wenzelm@28156
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(* Title: Pure/Concurrent/future.ML
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wenzelm@28156
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Author: Makarius
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wenzelm@32250
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Future values, see also
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http://www4.in.tum.de/~wenzelm/papers/parallel-isabelle.pdf
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wenzelm@28201
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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 (and variants). The idea is to model
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wenzelm@28201
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parallel value-oriented computations, but *not* communicating
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processes.
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* Futures are grouped; failure of one group member causes the whole
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wenzelm@32220
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group to be interrupted eventually. Groups are block-structured.
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wenzelm@28201
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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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wenzelm@28201
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the number of physical cores on the machine. Note that allocation
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of runtime resources is distorted either if workers yield CPU time
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(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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* Promised futures are fulfilled by external means. There is no
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associated evaluation task, but other futures can depend on them
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as usual.
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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 is_worker: unit -> bool
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wenzelm@32823
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val worker_task: unit -> Task_Queue.task option
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val worker_group: unit -> Task_Queue.group option
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type 'a future
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val task_of: 'a future -> task
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val group_of: 'a future -> group
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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 fork_group: group -> (unit -> 'a) -> 'a future
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val fork_deps_pri: 'b future list -> int -> (unit -> 'a) -> 'a future
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val fork_deps: 'b future list -> (unit -> 'a) -> 'a future
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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 value: 'a -> 'a future
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val map: ('a -> 'b) -> 'a future -> 'b future
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val promise_group: group -> 'a future
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val promise: 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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wenzelm@30621
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val interruptible_task: ('a -> 'b) -> 'a -> 'b
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val cancel_group: group -> unit
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val cancel: 'a future -> unit
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val shutdown: unit -> unit
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val report: (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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(* identifiers *)
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type task = Task_Queue.task;
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type group = Task_Queue.group;
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local
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val tag = Universal.tag () : (task * group) option Universal.tag;
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in
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fun thread_data () = the_default NONE (Thread.getLocal tag);
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fun setmp_thread_data data f x =
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Library.setmp_thread_data tag (thread_data ()) (SOME data) f x;
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end;
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val is_worker = is_some o thread_data;
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val worker_task = Option.map #1 o thread_data;
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val worker_group = Option.map #2 o thread_data;
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wenzelm@32074
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fun new_group () = Task_Queue.new_group (worker_group ());
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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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group: group,
