From 98f7b9594fa053b7d8dd717be94a73685a6a8b69 Mon Sep 17 00:00:00 2001
From: Justin Davis <124625725+jtd-formlabs@users.noreply.github.com>
Date: Tue, 2 Jul 2024 17:50:49 -0400
Subject: [PATCH] enqueue_detach a non-void returning function (#66)

* add capability to enqueue_detach a function that does not return void
---
 include/thread_pool/thread_pool.h | 26 ++++++++++++++++----------
 test/source/thread_pool.cpp       | 23 +++++++++++++++++++++++
 2 files changed, 39 insertions(+), 10 deletions(-)

diff --git a/include/thread_pool/thread_pool.h b/include/thread_pool/thread_pool.h
index 3017aa4..8ff6e3e 100644
--- a/include/thread_pool/thread_pool.h
+++ b/include/thread_pool/thread_pool.h
@@ -187,25 +187,31 @@ namespace dp {
         }
 
         /**
-         * @brief Enqueue a task to be executed in the thread pool that returns void.
+         * @brief Enqueue a task to be executed in the thread pool. Any return value of the function
+         * will be ignored.
          * @tparam Function An invokable type.
          * @tparam Args Argument parameter pack for Function
          * @param func The callable to be executed
          * @param args Arguments that will be passed to the function.
          */
         template <typename Function, typename... Args>
-            requires std::invocable<Function, Args...> &&
-                     std::is_same_v<void, std::invoke_result_t<Function &&, Args &&...>>
+            requires std::invocable<Function, Args...>
         void enqueue_detach(Function &&func, Args &&...args) {
-            enqueue_task(
-                std::move([f = std::forward<Function>(func),
-                           ... largs = std::forward<Args>(args)]() mutable -> decltype(auto) {
-                    // suppress exceptions
-                    try {
+            enqueue_task(std::move([f = std::forward<Function>(func),
+                                    ... largs =
+                                        std::forward<Args>(args)]() mutable -> decltype(auto) {
+                // suppress exceptions
+                try {
+                    if constexpr (std::is_same_v<void,
+                                                 std::invoke_result_t<Function &&, Args &&...>>) {
                         std::invoke(f, largs...);
-                    } catch (...) {
+                    } else {
+                        // the function returns an argument, but can be ignored
+                        std::ignore = std::invoke(f, largs...);
                     }
-                }));
+                } catch (...) {
+                }
+            }));
         }
 
         [[nodiscard]] auto size() const { return threads_.size(); }
diff --git a/test/source/thread_pool.cpp b/test/source/thread_pool.cpp
index 2c008a5..aeb6b0b 100644
--- a/test/source/thread_pool.cpp
+++ b/test/source/thread_pool.cpp
@@ -56,6 +56,29 @@ TEST_CASE("Support enqueue with void return type") {
     CHECK_EQ(value, 16);
 }
 
+TEST_CASE("Support enqueue_detach with void return type") {
+    auto value = 8;
+    {
+        dp::thread_pool pool;
+        pool.enqueue_detach([](int& x) { x *= 2; }, std::ref(value));
+    }
+    CHECK_EQ(value, 16);
+}
+
+TEST_CASE("Support enqueue_detach with non void return type") {
+    auto value = 8;
+    {
+        dp::thread_pool pool;
+        pool.enqueue_detach(
+            [](int& x) {
+                x *= 2;
+                return x;
+            },
+            std::ref(value));
+    }
+    CHECK_EQ(value, 16);
+}
+
 TEST_CASE("Ensure input params are properly passed") {
     dp::thread_pool pool(4);
     constexpr auto total_tasks = 30;