Common: Add AtomicMutex and SpinMutex classes as faster alternatives to std::mutex.

Source/Core/Common/CMakeLists.txt

@@ -111,6 +111,7 @@ add_library(common
   MinizipUtil.h
   MsgHandler.cpp
   MsgHandler.h
+  Mutex.h
   NandPaths.cpp
   NandPaths.h
   Network.cpp

Source/Core/Common/Mutex.h

@@ -0,0 +1,51 @@
+// Copyright 2025 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <atomic>
+
+namespace Common
+{
+namespace detail
+{
+template <bool UseAtomicWait>
+class AtomicMutexBase
+{
+public:
+  void lock()
+  {
+    while (m_lock.exchange(true, std::memory_order_acquire))
+    {
+      if constexpr (UseAtomicWait)
+        m_lock.wait(true, std::memory_order_relaxed);
+    }
+  }
+
+  bool try_lock()
+  {
+    bool expected = false;
+    return m_lock.compare_exchange_weak(expected, true, std::memory_order_acquire,
+                                        std::memory_order_relaxed);
+  }
+
+  // Unlike with std::mutex, this call may come from any thread.
+  void unlock()
+  {
+    m_lock.store(false, std::memory_order_release);
+    if constexpr (UseAtomicWait)
+      m_lock.notify_one();
+  }
+
+private:
+  std::atomic_bool m_lock{};
+};
+}  // namespace detail
+
+// Sometimes faster than std::mutex.
+using AtomicMutex = detail::AtomicMutexBase<true>;
+
+// Very fast to lock and unlock when uncontested (~3x faster than std::mutex).
+using SpinMutex = detail::AtomicMutexBase<false>;
+
+}  // namespace Common

Source/Core/DolphinLib.props

@@ -145,6 +145,7 @@
     <ClInclude Include="Common\MemoryUtil.h" />
     <ClInclude Include="Common\MinizipUtil.h" />
     <ClInclude Include="Common\MsgHandler.h" />
+    <ClInclude Include="Common\Mutex.h" />
     <ClInclude Include="Common\NandPaths.h" />
     <ClInclude Include="Common\Network.h" />
     <ClInclude Include="Common\PcapFile.h" />