From 990f02d7c5b5ab4c08239fd0d7e09d836dc774d8 Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Sat, 28 Jul 2018 04:57:23 +0200
Subject: [PATCH] - add support for specifying the exact thread count to
 r_multithreaded and r_scene_multithreaded

---
 src/polyrenderer/poly_renderthread.cpp |  6 +++--
 src/swrenderer/drawers/r_draw.h        |  2 +-
 src/swrenderer/drawers/r_thread.cpp    | 32 +++++++++++++++++---------
 src/swrenderer/drawers/r_thread.h      |  7 +++---
 src/swrenderer/scene/r_scene.cpp       |  6 +++--
 5 files changed, 33 insertions(+), 20 deletions(-)

diff --git a/src/polyrenderer/poly_renderthread.cpp b/src/polyrenderer/poly_renderthread.cpp
index 55d1c8469..7febb4bb7 100644
--- a/src/polyrenderer/poly_renderthread.cpp
+++ b/src/polyrenderer/poly_renderthread.cpp
@@ -44,7 +44,7 @@
 void PeekThreadedErrorPane();
 #endif
 
-EXTERN_CVAR(Bool, r_scene_multithreaded);
+EXTERN_CVAR(Int, r_scene_multithreaded);
 
 PolyRenderThread::PolyRenderThread(int threadIndex) : MainThread(threadIndex == 0), ThreadIndex(threadIndex)
 {
@@ -151,8 +151,10 @@ void PolyRenderThreads::RenderThreadSlices(int totalcount, std::function<void(Po
 	if (numThreads == 0)
 		numThreads = 4;
 
-	if (!r_scene_multithreaded || !r_multithreaded)
+	if (r_scene_multithreaded == 0 || r_multithreaded == 0)
 		numThreads = 1;
+	else if (r_scene_multithreaded != 1)
+		numThreads = r_scene_multithreaded;
 
 	if (numThreads != (int)Threads.size())
 	{
diff --git a/src/swrenderer/drawers/r_draw.h b/src/swrenderer/drawers/r_draw.h
index 5d699791b..790767ed8 100644
--- a/src/swrenderer/drawers/r_draw.h
+++ b/src/swrenderer/drawers/r_draw.h
@@ -8,7 +8,7 @@
 struct FSWColormap;
 struct FLightNode;
 
-EXTERN_CVAR(Bool, r_multithreaded);
+EXTERN_CVAR(Int, r_multithreaded);
 EXTERN_CVAR(Bool, r_magfilter);
 EXTERN_CVAR(Bool, r_minfilter);
 EXTERN_CVAR(Bool, r_mipmap);
diff --git a/src/swrenderer/drawers/r_thread.cpp b/src/swrenderer/drawers/r_thread.cpp
index b23ef58da..0edf0d7f7 100644
--- a/src/swrenderer/drawers/r_thread.cpp
+++ b/src/swrenderer/drawers/r_thread.cpp
@@ -39,7 +39,7 @@
 void PeekThreadedErrorPane();
 #endif
 
-CVAR(Bool, r_multithreaded, true, CVAR_ARCHIVE | CVAR_GLOBALCONFIG);
+CVAR(Int, r_multithreaded, 1, CVAR_ARCHIVE | CVAR_GLOBALCONFIG);
 CVAR(Int, r_debug_draw, 0, 0);
 
 /////////////////////////////////////////////////////////////////////////////
@@ -66,10 +66,11 @@ void DrawerThreads::Execute(DrawerCommandQueuePtr commands)
 	
 	auto queue = Instance();
 
+	queue->StartThreads();
+
 	// Add to queue and awaken worker threads
 	std::unique_lock<std::mutex> start_lock(queue->start_mutex);
 	std::unique_lock<std::mutex> end_lock(queue->end_mutex);
-	queue->StartThreads();
 	queue->active_commands.push_back(commands);
 	queue->tasks_left += queue->threads.size();
 	end_lock.unlock();
@@ -171,22 +172,31 @@ void DrawerThreads::WorkerMain(DrawerThread *thread)
 
 void DrawerThreads::StartThreads()
 {
-	if (!threads.empty())
-		return;
+	std::unique_lock<std::mutex> lock(threads_mutex);
 
 	int num_threads = std::thread::hardware_concurrency();
 	if (num_threads == 0)
 		num_threads = 4;
 
