src/Pure/Concurrent/future.ML
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(*  Title:      Pure/Concurrent/future.ML
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    Author:     Makarius
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Value-oriented parallelism via futures and promises.  See also
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http://www4.in.tum.de/~wenzelm/papers/parallel-isabelle.pdf
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http://www4.in.tum.de/~wenzelm/papers/parallel-ml.pdf
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Notes:
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  * Futures are similar to delayed evaluation, i.e. delay/force is
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    generalized to fork/join.  The idea is to model parallel
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    value-oriented computations (not communicating processes).
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  * Forked futures are evaluated spontaneously by a farm of worker
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    threads in the background; join resynchronizes the computation and
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    delivers results (values or exceptions).
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  * The pool of worker threads is limited, usually in correlation with
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    the number of physical cores on the machine.  Note that allocation
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    of runtime resources may be distorted either if workers yield CPU
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    time (e.g. via system sleep or wait operations), or if non-worker
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    threads contend for significant runtime resources independently.
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    There is a limited number of replacement worker threads that get
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    activated in certain explicit wait conditions.
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  * Future tasks are organized in groups, which are block-structured.
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    When forking a new new task, the default is to open an individual
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    subgroup, unless some common group is specified explicitly.
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    Failure of one group member causes the immediate peers to be
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    interrupted eventually (i.e. none by default).  Interrupted tasks
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    that lack regular result information, will pick up parallel
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    exceptions from the cumulative group context (as Par_Exn).
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  * Future task groups may be canceled: present and future group
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    members will be interrupted eventually.
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  * Promised "passive" futures are fulfilled by external means.  There
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    is no associated evaluation task, but other futures can depend on
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    them via regular join operations.
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*)
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signature FUTURE =
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sig
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  type task = Task_Queue.task
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  type group = Task_Queue.group
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  val new_group: group option -> group
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  val worker_task: unit -> task option
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  val worker_group: unit -> group option
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  val worker_subgroup: unit -> group
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  type 'a future
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  val task_of: 'a future -> task
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  val peek: 'a future -> 'a Exn.result option
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  val is_finished: 'a future -> bool
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  val get_finished: 'a future -> 'a
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  val interruptible_task: ('a -> 'b) -> 'a -> 'b
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  val cancel_group: group -> task list
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  val cancel: 'a future -> task list
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  type fork_params =
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    {name: string, group: group option, deps: task list, pri: int, interrupts: bool}
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  val forks: fork_params -> (unit -> 'a) list -> 'a future list
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  val fork_pri: int -> (unit -> 'a) -> 'a future
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  val fork: (unit -> 'a) -> 'a future
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  val join_results: 'a future list -> 'a Exn.result list
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  val join_result: 'a future -> 'a Exn.result
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  val join: 'a future -> 'a
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  val join_tasks: task list -> unit
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  val value_result: 'a Exn.result -> 'a future
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  val value: 'a -> 'a future
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  val map: ('a -> 'b) -> 'a future -> 'b future
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  val cond_forks: fork_params -> (unit -> 'a) list -> 'a future list
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  val promise_group: group -> (unit -> unit) -> 'a future
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  val promise: (unit -> unit) -> 'a future
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  val fulfill_result: 'a future -> 'a Exn.result -> unit
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  val fulfill: 'a future -> 'a -> unit
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  val shutdown: unit -> unit
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  val status: (unit -> 'a) -> 'a
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end;
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structure Future: FUTURE =
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struct
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(** future values **)
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type task = Task_Queue.task;
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type group = Task_Queue.group;
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val new_group = Task_Queue.new_group;
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(* identifiers *)
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local
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  val tag = Universal.tag () : task option Universal.tag;
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in
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  fun worker_task () = the_default NONE (Thread.getLocal tag);
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  fun setmp_worker_task task f x = setmp_thread_data tag (worker_task ()) (SOME task) f x;
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end;
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val worker_group = Option.map Task_Queue.group_of_task o worker_task;
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fun worker_subgroup () = new_group (worker_group ());
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fun worker_joining e =
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  (case worker_task () of
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    NONE => e ()
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  | SOME task => Task_Queue.joining task e);
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fun worker_waiting deps e =
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  (case worker_task () of
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    NONE => e ()
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  | SOME task => Task_Queue.waiting task deps e);
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(* datatype future *)
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type 'a result = 'a Exn.result Single_Assignment.var;
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datatype 'a future = Future of
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 {promised: bool,
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  task: task,
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  result: 'a result};
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fun task_of (Future {task, ...}) = task;
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fun result_of (Future {result, ...}) = result;
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fun peek x = Single_Assignment.peek (result_of x);
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fun is_finished x = is_some (peek x);
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fun get_finished x =
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  (case peek x of
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    SOME res => Exn.release res
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  | NONE => raise Fail "Unfinished future evaluation");
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(** scheduling **)
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(* synchronization *)
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val scheduler_event = ConditionVar.conditionVar ();
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val work_available = ConditionVar.conditionVar ();
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val work_finished = ConditionVar.conditionVar ();
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local
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  val lock = Mutex.mutex ();
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in
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fun SYNCHRONIZED name = Simple_Thread.synchronized name lock;
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fun wait cond = (*requires SYNCHRONIZED*)
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  Multithreading.sync_wait NONE NONE cond lock;
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fun wait_timeout timeout cond = (*requires SYNCHRONIZED*)
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  Multithreading.sync_wait NONE (SOME (Time.+ (Time.now (), timeout))) cond lock;
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fun signal cond = (*requires SYNCHRONIZED*)
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  ConditionVar.signal cond;
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fun broadcast cond = (*requires SYNCHRONIZED*)
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  ConditionVar.broadcast cond;
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fun broadcast_work () = (*requires SYNCHRONIZED*)
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 (ConditionVar.broadcast work_available;
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  ConditionVar.broadcast work_finished);
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end;
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(* global state *)
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val queue = Unsynchronized.ref Task_Queue.empty;
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val next = Unsynchronized.ref 0;
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val scheduler = Unsynchronized.ref (NONE: Thread.thread option);
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val canceled = Unsynchronized.ref ([]: group list);
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val do_shutdown = Unsynchronized.ref false;
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val max_workers = Unsynchronized.ref 0;
