src/dawn/native/BlobCache.h

// Copyright 2022 The Dawn & Tint Authors
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#ifndef SRC_DAWN_NATIVE_BLOBCACHE_H_
#define SRC_DAWN_NATIVE_BLOBCACHE_H_

#include <mutex>

#include "dawn/common/Platform.h"
#include "dawn/native/Blob.h"
#include "dawn/native/CacheResult.h"

namespace dawn::platform {
class CachingInterface;
}

namespace dawn::native {

class CacheKey;
class InstanceBase;

// This class should always be thread-safe because it may be called asynchronously. Its purpose
// is to wrap the CachingInterface provided via a platform.
class BlobCache {
  public:
    explicit BlobCache(dawn::platform::CachingInterface* cachingInterface = nullptr);

    // Returns empty blob if the key is not found in the cache.
    Blob Load(const CacheKey& key);

    // Value to store must be non-empty/non-null.
    void Store(const CacheKey& key, size_t valueSize, const void* value);
    void Store(const CacheKey& key, const Blob& value);

    // Store a CacheResult into the cache if it isn't cached yet.
    // Calls T::ToBlob which should be defined elsewhere.
    template <typename T>
    void EnsureStored(const CacheResult<T>& cacheResult) {
        if (!cacheResult.IsCached()) {
            Store(cacheResult.GetCacheKey(), cacheResult->ToBlob());
        }
    }

  private:
    // Non-thread safe internal implementations of load and store. Exposed callers that use
    // these helpers need to make sure that these are entered with `mMutex` held.
    Blob LoadInternal(const CacheKey& key);
    void StoreInternal(const CacheKey& key, size_t valueSize, const void* value);

    // Validates the cache key for this version of Dawn. At the moment, this is naively checking
    // that the cache key contains the dawn version string in it.
    bool ValidateCacheKey(const CacheKey& key);

    // Protects thread safety of access to mCache.
    std::mutex mMutex;
    dawn::platform::CachingInterface* mCache;
};

}  // namespace dawn::native

#endif  // SRC_DAWN_NATIVE_BLOBCACHE_H_