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result: 'a result};
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fun task_of (Future {task, ...}) = task;
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fun group_of (Future {group, ...}) = group;
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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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wenzelm@28320
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fun assign_result group result res =
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let
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val _ = Single_Assignment.assign result res;
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val ok =
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(case res of
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Exn.Exn exn => (Task_Queue.cancel_group group exn; false)
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| Exn.Result _ => true);
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in ok end;
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wenzelm@29002
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wenzelm@28177
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(** scheduling **)
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(* synchronization *)
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wenzelm@32219
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val scheduler_event = ConditionVar.conditionVar ();
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wenzelm@32219
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val work_available = ConditionVar.conditionVar ();
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wenzelm@32219
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val work_finished = ConditionVar.conditionVar ();
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wenzelm@32219
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local
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val lock = Mutex.mutex ();
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in
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wenzelm@37216
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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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wenzelm@32298
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Multithreading.sync_wait NONE NONE cond lock;
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wenzelm@28206
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wenzelm@32298
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fun wait_timeout timeout cond = (*requires SYNCHRONIZED*)
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wenzelm@32298
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Multithreading.sync_wait NONE (SOME (Time.+ (Time.now (), timeout))) cond lock;
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wenzelm@32219
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fun signal cond = (*requires SYNCHRONIZED*)
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ConditionVar.signal cond;
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wenzelm@32219
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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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wenzelm@32225
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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 ([]: Task_Queue.group list);
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wenzelm@33431
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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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wenzelm@33432
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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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wenzelm@33431
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wenzelm@32119
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(* execute future jobs *)
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wenzelm@32119
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wenzelm@32119
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fun future_job group (e: unit -> 'a) =
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let
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val result = Single_Assignment.var "future" : 'a result;
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wenzelm@37053
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val pos = Position.thread_data ();
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wenzelm@32127
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fun job ok =
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let
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val res =
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if ok then
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wenzelm@32230
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Exn.capture (fn () =>
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wenzelm@37053
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Multithreading.with_attributes Multithreading.private_interrupts
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wenzelm@37053
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(fn _ => Position.setmp_thread_data pos e ())) ()
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wenzelm@32127