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val max_active = Unsynchronized.ref 0;
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val worker_trend = Unsynchronized.ref 0;
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datatype worker_state = Working | Waiting | Sleeping;
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val workers = Unsynchronized.ref ([]: (Thread.thread * worker_state Unsynchronized.ref) list);
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fun count_workers state = (*requires SYNCHRONIZED*)
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  fold (fn (_, state_ref) => fn i => if ! state_ref = state then i + 1 else i) (! workers) 0;
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(* cancellation primitives *)
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fun cancel_now group = (*requires SYNCHRONIZED*)
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  Task_Queue.cancel (! queue) group;
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fun cancel_later group = (*requires SYNCHRONIZED*)
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 (Unsynchronized.change canceled (insert Task_Queue.eq_group group);
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  broadcast scheduler_event);
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fun interruptible_task f x =
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  (if Multithreading.available then
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    Multithreading.with_attributes
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      (if is_some (worker_task ())
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       then Multithreading.private_interrupts
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       else Multithreading.public_interrupts)
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      (fn _ => f x)
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   else interruptible f x)
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  before Multithreading.interrupted ();
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(* worker threads *)
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fun worker_exec (task, jobs) =
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  let
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    val group = Task_Queue.group_of_task task;
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    val valid = not (Task_Queue.is_canceled group);
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    val ok =
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      Task_Queue.running task (fn () =>
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        setmp_worker_task task (fn () =>
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          fold (fn job => fn ok => job valid andalso ok) jobs true) ());
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    val _ = Multithreading.tracing 2 (fn () =>
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      let
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        val s = Task_Queue.str_of_task_groups task;
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        fun micros time = string_of_int (Time.toNanoseconds time div 1000);
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        val (run, wait, deps) = Task_Queue.timing_of_task task;
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      in "TASK " ^ s ^ " " ^ micros run ^ " " ^ micros wait ^ " (" ^ commas deps ^ ")" end);
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    val _ = SYNCHRONIZED "finish" (fn () =>
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      let
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        val maximal = Unsynchronized.change_result queue (Task_Queue.finish task);
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        val test = Exn.capture Multithreading.interrupted ();
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        val _ =
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          if ok andalso not (Exn.is_interrupt_exn test) then ()
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          else if null (cancel_now group) then ()
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          else cancel_later group;
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        val _ = broadcast work_finished;
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        val _ = if maximal then () else signal work_available;
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      in () end);
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  in () end;
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fun worker_wait active cond = (*requires SYNCHRONIZED*)
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  let
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    val state =
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      (case AList.lookup Thread.equal (! workers) (Thread.self ()) of
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        SOME state => state
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      | NONE => raise Fail "Unregistered worker thread");
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    val _ = state := (if active then Waiting else Sleeping);
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    val _ = wait cond;
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    val _ = state := Working;
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  in () end;
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fun worker_next () = (*requires SYNCHRONIZED*)
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  if length (! workers) > ! max_workers then
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    (Unsynchronized.change workers (AList.delete Thread.equal (Thread.self ()));
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     signal work_available;
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     NONE)
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  else if count_workers Working > ! max_active then
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    (worker_wait false work_available; worker_next ())
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  else
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    (case Unsynchronized.change_result queue (Task_Queue.dequeue (Thread.self ())) of
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      NONE => (worker_wait false work_available; worker_next ())
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    | some => (signal work_available; some));
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fun worker_loop name =
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  (case SYNCHRONIZED name (fn () => worker_next ()) of
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    NONE => ()
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  | SOME work => (worker_exec work; worker_loop name));
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fun worker_start name = (*requires SYNCHRONIZED*)
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  Unsynchronized.change workers (cons (Simple_Thread.fork false (fn () => worker_loop name),
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    Unsynchronized.ref Working));
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(* scheduler *)
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val status_ticks = Unsynchronized.ref 0;
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val last_round = Unsynchronized.ref Time.zeroTime;
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val next_round = seconds 0.05;
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fun scheduler_next () = (*requires SYNCHRONIZED*)
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  let
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    val now = Time.now ();
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    val tick = Time.<= (Time.+ (! last_round, next_round), now);
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    val _ = if tick then last_round := now else ();
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    (* queue and worker status *)
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    val _ =
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      if tick then Unsynchronized.change status_ticks (fn i => (i + 1) mod 10) else ();
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    val _ =
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      if tick andalso ! status_ticks = 0 then
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        Multithreading.tracing 1 (fn () =>
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          let
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            val {ready, pending, running, passive} = Task_Queue.status (! queue);
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            val total = length (! workers);
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            val active = count_workers Working;
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            val waiting = count_workers Waiting;
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          in
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            "SCHEDULE " ^ Time.toString now ^ ": " ^
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              string_of_int ready ^ " ready, " ^
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              string_of_int pending ^ " pending, " ^
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              string_of_int running ^ " running, " ^
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              string_of_int passive ^ " passive; " ^
33407
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   300
              string_of_int total ^ " workers, " ^
33410
e351f4c1f18c worker activity: distinguish between waiting (formerly active) and sleeping;
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   301
              string_of_int active ^ " active, " ^
e351f4c1f18c worker activity: distinguish between waiting (formerly active) and sleeping;
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   302
              string_of_int waiting ^ " waiting "
33407
1427333220bc worker_next: ensure that work_available is passed on before sleeping (was occasionally lost when worker configuration changed, causing scheduler deadlock);
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   303
          end)
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   304
      else ();
32053
257eac3946e9 scheduler: tuned tracing (status);
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   305
28191
9e5f556409c6 future: allow explicit group;
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   306
    val _ =
32219
9a2566d1fdbd more specific conditions: scheduler_event, work_available, work_finished -- considereably reduces overhead with many threads;
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   307
      if forall (Thread.isActive o #1) (! workers) then ()
32095
ad4be204fdfe tuned tracing;
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diff changeset
   308
      else
33409
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   309
        let
37682
ad5489a6be48 tuned white space;
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   310
          val (alive, dead) = List.partition (Thread.isActive o #1) (! workers);
33409
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   311
          val _ = workers := alive;
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   312
        in
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   313
          Multithreading.tracing 0 (fn () =>
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diff changeset
   314
            "SCHEDULE: disposed " ^ string_of_int (length dead) ^ " dead worker threads")
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diff changeset
   315
        end;
28191
9e5f556409c6 future: allow explicit group;
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   316
33415
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   317
352fe8e9162d worker_next: plain signalling via work_available only, not scheduler_event;
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   318
    (* worker pool adjustments *)
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   319
352fe8e9162d worker_next: plain signalling via work_available only, not scheduler_event;
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   320
    val max_active0 = ! max_active;