-	threads.resize(num_threads);
+	if (r_multithreaded == 0)
+		num_threads = 1;
+	else if (r_multithreaded != 1)
+		num_threads = r_multithreaded;
 
-	for (int i = 0; i < num_threads; i++)
+	if (num_threads != (int)threads.size())
 	{
-		DrawerThreads *queue = this;
-		DrawerThread *thread = &threads[i];
-		thread->core = i;
-		thread->num_cores = num_threads;
-		thread->thread = std::thread([=]() { queue->WorkerMain(thread); });
+		StopThreads();
+
+		threads.resize(num_threads);
+
+		for (int i = 0; i < num_threads; i++)
+		{
+			DrawerThreads *queue = this;
+			DrawerThread *thread = &threads[i];
+			thread->core = i;
+			thread->num_cores = num_threads;
+			thread->thread = std::thread([=]() { queue->WorkerMain(thread); });
+		}
 	}
 }
 
diff --git a/src/swrenderer/drawers/r_thread.h b/src/swrenderer/drawers/r_thread.h
index dc7e0d8c4..c2e8b9c80 100644
--- a/src/swrenderer/drawers/r_thread.h
+++ b/src/swrenderer/drawers/r_thread.h
@@ -30,7 +30,7 @@
 #include <condition_variable>
 
 // Use multiple threads when drawing
-EXTERN_CVAR(Bool, r_multithreaded)
+EXTERN_CVAR(Int, r_multithreaded)
 
 class PolyTriangleThreadData;
 
@@ -149,6 +149,7 @@ private:
 
 	static DrawerThreads *Instance();
 	
+	std::mutex threads_mutex;
 	std::vector<DrawerThread> threads;
 
 	std::mutex start_mutex;
@@ -181,7 +182,7 @@ public:
 	void Push(Types &&... args)
 	{
 		DrawerThreads *threads = DrawerThreads::Instance();
-		if (ThreadedRender && r_multithreaded)
+		if (r_multithreaded != 0)
 		{
 			void *ptr = AllocMemory(sizeof(T));
 			T *command = new (ptr)T(std::forward<Types>(args)...);
@@ -194,8 +195,6 @@ public:
 		}
 	}
 	
-	bool ThreadedRender = true;
-	
 private:
 	// Allocate memory valid for the duration of a command execution
 	void *AllocMemory(size_t size);
diff --git a/src/swrenderer/scene/r_scene.cpp b/src/swrenderer/scene/r_scene.cpp
index e9f973d64..1666eb003 100644
--- a/src/swrenderer/scene/r_scene.cpp
+++ b/src/swrenderer/scene/r_scene.cpp
@@ -66,7 +66,7 @@ void PeekThreadedErrorPane();
 EXTERN_CVAR(Int, r_clearbuffer)
 EXTERN_CVAR(Int, r_debug_draw)
 
-CVAR(Bool, r_scene_multithreaded, false, 0);
+CVAR(Int, r_scene_multithreaded, 0, 0);
 CVAR(Bool, r_models, true, CVAR_ARCHIVE | CVAR_GLOBALCONFIG);
 
 bool r_modelscene = false;
@@ -210,8 +210,10 @@ namespace swrenderer
 		if (numThreads == 0)
 			numThreads = 4;
 
-		if (!r_scene_multithreaded || !r_multithreaded)
+		if (r_scene_multithreaded == 0 || r_multithreaded == 0)
 			numThreads = 1;
+		else if (r_scene_multithreaded != 1)
+			numThreads = r_scene_multithreaded;
 
 		if (numThreads != (int)Threads.size())
 		{