(*  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

   type task

   val dummy_task: unit -> 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 timing_of_task: task -> Time.time * Time.time * string list

   type queue

   val empty: queue

   val all_passive: queue -> bool

   val status: queue -> {ready: int, pending: int, running: int, passive: int}

   val cancel: queue -> group -> bool

   val cancel_all: queue -> group list

   val finish: task -> queue -> bool * queue

   val enqueue_passive: group -> (unit -> bool) -> queue -> task * queue

   val enqueue: string -> group -> task list -> int -> (bool -> bool) ->

     queue -> (task * bool) * queue

   val extend: task -> (bool -> bool) -> queue -> queue option

   val dequeue_passive: Thread.thread -> task -> queue -> bool * queue

   val dequeue: Thread.thread -> queue -> (task * (bool -> bool) list) option * queue

   type deps

   val init_deps: task list -> deps

   val finished_deps: deps -> bool

   val dequeue_deps: Thread.thread -> deps -> queue ->

     (((task * (bool -> bool) list) option * deps) * queue)

   val running: task -> (unit -> 'a) -> 'a

   val joining: task -> (unit -> 'a) -> 'a

   val waiting: task -> deps -> (unit -> 'a) -> 'a

 end;

 structure Task_Queue: TASK_QUEUE =

 struct

 val new_id = Synchronized.counter ();

 (** nested groups of tasks **)

 (* groups *)

 abstype group = Group of

  {parent: group option,

   id: int,

   status: exn list 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" []);

 fun group_id (Group {id, ...}) = id;

 fun eq_group (group1, group2) = group_id group1 = group_id group2;

 fun group_ancestry (Group {parent, id, ...}) =

   id :: (case parent of NONE => [] | SOME group => group_ancestry group);

 (* group status *)

 fun cancel_group (Group {status, ...}) exn =

   Synchronized.change status

     (fn exns =>

       if not (Exn.is_interrupt exn) orelse null exns then exn :: exns

       else exns);

 fun is_canceled (Group {parent, status, ...}) =

   not (null (Synchronized.value status)) orelse

     (case parent of NONE => false | SOME group => is_canceled group);

 fun group_status (Group {parent, status, ...}) =

   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));

 end;

 (* tasks *)

 type timing = Time.time * Time.time * string list;  (*run, wait, wait dependencies*)

 fun new_timing () =

   Synchronized.var "timing" ((Time.zeroTime, Time.zeroTime, []): timing);

 abstype task = Task of

  {group: group,

   name: string,

   id: int,

   pri: int option,

   timing: timing Synchronized.var}

 with

 fun dummy_task () =

   Task {group = new_group NONE, name = "", id = 0, pri = NONE, timing = new_timing ()};

 fun new_task group name pri =

   Task {group = group, name = name, id = new_id (), pri = pri, timing = new_timing ()};

 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 timing_of_task (Task {timing, ...}) = Synchronized.value timing;

 fun update_timing update (Task {timing, ...}) e =

   let

     val start = Time.now ();

     val result = Exn.capture e ();

     val t = Time.- (Time.now (), start);

     val _ = Synchronized.change timing (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));

 val eq_task = is_equal o task_ord;

 end;

 structure Task_Graph = Graph(type key = task val ord = task_ord);

 (** queue of jobs and groups **)

 (* jobs *)

 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;

 fun get_deps (jobs: jobs) task =

   Task_Graph.imm_preds jobs task handle Task_Graph.UNDEF _ => [];

 (* queue *)

 datatype queue = Queue of

  {groups: task list Inttab.table,   (*groups with presently known members*)

   jobs: jobs};                      (*job dependency graph*)

 fun make_queue groups jobs = Queue {groups = groups, jobs = jobs};

 val empty = make_queue Inttab.empty Task_Graph.empty;

 (* job status *)

 fun ready_job task (Job list, ([], _)) = SOME (task, rev list)

   | ready_job task (Passive abort, ([], _)) =

       if is_canceled (group_of_task task) then SOME (task, [fn _ => abort ()])

       else NONE

   | ready_job _ _ = NONE;

 fun active_job (_, (Job _, _)) = SOME ()

   | active_job (_, (Running _, _)) = SOME ()

   | active_job (task, (Passive _, _)) =

       if is_canceled (group_of_task task) then SOME () else NONE;

 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 null 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 tasks = Inttab.lookup_list groups (group_id group);

     val running =

       fold (get_job jobs #> (fn Running t => insert Thread.equal t | _ => I)) tasks [];

     val _ = List.app Simple_Thread.interrupt running;

   in null 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_groups, running) = Task_Graph.fold cancel_job jobs ([], []);

     val _ = List.app Simple_Thread.interrupt running;

   in running_groups end;

 (* finish *)

 fun finish task (Queue {groups, jobs}) =

   let

     val group = group_of_task task;

     val groups' = groups

       |> fold (fn gid => Inttab.remove_list eq_task (gid, task)) (group_ancestry group);

     val jobs' = Task_Graph.del_node task jobs;

     val maximal = null (Task_Graph.imm_succs jobs task);

   in (maximal, make_queue groups' jobs') end;

 (* enqueue *)

 fun enqueue_passive group abort (Queue {groups, jobs}) =

   let

     val task = new_task group "passive" NONE;

     val groups' = groups

       |> fold (fn gid => Inttab.cons_list (gid, task)) (group_ancestry group);

     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' = groups

       |> fold (fn gid => Inttab.cons_list (gid, task)) (group_ancestry group);

     val jobs' = jobs

       |> Task_Graph.new_node (task, Job [job])

       |> fold (add_job task) deps;

     val minimal = null (get_deps jobs' task);

   in ((task, minimal), 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 (true, make_queue groups jobs') end

   | _ => (false, queue));

 fun dequeue thread (queue as Queue {groups, jobs}) =

   (case Task_Graph.get_first (uncurry 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 *)

 abstype deps = Deps of task list

 with

 fun init_deps tasks = Deps tasks;

 fun finished_deps (Deps tasks) = null tasks;

 fun insert_deps (Deps tasks) = fold (insert (op =) o name_of_task) tasks;

 fun dequeue_deps thread (Deps 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, List.revAppend (rest, tasks))));

     fun ready_dep _ [] = NONE

       | ready_dep seen (task :: tasks) =

           if member eq_task seen task then ready_dep seen tasks

           else

             let val entry as (_, (ds, _)) = Task_Graph.get_entry jobs task in

               (case ready_job task entry of

                 NONE => ready_dep (task :: seen) (ds @ tasks)

               | some => some)

             end;

     fun result (res as (task, _)) deps' =

       let val jobs' = set_job task (Running thread) jobs

       in ((SOME res, Deps deps'), make_queue groups jobs') end;

   in

     (case ready deps [] of

       (SOME res, deps') => result res deps'

     | (NONE, deps') =>

         (case ready_dep [] deps' of

           SOME res => result res deps'

         | NONE => ((NONE, Deps deps'), queue)))

   end;

 end;

 (* 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), insert_deps deps ds)) task;

 end;