Module Scheduler

module Scheduler: Scheduler

val go : ?raise_unhandled_exn:bool -> unit -> Core.Std.never_returns

go ?raise_unhandled_exn () passes control to Async, at which point Async starts running handlers, one by one without interruption, until there are no more handlers to run. When Async is out of handlers it blocks until the outside world schedules more of them. Because of this, Async programs do not exit until shutdown is called.

go () calls handle_signal Sys.sigpipe, which causes the SIGPIPE signal to be ignored. Low-level syscalls (e.g. write) still raise EPIPE.

If any async job raises an unhandled exception that is not handled by any monitor, async execution ceases. Then, by default, async pretty prints the exception, and exits with status 1. If you don't want this, pass ~raise_unhandled_exn:true, which will cause the unhandled exception to be raised to the caller of go ().

val go_main : ?raise_unhandled_exn:bool ->
       main:(unit -> unit) -> unit -> Core.Std.never_returns

go_main is like go, except that one supplies a main function that will be run to initialize the async computation, and that go_main will fail if any async has been used prior to go_main being called.

type 'a with_options = ?work_group:Work_group.t ->
       ?monitor:Import.Monitor.t -> ?priority:Import.Priority.t -> 'a

val within_context : Import.Execution_context.t -> (unit -> 'a) -> ('a, unit) Core.Std.Result.t

within_context context f runs f () right now with the specified execution context. If f raises, then the exception is sent to the monitor of context, and Error () is returned.

val within' : ((unit -> 'a Import.Deferred.t) -> 'a Import.Deferred.t)
       with_options

within' f ~work_group ~monitor ~priority runs f () right now, with the specified block group, monitor, and priority set as specified. They will be reset to their original values when f returns. If f raises, then the result of within' will never become determined, but the exception will end up in the specified monitor.

val within : ((unit -> unit) -> unit) with_options

within is like within', but doesn't require thunk to return a deferred.

val within_v : ((unit -> 'a) -> 'a option) with_options

within_v is like within, but allows a value to be returned by f.

val schedule' : ((unit -> 'a Import.Deferred.t) -> 'a Import.Deferred.t)
       with_options

Just like within', but instead of running thunk right now, adds it to the async queue to be run with other async jobs.

val schedule : ((unit -> unit) -> unit) with_options

Just like schedule', but doesn't require thunk to return a deferred.

val cycle_start : unit -> Core.Std.Time.t

cycle_start () returns the result of Time.now () called at the beginning of cycle.

val cycle_times : unit -> Core.Std.Time.Span.t Import.Stream.t

cycle_times () returns a stream that will have one element for each cycle that Async runs, with the amount of time that the cycle took (as determined by calls to Time.now at the beginning and end of the cycle).

val report_long_cycle_times : ?cutoff:Core.Std.Time.Span.t -> unit -> unit

report_long_cycle_times ?cutoff () sets up something that will print a warning to stderr whenever there is an async cycle that is too long, as specified by cutoff, whose default is 1s.

val cycle_count : unit -> int

cycle_count () returns the total number of async cycles that have happened.

val is_running : unit -> bool

is_running () returns true if the scheduler has been started.

val set_max_num_jobs_per_priority_per_cycle : int -> unit

set_max_num_jobs_per_priority_per_cycle int sets the maximum number of jobs that will be done at each priority within each async cycle. The default is 500.

val is_ready_to_initialize : unit -> bool

val reset_in_forked_process : unit -> unit

If a process that has already created, but not started, the async scheduler would like to fork, and would like the child to have a clean async, i.e. not inherit any of the async work that was done in the parent, it can call reset_in_forked_process at the start of execution in the child process. After that, the child can do async stuff and then start the async scheduler.