picos 0.3.0 · OCaml Package

Lock-free hash table.

Example:

# let t : (int, string) Picos_htbl.t =
    Picos_htbl.create ~hashed_type:(module Int) ()
val t : (int, string) Picos_htbl.t = <abstr>

# Picos_htbl.try_add t 42 "The answer"
- : bool = true

# Picos_htbl.try_add t 101 "Basics"
- : bool = true

# Picos_htbl.find_exn t 42
- : string = "The answer"

# Picos_htbl.try_add t 101 "The basics"
- : bool = false

# Picos_htbl.remove_all t |> List.of_seq
- : (int * string) list = [(101, "Basics"); (42, "The answer")]

🏎️ Single key reads with this hash table are actually wait-free rather than just lock-free. Internal resizing automatically uses all the threads that are trying to write to the hash table.

type (!'k, !'v) t

Represents a lock-free hash table mapping keys of type 'k to values of type 'v.

type 'k hashed_type = (module Stdlib.Hashtbl.HashedType with type t = 'k)

First-class module type abbreviation.

val create : ?hashed_type:'k hashed_type -> unit -> ('k, 'v) t

create ~hashed_type:(module Key) () creates a new empty lock-free hash table.

The optional hashed_type argument can be used to specify the equal and hash operations on keys. Slow polymorphic equality (=) and slow polymorphic seeded_hash (Random.bits ()) is used by default.

val find_exn : ('k, 'v) t -> 'k -> 'v

find_exn htbl key returns the current binding of key in the hash table htbl or raises Not_found if no such binding exists.

val mem : ('k, 'v) t -> 'k -> bool

mem htbl key determines whether the hash table htbl has a binding for the key.

val try_add : ('k, 'v) t -> 'k -> 'v -> bool

try_add htbl key value tries to add a new binding of key to value to the hash table htbl. Returns true on success and false in case the hash table already contained a binding for key.

val try_remove : ('k, 'v) t -> 'k -> bool

try_remove htbl key tries to remove a binding of key from the hash table htbl. Returns true on success and false in case the hash table did not contain a binding for key.

val remove_exn : ('k, 'v) t -> 'k -> 'v

remove_exn htbl key tries to remove a binding of key from the hash table htbl and return it or raise Not_found if no such binding exists.

val remove_all : ('k, 'v) t -> ('k * 'v) Stdlib.Seq.t

remove_all htbl takes a snapshot of the bindings in the hash table, removes the bindings from the hash table, and returns the snapshot as an association sequence.

🐌 This is a linear time operation.

val to_seq : ('k, 'v) t -> ('k * 'v) Stdlib.Seq.t

to_seq htbl takes a snapshot of the bindings in the hash table and returns them as an association sequence.

🐌 This is a linear time operation.

package picos