TextureCache: Add content locking

Texture cache occasionally mutates textures for efficiency.
Which is awkward if we want to borrow those textures from texture cache
to do something else, such as a graphics debugger, or async presentation
on another thread.

Content locking provides a way to signal that the contents of a texture
cache entry should not change. Texture cache will be forced to use
alternative strategies.

Source/Core/VideoCommon/TextureCacheBase.cpp

@@ -700,7 +700,8 @@ void TextureCacheBase::DoLoadState(PointerWrap& p)
     // Even if the texture isn't valid, we still need to create the cache entry object
     // to update the point in the state state. We'll just throw it away if it's invalid.
     auto tex = DeserializeTexture(p);
-    auto entry = Common::make_rc<TCacheEntry>(std::move(tex->texture), std::move(tex->framebuffer));
+    auto entry =
+        std::make_shared<TCacheEntry>(std::move(tex->texture), std::move(tex->framebuffer));
     entry->textures_by_hash_iter = textures_by_hash.end();
     entry->DoState(p);
     if (entry->texture && commit_state)
@@ -809,6 +810,13 @@ RcTcacheEntry TextureCacheBase::DoPartialTextureUpdates(RcTcacheEntry& entry_to_
   if (entry_to_update->IsCopy())
     return entry_to_update;
 
+  if (entry_to_update->IsLocked())
+  {
+    // TODO: Shouldn't be too hard, just need to clone the texture entry + texture contents.
+    PanicAlertFmt("TextureCache: PartialTextureUpdates of locked textures is not implemented");
+    return {};
+  }
+
   u32 block_width = TexDecoder_GetBlockWidthInTexels(entry_to_update->format.texfmt);
   u32 block_height = TexDecoder_GetBlockHeightInTexels(entry_to_update->format.texfmt);
   u32 block_size = block_width * block_height *
@@ -1474,8 +1482,11 @@ RcTcacheEntry TextureCacheBase::GetTexture(const int textureCacheSafetyColorSamp
       {
         entry = DoPartialTextureUpdates(iter->second, texture_info.GetTlutAddress(),
                                         texture_info.GetTlutFormat());
-        entry->texture->FinishedRendering();
-        return entry;
+        if (entry)
+        {
+          entry->texture->FinishedRendering();
+          return entry;
+        }
       }
     }
 
@@ -1511,9 +1522,8 @@ RcTcacheEntry TextureCacheBase::GetTexture(const int textureCacheSafetyColorSamp
 
   if (unconverted_copy != textures_by_address.end())
   {
-    auto decoded_entry =
-        ApplyPaletteToEntry(unconverted_copy->second, texture_info.GetTlutAddress(),
-                            texture_info.GetTlutFormat());
+    auto decoded_entry = ApplyPaletteToEntry(
+        unconverted_copy->second, texture_info.GetTlutAddress(), texture_info.GetTlutFormat());
 
     if (decoded_entry)
     {
@@ -1543,8 +1553,11 @@ RcTcacheEntry TextureCacheBase::GetTexture(const int textureCacheSafetyColorSamp
       {
         entry = DoPartialTextureUpdates(hash_iter->second, texture_info.GetTlutAddress(),
                                         texture_info.GetTlutFormat());
-        entry->texture->FinishedRendering();
-        return entry;
+        if (entry)
+        {
+          entry->texture->FinishedRendering();
+          return entry;
+        }
       }
       ++hash_iter;
     }
@@ -1771,9 +1784,9 @@ RcTcacheEntry TextureCacheBase::GetXFBTexture(u32 address, u32 width, u32 height
     return {};
   }
 
-  // Do we currently have a version of this XFB copy in VRAM?
+  // Do we currently have a mutable version of this XFB copy in VRAM?
   RcTcacheEntry entry = GetXFBFromCache(address, width, height, stride);
-  if (entry)
+  if (entry && !entry->IsLocked())
   {
     if (entry->is_xfb_container)
     {
@@ -2265,8 +2278,8 @@ void TextureCacheBase::CopyRenderTargetToTexture(
       entry->may_have_overlapping_textures = false;
       entry->is_custom_tex = false;
 
