1 files changed, 60 insertions, 0 deletions
diff --git a/source/slang/slang-shader-cache-index.h b/source/slang/slang-shader-cache-index.h
new file mode 100644
index 000000000..530aacf11
--- /dev/null
+++ b/source/slang/slang-shader-cache-index.h
@@ -0,0 +1,60 @@
+#pragma once
+#include "../../slang.h"
+
+#include "../core/slang-string.h"
+#include "../core/slang-linked-list.h"
+#include "../core/slang-dictionary.h"
+
+namespace Slang
+{
+    class ShaderCacheIndex
+    {
+    public:
+        struct ShaderCacheEntry
+        {
+            slang::Digest dependencyBasedDigest;
+            slang::Digest astBasedDigest;
+        };
+
+        ShaderCacheIndex(SlangInt size)
+            : entryCountLimit(size)
+        {}
+
+        // Load a previous cache index saved to disk. If not found, create a new cache index
+        // and save it to disk as filename.
+        SlangResult loadCacheIndexFromFile(String filename);
+
+        // Fetch the cache entry corresponding to the provided key. If found, move the entry to
+        // the front of entries and return the entry. Else, return nullptr.
+        ShaderCacheEntry* findEntry(const slang::Digest& key);
+
+        // 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
+        // delete the least recently used entry.
+        void addEntry(const slang::Digest& dependencyDigest, const slang::Digest& astDigest);
+
+        // Update the contents hash for the specified entry in the cache and update the
+        // corresponding file on disk.
+        void updateEntry(const slang::Digest& dependencyDigest, const slang::Digest& astDigest);
+
+    private:
+        // Update the cache index on disk. This should be called any time an entry changes.
+        SlangResult saveCacheIndexToFile();
+
+        // Delete the last entry from entries and remove its key/value pair from keyToContents
+        // as well as remove the corresponding file on disk. This should only be used when the
+        // cache has reached the size limit specified by entryLimit to create space for a new entry.
+        void deleteEntry();
+
+        // 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 maximum number of cache entries allowed.
+        SlangInt entryCountLimit = -1;
+    }
+}