6 files changed, 266 insertions, 67 deletions

diff --git a/src/common/CMakeLists.txt b/src/common/CMakeLists.txt
index a6fa9a85d..e03fffd8d 100644
--- a/src/common/CMakeLists.txt
+++ b/src/common/CMakeLists.txt
@@ -180,7 +180,6 @@ add_library(common STATIC
     thread.cpp
     thread.h
     thread_queue_list.h
-    thread_worker.cpp
     thread_worker.h
     threadsafe_queue.h
     time_zone.cpp
@@ -188,6 +187,7 @@ add_library(common STATIC
     tiny_mt.h
     tree.h
     uint128.h
+    unique_function.h
     uuid.cpp
     uuid.h
     vector_math.h
diff --git a/src/common/thread_worker.cpp b/src/common/thread_worker.cpp
deleted file mode 100644
index 8f9bf447a..000000000
--- a/src/common/thread_worker.cpp
+++ /dev/null
@@ -1,58 +0,0 @@
-// Copyright 2020 yuzu emulator team
-// Licensed under GPLv2 or any later version
-// Refer to the license.txt file included.
-
-#include "common/thread.h"
-#include "common/thread_worker.h"
-
-namespace Common {
-
-ThreadWorker::ThreadWorker(std::size_t num_workers, const std::string& name) {
-    for (std::size_t i = 0; i < num_workers; ++i)
-        threads.emplace_back([this, thread_name{std::string{name}}] {
-            Common::SetCurrentThreadName(thread_name.c_str());
-
-            // Wait for first request
-            {
-                std::unique_lock lock{queue_mutex};
-                condition.wait(lock, [this] { return stop || !requests.empty(); });
-            }
-
-            while (true) {
-                std::function<void()> task;
-
-                {
-                    std::unique_lock lock{queue_mutex};
-                    condition.wait(lock, [this] { return stop || !requests.empty(); });
-                    if (stop || requests.empty()) {
-                        return;
-                    }
-                    task = std::move(requests.front());
-                    requests.pop();
-                }
-
-                task();
-            }
-        });
-}
-
-ThreadWorker::~ThreadWorker() {
-    {
-        std::unique_lock lock{queue_mutex};
-        stop = true;
-    }
-    condition.notify_all();
-    for (std::thread& thread : threads) {
-        thread.join();
-    }
-}
-
-void ThreadWorker::QueueWork(std::function<void()>&& work) {
-    {
-        std::unique_lock lock{queue_mutex};
-        requests.emplace(work);
-    }
-    condition.notify_one();
-}
-
-} // namespace Common
diff --git a/src/common/thread_worker.h b/src/common/thread_worker.h
index f1859971f..8272985ff 100644
--- a/src/common/thread_worker.h
+++ b/src/common/thread_worker.h
@@ -7,24 +7,110 @@
 #include <atomic>
 #include <functional>
 #include <mutex>
+#include <stop_token>
 #include <string>
+#include <thread>
+#include <type_traits>
 #include <vector>
 #include <queue>
 
+#include "common/thread.h"
+#include "common/unique_function.h"
+
 namespace Common {
 