352fe8e9162d worker_next: plain signalling via work_available only, not scheduler_event;
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diff changeset
   321
    val max_workers0 = ! max_workers;
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   322
28206
bcd48c6897d4 eliminated requests, use global state variables uniformly;
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diff changeset
   323
    val m = if ! do_shutdown then 0 else Multithreading.max_threads_value ();
33406
1ddcb8472bd2 slightly leaner and more direct control of worker activity etc.;
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diff changeset
   324
    val _ = max_active := m;
1ddcb8472bd2 slightly leaner and more direct control of worker activity etc.;
wenzelm
parents: 33061
diff changeset
   325
33411
a07558eb5029 worker_next: treat wait for work_available as Sleeping, not Waiting;
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diff changeset
   326
    val mm =
a07558eb5029 worker_next: treat wait for work_available as Sleeping, not Waiting;
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   327
      if ! do_shutdown then 0
a07558eb5029 worker_next: treat wait for work_available as Sleeping, not Waiting;
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   328
      else if m = 9999 then 1
33413
cb409680dda8 avoid broadcast work_available, use daisy-chained signal instead;
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parents: 33411
diff changeset
   329
      else Int.min (Int.max (count_workers Working + 2 * count_workers Waiting, m), 4 * m);
33411
a07558eb5029 worker_next: treat wait for work_available as Sleeping, not Waiting;
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diff changeset
   330
    val _ =
a07558eb5029 worker_next: treat wait for work_available as Sleeping, not Waiting;
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diff changeset
   331
      if tick andalso mm > ! max_workers then
a07558eb5029 worker_next: treat wait for work_available as Sleeping, not Waiting;
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parents: 33410
diff changeset
   332
        Unsynchronized.change worker_trend (fn w => if w < 0 then 0 else w + 1)
a07558eb5029 worker_next: treat wait for work_available as Sleeping, not Waiting;
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parents: 33410
diff changeset
   333
      else if tick andalso mm < ! max_workers then
a07558eb5029 worker_next: treat wait for work_available as Sleeping, not Waiting;
wenzelm
parents: 33410
diff changeset
   334
        Unsynchronized.change worker_trend (fn w => if w > 0 then 0 else w - 1)
a07558eb5029 worker_next: treat wait for work_available as Sleeping, not Waiting;
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parents: 33410
diff changeset
   335
      else ();
a07558eb5029 worker_next: treat wait for work_available as Sleeping, not Waiting;
wenzelm
parents: 33410
diff changeset
   336
    val _ =
33415
352fe8e9162d worker_next: plain signalling via work_available only, not scheduler_event;
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parents: 33413
diff changeset
   337
      if mm = 0 orelse ! worker_trend > 50 orelse ! worker_trend < ~50 then
352fe8e9162d worker_next: plain signalling via work_available only, not scheduler_event;
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parents: 33413
diff changeset
   338
        max_workers := mm
44173
aaaa13e297dc immediate fork of initial workers -- avoid 5 ticks (250ms) for adaptive scheme (a07558eb5029);
wenzelm
parents: 44115
diff changeset
   339
      else if ! worker_trend > 5 andalso ! max_workers < 2 * m orelse ! max_workers = 0 then
33415
352fe8e9162d worker_next: plain signalling via work_available only, not scheduler_event;
wenzelm
parents: 33413
diff changeset
   340
        max_workers := Int.min (mm, 2 * m)
33411
a07558eb5029 worker_next: treat wait for work_available as Sleeping, not Waiting;
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diff changeset
   341
      else ();
33406
1ddcb8472bd2 slightly leaner and more direct control of worker activity etc.;
wenzelm
parents: 33061
diff changeset
   342
33407
1427333220bc worker_next: ensure that work_available is passed on before sleeping (was occasionally lost when worker configuration changed, causing scheduler deadlock);
wenzelm
parents: 33406
diff changeset
   343
    val missing = ! max_workers - length (! workers);
28203
88f18387f1c9 shutdown: global join-and-shutdown operation;
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   344
    val _ =
33407
1427333220bc worker_next: ensure that work_available is passed on before sleeping (was occasionally lost when worker configuration changed, causing scheduler deadlock);
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parents: 33406
diff changeset
   345
      if missing > 0 then
33415
352fe8e9162d worker_next: plain signalling via work_available only, not scheduler_event;
wenzelm
parents: 33413
diff changeset
   346
        funpow missing (fn () =>
352fe8e9162d worker_next: plain signalling via work_available only, not scheduler_event;
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parents: 33413
diff changeset
   347
          ignore (worker_start ("worker " ^ string_of_int (Unsynchronized.inc next)))) ()
28203
88f18387f1c9 shutdown: global join-and-shutdown operation;
wenzelm
parents: 28202
diff changeset
   348
      else ();
28206
bcd48c6897d4 eliminated requests, use global state variables uniformly;
wenzelm
parents: 28203
diff changeset
   349
33415
352fe8e9162d worker_next: plain signalling via work_available only, not scheduler_event;
wenzelm
parents: 33413
diff changeset
   350
    val _ =
352fe8e9162d worker_next: plain signalling via work_available only, not scheduler_event;
wenzelm
parents: 33413
diff changeset
   351
      if ! max_active = max_active0 andalso ! max_workers = max_workers0 then ()
352fe8e9162d worker_next: plain signalling via work_available only, not scheduler_event;
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parents: 33413
diff changeset
   352
      else signal work_available;
352fe8e9162d worker_next: plain signalling via work_available only, not scheduler_event;
wenzelm
parents: 33413
diff changeset
   353
352fe8e9162d worker_next: plain signalling via work_available only, not scheduler_event;
wenzelm
parents: 33413
diff changeset
   354
352fe8e9162d worker_next: plain signalling via work_available only, not scheduler_event;
wenzelm
parents: 33413
diff changeset
   355
    (* canceled groups *)
352fe8e9162d worker_next: plain signalling via work_available only, not scheduler_event;
wenzelm
parents: 33413
diff changeset
   356
32225
d5d6f47fb018 cancel: improved reactivity due to more careful broadcasting;
wenzelm
parents: 32224
diff changeset
   357
    val _ =
d5d6f47fb018 cancel: improved reactivity due to more careful broadcasting;
wenzelm
parents: 32224
diff changeset
   358
      if null (! canceled) then ()
32293
e0b8da3fae4d tuned tracing;
wenzelm
parents: 32286
diff changeset
   359
      else
e0b8da3fae4d tuned tracing;
wenzelm
parents: 32286
diff changeset
   360
       (Multithreading.tracing 1 (fn () =>
e0b8da3fae4d tuned tracing;
wenzelm
parents: 32286
diff changeset
   361
          string_of_int (length (! canceled)) ^ " canceled groups");
44299
061599cb6eb0 refined Future.cancel: explicit future allows to join actual cancellation;
wenzelm
parents: 44298
diff changeset
   362
        Unsynchronized.change canceled (filter_out (null o cancel_now));
32293
e0b8da3fae4d tuned tracing;
wenzelm
parents: 32286
diff changeset
   363
        broadcast_work ());
28206
bcd48c6897d4 eliminated requests, use global state variables uniformly;
wenzelm
parents: 28203
diff changeset
   364
33415
352fe8e9162d worker_next: plain signalling via work_available only, not scheduler_event;
wenzelm
parents: 33413
diff changeset
   365
352fe8e9162d worker_next: plain signalling via work_available only, not scheduler_event;
wenzelm
parents: 33413
diff changeset
   366
    (* delay loop *)
352fe8e9162d worker_next: plain signalling via work_available only, not scheduler_event;
wenzelm
parents: 33413
diff changeset
   367
32295
400cc493d466 renamed Multithreading.regular_interrupts to Multithreading.public_interrupts;
wenzelm
parents: 32293
diff changeset
   368
    val _ = Exn.release (wait_timeout next_round scheduler_event);
28167
27e2ca41b58c more interrupt operations;
wenzelm
parents: 28166
diff changeset
   369
33415
352fe8e9162d worker_next: plain signalling via work_available only, not scheduler_event;
wenzelm
parents: 33413
diff changeset
   370
352fe8e9162d worker_next: plain signalling via work_available only, not scheduler_event;
wenzelm
parents: 33413
diff changeset
   371
    (* shutdown *)
352fe8e9162d worker_next: plain signalling via work_available only, not scheduler_event;
wenzelm
parents: 33413
diff changeset
   372
34277
7325a5e3587f added Future.promise/fulfill -- promised futures that are fulfilled by external means;
wenzelm
parents: 33416
diff changeset
   373
    val _ = if Task_Queue.all_passive (! queue) then do_shutdown := true else ();
32219
9a2566d1fdbd more specific conditions: scheduler_event, work_available, work_finished -- considereably reduces overhead with many threads;
wenzelm
parents: 32186
diff changeset
   374
    val continue = not (! do_shutdown andalso null (! workers));
9a2566d1fdbd more specific conditions: scheduler_event, work_available, work_finished -- considereably reduces overhead with many threads;
wenzelm
parents: 32186
diff changeset
   375
    val _ = if continue then () else scheduler := NONE;
33415
352fe8e9162d worker_next: plain signalling via work_available only, not scheduler_event;
wenzelm
parents: 33413
diff changeset
   376
32219
9a2566d1fdbd more specific conditions: scheduler_event, work_available, work_finished -- considereably reduces overhead with many threads;
wenzelm
parents: 32186
diff changeset
   377
    val _ = broadcast scheduler_event;
32295
400cc493d466 renamed Multithreading.regular_interrupts to Multithreading.public_interrupts;
wenzelm
parents: 32293
diff changeset
   378
  in continue end
39232
69c6d3e87660 more abstract treatment of interrupts in structure Exn -- hardly ever need to mention Interrupt literally;
wenzelm
parents: 38236
diff changeset
   379
  handle exn =>
69c6d3e87660 more abstract treatment of interrupts in structure Exn -- hardly ever need to mention Interrupt literally;
wenzelm
parents: 38236
diff changeset
   380
    if Exn.is_interrupt exn then
69c6d3e87660 more abstract treatment of interrupts in structure Exn -- hardly ever need to mention Interrupt literally;
wenzelm
parents: 38236
diff changeset
   381
     (Multithreading.tracing 1 (fn () => "Interrupt");
69c6d3e87660 more abstract treatment of interrupts in structure Exn -- hardly ever need to mention Interrupt literally;
wenzelm
parents: 38236
diff changeset
   382
      List.app cancel_later (Task_Queue.cancel_all (! queue));
69c6d3e87660 more abstract treatment of interrupts in structure Exn -- hardly ever need to mention Interrupt literally;
wenzelm
parents: 38236
diff changeset
   383
      broadcast_work (); true)
69c6d3e87660 more abstract treatment of interrupts in structure Exn -- hardly ever need to mention Interrupt literally;
wenzelm
parents: 38236
diff changeset
   384
    else reraise exn;
32295
400cc493d466 renamed Multithreading.regular_interrupts to Multithreading.public_interrupts;
wenzelm
parents: 32293
diff changeset
   385
28206
bcd48c6897d4 eliminated requests, use global state variables uniformly;
wenzelm
parents: 28203
diff changeset
   386
fun scheduler_loop () =
44173
aaaa13e297dc immediate fork of initial workers -- avoid 5 ticks (250ms) for adaptive scheme (a07558eb5029);
wenzelm
parents: 44115
diff changeset
   387
 (while
33416
13d00799fe49 scheduler: clarified interrupt attributes and handling;
wenzelm
parents: 33415
diff changeset
   388
    Multithreading.with_attributes
13d00799fe49 scheduler: clarified interrupt attributes and handling;
wenzelm
parents: 33415
diff changeset
   389
      (Multithreading.sync_interrupts Multithreading.public_interrupts)
13d00799fe49 scheduler: clarified interrupt attributes and handling;
wenzelm
parents: 33415
diff changeset
   390
      (fn _ => SYNCHRONIZED "scheduler" (fn () => scheduler_next ()))
44173
aaaa13e297dc immediate fork of initial workers -- avoid 5 ticks (250ms) for adaptive scheme (a07558eb5029);
wenzelm
parents: 44115
diff changeset
   391
  do (); last_round := Time.zeroTime);
28156
5205f7979b4f Functional threads as future values.
