1CPS::Governor::DeferredU(s3e)r Contributed Perl DocumentaCtPiSo:n:Governor::Deferred(3)
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NAME

6       "CPS::Governor::Deferred" - iterate at some later point
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SYNOPSIS

9        use CPS qw( gkforeach );
10        use CPS::Governor::Deferred;
11
12        my $gov = CPS::Governor::Deferred->new;
13
14        gkforeach( $gov, [ 1 .. 10 ],
15           sub {
16              my ( $item, $knext ) = @_;
17
18              print "A$item ";
19              goto &$knext;
20           },
21           sub {},
22        );
23
24        gkforeach( $gov, [ 1 .. 10 ],
25           sub {
26              my ( $item, $knext ) = @_;
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28              print "B$item ";
29              goto &$knext;
30           },
31           sub {},
32        );
33
34        $gov->flush;
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DESCRIPTION

37       This CPS::Governor allows the functions using it to delay their
38       iteration until some later point when the containing program invokes
39       it. This allows two main advantages:
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41       ·   CPU-intensive operations may be split apart and mixed with other IO
42           operations
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44       ·   Multiple control functions may be executed in pseudo-parallel,
45           interleaving iterations of each giving a kind of concurrency
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47       These are achieved by having the governor store a list of code
48       references that need to be invoked, rather than invoking them
49       immediately. These references can then be invoked later, perhaps by
50       using an idle watcher in an event framework.
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52       Because each code reference hasn't yet been invoked by the time the
53       "again" method is called, the original caller is free to store more
54       pending references with the governor. This allows multiple control
55       functions to be interleaved, as in the "A" and "B" example above.
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CONSTRUCTOR

58   $gov = CPS::Governor::Deferred->new( %args )
59       Returns a new instance of a "CPS::Governor::Deferred" object. Requires
60       no parameters but may take any of the following to adjust its default
61       behaviour:
62
63       defer_after => INT
64               If given some positive number, $n then the first "$n-1"
65               invocations of the "again" method will in fact be executed
66               immediately. Thereafter they will be enqueued in the normal
67               mechanism. This gives the effect that longrunning loops will be
68               executed in batches of $n.
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70               If not supplied then every invocation of "again" will use the
71               queueing mechanism.
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METHODS

74   $pending = $gov->is_pending
75       Returns true if at least one code reference has been stored that hasn't
76       yet been invoked.
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78   $gov->prod
79       Invokes all of the currently-stored code references, in the order they
80       were stored. If any new references are stored by these, they will not
81       yet be invoked, but will be available for the next time this method is
82       called.
83
84   $gov->flush
85       Repeatedly calls "prod" until no more code references are pending.
86

SUBCLASS METHODS

88       The following methods are used internally to implement the
89       functionality, which may be useful to implementors of subclasses.
90
91   $gov->later( $code, @args )
92       Used to enqueue the $code ref to be invoked later with the given @args,
93       once it is determined this should be deferred (rather than being
94       invoked immediately in the case of the first few invocations when
95       "defer_after" is set).
96

AUTHOR

98       Paul Evans <leonerd@leonerd.org.uk>
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102perl v5.28.1                      2019-02-02        CPS::Governor::Deferred(3)