvar {
+    condvar: UnsafeCell<AtomicU32>,
+}
+
+unsafe impl Send for Condvar {}
+unsafe impl Sync for Condvar {}
+
+const NEW: Condvar =
+    Condvar { condvar: UnsafeCell::new(AtomicU32::new(abi::CONDVAR_HAS_NO_WAITERS.0)) };
+
+impl Condvar {
+    pub const fn new() -> Condvar {
+        NEW
+    }
+
+    pub unsafe fn init(&mut self) {}
+
+    pub unsafe fn notify_one(&self) {
+        let condvar = self.condvar.get();
+        if (*condvar).load(Ordering::Relaxed) != abi::CONDVAR_HAS_NO_WAITERS.0 {
+            let ret = abi::condvar_signal(condvar as *mut abi::condvar, abi::scope::PRIVATE, 1);
+            assert_eq!(ret, abi::errno::SUCCESS, "Failed to signal on condition variable");
+        }
+    }
+
+    pub unsafe fn notify_all(&self) {
+        let condvar = self.condvar.get();
+        if (*condvar).load(Ordering::Relaxed) != abi::CONDVAR_HAS_NO_WAITERS.0 {
+            let ret = abi::condvar_signal(
+                condvar as *mut abi::condvar,
+                abi::scope::PRIVATE,
+                abi::nthreads::MAX,
+            );
+            assert_eq!(ret, abi::errno::SUCCESS, "Failed to broadcast on condition variable");
+        }
+    }
+
+    pub unsafe fn wait(&self, mutex: &Mutex) {
+        let mutex = mutex::raw(mutex);
+        assert_eq!(
+            (*mutex).load(Ordering::Relaxed) & !abi::LOCK_KERNEL_MANAGED.0,
+            __pthread_thread_id.0 | abi::LOCK_WRLOCKED.0,
+            "This lock is not write-locked by this thread"
+        );
+
+        // Call into the kernel to wait on the condition variable.
+        let condvar = self.condvar.get();
+        let subscription = abi::subscription {
+            type_: abi::eventtype::CONDVAR,
+            union: abi::subscription_union {
+                condvar: abi::subscription_condvar {
+                    condvar: condvar as *mut abi::condvar,
+                    condvar_scope: abi::scope::PRIVATE,
+                    lock: mutex as *mut abi::lock,
+                    lock_scope: abi::scope::PRIVATE,
+                },
+            },
+            ..mem::zeroed()
+        };
+        let mut event: mem::MaybeUninit<abi::event> = mem::MaybeUninit::uninit();
+        let mut nevents: mem::MaybeUninit<usize> = mem::MaybeUninit::uninit();
+        let ret = abi::poll(&subscription, event.as_mut_ptr(), 1, nevents.as_mut_ptr());
+        assert_eq!(ret, abi::errno::SUCCESS, "Failed to wait on condition variable");
+        assert_eq!(
+            event.assume_init().error,
+            abi::errno::SUCCESS,
+            "Failed to wait on condition variable"
+        );
+    }
+
+    pub unsafe fn wait_timeout(&self, mutex: &Mutex, dur: Duration) -> bool {
+        let mutex = mutex::raw(mutex);
+        assert_eq!(
+            (*mutex).load(Ordering::Relaxed) & !abi::LOCK_KERNEL_MANAGED.0,
+            __pthread_thread_id.0 | abi::LOCK_WRLOCKED.0,
+            "This lock is not write-locked by this thread"
+        );
+
+        // Call into the kernel to wait on the condition variable.
+        let condvar = self.condvar.get();
+        let timeout =
+            checked_dur2intervals(&dur).expect("overflow converting duration to nanoseconds");
+        let subscriptions = [
+            abi::subscription {
+                type_: abi::eventtype::CONDVAR,
+                union: abi::subscription_union {
+                    condvar: abi::subscription_condvar {
+                        condvar: condvar as *mut abi::condvar,
+                        condvar_scope: abi::scope::PRIVATE,
+                        lock: mutex as *mut abi::lock,
+                        lock_scope: abi::scope::PRIVATE,
+                    },
+                },
+                ..mem::zeroed()
+            },
+            abi::subscription {
+                type_: abi::eventtype::CLOCK,
+                union: abi::subscription_union {
+                    clock: abi::subscription_clock {
+                        clock_id: abi::clockid::MONOTONIC,
+                        timeout,
+                        ..mem::zeroed()
+                    },
+                },
+                ..mem::zeroed()
+            },
+        ];
+        let mut events: [mem::MaybeUninit<abi::event>; 2] = [mem::MaybeUninit::uninit(); 2];
+        let mut nevents: mem::MaybeUninit<usize> = mem::MaybeUninit::uninit();
+        let ret = abi::poll(
+            subscriptions.as_ptr(),
+            mem::MaybeUninit::first_ptr_mut(&mut events),
+            2,
+            nevents.as_mut_ptr(),
+        );
+        assert_eq!(ret, abi::errno::SUCCESS, "Failed to wait on condition variable");
+        let nevents = nevents.assume_init();
+        for i in 0..nevents {
+            assert_eq!(
+                events[i].assume_init().error,
+                abi::errno::SUCCESS,
+                "Failed to wait on condition variable"
+            );
+            if events[i].assume_init().type_ == abi::eventtype::CONDVAR {
+                return true;
+            }
+        }
+        false
+    }
+
+    pub unsafe fn destroy(&self) {
+        let condvar = self.condvar.get();
+        assert_eq!(
+            (*condvar).load(Ordering::Relaxed),
+            abi::CONDVAR_HAS_NO_WAITERS.0,
+            "Attempted to destroy a condition variable with blocked threads"
+        );
+    }
+}