class MetadataManager {
public:
    /**
     * Increments the usage counter of the active metadata and returns a RAII object, which contains the currently active
     * metadata. When the RAII object goes out of scope it will call removeMetadataUser.
     */
    ScopedCollectionMetadata getActiveMetadata();

    /**
     * Changes the active metadata and if there are current users of the current active metadata puts it on the
     * _metadataInUse set.
     */
    void setActiveMetadata(std::unique_ptr<CollectionMetadata> newActiveMetadata);

    /**
     * Decrements the usage counter of the specified metadata tracker and if that count is zero and the tracker is on the
     * _metadataInUse set, removes it from there.
     */
    void removeMetadataUsage(CollectionMetadataTracker* metadataTracker);
    
private:
    struct CollectionMetadataTracker {
        std::unique_ptr<CollectionMetadata> metadata;
        uint32_t usageCounter;
    };

    friend class ScopedCollectionMetadata;

    CollectionMetadataTracker _activeMetadata;

    std::set<CollectionMetadataTracker> _metadataInUse;
};