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

In my approach, it's needed to have a hash-table for lookup stored objects quickly and a linked-list for maintain the sequence of last used.

When an object are requested. 1) try to find a object from the hash table 2.yes) if found(the value have an pointer of the object in linked-list), move the object in linked-list to the top of the linked-list. 2.no) if not, remove last object from the linked-list and remove the data also from hash-table then put object into hash-table and top of linked-list.

For example Let's say we have a cache memory only for 3 objects.

The request sequence is 1 3 2 1 4.

1) Hash-table : [1] Linked-list : [1]

2) Hash-table : [1, 3] Linked-list : [3, 1]

3) Hash-table : [1,2,3] Linked-list : [2,3,1]

4) Hash-table : [1,2,3] Linked-list : [1,2,3]

5) Hash-table : [1,2,4] Linked-list : [4,1,2] => 3 out