Chore: improve concept definitions (#521)

* Clean up concept definitions
* Fix ParallelTests/NodeMultiThread bug

Authors:
  - Will Killian (https://github.com/willkill07)

Approvers:
  - David Gardner (https://github.com/dagardner-nv)
  - Michael Demoret (https://github.com/mdemoret-nv)

URL: #521

cpp/mrc/include/mrc/core/concepts/not_void.hpp

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: Copyright (c) 2022-2023, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+ * SPDX-FileCopyrightText: Copyright (c) 2022-2024, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
  * SPDX-License-Identifier: Apache-2.0
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -22,6 +22,6 @@
 namespace mrc::core::concepts {
 
 template <typename T>
-concept not_void = requires { requires not std::same_as<T, void>; };
+concept not_void = (not std::same_as<T, void>);
 
 }  // namespace mrc::core::concepts

cpp/mrc/include/mrc/coroutines/concepts/awaitable.hpp

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: Copyright (c) 2022-2023, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+ * SPDX-FileCopyrightText: Copyright (c) 2022-2024, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
  * SPDX-License-Identifier: Apache-2.0
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -44,6 +44,14 @@
 #include <utility>
 
 namespace mrc::coroutines::concepts {
+
+// clang-format off
+/**
+ * The concept declares a type that is required to be one of the passed types
+ */
+template<typename T, typename ... CandidatesT>
+concept one_of = (... or std::same_as<T, CandidatesT>);
+
 /**
  * This concept declares a type that is required to meet the c++20 coroutine operator co_await()
  * retun type.  It requires the following three member functions:
@@ -52,14 +60,11 @@ namespace mrc::coroutines::concepts {
  *      await_resume() -> decltype(auto)
  *          Where the return type on await_resume is the requested return of the awaitable.
  */
-// clang-format off
 template<typename T>
 concept awaiter = requires(T t, std::coroutine_handle<> c)
 {
     { t.await_ready() } -> std::same_as<bool>;
-    requires std::same_as<decltype(t.await_suspend(c)), void> ||
-             std::same_as<decltype(t.await_suspend(c)), bool> ||
-             std::same_as<decltype(t.await_suspend(c)), std::coroutine_handle<>>;
+    { t.await_suspend(c) } -> one_of<void, bool, std::coroutine_handle<>>;
     { t.await_resume() };
 };
 
@@ -77,10 +82,8 @@ template<typename T>
 concept awaiter_void = requires(T t, std::coroutine_handle<> c)
 {
     { t.await_ready() } -> std::same_as<bool>;
-    requires std::same_as<decltype(t.await_suspend(c)), void> ||
-        std::same_as<decltype(t.await_suspend(c)), bool> ||
-        std::same_as<decltype(t.await_suspend(c)), std::coroutine_handle<>>;
-    {t.await_resume()} -> std::same_as<void>;
+    { t.await_suspend(c) } -> one_of<void, bool, std::coroutine_handle<>>;
+    { t.await_resume() } -> std::same_as<void>;
 };
 
 template<typename T>

cpp/mrc/tests/test_node.cpp

@@ -32,6 +32,7 @@
 #include "mrc/segment/object.hpp"
 #include "mrc/utils/string_utils.hpp"
 
+#include <boost/fiber/operations.hpp>
 #include <glog/logging.h>
 #include <gtest/gtest.h>
 #include <rxcpp/rx.hpp>
@@ -743,7 +744,7 @@ TEST_P(ParallelTests, NodeMultiThread)
                                            }
 
                                            DVLOG(1) << context.info() << " Node got value: '" << x << "'" << std::endl;
-
+                                           boost::this_fiber::yield();
                                            EXPECT_TRUE(parallel_test.wait_for(250ms));
                                            // Double the value
                                            return x * 2;