C++ design: How to cache most recent used

Question

We have a C++ application for which we try to improve performance. We identified that data retrieval takes a lot of time, and want to cache data. We can\'t store all data in mem

Answer 1

An alternative implementation that might make the 'aging' of the elements easier but at the cost of lower search performance would be to keep your CacheEntry elements in a std::list (or use a std::pair. The newest element gets added at the front of the list so they 'migrate' towards the end of the list as they age. When you check if an element is already present in the cache, you scan the list (which is admittedly an O(n) operation as opposed to being an O(log n) operation in a map). If you find it, you remove it from its current location and re-insert it at the start of the list. If the list length extends over 1000 elements, you remove the required number of elements from the end of the list to trim it back below 1000 elements.