role Scheduler
Scheme for automatically assigning tasks to threads
Common role for schedulers. A scheduler is a piece of code that determines which resources to use to run which task, and when.
Some operations for example on Proc::Async, Promise, Supply allow you to specify a scheduler explicitly; they generally expect those schedulers to follow the interface defined by Scheduler
Methods
method uncaught_handler
method uncaught_handler() is rw
RW-Accessor for the handler that is caught for uncaught exceptions from the code that is being scheduled and run.
method cue
method cue(, Instant :, :, :, : = 1; : --> Cancellation)
Schedules a callable (&code
) for execution and returns an instantiated Cancellation
object to cancel the scheduling of the code for execution (which is especially important if you specify the every =
time> named parameter. The adverbs control when and how the code is run:
$at
can be an Instant before which the code won't be run. Alternatively $in
is the number of seconds (possibly fractional) to wait before running the code. If $at
is in the past or $in
is negative, the delay is treated as zero. Implementations may equate to zero very small values (e.g. lower than 0.001s) of $in
or result of $at
- now.
If $every
is specified, it is interpreted as the number of seconds (possibly fractional) to wait before re-executing the code. Implementations may treat too-small values as lowest resolution they support, possibly warning in such situations; e.g. treating 0.0001
as 0.001
.
$times
tells the scheduler how many times to run the code.
&catch
is called with the Exception as its sole argument if &code
dies.
If $at
or $in
are Inf
, &code
will never be run; if $every
is Inf
, &code
will only be run once. If any of the three are -Inf
, &code
will be run immediately. If any of the three are NaN
, an X::Scheduler::CueInNaNSeconds exception will be thrown. This only applies to releases 2019.05 and later.
One should call the cancel
method on the returned Cancellation
object to cancel the (possibly repeated) cueing of the code.