handle 0 sized types correctly

src/signal.rs

@@ -57,6 +57,17 @@ impl<T> Future for &AsyncSignal<T> {
  }
 }
 
+/// read the pointer value for types with size bigger than zero, in case of zero sized types returns std::mem::zeroed
+#[inline(always)]
+unsafe fn read_ptr<T>(ptr: *const T) -> T {
+ if std::mem::size_of::<T>() > 0 {
+ return std::ptr::read(ptr);
+ } else {
+ // for zero types
+ return std::mem::zeroed();
+ }
+}
+
 impl<T> AsyncSignal<T> {
  #[inline(always)]
  pub fn new(ptr: AtomicPtr<T>) -> Arc<Self> {
@@ -85,7 +96,9 @@ impl<T> AsyncSignal<T> {
  // writes data to pointer, shall not be called more than once
  #[inline(always)]
  pub unsafe fn send(&self, d: T) {
- std::ptr::write(self.ptr.load(Ordering::SeqCst), d);
+ if std::mem::size_of::<T>() > 0 {
+ std::ptr::write(self.ptr.load(Ordering::SeqCst), d);
+ }
  self.state.store(0);
  self.wake();
  }
@@ -103,7 +116,7 @@ impl<T> AsyncSignal<T> {
  // read data from pointer, shall not be called more than once
  #[inline(always)]
  pub unsafe fn recv(&self) -> T {
- let d = std::ptr::read(self.ptr.load(Ordering::SeqCst));
+ let d = read_ptr(self.ptr.load(Ordering::SeqCst));
  self.state.store(0);
  self.wake();
  d
@@ -154,7 +167,7 @@ impl<T> SyncSignal<T> {
  // read data from pointer, shall not be called more than once
  #[inline(always)]
  pub unsafe fn recv(&self) -> T {
- let d = std::ptr::read(self.ptr);
+ let d = read_ptr(self.ptr);
  self.s.unlock();
  d
  }