wenzelm
parents:
diff changeset
   392
28203
88f18387f1c9 shutdown: global join-and-shutdown operation;
wenzelm
parents: 28202
diff changeset
   393
fun scheduler_active () = (*requires SYNCHRONIZED*)
88f18387f1c9 shutdown: global join-and-shutdown operation;
wenzelm
parents: 28202
diff changeset
   394
  (case ! scheduler of NONE => false | SOME thread => Thread.isActive thread);
88f18387f1c9 shutdown: global join-and-shutdown operation;
wenzelm
parents: 28202
diff changeset
   395
32228
7622c03141b0 scheduler: shutdown spontaneously (after some delay) if queue is empty;
wenzelm
parents: 32227
diff changeset
   396
fun scheduler_check () = (*requires SYNCHRONIZED*)
7622c03141b0 scheduler: shutdown spontaneously (after some delay) if queue is empty;
wenzelm
parents: 32227
diff changeset
   397
 (do_shutdown := false;
32248
0241916a5f06 more precise treatment of scheduler_event: continous pulse (50ms) instead of flooding, which was burning many CPU cycles in spare threads;
wenzelm
parents: 32247
diff changeset
   398
  if scheduler_active () then ()
37216
3165bc303f66 modernized some structure names, keeping a few legacy aliases;
wenzelm
parents: 37182
diff changeset
   399
  else scheduler := SOME (Simple_Thread.fork false scheduler_loop));
28156
5205f7979b4f Functional threads as future values.
wenzelm
parents:
diff changeset
   400
44301
65f60d9ac4bf tuned signature (again);
wenzelm
parents: 44300
diff changeset
   401
65f60d9ac4bf tuned signature (again);
wenzelm
parents: 44300
diff changeset
   402
65f60d9ac4bf tuned signature (again);
wenzelm
parents: 44300
diff changeset
   403
(** futures **)
65f60d9ac4bf tuned signature (again);
wenzelm
parents: 44300
diff changeset
   404
65f60d9ac4bf tuned signature (again);
wenzelm
parents: 44300
diff changeset
   405
(* cancel *)
65f60d9ac4bf tuned signature (again);
wenzelm
parents: 44300
diff changeset
   406
65f60d9ac4bf tuned signature (again);
wenzelm
parents: 44300
diff changeset
   407
fun cancel_group group = SYNCHRONIZED "cancel_group" (fn () =>
44299
061599cb6eb0 refined Future.cancel: explicit future allows to join actual cancellation;
wenzelm
parents: 44298
diff changeset
   408
  let
061599cb6eb0 refined Future.cancel: explicit future allows to join actual cancellation;
wenzelm
parents: 44298
diff changeset
   409
    val running = cancel_now group;
061599cb6eb0 refined Future.cancel: explicit future allows to join actual cancellation;
wenzelm
parents: 44298
diff changeset
   410
    val _ =
061599cb6eb0 refined Future.cancel: explicit future allows to join actual cancellation;
wenzelm
parents: 44298
diff changeset
   411
      if null running then ()
061599cb6eb0 refined Future.cancel: explicit future allows to join actual cancellation;
wenzelm
parents: 44298
diff changeset
   412
      else (cancel_later group; signal work_available; scheduler_check ());
061599cb6eb0 refined Future.cancel: explicit future allows to join actual cancellation;
wenzelm
parents: 44298
diff changeset
   413
  in running end);
061599cb6eb0 refined Future.cancel: explicit future allows to join actual cancellation;
wenzelm
parents: 44298
diff changeset
   414
44301
65f60d9ac4bf tuned signature (again);
wenzelm
parents: 44300
diff changeset
   415
fun cancel x = cancel_group (Task_Queue.group_of_task (task_of x));
29366
1ffc8cbf39ec tuned map: reduced overhead due to bulk jobs;
wenzelm
parents: 29341
diff changeset
   416
28156
5205f7979b4f Functional threads as future values.
wenzelm
parents:
diff changeset
   417
44110
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   418
(* future jobs *)
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   419
44249
64620f1d6f87 identify parallel exceptions where they emerge first -- to achieve unique results within evaluation graph;
wenzelm
parents: 44247
diff changeset
   420
fun assign_result group result raw_res =
44110
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   421
  let
44249
64620f1d6f87 identify parallel exceptions where they emerge first -- to achieve unique results within evaluation graph;
wenzelm
parents: 44247
diff changeset
   422
    val res =
64620f1d6f87 identify parallel exceptions where they emerge first -- to achieve unique results within evaluation graph;
wenzelm
parents: 44247
diff changeset
   423
      (case raw_res of
64620f1d6f87 identify parallel exceptions where they emerge first -- to achieve unique results within evaluation graph;
wenzelm
parents: 44247
diff changeset
   424
        Exn.Exn exn => Exn.Exn (#2 (Par_Exn.serial exn))
64620f1d6f87 identify parallel exceptions where they emerge first -- to achieve unique results within evaluation graph;
wenzelm
parents: 44247
diff changeset
   425
      | _ => raw_res);
44110
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   426
    val _ = Single_Assignment.assign result res
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   427
      handle exn as Fail _ =>
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   428
        (case Single_Assignment.peek result of
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   429
          SOME (Exn.Exn e) => reraise (if Exn.is_interrupt e then e else exn)
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   430
        | _ => reraise exn);
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   431
    val ok =
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   432
      (case the (Single_Assignment.peek result) of
44111
2d16c693d536 synchronized cancel and flushing of Multithreading.interrupted state, to ensure that interrupts stay within task boundaries;
wenzelm
parents: 44110
diff changeset
   433
        Exn.Exn exn =>
2d16c693d536 synchronized cancel and flushing of Multithreading.interrupted state, to ensure that interrupts stay within task boundaries;
wenzelm
parents: 44110
diff changeset
   434
          (SYNCHRONIZED "cancel" (fn () => Task_Queue.cancel_group group exn); false)
44110
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   435
      | Exn.Res _ => true);
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   436
  in ok end;
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   437
44113
0baa8bbd355a future_job: explicit indication of interrupts;
wenzelm
parents: 44111
diff changeset
   438
fun future_job group interrupts (e: unit -> 'a) =
44110
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   439
  let
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   440
    val result = Single_Assignment.var "future" : 'a result;
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   441
    val pos = Position.thread_data ();
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   442
    fun job ok =
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   443
      let
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   444
        val res =
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   445
          if ok then
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   446
            Exn.capture (fn () =>
44113
0baa8bbd355a future_job: explicit indication of interrupts;
wenzelm
parents: 44111
diff changeset
   447
              Multithreading.with_attributes
0baa8bbd355a future_job: explicit indication of interrupts;
wenzelm
parents: 44111
diff changeset
   448
                (if interrupts
0baa8bbd355a future_job: explicit indication of interrupts;
wenzelm
parents: 44111
diff changeset
   449
                 then Multithreading.private_interrupts else Multithreading.no_interrupts)
44295
e43f0ea90c9a more focused use of Multithreading.interrupted: retain interrupts within task group boundary, without loss of information;
wenzelm
parents: 44294
diff changeset
   450
                (fn _ => Position.setmp_thread_data pos e ())) ()
44110
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   451
          else Exn.interrupt_exn;
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   452
      in assign_result group result res end;
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   453
  in (result, job) end;
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   454
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   455
29366
1ffc8cbf39ec tuned map: reduced overhead due to bulk jobs;
wenzelm
parents: 29341
diff changeset
   456
(* fork *)
1ffc8cbf39ec tuned map: reduced overhead due to bulk jobs;
wenzelm
parents: 29341