-class ThreadWorker final {
+template <class StateType = void>
+class StatefulThreadWorker {
+    static constexpr bool with_state = !std::is_same_v<StateType, void>;
+
+    struct DummyCallable {
+        int operator()() const noexcept {
+            return 0;
+        }
+    };
+
+    using Task =
+        std::conditional_t<with_state, UniqueFunction<void, StateType*>, UniqueFunction<void>>;
+    using StateMaker = std::conditional_t<with_state, std::function<StateType()>, DummyCallable>;
+
 public:
-    explicit ThreadWorker(std::size_t num_workers, const std::string& name);
-    ~ThreadWorker();
-    void QueueWork(std::function<void()>&& work);
+    explicit StatefulThreadWorker(size_t num_workers, std::string name, StateMaker func = {})
+        : workers_queued{num_workers}, thread_name{std::move(name)} {
+        const auto lambda = [this, func](std::stop_token stop_token) {
+            Common::SetCurrentThreadName(thread_name.c_str());
+            {
+                std::conditional_t<with_state, StateType, int> state{func()};
+                while (!stop_token.stop_requested()) {
+                    Task task;
+                    {
+                        std::unique_lock lock{queue_mutex};
+                        if (requests.empty()) {
+                            wait_condition.notify_all();
+                        }
+                        condition.wait(lock, stop_token, [this] { return !requests.empty(); });
+                        if (stop_token.stop_requested()) {
+                            break;
+                        }
+                        task = std::move(requests.front());
+                        requests.pop();
+                    }
+                    if constexpr (with_state) {
+                        task(&state);
+                    } else {
+                        task();
+                    }
+                    ++work_done;
+                }
+            }
+            ++workers_stopped;
+            wait_condition.notify_all();
+        };
+        threads.reserve(num_workers);
+        for (size_t i = 0; i < num_workers; ++i) {
+            threads.emplace_back(lambda);
+        }
+    }
+
+    StatefulThreadWorker& operator=(const StatefulThreadWorker&) = delete;
+    StatefulThreadWorker(const StatefulThreadWorker&) = delete;
+
+    StatefulThreadWorker& operator=(StatefulThreadWorker&&) = delete;
+    StatefulThreadWorker(StatefulThreadWorker&&) = delete;
+
+    void QueueWork(Task work) {
+        {
+            std::unique_lock lock{queue_mutex};
+            requests.emplace(std::move(work));
+            ++work_scheduled;
+        }
+        condition.notify_one();
+    }
+
+    void WaitForRequests(std::stop_token stop_token = {}) {
+        std::stop_callback callback(stop_token, [this] {
+            for (auto& thread : threads) {
+                thread.request_stop();
+            }
+        });
+        std::unique_lock lock{queue_mutex};
+        wait_condition.wait(lock, [this] {
+            return workers_stopped >= workers_queued || work_done >= work_scheduled;
+        });
+    }
 
 private:
-    std::vector<std::thread> threads;
-    std::queue<std::function<void()>> requests;
+    std::queue<Task> requests;
     std::mutex queue_mutex;
-    std::condition_variable condition;
-    std::atomic_bool stop{};
+    std::condition_variable_any condition;
+    std::condition_variable wait_condition;
+    std::atomic<size_t> work_scheduled{};
+    std::atomic<size_t> work_done{};
+    std::atomic<size_t> workers_stopped{};
+    std::atomic<size_t> workers_queued{};
+    std::string thread_name;
+    std::vector<std::jthread> threads;
 };
 
