1 files changed, 44 insertions, 21 deletions

diff --git a/tools/gfx/persistent-shader-cache.h b/tools/gfx/persistent-shader-cache.h
index 8d4ded4b9..8e05eddf6 100644
--- a/tools/gfx/persistent-shader-cache.h
+++ b/tools/gfx/persistent-shader-cache.h
@@ -7,27 +7,42 @@
 #include "../../source/core/slang-string.h"
 #include "../../source/core/slang-dictionary.h"
 #include "../../source/core/slang-linked-list.h"
+#include "../../source/core/slang-stream.h"
 
 namespace gfx
 {
 
-    using namespace Slang;
+using namespace Slang;
 
 struct ShaderCacheEntry
 {
     slang::Digest dependencyBasedDigest;
     slang::Digest contentsBasedDigest;
+    double lastAccessedTime;
+
+    bool operator==(const ShaderCacheEntry& rhs)
+    {
+        return dependencyBasedDigest == rhs.dependencyBasedDigest
+            && contentsBasedDigest == rhs.contentsBasedDigest
+            && lastAccessedTime == rhs.lastAccessedTime;
+    }
+
+    uint32_t getHashCode()
+    {
+        return dependencyBasedDigest.getHashCode();
+    }
 };
 
 class PersistentShaderCache : public RefObject
 {
 public:
     PersistentShaderCache(const IDevice::ShaderCacheDesc& inDesc);
+    ~PersistentShaderCache();
 
     // Fetch the cache entry corresponding to the provided key. If found, move the entry to
     // the front of entries and return the entry and the corresponding compiled code in
     // outCompiledCode. Else, return nullptr.
-    LinkedNode<ShaderCacheEntry>* findEntry(const slang::Digest& key, ISlangBlob** outCompiledCode);
+    ShaderCacheEntry* findEntry(const slang::Digest& key, ISlangBlob** outCompiledCode);
 
     // Add an entry to the cache with the provided key and contents hashes. If
     // adding an entry causes the cache to exceed size limitations, this will also
@@ -36,38 +51,46 @@ public:
 
     // Update the contents hash for the specified entry in the cache and update the
     // corresponding file on disk.
-    void updateEntry(
-        LinkedNode<ShaderCacheEntry>* entryNode,
-        const slang::Digest& dependencyDigest,
-        const slang::Digest& contentsDigest,
-        ISlangBlob* updatedCode);
+    void updateEntry(const slang::Digest& dependencyDigest, const slang::Digest& contentsDigest, ISlangBlob* updatedCode);
 
 private:
     // Load a previous cache index saved to disk. If not found, create a new cache index
     // and save it to disk as filename.
     void loadCacheFromFile();
 
-    // Update the cache index on disk. This should be called any time an entry changes.
-    void saveCacheToFile();
-
     // Delete the last entry (the least recently used) from entries, remove its key/value pair
-    // from keyToEntry, and remove the corresponding file on disk. This should only be called
-    // by addEntry() when the cache reaches maximum capacity.
-    void deleteLRUEntry();
+    // from keyToEntry, and remove the corresponding file on disk. Returns the index in 'entries'
+    // of the removed entry so addEntry() can overwrite the corresponding entry in 'entries'
+    // with the new entry. This should only be called by addEntry() when the cache reaches maximum capacity.
+    Index deleteLRUEntry();
+
+    // Without access to a physical file path, in-memory file systems cannot leverage file streams and
+    // need to fall back on a different implementation for loading and saving the cache to memory.
+    void loadCacheFromMemory();
+    void saveCacheToMemory();
 
     // The shader cache's description.
     IDevice::ShaderCacheDesc desc;
 
-    // Dictionary mapping each shader's key to its corresponding node (entry) in the list
-    // of entries.
-    Dictionary<slang::Digest, LinkedNode<ShaderCacheEntry>*> keyToEntry;
-
-    // Linked list containing the entries stored in the shader cache in order
-    // of most to least recently used.
-    LinkedList<ShaderCacheEntry> entries;
-
     // The underlying file system used for the shader cache.
     ComPtr<ISlangMutableFileSystem> mutableShaderCacheFileSystem = nullptr;
+    bool isMemoryFileSystem = false;
+
+    // A file stream to the index file opened during cache load. This will only
+    // exist for a cache that exists on-disk.
+    FileStream indexStream;
+
+    // Dictionary mapping each shader's key to its corresponding node (entry) in the
+    // linked list 'orderedEntries'.
+    Dictionary<slang::Digest, LinkedNode<Index>*> keyToEntry;
+
+    // Linked list containing the corresponding indices in 'entries' for entries in the
+    // shader cache ordered from most to least recently used.
+    LinkedList<Index> orderedEntries;
+
+    // List of entries in the shader cache. This list is not guaranteed to be in order of recency
+    // as the main and fall back implementations handle outputting to the file differently.
+    List<ShaderCacheEntry> entries;
 };
 
 }