clarified active_job: take dependencies into account (e.g. future based on promise);
(* Title: Pure/Concurrent/task_queue.ML
Author: Makarius
Ordered queue of grouped tasks.
*)
signature TASK_QUEUE =
sig
type group
val new_group: group option -> group
val group_id: group -> int
val eq_group: group * group -> bool
val cancel_group: group -> exn -> unit
val is_canceled: group -> bool
val group_status: group -> exn list
val str_of_group: group -> string
val str_of_groups: group -> string
type task
val dummy_task: task
val group_of_task: task -> group
val name_of_task: task -> string
val pri_of_task: task -> int
val str_of_task: task -> string
val str_of_task_groups: task -> string
val task_statistics: task -> Properties.T
val running: task -> (unit -> 'a) -> 'a
val joining: task -> (unit -> 'a) -> 'a
val waiting: task -> task list -> (unit -> 'a) -> 'a
type queue
val empty: queue
val group_tasks: queue -> group -> task list
val known_task: queue -> task -> bool
val all_passive: queue -> bool
val status: queue -> {ready: int, pending: int, running: int, passive: int}
val cancel: queue -> group -> Thread.thread list
val cancel_all: queue -> group list * Thread.thread list
val finish: task -> queue -> bool * queue
val enroll: Thread.thread -> string -> group -> queue -> task * queue
val enqueue_passive: group -> (unit -> bool) -> queue -> task * queue
val enqueue: string -> group -> task list -> int -> (bool -> bool) -> queue -> task * queue
val extend: task -> (bool -> bool) -> queue -> queue option
val dequeue_passive: Thread.thread -> task -> queue -> bool option * queue
val dequeue: Thread.thread -> queue -> (task * (bool -> bool) list) option * queue
val dequeue_deps: Thread.thread -> task list -> queue ->
(((task * (bool -> bool) list) option * task list) * queue)
end;
structure Task_Queue: TASK_QUEUE =
struct
val new_id = Counter.make ();
(** nested groups of tasks **)
(* groups *)
abstype group = Group of
{parent: group option,
id: int,
status: exn option Synchronized.var}
with
fun make_group (parent, id, status) = Group {parent = parent, id = id, status = status};
fun new_group parent = make_group (parent, new_id (), Synchronized.var "group_status" NONE);
fun group_id (Group {id, ...}) = id;
fun eq_group (group1, group2) = group_id group1 = group_id group2;
fun fold_groups f (g as Group {parent = NONE, ...}) a = f g a
| fold_groups f (g as Group {parent = SOME group, ...}) a = fold_groups f group (f g a);
(* group status *)
fun cancel_group (Group {status, ...}) exn =
Synchronized.change status
(fn exns => SOME (Par_Exn.make (exn :: the_list exns)));
fun is_canceled (Group {parent, status, ...}) =
is_some (Synchronized.value status) orelse
(case parent of NONE => false | SOME group => is_canceled group);
fun group_status (Group {parent, status, ...}) =
the_list (Synchronized.value status) @
(case parent of NONE => [] | SOME group => group_status group);
fun str_of_group group =
(is_canceled group ? enclose "(" ")") (string_of_int (group_id group));
fun str_of_groups group =
space_implode "/" (map str_of_group (rev (fold_groups cons group [])));
end;
(* tasks *)
type timing = Time.time * Time.time * string list; (*run, wait, wait dependencies*)
val timing_start = (Time.zeroTime, Time.zeroTime, []): timing;
fun new_timing () =
if ! Multithreading.trace < 2 then NONE
else SOME (Synchronized.var "timing" timing_start);
abstype task = Task of
{group: group,
name: string,
id: int,
pri: int option,
timing: timing Synchronized.var option,
pos: Position.T}
with
val dummy_task =
Task {group = new_group NONE, name = "", id = 0, pri = NONE, timing = NONE,
pos = Position.none};
fun new_task group name pri =
Task {group = group, name = name, id = new_id (), pri = pri, timing = new_timing (),
pos = Position.thread_data ()};
fun group_of_task (Task {group, ...}) = group;
