Module Tuple_pool.Unsafe

An Unsafe pool is like an ordinary pool, except that the create function does not require an initial element. The pool stores a dummy value for each slot. Such a pool is only safe if one never accesses a slot from a freed tuple.

It makes sense to use Unsafe if one has a small constrained chunk of code where one can prove that one never accesses a freed tuple, and one needs a pool where it is difficult to construct a dummy value.

Some Unsafe functions are faster than the corresponding safe version because they do not have to maintain values with the correct represention in the Uniform_array backing the pool: free, create, grow.

include S with type 'a Pointer.t = private int
module Pointer : sig ... end with type 'a t = private int
type 'slots t

A pool. 'slots will look like ('a1, ..., 'an) Slots.tn, and the pool holds tuples of type 'a1 * ... * 'an.

val sexp_of_t : ('slots -> Ppx_sexp_conv_lib.Sexp.t) -> 'slots t -> Ppx_sexp_conv_lib.Sexp.t
include Core_kernel.Invariant.S1 with type 'a t := 'a t
type 'a t
val invariant : 'a Base__.Invariant_intf.inv -> 'a t Base__.Invariant_intf.inv
val pointer_is_valid : 'slots t -> 'slots Pointer.t -> bool

pointer_is_valid t pointer returns true iff pointer points to a live tuple in t, i.e. pointer is not null, not free, and is in the range of t.

A pointer might not be in the range of a pool if it comes from another pool for example. In this case unsafe_get/set functions would cause a segfault.

val id_of_pointer : 'slots t -> 'slots Pointer.t -> Pointer.Id.t

id_of_pointer t pointer returns an id that is unique for the lifetime of pointer's tuple. When the tuple is freed, the id is no longer valid, and pointer_of_id_exn will fail on it. Pointer.null () has a distinct id from all non-null pointers.

val pointer_of_id_exn : 'slots t -> Pointer.Id.t -> 'slots Pointer.t

pointer_of_id_exn t id returns the pointer corresponding to id. It fails if the tuple corresponding to id was already freed.

val create : ('tuple, _) Slots.t as 'slots -> capacity:int -> dummy:'tuple -> 'slots t

create slots ~capacity ~dummy creates an empty pool that can hold up to capacity N-tuples. The slots of dummy are stored in free tuples. create raises if capacity < 0 || capacity > max_capacity ~slots_per_tuple.

val max_capacity : slots_per_tuple:int -> int

max_capacity returns the maximum capacity allowed when creating a pool.

val capacity : _ t -> int

capacity returns the maximum number of tuples that the pool can hold.

val length : _ t -> int

length returns the number of tuples currently in the pool.

0 <= length t <= capacity t
val grow : ?⁠capacity:int -> 'a t -> 'a t

grow t ~capacity returns a new pool t' with the supplied capacity. The new pool is to be used as a replacement for t. All live tuples in t are now live in t', and valid pointers to tuples in t are now valid pointers to the identical tuple in t'. It is an error to use t after calling grow t.

grow raises if the supplied capacity isn't larger than capacity t.

val is_full : _ t -> bool

is_full t returns true if no more tuples can be allocated in t.

val free : 'slots t -> 'slots Pointer.t -> unit

free t pointer frees the tuple pointed to by pointer from t.

val unsafe_free : 'slots t -> 'slots Pointer.t -> unit

unsafe_free t pointer frees the tuple pointed to by pointer without checking pointer_is_valid

val new1 : 'a0 Slots.t1 as 'slots t -> 'a0 -> 'slots Pointer.t

new<N> t a0 ... a<N-1> returns a new tuple from the pool, with the tuple's slots initialized to a0 ... a<N-1>. new raises if is_full t.

