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(************************************************************************)
(* * The Coq Proof Assistant / The Coq Development Team *)
(* v * INRIA, CNRS and contributors - Copyright 1999-2019 *)
(* <O___,, * (see CREDITS file for the list of authors) *)
(* \VV/ **************************************************************)
(* // * This file is distributed under the terms of the *)
(* * GNU Lesser General Public License Version 2.1 *)
(* * (see LICENSE file for the text of the license) *)
(************************************************************************)
module PriorityQueue : sig
type 'a t
val create : unit -> 'a t
val set_rel : ('a -> 'a -> int) -> 'a t -> unit
val is_empty : 'a t -> bool
val exists : ('a -> bool) -> 'a t -> bool
val pop : ?picky:('a -> bool) -> 'a t -> 'a
val push : 'a t -> 'a -> unit
val clear : 'a t -> unit
val length : 'a t -> int
end = struct
type 'a item = int * 'a
type 'a rel = 'a item -> 'a item -> int
type 'a t = ('a item list * 'a rel) ref
let sort_timestamp (i,_) (j,_) = i - j
let age = ref 0
let create () = ref ([],sort_timestamp)
let is_empty t = fst !t = []
let exists p t = List.exists (fun (_,x) -> p x) (fst !t)
let pop ?(picky=(fun _ -> true)) ({ contents = (l, rel) } as t) =
let rec aux acc = function
| [] -> raise Queue.Empty
| (_,x) :: xs when picky x -> t := (List.rev acc @ xs, rel); x
| (_,x) as hd :: xs -> aux (hd :: acc) xs in
aux [] l
let push ({ contents = (xs, rel) } as t) x =
incr age;
(* re-roting the whole list is not the most efficient way... *)
t := (List.sort rel (xs @ [!age,x]), rel)
let clear ({ contents = (l, rel) } as t) = t := ([], rel)
let set_rel rel ({ contents = (xs, _) } as t) =
let rel (_,x) (_,y) = rel x y in
t := (List.sort rel xs, rel)
let length ({ contents = (l, _) }) = List.length l
end
type 'a t = {
queue: 'a PriorityQueue.t;
lock : Mutex.t;
cond : Condition.t;
mutable nwaiting : int;
cond_waiting : Condition.t;
mutable release : bool;
}
exception BeingDestroyed
let create () = {
queue = PriorityQueue.create ();
lock = Mutex.create ();
cond = Condition.create ();
nwaiting = 0;
cond_waiting = Condition.create ();
release = false;
}
let pop ?(picky=(fun _ -> true)) ?(destroy=ref false)
({ queue = q; lock = m; cond = c; cond_waiting = cn } as tq)
=
Mutex.lock m;
if tq.release then (Mutex.unlock m; raise BeingDestroyed);
while not (PriorityQueue.exists picky q || !destroy) do
tq.nwaiting <- tq.nwaiting + 1;
Condition.broadcast cn;
Condition.wait c m;
tq.nwaiting <- tq.nwaiting - 1;
if tq.release || !destroy then (Mutex.unlock m; raise BeingDestroyed)
done;
if !destroy then (Mutex.unlock m; raise BeingDestroyed);
let x = PriorityQueue.pop ~picky q in
Condition.signal c;
Condition.signal cn;
Mutex.unlock m;
x
let broadcast { lock = m; cond = c } =
Mutex.lock m;
Condition.broadcast c;
Mutex.unlock m
let push { queue = q; lock = m; cond = c; release } x =
if release then CErrors.anomaly(Pp.str
"TQueue.push while being destroyed! Only 1 producer/destroyer allowed.");
Mutex.lock m;
PriorityQueue.push q x;
Condition.broadcast c;
Mutex.unlock m
let length { queue = q; lock = m } =
Mutex.lock m;
let n = PriorityQueue.length q in
Mutex.unlock m;
n
let clear { queue = q; lock = m; cond = c } =
Mutex.lock m;
PriorityQueue.clear q;
Mutex.unlock m
let clear_saving { queue = q; lock = m; cond = c } f =
Mutex.lock m;
let saved = ref [] in
while not (PriorityQueue.is_empty q) do
let elem = PriorityQueue.pop q in
match f elem with
| Some x -> saved := x :: !saved
| None -> ()
done;
Mutex.unlock m;
List.rev !saved
let is_empty { queue = q } = PriorityQueue.is_empty q
let destroy tq =
tq.release <- true;
while tq.nwaiting > 0 do
Mutex.lock tq.lock;
Condition.broadcast tq.cond;
Mutex.unlock tq.lock;
done;
tq.release <- false
let wait_until_n_are_waiting_and_queue_empty j tq =
Mutex.lock tq.lock;
while not (PriorityQueue.is_empty tq.queue) || tq.nwaiting < j do
Condition.wait tq.cond_waiting tq.lock
done;
Mutex.unlock tq.lock
let wait_until_n_are_waiting_then_snapshot j tq =
let l = ref [] in
Mutex.lock tq.lock;
while not (PriorityQueue.is_empty tq.queue) do
l := PriorityQueue.pop tq.queue :: !l
done;
while tq.nwaiting < j do Condition.wait tq.cond_waiting tq.lock done;
List.iter (PriorityQueue.push tq.queue) (List.rev !l);
if !l <> [] then Condition.broadcast tq.cond;
Mutex.unlock tq.lock;
List.rev !l
let set_order tq rel =
Mutex.lock tq.lock;
PriorityQueue.set_rel rel tq.queue;
Mutex.unlock tq.lock