fix futureAwaiter test failed in aarch64 (#433)

Author: poor-circle

async_simple/coro/FutureAwaiter.h

@@ -44,9 +44,11 @@ struct FutureAwaiter {
         future_ = makeReadyFuture<T>(
             std::make_exception_ptr(async_simple::SignalException(
                 SignalType::Terminate,
-                "FutureAwaiter is only allowed to be called by Lazy")));
+                "FutureAwaiter is cancelled by signal")));
+        // Add thread fence, make sure future_ has being assigned before
+        // continuation or cancellation in arm.
+        std::atomic_thread_fence(std::memory_order_acq_rel);
         auto state = std::make_shared<std::atomic<bool>>(true);
-
         if (!signalHelper{Terminate}.tryEmplace(
                 cancellationSlot,
                 [continuation, ex, ctx, state](auto&&...) mutable {
@@ -116,8 +118,9 @@ auto operator co_await(Future<T>&& future) {
 }
 
 template <typename T>
-[[deprecated("Require an rvalue future.")]]
-auto operator co_await(T&& future) requires IsFuture<std::decay_t<T>>::value {
+[[deprecated("Require an rvalue future.")]] auto operator co_await(T&& future)
+    requires IsFuture<std::decay_t<T>>::value
+{
     return std::move(operator co_await(std::move(future)));
 }
 

async_simple/coro/test/FutureAwaiterTest.cpp

@@ -79,8 +79,6 @@ TEST_F(FutureAwaiterTest, testWithFuture) {
     syncAwait(lazy3().via(&ex2));
 }
 
-// The test fails in debug mode with internal CI. Disable it to keep the CI green.
-#if 0
 TEST_F(FutureAwaiterTest, testWithFutureCancel) {
     async_simple::executors::SimpleExecutor ex1(2);
     auto lazy = [&]() -> Lazy<> {
@@ -109,15 +107,15 @@ TEST_F(FutureAwaiterTest, testWithFutureCancel) {
         int ret = 0;
         try {
             ret = co_await std::move(fut);
-        } catch (...) {
+        } catch (const std::exception& e) {
+            std::cout << e.what() << std::endl;
         }
         EXPECT_EQ(ret, 2);
     };
     syncAwait(collectAll<async_simple::Terminate>(
         lazy2().via(&ex1),
         async_simple::coro::sleep(std::chrono::seconds::max()).via(&ex1)));
 }
-#endif
 
 namespace detail {