Module `Vache`Source

Vache

Vache is a library for in-memory value caches.

More specifically, Vache provides modules implementing caches for values. These caches are parametrised by cache-policies: maximum size, retention, etc.

Note that Vache should not be used to cache resources which may need any form of clean-up (e.g., file-descriptors or network connections). Vache should only be used for values which can be entirely managed by the garbage-collector. If you need resource caches, check-out Rache.

Preamble

Caches

Sourcemodule type MAP = sig ... end

A Mutable structure akin to a hash-table, but with a size bound. Note that, different caches have different policies towards the size bounds: some uphold the bound strictly, some treat the bound as a suggestion. In addition, some caches count their elements somewhat sloppily.

Sourcemodule type SET = sig ... end

A Mutable structure akin to a set, but with a size bound. Note that, different caches have different policies towards the size bounds: some uphold the bound strictly, some treat the bound as a suggestion. In addition, some caches count their elements somewhat sloppily.

All caches of Vache have either the MAP interface (for key-value stores) or the SET interface (for value stores). Their behavior can be tweaked by the parameters below.

Cache policies

Sourcemodule type REPLACEMENT_AND_ACCOUNTING

REPLACEMENT_AND_ACCOUNTING is for defining the replacement policy and the accounting policy of a cache. Because of implementation details which are not relevant to go into details here, these two policies are governed by a single, joined parameter.

Sourcemodule LRU_Precise : REPLACEMENT_AND_ACCOUNTING

Sourcemodule LRU_Sloppy : REPLACEMENT_AND_ACCOUNTING

Sourcemodule FIFO_Precise : REPLACEMENT_AND_ACCOUNTING

Sourcemodule FIFO_Sloppy : REPLACEMENT_AND_ACCOUNTING

Sourcemodule type OVERFLOW

OVERFLOW is for defining the overflow policy of a cache. Strong means that the cache never holds more element than is specified when calling create. Weak means that the cache may hold more elements than specified when calling create but that supernumerary elements may be collected by the Garbage Collector.

Sourcemodule Strong : OVERFLOW

Sourcemodule Weak : OVERFLOW

Cache instantiating

Source

module Map
  (RA : REPLACEMENT_AND_ACCOUNTING)
  (O : OVERFLOW)
  (H : Hashtbl.HashedType) : 
  MAP with type key = H.t

Map(RA)(O)(H) is a MAP indexed by H and governed by RA and O.

Sourcemodule EmptyMap (H : Hashtbl.HashedType) : MAP with type key = H.t

EmptyMap(H) is a map module but it only supports the empty map: a map with zero elements.

Sourcemodule SingletonMap (H : Hashtbl.HashedType) : MAP with type key = H.t

SingletonMap(H) is a map module but it only supports singleton maps: maps with at most one element.

Source

module Set
  (RA : REPLACEMENT_AND_ACCOUNTING)
  (O : OVERFLOW)
  (H : Hashtbl.HashedType) : 
  SET with type elt = H.t

Set(RA)(O)(H) is a SET indexed by H and governed by RA and O.

Sourcemodule EmptySet (H : Hashtbl.HashedType) : SET with type elt = H.t

EmptySet(H) is a set module but it only supports the empty set: a set with zero elements.

Sourcemodule SingletonSet (H : Hashtbl.HashedType) : SET with type elt = H.t

SingletonSet(H) is a set module but it only supports singleton sets: sets with at most one element.

package aches