From aaaa3896c09369ee0610992f14ab5a845e040315 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?L=C3=A9o=20Lam?= <leo@leolam.fr>
Date: Wed, 21 Oct 2020 21:34:38 +0200
Subject: VideoCommon: Get rid of the global g_available_video_backends

Replace it with a function-local static that is initialized on first
use. This gets rid of a global variable and removes the need for
manual initialization in UICommon.

This commit also replaces the weird find_if that looks for a non-null
unique_ptr with a simple "is vector empty" check considering that
none of the pointers can be null by construction.
---
 Source/Core/VideoCommon/VideoBackendBase.cpp | 58 ++++++++++++++--------------
 1 file changed, 30 insertions(+), 28 deletions(-)

(limited to 'Source/Core/VideoCommon/VideoBackendBase.cpp')

diff --git a/Source/Core/VideoCommon/VideoBackendBase.cpp b/Source/Core/VideoCommon/VideoBackendBase.cpp
index a8633892bd..d793727ebc 100644
--- a/Source/Core/VideoCommon/VideoBackendBase.cpp
+++ b/Source/Core/VideoCommon/VideoBackendBase.cpp
@@ -58,9 +58,7 @@
 #include "VideoCommon/VideoConfig.h"
 #include "VideoCommon/VideoState.h"
 
-std::vector<std::unique_ptr<VideoBackendBase>> g_available_video_backends;
 VideoBackendBase* g_video_backend = nullptr;
-static VideoBackendBase* s_default_backend = nullptr;
 
 #ifdef _WIN32
 #include <windows.h>
@@ -200,6 +198,14 @@ u16 VideoBackendBase::Video_GetBoundingBox(int index)
   return result;
 }
 
+static VideoBackendBase* GetDefaultVideoBackend()
+{
+  const auto& backends = VideoBackendBase::GetAvailableBackends();
+  if (backends.empty())
+    return nullptr;
+  return backends.front().get();
+}
+
 // This function is called at static initialization, so we can't rely on s_default_backend being set
 std::string VideoBackendBase::GetDefaultBackendName()
 {
@@ -212,49 +218,45 @@ std::string VideoBackendBase::GetDefaultBackendName()
 #endif
 }
 
-void VideoBackendBase::PopulateList()
+const std::vector<std::unique_ptr<VideoBackendBase>>& VideoBackendBase::GetAvailableBackends()
 {
-  // OGL > D3D11 > D3D12 > Vulkan > SW > Null
+  static auto s_available_backends = [] {
+    std::vector<std::unique_ptr<VideoBackendBase>> backends;
+
+    // OGL > D3D11 > D3D12 > Vulkan > SW > Null
 #ifdef HAS_OPENGL
-  g_available_video_backends.push_back(std::make_unique<OGL::VideoBackend>());
+    backends.push_back(std::make_unique<OGL::VideoBackend>());
 #endif
 #ifdef _WIN32
-  g_available_video_backends.push_back(std::make_unique<DX11::VideoBackend>());
-  g_available_video_backends.push_back(std::make_unique<DX12::VideoBackend>());
+    backends.push_back(std::make_unique<DX11::VideoBackend>());
+    backends.push_back(std::make_unique<DX12::VideoBackend>());
 #endif
-  g_available_video_backends.push_back(std::make_unique<Vulkan::VideoBackend>());
+    backends.push_back(std::make_unique<Vulkan::VideoBackend>());
 #ifdef HAS_OPENGL
-  g_available_video_backends.push_back(std::make_unique<SW::VideoSoftware>());
+    backends.push_back(std::make_unique<SW::VideoSoftware>());
 #endif
-  g_available_video_backends.push_back(std::make_unique<Null::VideoBackend>());
-
-  const auto iter =
-      std::find_if(g_available_video_backends.begin(), g_available_video_backends.end(),
-                   [](const auto& backend) { return backend != nullptr; });
+    backends.push_back(std::make_unique<Null::VideoBackend>());
 
-  if (iter == g_available_video_backends.end())
-    return;
+    if (!backends.empty())
+      g_video_backend = backends.front().get();
 
-  s_default_backend = iter->get();
-  g_video_backend = iter->get();
-}
-
-void VideoBackendBase::ClearList()
-{
-  g_available_video_backends.clear();
+    return backends;
+  }();
+  return s_available_backends;
 }
 
 void VideoBackendBase::ActivateBackend(const std::string& name)
 {
   // If empty, set it to the default backend (expected behavior)
   if (name.empty())
-    g_video_backend = s_default_backend;
+    g_video_backend = GetDefaultVideoBackend();
 
-  const auto iter =
-      std::find_if(g_available_video_backends.begin(), g_available_video_backends.end(),
-                   [&name](const auto& backend) { return name == backend->GetName(); });
+  const auto& backends = GetAvailableBackends();
+  const auto iter = std::find_if(backends.begin(), backends.end(), [&name](const auto& backend) {
+    return name == backend->GetName();
+  });
 
-  if (iter == g_available_video_backends.end())
+  if (iter == backends.end())
     return;
 
   g_video_backend = iter->get();
-- 
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