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else Exn.Exn Exn.Interrupt;
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in assign_result group result res end;
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wenzelm@32119
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in (result, job) end;
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wenzelm@34279
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fun cancel_now group = (*requires SYNCHRONIZED*)
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wenzelm@34280
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Task_Queue.cancel (! queue) group;
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wenzelm@34279
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wenzelm@34279
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fun cancel_later group = (*requires SYNCHRONIZED*)
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wenzelm@32738
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(Unsynchronized.change canceled (insert Task_Queue.eq_group group);
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broadcast scheduler_event);
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wenzelm@29341
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wenzelm@33429
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fun execute (task, group, jobs) =
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let
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val valid = not (Task_Queue.is_canceled group);
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wenzelm@33429
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val ok = setmp_thread_data (task, group) (fn () =>
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wenzelm@29384
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fold (fn job => fn ok => job valid andalso ok) jobs true) ();
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wenzelm@32250
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val _ = SYNCHRONIZED "finish" (fn () =>
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wenzelm@32219
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let
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wenzelm@32738
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val maximal = Unsynchronized.change_result queue (Task_Queue.finish task);
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wenzelm@32219
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val _ =
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wenzelm@32219
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if ok then ()
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wenzelm@34279
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else if cancel_now group then ()
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wenzelm@34279
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else cancel_later group;
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wenzelm@32219
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val _ = broadcast work_finished;
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wenzelm@33434
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val _ = if maximal then () else signal work_available;
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wenzelm@32219
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in () end);
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wenzelm@28167
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in () end;
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wenzelm@28167
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wenzelm@28167
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wenzelm@28167
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(* worker threads *)
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wenzelm@33431
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fun worker_wait active cond = (*requires SYNCHRONIZED*)
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wenzelm@33427
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let
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wenzelm@33431
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val state =
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wenzelm@33431
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(case AList.lookup Thread.equal (! workers) (Thread.self ()) of
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wenzelm@33431
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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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wenzelm@33427
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val _ = wait cond;
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wenzelm@33431
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val _ = state := Working;
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wenzelm@33427
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in () end;
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wenzelm@28162
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wenzelm@33436
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fun worker_next () = (*requires SYNCHRONIZED*)
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wenzelm@33427
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if length (! workers) > ! max_workers then
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wenzelm@33427
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(Unsynchronized.change workers (AList.delete Thread.equal (Thread.self ()));
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wenzelm@33436