diff changeset
   457
44113
0baa8bbd355a future_job: explicit indication of interrupts;
wenzelm
parents: 44111
diff changeset
   458
type fork_params =
44300
349cc426d929 tuned signature -- treat structure Task_Queue as private to implementation;
wenzelm
parents: 44299
diff changeset
   459
  {name: string, group: group option, deps: task list, pri: int, interrupts: bool};
44113
0baa8bbd355a future_job: explicit indication of interrupts;
wenzelm
parents: 44111
diff changeset
   460
0baa8bbd355a future_job: explicit indication of interrupts;
wenzelm
parents: 44111
diff changeset
   461
fun forks ({name, group, deps, pri, interrupts}: fork_params) es =
41674
7da257539a8d tuned signature;
wenzelm
parents: 41673
diff changeset
   462
  if null es then []
7da257539a8d tuned signature;
wenzelm
parents: 41673
diff changeset
   463
  else
7da257539a8d tuned signature;
wenzelm
parents: 41673
diff changeset
   464
    let
7da257539a8d tuned signature;
wenzelm
parents: 41673
diff changeset
   465
      val grp =
7da257539a8d tuned signature;
wenzelm
parents: 41673
diff changeset
   466
        (case group of
7da257539a8d tuned signature;
wenzelm
parents: 41673
diff changeset
   467
          NONE => worker_subgroup ()
7da257539a8d tuned signature;
wenzelm
parents: 41673
diff changeset
   468
        | SOME grp => grp);
41708
d2e6b1132df2 tuned signature;
wenzelm
parents: 41695
diff changeset
   469
      fun enqueue e queue =
41674
7da257539a8d tuned signature;
wenzelm
parents: 41673
diff changeset
   470
        let
44113
0baa8bbd355a future_job: explicit indication of interrupts;
wenzelm
parents: 44111
diff changeset
   471
          val (result, job) = future_job grp interrupts e;
41708
d2e6b1132df2 tuned signature;
wenzelm
parents: 41695
diff changeset
   472
          val (task, queue') = Task_Queue.enqueue name grp deps pri job queue;
41683
73dde8006820 maintain Task_Queue.group within Task_Queue.task;
wenzelm
parents: 41681
diff changeset
   473
          val future = Future {promised = false, task = task, result = result};
41708
d2e6b1132df2 tuned signature;
wenzelm
parents: 41695
diff changeset
   474
        in (future, queue') end;
41674
7da257539a8d tuned signature;
wenzelm
parents: 41673
diff changeset
   475
    in
7da257539a8d tuned signature;
wenzelm
parents: 41673
diff changeset
   476
      SYNCHRONIZED "enqueue" (fn () =>
7da257539a8d tuned signature;
wenzelm
parents: 41673
diff changeset
   477
        let
41708
d2e6b1132df2 tuned signature;
wenzelm
parents: 41695
diff changeset
   478
          val (futures, queue') = fold_map enqueue es (! queue);
d2e6b1132df2 tuned signature;
wenzelm
parents: 41695
diff changeset
   479
          val _ = queue := queue';
d2e6b1132df2 tuned signature;
wenzelm
parents: 41695
diff changeset
   480
          val minimal = forall (not o Task_Queue.known_task queue') deps;
41674
7da257539a8d tuned signature;
wenzelm
parents: 41673
diff changeset
   481
          val _ = if minimal then signal work_available else ();
7da257539a8d tuned signature;
wenzelm
parents: 41673
diff changeset
   482
          val _ = scheduler_check ();
7da257539a8d tuned signature;
wenzelm
parents: 41673
diff changeset
   483
        in futures end)
7da257539a8d tuned signature;
wenzelm
parents: 41673
diff changeset
   484
    end;
28162
55772e4e95e0 tuned check_cache;
wenzelm
parents: 28156
diff changeset
   485
44113
0baa8bbd355a future_job: explicit indication of interrupts;
wenzelm
parents: 44111
diff changeset
   486
fun fork_pri pri e =
44301
65f60d9ac4bf tuned signature (again);
wenzelm
parents: 44300
diff changeset
   487
  (singleton o forks) {name = "fork", group = NONE, deps = [], pri = pri, interrupts = true} e;
44113
0baa8bbd355a future_job: explicit indication of interrupts;
wenzelm
parents: 44111
diff changeset
   488
41672
2f70b1ddd09f more direct Future.bulk, which potentially reduces overhead for Par_List;
wenzelm
parents: 41670
diff changeset
   489
fun fork e = fork_pri 0 e;
28186
6a8417f36837 cancel: check_scheduler;
wenzelm
parents: 28177
diff changeset
   490
6a8417f36837 cancel: check_scheduler;
wenzelm
parents: 28177
diff changeset
   491
29366
1ffc8cbf39ec tuned map: reduced overhead due to bulk jobs;
wenzelm
parents: 29341
diff changeset
   492
(* join *)
1ffc8cbf39ec tuned map: reduced overhead due to bulk jobs;
wenzelm
parents: 29341
diff changeset
   493
29551
95e469919c3e join_results: when dependencies are resulved (but not finished yet),
wenzelm
parents: 29431
diff changeset
   494
local
95e469919c3e join_results: when dependencies are resulved (but not finished yet),
wenzelm
parents: 29431
diff changeset
   495
32099
5382c93108db propagate exceptions within future groups;
wenzelm
parents: 32096
diff changeset
   496
fun get_result x =
5382c93108db propagate exceptions within future groups;
wenzelm
parents: 32096
diff changeset
   497
  (case peek x of
37852
a902f158b4fc eliminated old-style sys_error/SYS_ERROR in favour of exception Fail -- after careful checking that there is no overlap with existing handling of that;
wenzelm
parents: 37690
diff changeset
   498
    NONE => Exn.Exn (Fail "Unfinished future")
39232
69c6d3e87660 more abstract treatment of interrupts in structure Exn -- hardly ever need to mention Interrupt literally;
wenzelm
parents: 38236
diff changeset
   499
  | SOME res =>
69c6d3e87660 more abstract treatment of interrupts in structure Exn -- hardly ever need to mention Interrupt literally;
wenzelm
parents: 38236
diff changeset
   500
      if Exn.is_interrupt_exn res then
44247
270366301bd7 more systematic handling of parallel exceptions;
wenzelm
parents: 44198
diff changeset
   501
        (case Task_Queue.group_status (Task_Queue.group_of_task (task_of x)) of
270366301bd7 more systematic handling of parallel exceptions;
wenzelm
parents: 44198
diff changeset
   502
          NONE => res
270366301bd7 more systematic handling of parallel exceptions;
wenzelm
parents: 44198
diff changeset
   503
        | SOME exn => Exn.Exn exn)
39232
69c6d3e87660 more abstract treatment of interrupts in structure Exn -- hardly ever need to mention Interrupt literally;
wenzelm
parents: 38236
diff changeset
   504
      else res);
28186
6a8417f36837 cancel: check_scheduler;
wenzelm
parents: 28177
diff changeset
   505
32095
ad4be204fdfe tuned tracing;
wenzelm
parents: 32058
diff changeset
   506
fun join_next deps = (*requires SYNCHRONIZED*)
41695
afdbec23b92b eliminated slightly odd abstract type Task_Queue.deps;
wenzelm
parents: 41683
diff changeset
   507
  if null deps then NONE
32224
a46f5e9b1718 dequeue_towards: always return active tasks;
wenzelm
parents: 32222
diff changeset
   508
  else
41681
b5d7b15166bf Future.join_results: discontinued post-hoc recording of dynamic dependencies;
wenzelm
parents: 41680
diff changeset
   509
    (case Unsynchronized.change_result queue (Task_Queue.dequeue_deps (Thread.self ()) deps) of
41695
afdbec23b92b eliminated slightly odd abstract type Task_Queue.deps;
wenzelm
parents: 41683
diff changeset
   510
      (NONE, []) => NONE
afdbec23b92b eliminated slightly odd abstract type Task_Queue.deps;
wenzelm
parents: 41683
diff changeset
   511
    | (NONE, deps') =>
afdbec23b92b eliminated slightly odd abstract type Task_Queue.deps;
wenzelm
parents: 41683
diff changeset
   512
        (worker_waiting deps' (fn () => worker_wait true work_finished); join_next deps')
32224
a46f5e9b1718 dequeue_towards: always return active tasks;
wenzelm
parents: 32222
diff changeset
   513
    | (SOME work, deps') => SOME (work, deps'));
32095
ad4be204fdfe tuned tracing;
wenzelm
parents: 32058
diff changeset
   514
32814
81897d30b97f added Task_Queue.depend (again) -- light-weight version for transitive graph;
wenzelm
parents: 32738
diff changeset
   515
fun execute_work NONE = ()
44110
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   516
  | execute_work (SOME (work, deps')) =
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   517
      (worker_joining (fn () => worker_exec work); join_work deps')
32814
81897d30b97f added Task_Queue.depend (again) -- light-weight version for transitive graph;
wenzelm
parents: 32738
diff changeset
   518
and join_work deps =
43538
de5c79682b56 more robust join_results: join_work needs to be uninterruptible, otherwise the task being dequeued by join_next might be never executed/finished!
