CPS::Governor::DeferreUser Contributed Perl DocumentCPS::Governor::Deferred(3)NAME
"CPS::Governor::Deferred" - iterate at some later point
SYNOPSIS
use CPS qw( gkforeach );
use CPS::Governor::Deferred;
my $gov = CPS::Governor::Deferred->new;
gkforeach( $gov, [ 1 .. 10 ],
sub {
my ( $item, $knext ) = @_;
print "A$item ";
goto &$knext;
},
sub {},
);
gkforeach( $gov, [ 1 .. 10 ],
sub {
my ( $item, $knext ) = @_;
print "B$item ";
goto &$knext;
},
sub {},
);
$gov->flush;
DESCRIPTION
This CPS::Governor allows the functions using it to delay their
iteration until some later point when the containing program invokes
it. This allows two main advantages:
· CPU-intensive operations may be split apart and mixed with other IO
operations
· Multiple control functions may be executed in pseudo-parallel,
interleaving iterations of each giving a kind of concurrency
These are achieved by having the governor store a list of code
references that need to be invoked, rather than invoking them
immediately. These references can then be invoked later, perhaps by
using an idle watcher in an event framework.
Because each code reference hasn't yet been invoked by the time the
"again" method is called, the original caller is free to store more
pending references with the governor. This allows multiple control
functions to be interleaved, as in the "A" and "B" example above.
CONSTRUCTOR
$gov = CPS::Governor::Deferred->new( %args )
Returns a new instance of a "CPS::Governor::Deferred" object. Requires
no parameters but may take any of the following to adjust its default
behaviour:
defer_after => INT
If given some positive number, $n then the first "$n-1"
invocations of the "again" method will in fact be executed
immediately. Thereafter they will be enqueued in the normal
mechanism. This gives the effect that longrunning loops will be
executed in batches of $n.
If not supplied then every invocation of "again" will use the
queueing mechanism.
METHODS
$pending = $gov->is_pending
Returns true if at least one code reference has been stored that hasn't
yet been invoked.
$gov->prod
Invokes all of the currently-stored code references, in the order they
were stored. If any new references are stored by these, they will not
yet be invoked, but will be available for the next time this method is
called.
$gov->flush
Repeatedly calls "prod" until no more code references are pending.
SUBCLASS METHODS
The following methods are used internally to implement the
functionality, which may be useful to implementors of subclasses.
$gov->later( $code, @args )
Used to enqueue the $code ref to be invoked later with the given @args,
once it is determined this should be deferred (rather than being
invoked immediately in the case of the first few invocations when
"defer_after" is set).
AUTHOR
Paul Evans <leonerd@leonerd.org.uk>
perl v5.18.2 2014-05-14 CPS::Governor::Deferred(3)