+using ThreadWorker = StatefulThreadWorker<>;
+
 } // namespace Common
diff --git a/src/common/unique_function.h b/src/common/unique_function.h
new file mode 100644
index 000000000..ca0559071
--- /dev/null
+++ b/src/common/unique_function.h
@@ -0,0 +1,62 @@
+// Copyright 2021 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <memory>
+#include <utility>
+
+namespace Common {
+
+/// General purpose function wrapper similar to std::function.
+/// Unlike std::function, the captured values don't have to be copyable.
+/// This class can be moved but not copied.
+template <typename ResultType, typename... Args>
+class UniqueFunction {
+    class CallableBase {
+    public:
+        virtual ~CallableBase() = default;
+        virtual ResultType operator()(Args&&...) = 0;
+    };
+
+    template <typename Functor>
+    class Callable final : public CallableBase {
+    public:
+        Callable(Functor&& functor_) : functor{std::move(functor_)} {}
+        ~Callable() override = default;
+
+        ResultType operator()(Args&&... args) override {
+            return functor(std::forward<Args>(args)...);
+        }
+
+    private:
+        Functor functor;
+    };
+
+public:
+    UniqueFunction() = default;
+
+    template <typename Functor>
+    UniqueFunction(Functor&& functor)
+        : callable{std::make_unique<Callable<Functor>>(std::move(functor))} {}
+
+    UniqueFunction& operator=(UniqueFunction&& rhs) noexcept = default;
+    UniqueFunction(UniqueFunction&& rhs) noexcept = default;
+
+    UniqueFunction& operator=(const UniqueFunction&) = delete;
+    UniqueFunction(const UniqueFunction&) = delete;
+
+    ResultType operator()(Args&&... args) const {
+        return (*callable)(std::forward<Args>(args)...);
+    }
+
+    explicit operator bool() const noexcept {
+        return static_cast<bool>(callable);
+    }
+
+private:
+    std::unique_ptr<CallableBase> callable;
+};
+
+} // namespace Common
diff --git a/src/tests/CMakeLists.txt b/src/tests/CMakeLists.txt
index 96bc30cac..c4c012f3d 100644
--- a/src/tests/CMakeLists.txt
+++ b/src/tests/CMakeLists.txt
@@ -5,6 +5,7 @@ add_executable(tests
     common/host_memory.cpp
     common/param_package.cpp
     common/ring_buffer.cpp
+    common/unique_function.cpp
     core/core_timing.cpp
     core/network/network.cpp
     tests.cpp
diff --git a/src/tests/common/unique_function.cpp b/src/tests/common/unique_function.cpp
new file mode 100644
index 000000000..ac9912738
--- /dev/null
+++ b/src/tests/common/unique_function.cpp
@@ -0,0 +1,108 @@
+// Copyright 2021 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <string>
+
+#include <catch2/catch.hpp>
+
+#include "common/unique_function.h"
+
+namespace {
+struct Noisy {
+    Noisy() : state{"Default constructed"} {}
+    Noisy(Noisy&& rhs) noexcept : state{"Move constructed"} {
+        rhs.state = "Moved away";
+    }
+    Noisy& operator=(Noisy&& rhs) noexcept {
+        state = "Move assigned";
+        rhs.state = "Moved away";
+    }
+    Noisy(const Noisy&) : state{"Copied constructed"} {}
+    Noisy& operator=(const Noisy&) {
+        state = "Copied assigned";
+    }
+
+    std::string state;
+};
+} // Anonymous namespace
+
+TEST_CASE("UniqueFunction", "[common]") {
+    SECTION("Capture reference") {
+        int value = 0;
+        Common::UniqueFunction<void> func = [&value] { value = 5; };
+        func();
+        REQUIRE(value == 5);
+    }
+    SECTION("Capture pointer") {
+        int value = 0;
+        int* pointer = &value;
+        Common::UniqueFunction<void> func = [pointer] { *pointer = 5; };
+        func();
+        REQUIRE(value == 5);
+    }
+    SECTION("Move object") {
+        Noisy noisy;
+        REQUIRE(noisy.state == "Default constructed");
+
+        Common::UniqueFunction<void> func = [noisy = std::move(noisy)] {
+            REQUIRE(noisy.state == "Move constructed");
+        };
+        REQUIRE(noisy.state == "Moved away");
+        func();
+    }
+    SECTION("Move construct function") {
+        int value = 0;
+        Common::UniqueFunction<void> func = [&value] { value = 5; };
+        Common::UniqueFunction<void> new_func = std::move(func);
+        new_func();
+        REQUIRE(value == 5);
+    }
+    SECTION("Move assign function") {
+        int value = 0;
+        Common::UniqueFunction<void> func = [&value] { value = 5; };
+        Common::UniqueFunction<void> new_func;
+        new_func = std::move(func);
+        new_func();
+        REQUIRE(value == 5);
+    }
+    SECTION("Default construct then assign function") {
+        int value = 0;
+        Common::UniqueFunction<void> func;
+        func = [&value] { value = 5; };
+        func();
+        REQUIRE(value == 5);
+    }
+    SECTION("Pass arguments") {
+        int result = 0;
+        Common::UniqueFunction<void, int, int> func = [&result](int a, int b) { result = a + b; };
+        func(5, 4);
+        REQUIRE(result == 9);
+    }
+    SECTION("Pass arguments and return value") {
+        Common::UniqueFunction<int, int, int> func = [](int a, int b) { return a + b; };
+        REQUIRE(func(5, 4) == 9);
+    }
+    SECTION("Destructor") {
+        int num_destroyed = 0;
+        struct Foo {
+            Foo(int* num_) : num{num_} {}
+            Foo(Foo&& rhs) : num{std::exchange(rhs.num, nullptr)} {}
+            Foo(const Foo&) = delete;
+
+            ~Foo() {
+                if (num) {
+                    ++*num;
+                }
+            }
+
+            int* num = nullptr;
+        };
+        Foo object{&num_destroyed};
+        {
+            Common::UniqueFunction<void> func = [object = std::move(object)] {};
+            REQUIRE(num_destroyed == 0);
+        }
+        REQUIRE(num_destroyed == 1);
+    }
+}