-      CopyEFBToCacheEntry(entry, is_depth_copy, srcRect, scaleByHalf, linear_filter,
-                          dstFormat, isIntensity, gamma, clamp_top, clamp_bottom,
+      CopyEFBToCacheEntry(entry, is_depth_copy, srcRect, scaleByHalf, linear_filter, dstFormat,
+                          isIntensity, gamma, clamp_top, clamp_bottom,
                           GetVRAMCopyFilterCoefficients(filter_coefficients));
 
       if (is_xfb_copy && (g_ActiveConfig.bDumpXFBTarget || g_ActiveConfig.bGraphicMods))
@@ -2584,7 +2597,7 @@ RcTcacheEntry TextureCacheBase::AllocateCacheEntry(const TextureConfig& config)
     return {};
 
   auto cacheEntry =
-      Common::make_rc<TCacheEntry>(std::move(alloc->texture), std::move(alloc->framebuffer));
+      std::make_shared<TCacheEntry>(std::move(alloc->texture), std::move(alloc->framebuffer));
   cacheEntry->textures_by_hash_iter = textures_by_hash.end();
   cacheEntry->id = last_entry_id++;
   return cacheEntry;
@@ -2710,7 +2723,8 @@ TextureCacheBase::InvalidateTexture(TexAddrCache::iterator iter, bool discard_pe
     {
       // The texture data has already been copied into the staging texture, so it's valid to
       // optimistically release the texture data. Will slightly lower VRAM usage.
-      ReleaseToPool(entry.get());
+      if (!entry->IsLocked())
+        ReleaseToPool(entry.get());
     }
   }
   entry->invalidated = true;

Source/Core/VideoCommon/TextureCacheBase.h

@@ -19,7 +19,6 @@
 #include "Common/BitSet.h"
 #include "Common/CommonTypes.h"
 #include "Common/MathUtil.h"
-#include "Common/RcPtr.h"
 #include "VideoCommon/AbstractTexture.h"
 #include "VideoCommon/BPMemory.h"
 #include "VideoCommon/TextureConfig.h"
@@ -127,6 +126,7 @@ struct TCacheEntry
   bool is_xfb_copy = false;
   bool is_xfb_container = false;
   u64 id = 0;
+  u32 content_semaphore = 0;  // Counts up
 
   // Indicates that this TCacheEntry has been invalided from textures_by_address
   bool invalidated = false;
@@ -143,7 +143,7 @@ struct TCacheEntry
 
   // Keep an iterator to the entry in textures_by_hash, so it does not need to be searched when
   // removing the cache entry
-  std::multimap<u64, Common::rc_ptr<TCacheEntry>>::iterator textures_by_hash_iter;
+  std::multimap<u64, std::shared_ptr<TCacheEntry>>::iterator textures_by_hash_iter;
 
   // This is used to keep track of both:
   //   * efb copies used by this partially updated texture
@@ -194,6 +194,14 @@ struct TCacheEntry
     other_entry->references.emplace(this);
   }
 
+  // Acquiring a content lock will lock the current contents and prevent texture cache from
+  // reusing the same entry for a newer version of the texture.
+  void AcquireContentLock() { content_semaphore++; }
+  void ReleaseContentLock() { content_semaphore--; }
+
+  // Can this be mutated?
+  bool IsLocked() const { return content_semaphore > 0; }
+
   void SetXfbCopy(u32 stride);
   void SetEfbCopy(u32 stride);
   void SetNotCopy();
@@ -217,7 +225,7 @@ struct TCacheEntry
   void DoState(PointerWrap& p);
 };
 
-using RcTcacheEntry = Common::rc_ptr<TCacheEntry>;
+using RcTcacheEntry = std::shared_ptr<TCacheEntry>;
 
 class TextureCacheBase
 {