fun name_of_task (Task {name, ...}) = name;
fun pri_of_task (Task {pri, ...}) = the_default 0 pri;
fun str_of_task (Task {name, id, ...}) =
if name = "" then string_of_int id else string_of_int id ^ " (" ^ name ^ ")";
fun str_of_task_groups task = str_of_task task ^ " in " ^ str_of_groups (group_of_task task);
fun update_timing update (Task {timing, ...}) e =
uninterruptible (fn restore_attributes => fn () =>
let
val start = Time.now ();
val result = Exn.capture (restore_attributes e) ();
val t = Time.- (Time.now (), start);
val _ = (case timing of NONE => () | SOME var => Synchronized.change var (update t));
in Exn.release result end) ();
fun task_ord (Task {id = id1, pri = pri1, ...}, Task {id = id2, pri = pri2, ...}) =
prod_ord (rev_order o option_ord int_ord) int_ord ((pri1, id1), (pri2, id2));
fun task_statistics (Task {name, id, timing, pos, ...}) =
let
val (run, wait, wait_deps) =
(case timing of NONE => timing_start | SOME var => Synchronized.value var);
fun micros time = string_of_int (Time.toNanoseconds time div 1000);
in
[("now", Markup.print_real (Time.toReal (Time.now ()))),
("task_name", name), ("task_id", Markup.print_int id),
("run", micros run), ("wait", micros wait), ("wait_deps", commas wait_deps)] @
Position.properties_of pos
end;
end;
structure Tasks = Table(type key = task val ord = task_ord);
structure Task_Graph = Graph(type key = task val ord = task_ord);
(* timing *)
fun running task =
update_timing (fn t => fn (a, b, ds) => (Time.+ (a, t), b, ds)) task;
fun joining task =
update_timing (fn t => fn (a, b, ds) => (Time.- (a, t), b, ds)) task;
fun waiting task deps =
update_timing (fn t => fn (a, b, ds) =>
(Time.- (a, t), Time.+ (b, t),
if ! Multithreading.trace > 0
then fold (insert (op =) o name_of_task) deps ds else ds)) task;
(** queue of jobs and groups **)
(* known group members *)
type groups = unit Tasks.table Inttab.table;
fun get_tasks (groups: groups) gid =
the_default Tasks.empty (Inttab.lookup groups gid);
fun add_task (gid, task) groups =
Inttab.update (gid, Tasks.update (task, ()) (get_tasks groups gid)) groups;
fun del_task (gid, task) groups =
let val tasks = Tasks.delete_safe task (get_tasks groups gid) in
if Tasks.is_empty tasks then Inttab.delete_safe gid groups
else Inttab.update (gid, tasks) groups
end;
(* job dependency graph *)
datatype job =
Job of (bool -> bool) list |
Running of Thread.thread |
Passive of unit -> bool;
type jobs = job Task_Graph.T;
fun get_job (jobs: jobs) task = Task_Graph.get_node jobs task;
fun set_job task job (jobs: jobs) = Task_Graph.map_node task (K job) jobs;
fun add_job task dep (jobs: jobs) =
Task_Graph.add_edge (dep, task) jobs handle Task_Graph.UNDEF _ => jobs;
(* queue *)
datatype queue = Queue of {groups: groups, jobs: jobs};
fun make_queue groups jobs = Queue {groups = groups, jobs = jobs};
val empty = make_queue Inttab.empty Task_Graph.empty;
fun group_tasks (Queue {groups, ...}) group = Tasks.keys (get_tasks groups (group_id group));
fun known_task (Queue {jobs, ...}) task = can (Task_Graph.get_entry jobs) task;
(* job status *)
fun ready_job (task, (Job list, (deps, _))) =
if Task_Graph.Keys.is_empty deps then SOME (task, rev list) else NONE
| ready_job (task, (Passive abort, (deps, _))) =
if Task_Graph.Keys.is_empty deps andalso is_canceled (group_of_task task)
then SOME (task, [fn _ => abort ()])
else NONE
| ready_job _ = NONE;
fun active_job (task, (Running _, _)) = SOME (task, [])
| active_job arg = ready_job arg;
fun all_passive (Queue {jobs, ...}) = is_none (Task_Graph.get_first active_job jobs);
(* queue status *)
fun status (Queue {jobs, ...}) =
let
val (x, y, z, w) =
Task_Graph.fold (fn (_, (job, (deps, _))) => fn (x, y, z, w) =>
(case job of
Job _ => if Task_Graph.Keys.is_empty deps then (x + 1, y, z, w) else (x, y + 1, z, w)