wenzelm
parents: 42128
diff changeset
   519
  Multithreading.with_attributes Multithreading.no_interrupts
de5c79682b56 more robust join_results: join_work needs to be uninterruptible, otherwise the task being dequeued by join_next might be never executed/finished!
wenzelm
parents: 42128
diff changeset
   520
    (fn _ => execute_work (SYNCHRONIZED "join" (fn () => join_next deps)));
32814
81897d30b97f added Task_Queue.depend (again) -- light-weight version for transitive graph;
wenzelm
parents: 32738
diff changeset
   521
29551
95e469919c3e join_results: when dependencies are resulved (but not finished yet),
wenzelm
parents: 29431
diff changeset
   522
in
95e469919c3e join_results: when dependencies are resulved (but not finished yet),
wenzelm
parents: 29431
diff changeset
   523
29366
1ffc8cbf39ec tuned map: reduced overhead due to bulk jobs;
wenzelm
parents: 29341
diff changeset
   524
fun join_results xs =
41679
79716cb61bfd refined task timing: joining vs. waiting;
wenzelm
parents: 41674
diff changeset
   525
  let
79716cb61bfd refined task timing: joining vs. waiting;
wenzelm
parents: 41674
diff changeset
   526
    val _ =
79716cb61bfd refined task timing: joining vs. waiting;
wenzelm
parents: 41674
diff changeset
   527
      if forall is_finished xs then ()
79716cb61bfd refined task timing: joining vs. waiting;
wenzelm
parents: 41674
diff changeset
   528
      else if Multithreading.self_critical () then
79716cb61bfd refined task timing: joining vs. waiting;
wenzelm
parents: 41674
diff changeset
   529
        error "Cannot join future values within critical section"
41695
afdbec23b92b eliminated slightly odd abstract type Task_Queue.deps;
wenzelm
parents: 41683
diff changeset
   530
      else if is_some (worker_task ()) then join_work (map task_of xs)
41681
b5d7b15166bf Future.join_results: discontinued post-hoc recording of dynamic dependencies;
wenzelm
parents: 41680
diff changeset
   531
      else List.app (ignore o Single_Assignment.await o result_of) xs;
41679
79716cb61bfd refined task timing: joining vs. waiting;
wenzelm
parents: 41674
diff changeset
   532
  in map get_result xs end;
28186
6a8417f36837 cancel: check_scheduler;
wenzelm
parents: 28177
diff changeset
   533
29551
95e469919c3e join_results: when dependencies are resulved (but not finished yet),
wenzelm
parents: 29431
diff changeset
   534
end;
95e469919c3e join_results: when dependencies are resulved (but not finished yet),
wenzelm
parents: 29431
diff changeset
   535
28647
8068cdc84e7e join_results: allow CRITICAL join of finished futures;
wenzelm
parents: 28645
diff changeset
   536
fun join_result x = singleton join_results x;
8068cdc84e7e join_results: allow CRITICAL join of finished futures;
wenzelm
parents: 28645
diff changeset
   537
fun join x = Exn.release (join_result x);
28156
5205f7979b4f Functional threads as future values.
wenzelm
parents:
diff changeset
   538
44301
65f60d9ac4bf tuned signature (again);
wenzelm
parents: 44300
diff changeset
   539
fun join_tasks [] = ()
65f60d9ac4bf tuned signature (again);
wenzelm
parents: 44300
diff changeset
   540
  | join_tasks tasks =
65f60d9ac4bf tuned signature (again);
wenzelm
parents: 44300
diff changeset
   541
      (singleton o forks)
65f60d9ac4bf tuned signature (again);
wenzelm
parents: 44300
diff changeset
   542
        {name = "join_tasks", group = SOME (new_group NONE),
65f60d9ac4bf tuned signature (again);
wenzelm
parents: 44300
diff changeset
   543
          deps = tasks, pri = 0, interrupts = false} I
65f60d9ac4bf tuned signature (again);
wenzelm
parents: 44300
diff changeset
   544
      |> join;
65f60d9ac4bf tuned signature (again);
wenzelm
parents: 44300
diff changeset
   545
29366
1ffc8cbf39ec tuned map: reduced overhead due to bulk jobs;
wenzelm
parents: 29341
diff changeset
   546
44110
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   547
(* fast-path versions -- bypassing task queue *)
34277
7325a5e3587f added Future.promise/fulfill -- promised futures that are fulfilled by external means;
wenzelm
parents: 33416
diff changeset
   548
44294
a0ddd5760444 clarified Future.cond_forks: more uniform handling of exceptional situations;
wenzelm
parents: 44268
diff changeset
   549
fun value_result (res: 'a Exn.result) =
34277
7325a5e3587f added Future.promise/fulfill -- promised futures that are fulfilled by external means;
wenzelm
parents: 33416
diff changeset
   550
  let
41683
73dde8006820 maintain Task_Queue.group within Task_Queue.task;
wenzelm
parents: 41681
diff changeset
   551
    val task = Task_Queue.dummy_task ();
73dde8006820 maintain Task_Queue.group within Task_Queue.task;
wenzelm
parents: 41681
diff changeset
   552
    val group = Task_Queue.group_of_task task;
35016
c0f2e49bccfc result: Single_Assignment.var;
wenzelm
parents: 34281
diff changeset
   553
    val result = Single_Assignment.var "value" : 'a result;
44294
a0ddd5760444 clarified Future.cond_forks: more uniform handling of exceptional situations;
wenzelm
parents: 44268
diff changeset
   554
    val _ = assign_result group result res;
41683
73dde8006820 maintain Task_Queue.group within Task_Queue.task;
wenzelm
parents: 41681
diff changeset
   555
  in Future {promised = false, task = task, result = result} end;
29366
1ffc8cbf39ec tuned map: reduced overhead due to bulk jobs;
wenzelm
parents: 29341
diff changeset
   556
44294
a0ddd5760444 clarified Future.cond_forks: more uniform handling of exceptional situations;
wenzelm
parents: 44268
diff changeset
   557
fun value x = value_result (Exn.Res x);
a0ddd5760444 clarified Future.cond_forks: more uniform handling of exceptional situations;
wenzelm
parents: 44268
diff changeset
   558
29384
a3c7e9ae9b71 more robust propagation of errors through bulk jobs;
wenzelm
parents: 29366
diff changeset
   559
fun map_future f x =
29366
1ffc8cbf39ec tuned map: reduced overhead due to bulk jobs;
wenzelm
parents: 29341
diff changeset
   560
  let
29384
a3c7e9ae9b71 more robust propagation of errors through bulk jobs;
wenzelm
parents: 29366
diff changeset
   561
    val task = task_of x;
44300
349cc426d929 tuned signature -- treat structure Task_Queue as private to implementation;
wenzelm
parents: 44299
diff changeset
   562
    val group = new_group (SOME (Task_Queue.group_of_task task));
44113
0baa8bbd355a future_job: explicit indication of interrupts;
wenzelm
parents: 44111
diff changeset
   563
    val (result, job) = future_job group true (fn () => f (join x));
29384
a3c7e9ae9b71 more robust propagation of errors through bulk jobs;
wenzelm
parents: 29366
diff changeset
   564
32246
d4f7934e9555 misc tuning;
wenzelm
parents: 32230
diff changeset
   565
    val extended = SYNCHRONIZED "extend" (fn () =>
29366
1ffc8cbf39ec tuned map: reduced overhead due to bulk jobs;
wenzelm
parents: 29341
diff changeset
   566
      (case Task_Queue.extend task job (! queue) of
1ffc8cbf39ec tuned map: reduced overhead due to bulk jobs;
wenzelm
parents: 29341
diff changeset
   567
