From 255947b2fc3d676554d02e467267b0f3c789ac86 Mon Sep 17 00:00:00 2001
From: Sky <skylersaleh@gmail.com>
Date: Thu, 6 Jul 2023 08:42:34 -0700
Subject: [PATCH] [GPU] Add texture surface cache eviction

Implemented as a simple ring buffer evicting the oldest entry for now.
---
 include/renderer_gl/renderer_gl.hpp   |  2 +-
 include/renderer_gl/surface_cache.hpp | 19 +++++++++++++++----
 src/core/renderer_gl/textures.cpp     |  5 +++--
 3 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/include/renderer_gl/renderer_gl.hpp b/include/renderer_gl/renderer_gl.hpp
index 4fe0a37c..3ede19ff 100644
--- a/include/renderer_gl/renderer_gl.hpp
+++ b/include/renderer_gl/renderer_gl.hpp
@@ -45,7 +45,7 @@ class Renderer {
 
 	SurfaceCache<DepthBuffer, 10> depthBufferCache;
 	SurfaceCache<ColourBuffer, 10> colourBufferCache;
-	SurfaceCache<Texture, 256> textureCache;
+	SurfaceCache<Texture, 256, true> textureCache;
 
 	OpenGL::uvec2 fbSize;  // The size of the framebuffer (ie both the colour and depth buffer)'
 
diff --git a/include/renderer_gl/surface_cache.hpp b/include/renderer_gl/surface_cache.hpp
index e6b07763..fb0a469d 100644
--- a/include/renderer_gl/surface_cache.hpp
+++ b/include/renderer_gl/surface_cache.hpp
@@ -5,8 +5,9 @@
 #include "textures.hpp"
 
 // Surface cache class that can fit "capacity" instances of the "SurfaceType" class of surfaces
-// SurfaceType *must* have all of the following
-// - An "allocate" function that allocates GL resources for the surfaces
+// SurfaceType *must* have all of the following.
+// - An "allocate" function that allocates GL resources for the surfaces. On overflow it will panic
+//   if evict_on_overflow is false, or kick out the oldest item if it is true.
 // - A "free" function that frees up all resources the surface is taking up
 // - A "matches" function that, when provided with a SurfaceType object reference
 // Will tell us if the 2 surfaces match (Only as far as location in VRAM, format, dimensions, etc)
@@ -14,7 +15,7 @@
 // Including equality of the allocated OpenGL resources, which we don't want
 // - A "valid" member that tells us whether the function is still valid or not
 // - A "location" member which tells us which location in 3DS memory this surface occupies
-template <typename SurfaceType, size_t capacity>
+template <typename SurfaceType, size_t capacity, bool evict_on_overflow=false>
 class SurfaceCache {
     // Vanilla std::optional can't hold actual references
     using OptionalRef = std::optional<std::reference_wrapper<SurfaceType>>;
@@ -22,11 +23,13 @@ class SurfaceCache {
         std::is_same<SurfaceType, Texture>(), "Invalid surface type");
 
     size_t size;
+    size_t eviction_index;
     std::array<SurfaceType, capacity> buffer;
 
 public:
     void reset() {
         size = 0;
+        eviction_index=0;
         for (auto& e : buffer) { // Free the VRAM of all surfaces
             e.free();
         }
@@ -53,7 +56,15 @@ public:
     // Adds a surface object to the cache and returns it
     SurfaceType& add(const SurfaceType& surface) {
         if (size >= capacity) {
-            Helpers::panic("Surface cache full! Add emptying!");
+            if(evict_on_overflow){
+                auto & e = buffer[eviction_index % size];
+                eviction_index++;
+                e.free();
+                e.valid = false;
+                e = surface;
+                e.allocate();
+                return e; 
+            }else Helpers::panic("Surface cache full! Add emptying!");
         }
         size++;
 
diff --git a/src/core/renderer_gl/textures.cpp b/src/core/renderer_gl/textures.cpp
index a806e1eb..e05be35a 100644
--- a/src/core/renderer_gl/textures.cpp
+++ b/src/core/renderer_gl/textures.cpp
@@ -35,8 +35,9 @@ void Texture::setNewConfig(u32 cfg) {
 void Texture::free() {
     valid = false;
 
-    if (texture.exists())
-        Helpers::panic("Make this texture free itself");
+    if (texture.exists()){
+        glDeleteTextures(1, &texture.m_handle);
+    }
 }
 
 u64 Texture::sizeInBytes() {