entry() allows to lookup the position where and entry belongs and update/insert
it in the HashMap more efficiently than get_mut() and insert().
Details: https://gankra.github.io/blah/hashbrown-insert/
In addition, use the struct LinkedList and remove the outdated code.
Signed-off-by: Christian Ebner <c.ebner@proxmox.com>
This will return a mutable reference just like get_mut, but on a cache miss
it will get and insert the missing value via the fetch method provided via the
Cacher trait.
Signed-off-by: Christian Ebner <c.ebner@proxmox.com>
Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
Implements a cache with least recently used cache replacement policy.
Internally the state is tracked by a HashMap (for fast access) and a doubly
linked list (for the access order).
Signed-off-by: Christian Ebner <c.ebner@proxmox.com>