        SOME queue' => (queue := queue'; true)
1ffc8cbf39ec tuned map: reduced overhead due to bulk jobs;
wenzelm
parents: 29341
diff changeset
   568
      | NONE => false));
1ffc8cbf39ec tuned map: reduced overhead due to bulk jobs;
wenzelm
parents: 29341
diff changeset
   569
  in
41683
73dde8006820 maintain Task_Queue.group within Task_Queue.task;
wenzelm
parents: 41681
diff changeset
   570
    if extended then Future {promised = false, task = task, result = result}
41672
2f70b1ddd09f more direct Future.bulk, which potentially reduces overhead for Par_List;
wenzelm
parents: 41670
diff changeset
   571
    else
44301
65f60d9ac4bf tuned signature (again);
wenzelm
parents: 44300
diff changeset
   572
      (singleton o forks)
65f60d9ac4bf tuned signature (again);
wenzelm
parents: 44300
diff changeset
   573
        {name = "map_future", group = SOME group, deps = [task],
65f60d9ac4bf tuned signature (again);
wenzelm
parents: 44300
diff changeset
   574
          pri = Task_Queue.pri_of_task task, interrupts = true}
41672
2f70b1ddd09f more direct Future.bulk, which potentially reduces overhead for Par_List;
wenzelm
parents: 41670
diff changeset
   575
        (fn () => f (join x))
29366
1ffc8cbf39ec tuned map: reduced overhead due to bulk jobs;
wenzelm
parents: 29341
diff changeset
   576
  end;
28979
3ce619d8d432 fork/map: no inheritance of group (structure is nested, not parallel);
wenzelm
parents: 28972
diff changeset
   577
42128
eb84d28961a9 added Future.cond_forks convenience;
wenzelm
parents: 41776
diff changeset
   578
fun cond_forks args es =
eb84d28961a9 added Future.cond_forks convenience;
wenzelm
parents: 41776
diff changeset
   579
  if Multithreading.enabled () then forks args es
44294
a0ddd5760444 clarified Future.cond_forks: more uniform handling of exceptional situations;
wenzelm
parents: 44268
diff changeset
   580
  else map (fn e => value_result (Exn.interruptible_capture e ())) es;
42128
eb84d28961a9 added Future.cond_forks convenience;
wenzelm
parents: 41776
diff changeset
   581
28191
9e5f556409c6 future: allow explicit group;
wenzelm
parents: 28186
diff changeset
   582
34277
7325a5e3587f added Future.promise/fulfill -- promised futures that are fulfilled by external means;
wenzelm
parents: 33416
diff changeset
   583
(* promised futures -- fulfilled by external means *)
7325a5e3587f added Future.promise/fulfill -- promised futures that are fulfilled by external means;
wenzelm
parents: 33416
diff changeset
   584
44298
b8f8488704e2 Future.promise: explicit abort operation (like uninterruptible future job);
wenzelm
parents: 44295
diff changeset
   585
fun promise_group group abort : 'a future =
34277
7325a5e3587f added Future.promise/fulfill -- promised futures that are fulfilled by external means;
wenzelm
parents: 33416
diff changeset
   586
  let
35016
c0f2e49bccfc result: Single_Assignment.var;
wenzelm
parents: 34281
diff changeset
   587
    val result = Single_Assignment.var "promise" : 'a result;
44298
b8f8488704e2 Future.promise: explicit abort operation (like uninterruptible future job);
wenzelm
parents: 44295
diff changeset
   588
    fun assign () = assign_result group result Exn.interrupt_exn
39243
307e3d07d19f Future.promise: more robust treatment of concurrent abort vs. fulfill (amending 047c96f41455);
wenzelm
parents: 39232
diff changeset
   589
      handle Fail _ => true
307e3d07d19f Future.promise: more robust treatment of concurrent abort vs. fulfill (amending 047c96f41455);
wenzelm
parents: 39232
diff changeset
   590
        | exn =>
44298
b8f8488704e2 Future.promise: explicit abort operation (like uninterruptible future job);
wenzelm
parents: 44295
diff changeset
   591
            if Exn.is_interrupt exn
b8f8488704e2 Future.promise: explicit abort operation (like uninterruptible future job);
wenzelm
parents: 44295
diff changeset
   592
            then raise Fail "Concurrent attempt to fulfill promise"
39243
307e3d07d19f Future.promise: more robust treatment of concurrent abort vs. fulfill (amending 047c96f41455);
wenzelm
parents: 39232
diff changeset
   593
            else reraise exn;
44298
b8f8488704e2 Future.promise: explicit abort operation (like uninterruptible future job);
wenzelm
parents: 44295
diff changeset
   594
    fun job () =
b8f8488704e2 Future.promise: explicit abort operation (like uninterruptible future job);
wenzelm
parents: 44295
diff changeset
   595
      Multithreading.with_attributes Multithreading.no_interrupts
b8f8488704e2 Future.promise: explicit abort operation (like uninterruptible future job);
wenzelm
parents: 44295
diff changeset
   596
        (fn _ => assign () before abort ());
37854
047c96f41455 back to more strict dependencies, even for canceled groups (reverting parts of 02936e77a07c);
wenzelm
parents: 37852
diff changeset
   597
    val task = SYNCHRONIZED "enqueue_passive" (fn () =>
44298
b8f8488704e2 Future.promise: explicit abort operation (like uninterruptible future job);
wenzelm
parents: 44295
diff changeset
   598
      Unsynchronized.change_result queue (Task_Queue.enqueue_passive group job));
41683
73dde8006820 maintain Task_Queue.group within Task_Queue.task;
wenzelm
parents: 41681
diff changeset
   599
  in Future {promised = true, task = task, result = result} end;
34277
7325a5e3587f added Future.promise/fulfill -- promised futures that are fulfilled by external means;
wenzelm
parents: 33416
diff changeset
   600
44298
b8f8488704e2 Future.promise: explicit abort operation (like uninterruptible future job);
wenzelm
parents: 44295
diff changeset
   601
fun promise abort = promise_group (worker_subgroup ()) abort;
34277
7325a5e3587f added Future.promise/fulfill -- promised futures that are fulfilled by external means;
wenzelm
parents: 33416
diff changeset
   602
41683
73dde8006820 maintain Task_Queue.group within Task_Queue.task;
wenzelm
parents: 41681
diff changeset
   603
fun fulfill_result (Future {promised, task, result}) res =
39243
307e3d07d19f Future.promise: more robust treatment of concurrent abort vs. fulfill (amending 047c96f41455);
wenzelm
parents: 39232
diff changeset
   604
  if not promised then raise Fail "Not a promised future"
307e3d07d19f Future.promise: more robust treatment of concurrent abort vs. fulfill (amending 047c96f41455);
wenzelm
parents: 39232
diff changeset
   605
  else
307e3d07d19f Future.promise: more robust treatment of concurrent abort vs. fulfill (amending 047c96f41455);
wenzelm
parents: 39232
diff changeset
   606
    let
41683
73dde8006820 maintain Task_Queue.group within Task_Queue.task;
wenzelm
parents: 41681
diff changeset
   607
      val group = Task_Queue.group_of_task task;
39243
307e3d07d19f Future.promise: more robust treatment of concurrent abort vs. fulfill (amending 047c96f41455);
wenzelm
parents: 39232
diff changeset
   608
      fun job ok = assign_result group result (if ok then res else Exn.interrupt_exn);
307e3d07d19f Future.promise: more robust treatment of concurrent abort vs. fulfill (amending 047c96f41455);
wenzelm
parents: 39232