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signal work_available;
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wenzelm@28167
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NONE)
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wenzelm@33431
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else if count_workers Working > ! max_active then
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wenzelm@33436
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(worker_wait false work_available; worker_next ())
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wenzelm@28166
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else
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wenzelm@32738
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(case Unsynchronized.change_result queue (Task_Queue.dequeue (Thread.self ())) of
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wenzelm@33436
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NONE => (worker_wait false work_available; worker_next ())
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wenzelm@33434
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| some => (signal work_available; some));
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wenzelm@28156
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wenzelm@28167
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fun worker_loop name =
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wenzelm@33436
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(case SYNCHRONIZED name (fn () => worker_next ()) of
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wenzelm@29120
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NONE => ()
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wenzelm@33429
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| SOME work => (execute work; worker_loop name));
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wenzelm@28156
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wenzelm@33428
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fun worker_start name = (*requires SYNCHRONIZED*)
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wenzelm@37216
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Unsynchronized.change workers (cons (Simple_Thread.fork false (fn () => worker_loop name),
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wenzelm@33431
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Unsynchronized.ref Working));
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wenzelm@28156
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wenzelm@28156
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wenzelm@28156
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(* scheduler *)
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wenzelm@28156
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wenzelm@33428
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val status_ticks = Unsynchronized.ref 0;
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wenzelm@33428
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wenzelm@33428
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val last_round = Unsynchronized.ref Time.zeroTime;
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wenzelm@32252
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val next_round = Time.fromMilliseconds 50;
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wenzelm@32226
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wenzelm@28206
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fun scheduler_next () = (*requires SYNCHRONIZED*)
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wenzelm@28156
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let
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wenzelm@33428
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val now = Time.now ();
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wenzelm@33428
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val tick = Time.<= (Time.+ (! last_round, next_round), now);
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wenzelm@33428
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val _ = if tick then last_round := now else ();
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wenzelm@33428
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wenzelm@33436
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wenzelm@33436
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(* queue and worker status *)
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wenzelm@33436
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wenzelm@32226
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val _ =
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wenzelm@33428
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if tick then Unsynchronized.change status_ticks (fn i => (i + 1) mod 10) else ();
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wenzelm@33428
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val _ =
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wenzelm@33428
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if tick andalso ! status_ticks = 0 then
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wenzelm@33428
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Multithreading.tracing 1 (fn () =>
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wenzelm@33428
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let
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wenzelm@34277
