Module Pooled_hashtbl

module Pooled_hashtbl: sig .. end

A polymorphic hashtbl that uses Pool to avoid allocation.

This uses the standard linked-chain hashtable algorithm, albeit with links performed through a pool and hence avoiding caml_modify (for table manipulation), even when hashing object keys/values.

This implementation is worth exploring for your application if profiling demonstrates that garbage collection and the caml_modify write barrier are a significant part of your execution time.

include Core_hashtbl_intf.Hashtbl

val resize : ('a, 'b) t -> int -> unit

resize t size ensures that t can hold at least size entries without resizing (again), provided that t has growth enabled. This is useful for sizing global tables during application initialization, to avoid subsequent, expensive growth online. See Zero.Immediate.String.resize, for example.

val on_grow : before:(unit -> 'a) ->
       after:('a -> old_capacity:int -> new_capacity:int -> unit) -> unit

on_grow ~before ~after allows you to connect higher level loggers to the point where these hashtbls grow. before is called before the table grows, and after after it. This permits you to e.g. measure the time elapsed between the two.

This is only meant for debugging and profiling, e.g. note that once a callback is installed, there is no way to remove it.