| Running _ => (x, y, z + 1, w)
| Passive _ => (x, y, z, w + 1)))
jobs (0, 0, 0, 0);
in {ready = x, pending = y, running = z, passive = w} end;
(** task queue operations **)
(* cancel -- peers and sub-groups *)
fun cancel (Queue {groups, jobs}) group =
let
val _ = cancel_group group Exn.Interrupt;
val running =
Tasks.fold (fn (task, _) =>
(case get_job jobs task of Running thread => insert Thread.equal thread | _ => I))
(get_tasks groups (group_id group)) [];
in running end;
fun cancel_all (Queue {jobs, ...}) =
let
fun cancel_job (task, (job, _)) (groups, running) =
let
val group = group_of_task task;
val _ = cancel_group group Exn.Interrupt;
in
(case job of
Running t => (insert eq_group group groups, insert Thread.equal t running)
| _ => (groups, running))
end;
val running = Task_Graph.fold cancel_job jobs ([], []);
in running end;
(* finish *)
fun finish task (Queue {groups, jobs}) =
let
val group = group_of_task task;
val groups' = fold_groups (fn g => del_task (group_id g, task)) group groups;
val jobs' = Task_Graph.del_node task jobs;
val maximal = Task_Graph.is_maximal jobs task;
in (maximal, make_queue groups' jobs') end;
(* enroll *)
fun enroll thread name group (Queue {groups, jobs}) =
let
val task = new_task group name NONE;
val groups' = fold_groups (fn g => add_task (group_id g, task)) group groups;
val jobs' = jobs |> Task_Graph.new_node (task, Running thread);
in (task, make_queue groups' jobs') end;
(* enqueue *)
fun enqueue_passive group abort (Queue {groups, jobs}) =
let
val task = new_task group "passive" NONE;
val groups' = fold_groups (fn g => add_task (group_id g, task)) group groups;
val jobs' = jobs |> Task_Graph.new_node (task, Passive abort);
in (task, make_queue groups' jobs') end;
fun enqueue name group deps pri job (Queue {groups, jobs}) =
let
val task = new_task group name (SOME pri);
val groups' = fold_groups (fn g => add_task (group_id g, task)) group groups;
val jobs' = jobs
|> Task_Graph.new_node (task, Job [job])
|> fold (add_job task) deps;
in (task, make_queue groups' jobs') end;
fun extend task job (Queue {groups, jobs}) =
(case try (get_job jobs) task of
SOME (Job list) => SOME (make_queue groups (set_job task (Job (job :: list)) jobs))
| _ => NONE);
(* dequeue *)
fun dequeue_passive thread task (queue as Queue {groups, jobs}) =
(case try (get_job jobs) task of
SOME (Passive _) =>
let val jobs' = set_job task (Running thread) jobs
in (SOME true, make_queue groups jobs') end
| SOME _ => (SOME false, queue)
| NONE => (NONE, queue));
fun dequeue thread (queue as Queue {groups, jobs}) =
(case Task_Graph.get_first ready_job jobs of
SOME (result as (task, _)) =>
let val jobs' = set_job task (Running thread) jobs
in (SOME result, make_queue groups jobs') end
| NONE => (NONE, queue));
(* dequeue wrt. dynamic dependencies *)
fun dequeue_deps thread deps (queue as Queue {groups, jobs}) =
let
fun ready [] rest = (NONE, rev rest)
| ready (task :: tasks) rest =
(case try (Task_Graph.get_entry jobs) task of
NONE => ready tasks rest
| SOME (_, entry) =>
(case ready_job (task, entry) of
NONE => ready tasks (task :: rest)
| some => (some, fold cons rest tasks)));
fun ready_dep _ [] = NONE
| ready_dep seen (task :: tasks) =
if Tasks.defined seen task then ready_dep seen tasks
else
let val entry as (_, (ds, _)) = #2 (Task_Graph.get_entry jobs task) in
(case ready_job (task, entry) of
NONE => ready_dep (Tasks.update (task, ()) seen) (Task_Graph.Keys.dest ds @ tasks)
| some => some)
end;
fun result (res as (task, _)) deps' =
let val jobs' = set_job task (Running thread) jobs
in ((SOME res, deps'), make_queue groups jobs') end;
in
(case ready deps [] of
(SOME res, deps') => result res deps'
| (NONE, deps') =>
(case ready_dep Tasks.empty deps' of
SOME res => result res deps'
| NONE => ((NONE, deps'), queue)))
end;
end;