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val {ready, pending, running, passive} = Task_Queue.status (! queue);
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wenzelm@33428
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val total = length (! workers);
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wenzelm@33431
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val active = count_workers Working;
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wenzelm@33431
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val waiting = count_workers Waiting;
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wenzelm@33428
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in
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wenzelm@33428
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"SCHEDULE " ^ Time.toString now ^ ": " ^
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wenzelm@33428
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string_of_int ready ^ " ready, " ^
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wenzelm@33428
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string_of_int pending ^ " pending, " ^
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wenzelm@34277
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string_of_int running ^ " running, " ^
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wenzelm@34277
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string_of_int passive ^ " passive; " ^
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wenzelm@33428
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string_of_int total ^ " workers, " ^
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wenzelm@33431
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string_of_int active ^ " active, " ^
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wenzelm@33431
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string_of_int waiting ^ " waiting "
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wenzelm@33428
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end)
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wenzelm@33428
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else ();
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wenzelm@32053
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wenzelm@28191
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val _ =
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wenzelm@32219
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if forall (Thread.isActive o #1) (! workers) then ()
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wenzelm@32115
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else
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wenzelm@33430
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let
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wenzelm@37698
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val (alive, dead) = List.partition (Thread.isActive o #1) (! workers);
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wenzelm@33430
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val _ = workers := alive;
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wenzelm@33430
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in
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wenzelm@33430
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Multithreading.tracing 0 (fn () =>
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wenzelm@33430
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"SCHEDULE: disposed " ^ string_of_int (length dead) ^ " dead worker threads")
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wenzelm@33430
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293 |
end;
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wenzelm@28191
|
294 |
|
wenzelm@33436
|
295 |
|
wenzelm@33436
|
296 |
(* worker pool adjustments *)
|
wenzelm@33436
|
297 |
|
wenzelm@33436
|
298 |
val max_active0 = ! max_active;
|
wenzelm@33436
|
299 |
val max_workers0 = ! max_workers;
|
wenzelm@33436
|
300 |
|
wenzelm@28206
|
301 |
val m = if ! do_shutdown then 0 else Multithreading.max_threads_value ();
|
wenzelm@33427
|
302 |
val _ = max_active := m;
|
wenzelm@33427
|
303 |
|
wenzelm@33432
|
304 |
val mm =
|
wenzelm@33432
|
305 |
if ! do_shutdown then 0
|
wenzelm@33432
|
306 |
else if m = 9999 then 1
|
wenzelm@33434
|
307 |
else Int.min (Int.max (count_workers Working + 2 * count_workers Waiting, m), 4 * m);
|
wenzelm@33432
|
308 |
val _ =
|
wenzelm@33432
|
309 |
if tick andalso mm > ! max_workers then
|
wenzelm@33432
|
310 |
Unsynchronized.change worker_trend (fn w => if w < 0 then 0 else w + 1)
|
wenzelm@33432
|
311 |
else if tick andalso mm < ! max_workers then
|
wenzelm@33432
|
312 |
Unsynchronized.change worker_trend (fn w => if w > 0 then 0 else w - 1)
|
wenzelm@33432
|
313 |
else ();
|
wenzelm@33432
|
314 |
val _ =
|
wenzelm@33436
|
315 |
if mm = 0 orelse ! worker_trend > 50 orelse ! worker_trend < ~50 then
|
wenzelm@33436
|
316 |
max_workers := mm
|
wenzelm@33436
|
317 |
else if ! worker_trend > 5 andalso ! max_workers < 2 * m then
|
wenzelm@33436
|
318 |
max_workers := Int.min (mm, 2 * m)
|
wenzelm@33432
|
319 |
else ();
|
wenzelm@33427
|
320 |
|
wenzelm@33428
|
321 |
val missing = ! max_workers - length (! workers);
|
wenzelm@28203
|
322 |
val _ =
|
wenzelm@33428
|
323 |
if missing > 0 then
|
wenzelm@33436
|
324 |
funpow missing (fn () =>
|
wenzelm@33436
|
325 |
ignore (worker_start ("worker " ^ string_of_int (Unsynchronized.inc next)))) ()
|
wenzelm@28203
|