diff changeset
   609
      val _ =
307e3d07d19f Future.promise: more robust treatment of concurrent abort vs. fulfill (amending 047c96f41455);
wenzelm
parents: 39232
diff changeset
   610
        Multithreading.with_attributes Multithreading.no_interrupts (fn _ =>
307e3d07d19f Future.promise: more robust treatment of concurrent abort vs. fulfill (amending 047c96f41455);
wenzelm
parents: 39232
diff changeset
   611
          let
307e3d07d19f Future.promise: more robust treatment of concurrent abort vs. fulfill (amending 047c96f41455);
wenzelm
parents: 39232
diff changeset
   612
            val still_passive =
307e3d07d19f Future.promise: more robust treatment of concurrent abort vs. fulfill (amending 047c96f41455);
wenzelm
parents: 39232
diff changeset
   613
              SYNCHRONIZED "fulfill_result" (fn () =>
307e3d07d19f Future.promise: more robust treatment of concurrent abort vs. fulfill (amending 047c96f41455);
wenzelm
parents: 39232
diff changeset
   614
                Unsynchronized.change_result queue
307e3d07d19f Future.promise: more robust treatment of concurrent abort vs. fulfill (amending 047c96f41455);
wenzelm
parents: 39232
diff changeset
   615
                  (Task_Queue.dequeue_passive (Thread.self ()) task));
44110
058520fa03a8 tuned source structure;
wenzelm
parents: 43952
diff changeset
   616
          in if still_passive then worker_exec (task, [job]) else () end);
41681
b5d7b15166bf Future.join_results: discontinued post-hoc recording of dynamic dependencies;
wenzelm
parents: 41680
diff changeset
   617
      val _ =
41695
afdbec23b92b eliminated slightly odd abstract type Task_Queue.deps;
wenzelm
parents: 41683
diff changeset
   618
        if is_some (Single_Assignment.peek result) then ()
afdbec23b92b eliminated slightly odd abstract type Task_Queue.deps;
wenzelm
parents: 41683
diff changeset
   619
        else worker_waiting [task] (fn () => ignore (Single_Assignment.await result));
39243
307e3d07d19f Future.promise: more robust treatment of concurrent abort vs. fulfill (amending 047c96f41455);
wenzelm
parents: 39232
diff changeset
   620
    in () end;
34277
7325a5e3587f added Future.promise/fulfill -- promised futures that are fulfilled by external means;
wenzelm
parents: 33416
diff changeset
   621
43761
e72ba84ae58f tuned signature -- corresponding to Scala version;
wenzelm
parents: 43665
diff changeset
   622
fun fulfill x res = fulfill_result x (Exn.Res res);
34277
7325a5e3587f added Future.promise/fulfill -- promised futures that are fulfilled by external means;
wenzelm
parents: 33416
diff changeset
   623
7325a5e3587f added Future.promise/fulfill -- promised futures that are fulfilled by external means;
wenzelm
parents: 33416
diff changeset
   624
32228
7622c03141b0 scheduler: shutdown spontaneously (after some delay) if queue is empty;
wenzelm
parents: 32227
diff changeset
   625
(* shutdown *)
29366
1ffc8cbf39ec tuned map: reduced overhead due to bulk jobs;
wenzelm
parents: 29341
diff changeset
   626
28203
88f18387f1c9 shutdown: global join-and-shutdown operation;
wenzelm
parents: 28202
diff changeset
   627
fun shutdown () =
28276
fbc707811203 shutdown only if Multithreading.available;
wenzelm
parents: 28242
diff changeset
   628
  if Multithreading.available then
fbc707811203 shutdown only if Multithreading.available;
wenzelm
parents: 28242
diff changeset
   629
    SYNCHRONIZED "shutdown" (fn () =>
32228
7622c03141b0 scheduler: shutdown spontaneously (after some delay) if queue is empty;
wenzelm
parents: 32227
diff changeset
   630
     while scheduler_active () do
34279
02936e77a07c tasks of canceled groups are considered "ready" -- enables to purge the queue from tasks depending on unfinished promises (also improves general reactivity);
wenzelm
parents: 34277
diff changeset
   631
      (wait scheduler_event; broadcast_work ()))
28276
fbc707811203 shutdown only if Multithreading.available;
wenzelm
parents: 28242
diff changeset
   632
  else ();
28203
88f18387f1c9 shutdown: global join-and-shutdown operation;
wenzelm
parents: 28202
diff changeset
   633
29366
1ffc8cbf39ec tuned map: reduced overhead due to bulk jobs;
wenzelm
parents: 29341
diff changeset
   634
38236
d8c7be27e01d explicitly distinguish Output.status (essential feedback) vs. Output.report (useful markup);
wenzelm
parents: 37904
diff changeset
   635
(* status markup *)
37690
b16231572c61 general Future.report -- also for Toplevel.async_state;
wenzelm
parents: 37682
diff changeset
   636
38236
d8c7be27e01d explicitly distinguish Output.status (essential feedback) vs. Output.report (useful markup);
wenzelm
parents: 37904
diff changeset
   637
fun status e =
37690
b16231572c61 general Future.report -- also for Toplevel.async_state;
wenzelm
parents: 37682
diff changeset
   638
  let
40448
f9347a30d1b2 explicitly identify forked/joined tasks;
wenzelm
parents: 40301
diff changeset
   639
    val task_props =
f9347a30d1b2 explicitly identify forked/joined tasks;
wenzelm
parents: 40301
diff changeset
   640
      (case worker_task () of
f9347a30d1b2 explicitly identify forked/joined tasks;
wenzelm
parents: 40301
diff changeset
   641
        NONE => I
f9347a30d1b2 explicitly identify forked/joined tasks;
wenzelm
parents: 40301
diff changeset
   642
      | SOME task => Markup.properties [(Markup.taskN, Task_Queue.str_of_task task)]);
43665
573d1272f36d tuned signature;
wenzelm
parents: 43538
diff changeset
   643
    val _ = Output.status (Markup.markup_only (task_props Markup.forked));
37690
b16231572c61 general Future.report -- also for Toplevel.async_state;
wenzelm
parents: 37682
diff changeset
   644
    val x = e ();  (*sic -- report "joined" only for success*)
43665
573d1272f36d tuned signature;
wenzelm
parents: 43538
diff changeset
   645
    val _ = Output.status (Markup.markup_only (task_props Markup.joined));
37690
b16231572c61 general Future.report -- also for Toplevel.async_state;
wenzelm
parents: 37682
diff changeset
   646
  in x end;
b16231572c61 general Future.report -- also for Toplevel.async_state;
wenzelm
parents: 37682
diff changeset
   647
b16231572c61 general Future.report -- also for Toplevel.async_state;
wenzelm
parents: 37682
diff changeset
   648
29366
1ffc8cbf39ec tuned map: reduced overhead due to bulk jobs;
wenzelm
parents: 29341
diff changeset
   649
(*final declarations of this structure!*)
1ffc8cbf39ec tuned map: reduced overhead due to bulk jobs;
wenzelm
parents: 29341
diff changeset
   650
val map = map_future;
1ffc8cbf39ec tuned map: reduced overhead due to bulk jobs;
wenzelm
parents: 29341
diff changeset
   651
28156
5205f7979b4f Functional threads as future values.
wenzelm
parents:
diff changeset
   652
end;
28972
cb8a2c3e188f renamed type Future.T to future;
wenzelm
parents: 28647
diff changeset
   653
cb8a2c3e188f renamed type Future.T to future;
wenzelm
parents: 28647
diff changeset
   654
type 'a future = 'a Future.future;
cb8a2c3e188f renamed type Future.T to future;
wenzelm
parents: 28647
diff changeset
   655