val new2 : ('a0, 'a1) Slots.t2 as 'slots t -> 'a0 -> 'a1 -> 'slots Pointer.t
val new3 : ('a0, 'a1, 'a2) Slots.t3 as 'slots t -> 'a0 -> 'a1 -> 'a2 -> 'slots Pointer.t
val new4 : ('a0, 'a1, 'a2, 'a3) Slots.t4 as 'slots t -> 'a0 -> 'a1 -> 'a2 -> 'a3 -> 'slots Pointer.t
val new5 : ('a0, 'a1, 'a2, 'a3, 'a4) Slots.t5 as 'slots t -> 'a0 -> 'a1 -> 'a2 -> 'a3 -> 'a4 -> 'slots Pointer.t
val new6 : ('a0, 'a1, 'a2, 'a3, 'a4, 'a5) Slots.t6 as 'slots t -> 'a0 -> 'a1 -> 'a2 -> 'a3 -> 'a4 -> 'a5 -> 'slots Pointer.t
val new7 : ('a0, 'a1, 'a2, 'a3, 'a4, 'a5, 'a6) Slots.t7 as 'slots t -> 'a0 -> 'a1 -> 'a2 -> 'a3 -> 'a4 -> 'a5 -> 'a6 -> 'slots Pointer.t
val new8 : ('a0, 'a1, 'a2, 'a3, 'a4, 'a5, 'a6, 'a7) Slots.t8 as 'slots t -> 'a0 -> 'a1 -> 'a2 -> 'a3 -> 'a4 -> 'a5 -> 'a6 -> 'a7 -> 'slots Pointer.t
val new9 : ('a0, 'a1, 'a2, 'a3, 'a4, 'a5, 'a6, 'a7, 'a8) Slots.t9 as 'slots t -> 'a0 -> 'a1 -> 'a2 -> 'a3 -> 'a4 -> 'a5 -> 'a6 -> 'a7 -> 'a8 -> 'slots Pointer.t
val new10 : ('a0, 'a1, 'a2, 'a3, 'a4, 'a5, 'a6, 'a7, 'a8, 'a9) Slots.t10 as 'slots t -> 'a0 -> 'a1 -> 'a2 -> 'a3 -> 'a4 -> 'a5 -> 'a6 -> 'a7 -> 'a8 -> 'a9 -> 'slots Pointer.t
val new11 : ('a0, 'a1, 'a2, 'a3, 'a4, 'a5, 'a6, 'a7, 'a8, 'a9, 'a10) Slots.t11 as 'slots t -> 'a0 -> 'a1 -> 'a2 -> 'a3 -> 'a4 -> 'a5 -> 'a6 -> 'a7 -> 'a8 -> 'a9 -> 'a10 -> 'slots Pointer.t
val new12 : ('a0, 'a1, 'a2, 'a3, 'a4, 'a5, 'a6, 'a7, 'a8, 'a9, 'a10, 'a11) Slots.t12 as 'slots t -> 'a0 -> 'a1 -> 'a2 -> 'a3 -> 'a4 -> 'a5 -> 'a6 -> 'a7 -> 'a8 -> 'a9 -> 'a10 -> 'a11 -> 'slots Pointer.t
val new13 : ('a0, 'a1, 'a2, 'a3, 'a4, 'a5, 'a6, 'a7, 'a8, 'a9, 'a10, 'a11, 'a12) Slots.t13 as 'slots t -> 'a0 -> 'a1 -> 'a2 -> 'a3 -> 'a4 -> 'a5 -> 'a6 -> 'a7 -> 'a8 -> 'a9 -> 'a10 -> 'a11 -> 'a12 -> 'slots Pointer.t
val new14 : ('a0, 'a1, 'a2, 'a3, 'a4, 'a5, 'a6, 'a7, 'a8, 'a9, 'a10, 'a11, 'a12, 'a13) Slots.t14 as 'slots t -> 'a0 -> 'a1 -> 'a2 -> 'a3 -> 'a4 -> 'a5 -> 'a6 -> 'a7 -> 'a8 -> 'a9 -> 'a10 -> 'a11 -> 'a12 -> 'a13 -> 'slots Pointer.t
val get_tuple : ('tuple, _) Slots.t as 'slots t -> 'slots Pointer.t -> 'tuple

get_tuple t pointer allocates an OCaml tuple isomorphic to the pool t's tuple pointed to by pointer. The tuple gets copied, but its slots do not.

val get : (_, 'variant) Slots.t as 'slots t -> 'slots Pointer.t -> ('variant, 'slot) Slot.t -> 'slot

get t pointer slot gets slot of the tuple pointed to by pointer in pool t.

set t pointer slot a sets to a the slot of the tuple pointed to by pointer in pool t.

In get and set, it is an error to refer to a pointer that has been freed. It is also an error to use a pointer with any pool other than the one the pointer was new'd from or grown to. These errors will lead to undefined behavior, but will not segfault.

unsafe_get is comparable in speed to get for immediate values, and 5%-10% faster for pointers.

unsafe_get and unsafe_set skip bounds checking, and can thus segfault.

val unsafe_get : (_, 'variant) Slots.t as 'slots t -> 'slots Pointer.t -> ('variant, 'slot) Slot.t -> 'slot
val set : (_, 'variant) Slots.t as 'slots t -> 'slots Pointer.t -> ('variant, 'slot) Slot.t -> 'slot -> unit
val unsafe_set : (_, 'variant) Slots.t as 'slots t -> 'slots Pointer.t -> ('variant, 'slot) Slot.t -> 'slot -> unit
val create : (_, _) Slots.t as 'slots -> capacity:int -> 'slots t

create slots ~capacity creates an empty pool that can hold up to capacity N-tuples. The elements of a free tuple may contain stale and/or invalid values for their types, and as such any access to a free tuple from this pool is unsafe.