326 |
else ();
|
wenzelm@28206
|
327 |
|
wenzelm@33436
|
328 |
val _ =
|
wenzelm@33436
|
329 |
if ! max_active = max_active0 andalso ! max_workers = max_workers0 then ()
|
wenzelm@33436
|
330 |
else signal work_available;
|
wenzelm@33436
|
331 |
|
wenzelm@33436
|
332 |
|
wenzelm@33436
|
333 |
(* canceled groups *)
|
wenzelm@33436
|
334 |
|
wenzelm@32225
|
335 |
val _ =
|
wenzelm@32225
|
336 |
if null (! canceled) then ()
|
wenzelm@32293
|
337 |
else
|
wenzelm@32293
|
338 |
(Multithreading.tracing 1 (fn () =>
|
wenzelm@32293
|
339 |
string_of_int (length (! canceled)) ^ " canceled groups");
|
wenzelm@34279
|
340 |
Unsynchronized.change canceled (filter_out cancel_now);
|
wenzelm@32293
|
341 |
broadcast_work ());
|
wenzelm@28206
|
342 |
|
wenzelm@33436
|
343 |
|
wenzelm@33436
|
344 |
(* delay loop *)
|
wenzelm@33436
|
345 |
|
wenzelm@32298
|
346 |
val _ = Exn.release (wait_timeout next_round scheduler_event);
|
wenzelm@32219
|
347 |
|
wenzelm@33436
|
348 |
|
wenzelm@33436
|
349 |
(* shutdown *)
|
wenzelm@33436
|
350 |
|
wenzelm@34277
|
351 |
val _ = if Task_Queue.all_passive (! queue) then do_shutdown := true else ();
|
wenzelm@32219
|
352 |
val continue = not (! do_shutdown andalso null (! workers));
|
wenzelm@28206
|
353 |
val _ = if continue then () else scheduler := NONE;
|
wenzelm@33436
|
354 |
|
wenzelm@32219
|
355 |
val _ = broadcast scheduler_event;
|
wenzelm@32298
|
356 |
in continue end
|
wenzelm@32298
|
357 |
handle Exn.Interrupt =>
|
wenzelm@32298
|
358 |
(Multithreading.tracing 1 (fn () => "Interrupt");
|
wenzelm@34280
|
359 |
List.app cancel_later (Task_Queue.cancel_all (! queue));
|
wenzelm@34279
|
360 |
broadcast_work (); true);
|
wenzelm@32298
|
361 |
|
wenzelm@28206
|
362 |
fun scheduler_loop () =
|
wenzelm@33437
|
363 |
while
|
wenzelm@33437
|
364 |
Multithreading.with_attributes
|
wenzelm@33437
|
365 |
(Multithreading.sync_interrupts Multithreading.public_interrupts)
|
wenzelm@33437
|
366 |
(fn _ => SYNCHRONIZED "scheduler" (fn () => scheduler_next ()))
|
wenzelm@33437
|
367 |
do ();
|
wenzelm@28191
|
368 |
|
wenzelm@28203
|
369 |
fun scheduler_active () = (*requires SYNCHRONIZED*)
|
wenzelm@28203
|
370 |
(case ! scheduler of NONE => false | SOME thread => Thread.isActive thread);
|
wenzelm@28203
|
371 |
|
wenzelm@32228
|
372 |
fun scheduler_check () = (*requires SYNCHRONIZED*)
|
wenzelm@32228
|
373 |
(do_shutdown := false;
|
wenzelm@32252
|
374 |
if scheduler_active () then ()
|
wenzelm@37216
|
375 |
else scheduler := SOME (Simple_Thread.fork false scheduler_loop));
|
wenzelm@28191
|
376 |
|
wenzelm@28191
|
377 |
|
wenzelm@28191
|
378 |
|
wenzelm@29370
|
379 |
(** futures **)
|
wenzelm@29370
|
380 |
|
wenzelm@29370
|
381 |
(* fork *)
|
wenzelm@29370
|
382 |
|
wenzelm@29370
|
383 |
fun fork_future opt_group deps pri e =
|
wenzelm@29370
|
384 |
let
|
wenzelm@32122
|
385 |
val group =
|
wenzelm@32122
|
386 |
(case opt_group of
|
wenzelm@34277
|
387 |
NONE => new_group ()
|
wenzelm@34277
|
388 |
| SOME group => group);
|
wenzelm@29370
|
389 |
val (result, job) = future_job group e;
|
wenzelm@32250
|
390 |
val task = SYNCHRONIZED "enqueue" (fn () =>
|
wenzelm@32219
|
391 |
let
|
wenzelm@32738
|
392 |
val (task, minimal) =
|
wenzelm@32738
|
393 |
Unsynchronized.change_result queue (Task_Queue.enqueue group deps pri job);
|
wenzelm@32219
|
394 |
val _ = if minimal then signal work_available else ();
|
wenzelm@32228
|
395 |
val _ = scheduler_check ();
|
wenzelm@32219
|
396 |
in task end);
|
wenzelm@34277
|
397 |
in Future {promised = false, task = task, group = group, result = result} end;
|
wenzelm@28162
|
398 |
|
wenzelm@29370
|
399 |
fun fork_group group e = fork_future (SOME group) [] 0 e;
|
wenzelm@32729
|
400 |
fun fork_deps_pri deps pri e = fork_future NONE (map task_of deps) pri e;
|
wenzelm@32729
|
401 |
fun fork_deps deps e = fork_deps_pri deps 0 e;
|
wenzelm@32729
|
402 |
fun fork_pri pri e = fork_deps_pri [] pri e;
|
wenzelm@32729
|
403 |
fun fork e = fork_deps [] e;
|
wenzelm@28162
|
404 |
|
wenzelm@28186
|
405 |
|
wenzelm@29370
|
406 |
(* join *)
|
wenzelm@28186
|
407 |
|
wenzelm@29551
|
408 |
local
|
wenzelm@29551
|
409 |
|
wenzelm@32119
|
410 |
fun get_result x =
|
wenzelm@32119
|
411 |
(case peek x of
|
wenzelm@32122
|
412 |
NONE => Exn.Exn (SYS_ERROR "unfinished future")
|
wenzelm@37182
|
413 |
| SOME (exn as Exn.Exn Exn.Interrupt) =>
|
wenzelm@37182
|
414 |
(case Exn.flatten_list (Task_Queue.group_status (group_of x)) of
|
wenzelm@37182
|
415 |
[] => exn
|
wenzelm@37182
|
416 |
| exns => Exn.Exn (Exn.EXCEPTIONS exns))
|
wenzelm@32122
|
417 |
| SOME res => res);
|
wenzelm@28177
|
418 |
|
wenzelm@32115
|
419 |
fun join_next deps = (*requires SYNCHRONIZED*)
|
wenzelm@32224
|
420 |
if null deps then NONE
|
wenzelm@32224
|
421 |
else
|
wenzelm@32738
|
422 |
(case Unsynchronized.change_result queue (Task_Queue.dequeue_towards (Thread.self ()) deps) of
|
wenzelm@32224
|
423 |
(NONE, []) => NONE
|
wenzelm@33431
|
424 |
| (NONE, deps') => (worker_wait true work_finished; join_next deps')
|
wenzelm@32224
|
425 |
| (SOME work, deps') => SOME (work, deps'));
|
wenzelm@32115
|
426 |
|
wenzelm@32823
|
427 |
fun execute_work NONE = ()
|
wenzelm@33429
|
428 |
| execute_work (SOME (work, deps')) = (execute work; join_work deps')
|
wenzelm@32823
|
429 |
and join_work deps =
|
wenzelm@32823
|
430 |
execute_work (SYNCHRONIZED "join" (fn () => join_next deps));
|
wenzelm@32823
|
431 |
|
wenzelm@32823
|
432 |
fun join_depend task deps =
|
wenzelm@32823
|
433 |
execute_work (SYNCHRONIZED "join" (fn () =>
|
wenzelm@32823
|
434 |
(Unsynchronized.change queue (Task_Queue.depend task deps); join_next deps)));
