Method getIfExists

fdbserver/VersionedBTree.actor.cpp:1997–2004

Get the object for i if it exists, else return nullptr. If the object exists, its eviction order will NOT change as this is not a cache hit.

	// Get the object for i if it exists, else return nullptr.
	// If the object exists, its eviction order will NOT change as this is not a cache hit.
	ObjectType* getIfExists(const IndexType& index) {
		auto i = cache.find(index);
		if (i != cache.end()) {
			++i->second.hits;
			return &i->second.item;
		}
		return nullptr;
	}

	// If index is in cache and not on the prioritized eviction order list, move it there.
	void prioritizeEviction(const IndexType& index) {