|
wenzelm@29551
|
435 |
|
wenzelm@29551
|
436 |
in
|
wenzelm@29551
|
437 |
|
wenzelm@29370
|
438 |
fun join_results xs =
|
wenzelm@29370
|
439 |
if forall is_finished xs then map get_result xs
|
wenzelm@32250
|
440 |
else if Multithreading.self_critical () then
|
wenzelm@32250
|
441 |
error "Cannot join future values within critical section"
|
wenzelm@32823
|
442 |
else
|
wenzelm@32823
|
443 |
(case worker_task () of
|
wenzelm@32823
|
444 |
SOME task => join_depend task (map task_of xs)
|
wenzelm@35016
|
445 |
| NONE => List.app (ignore o Single_Assignment.await o result_of) xs;
|
wenzelm@32823
|
446 |
map get_result xs);
|
wenzelm@28186
|
447 |
|
wenzelm@29551
|
448 |
end;
|
wenzelm@29551
|
449 |
|
wenzelm@28647
|
450 |
fun join_result x = singleton join_results x;
|
wenzelm@28647
|
451 |
fun join x = Exn.release (join_result x);
|
wenzelm@28156
|
452 |
|
wenzelm@28979
|
453 |
|
wenzelm@34277
|
454 |
(* fast-path versions -- bypassing full task management *)
|
wenzelm@34277
|
455 |
|
wenzelm@34277
|
456 |
fun value (x: 'a) =
|
wenzelm@34277
|
457 |
let
|
wenzelm@34277
|
458 |
val group = Task_Queue.new_group NONE;
|
wenzelm@35016
|
459 |
val result = Single_Assignment.var "value" : 'a result;
|
wenzelm@34277
|
460 |
val _ = assign_result group result (Exn.Result x);
|
wenzelm@34277
|
461 |
in Future {promised = false, task = Task_Queue.dummy_task, group = group, result = result} end;
|
wenzelm@28191
|
462 |
|
wenzelm@29384
|
463 |
fun map_future f x =
|
wenzelm@29370
|
464 |
let
|
wenzelm@29384
|
465 |
val task = task_of x;
|
wenzelm@32122
|
466 |
val group = Task_Queue.new_group (SOME (group_of x));
|
wenzelm@29384
|
467 |
val (result, job) = future_job group (fn () => f (join x));
|
wenzelm@29384
|
468 |
|
wenzelm@32250
|
469 |
val extended = SYNCHRONIZED "extend" (fn () =>
|
wenzelm@29370
|
470 |
(case Task_Queue.extend task job (! queue) of
|
wenzelm@29370
|
471 |
SOME queue' => (queue := queue'; true)
|
wenzelm@29370
|
472 |
| NONE => false));
|
wenzelm@29370
|
473 |
in
|
wenzelm@34277
|
474 |
if extended then Future {promised = false, task = task, group = group, result = result}
|
wenzelm@32119
|
475 |
else fork_future (SOME group) [task] (Task_Queue.pri_of_task task) (fn () => f (join x))
|
wenzelm@29370
|
476 |
end;
|
wenzelm@29370
|
477 |
|
wenzelm@29370
|
478 |
|
wenzelm@34277
|
479 |
(* promised futures -- fulfilled by external means *)
|
wenzelm@34277
|
480 |
|
wenzelm@34277
|
481 |
fun promise_group group : 'a future =
|
wenzelm@34277
|
482 |
let
|
wenzelm@35016
|
483 |
val result = Single_Assignment.var "promise" : 'a result;
|
wenzelm@34277
|
484 |
val task = SYNCHRONIZED "enqueue" (fn () =>
|
wenzelm@34277
|
485 |
Unsynchronized.change_result queue (Task_Queue.enqueue_passive group));
|
wenzelm@34277
|
486 |
in Future {promised = true, task = task, group = group, result = result} end;
|
wenzelm@34277
|
487 |
|
wenzelm@34277
|
488 |
fun promise () = promise_group (new_group ());
|
wenzelm@34277
|
489 |
|
wenzelm@34277
|
490 |
fun fulfill_result (Future {promised, task, group, result}) res =
|
wenzelm@34277
|
491 |
let
|
wenzelm@34277
|
492 |
val _ = promised orelse raise Fail "Not a promised future";
|
wenzelm@34277
|
493 |
fun job ok = assign_result group result (if ok then res else Exn.Exn Exn.Interrupt);
|
wenzelm@34277
|
494 |
val _ = execute (task, group, [job]);
|
wenzelm@34277
|
495 |
in () end;
|
wenzelm@34277
|
496 |
|
wenzelm@34277
|
497 |
fun fulfill x res = fulfill_result x (Exn.Result res);
|
wenzelm@34277
|
498 |
|
wenzelm@34277
|
499 |
|
wenzelm@29431
|
500 |
(* cancellation *)
|
wenzelm@28202
|
501 |
|
wenzelm@30621
|
502 |
fun interruptible_task f x =
|
wenzelm@30621
|
503 |
if Multithreading.available then
|
wenzelm@30621
|
504 |
Multithreading.with_attributes
|
wenzelm@32074
|
505 |
(if is_worker ()
|
wenzelm@32298
|
506 |
then Multithreading.private_interrupts
|
wenzelm@32298
|
507 |
else Multithreading.public_interrupts)
|
wenzelm@32298
|
508 |
(fn _ => f x)
|
wenzelm@30621
|
509 |
else interruptible f x;
|
wenzelm@30621
|
510 |
|
wenzelm@32228
|
511 |
(*cancel: present and future group members will be interrupted eventually*)
|
wenzelm@34281
|
512 |
fun cancel_group group =
|
wenzelm@34281
|
513 |
SYNCHRONIZED "cancel" (fn () => if cancel_now group then () else cancel_later group);
|
wenzelm@29431
|
514 |
fun cancel x = cancel_group (group_of x);
|
wenzelm@28206
|
515 |
|
wenzelm@29370
|
516 |
|
wenzelm@32228
|
517 |
(* shutdown *)
|
wenzelm@29370
|
518 |
|
wenzelm@28203
|
519 |
fun shutdown () =
|
wenzelm@28276
|
520 |
if Multithreading.available then
|
wenzelm@28276
|
521 |
SYNCHRONIZED "shutdown" (fn () =>
|
wenzelm@32228
|
522 |
while scheduler_active () do
|
wenzelm@34279
|
523 |
(wait scheduler_event; broadcast_work ()))
|
wenzelm@28276
|
524 |
else ();
|
wenzelm@28203
|
525 |
|
wenzelm@29370
|
526 |
|
wenzelm@37706
|
527 |
(* report markup *)
|
wenzelm@37706
|
528 |
|
wenzelm@37706
|
529 |
fun report e =
|
wenzelm@37706
|
530 |
let
|
wenzelm@37706
|
531 |
val _ = Output.status (Markup.markup Markup.forked "");
|
wenzelm@37706
|
532 |
val x = e (); (*sic -- report "joined" only for success*)
|
wenzelm@37706
|
533 |
val _ = Output.status (Markup.markup Markup.joined "");
|
wenzelm@37706
|
534 |
in x end;
|
wenzelm@37706
|
535 |
|
wenzelm@37706
|
536 |
|
wenzelm@29370
|
537 |
(*final declarations of this structure!*)
|
wenzelm@29370
|
538 |
val map = map_future;
|
wenzelm@29370
|
539 |
|
wenzelm@28156
|
540 |
end;
|
wenzelm@28972
|
541 |
|
wenzelm@28972
|
542 |
type 'a future = 'a Future.future;
|
wenzelm@28972
|
543 |
|