This file is indexed.

/usr/share/perl5/IO/Async/Function.pm is in libio-async-perl 0.64-1.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
#  You may distribute under the terms of either the GNU General Public License
#  or the Artistic License (the same terms as Perl itself)
#
#  (C) Paul Evans, 2011-2014 -- leonerd@leonerd.org.uk

package IO::Async::Function;

use strict;
use warnings;

our $VERSION = '0.64';

use base qw( IO::Async::Notifier );
use IO::Async::Timer::Countdown;

use Carp;

use Storable qw( freeze );

=head1 NAME

C<IO::Async::Function> - call a function asynchronously

=head1 SYNOPSIS

 use IO::Async::Function;

 use IO::Async::Loop;
 my $loop = IO::Async::Loop->new;

 my $function = IO::Async::Function->new(
    code => sub {
       my ( $number ) = @_;
       return is_prime( $number );
    },
 );

 $loop->add( $function );

 $function->call(
    args => [ 123454321 ],
 )->on_done( sub {
    my $isprime = shift;
    print "123454321 " . ( $isprime ? "is" : "is not" ) . " a prime number\n";
 })->on_fail( sub {
    print STDERR "Cannot determine if it's prime - $_[0]\n";
 })->get;

=head1 DESCRIPTION

This subclass of L<IO::Async::Notifier> wraps a function body in a collection
of worker processes, to allow it to execute independently of the main process.
The object acts as a proxy to the function, allowing invocations to be made by
passing in arguments, and invoking a continuation in the main process when the
function returns.

The object represents the function code itself, rather than one specific
invocation of it. It can be called multiple times, by the C<call> method.
Multiple outstanding invocations can be called; they will be dispatched in
the order they were queued. If only one worker process is used then results
will be returned in the order they were called. If multiple are used, then
each request will be sent in the order called, but timing differences between
each worker may mean results are returned in a different order.

Since the code block will be called multiple times within the same child
process, it must take care not to modify any of its state that might affect
subsequent calls. Since it executes in a child process, it cannot make any
modifications to the state of the parent program. Therefore, all the data
required to perform its task must be represented in the call arguments, and
all of the result must be represented in the return values.

The Function object is implemented using an L<IO::Async::Routine> with two
L<IO::Async::Channel> objects to pass calls into and results out from it.

The C<IO::Async> framework generally provides mechanisms for multiplexing IO
tasks between different handles, so there aren't many occasions when such an
asynchronous function is necessary. Two cases where this does become useful
are:

=over 4

=item 1.

When a large amount of computationally-intensive work needs to be performed
(for example, the C<is_prime> test in the example in the C<SYNOPSIS>).

=item 2.

When a blocking OS syscall or library-level function needs to be called, and
no nonblocking or asynchronous version is supplied. This is used by
C<IO::Async::Resolver>.

=back

This object is ideal for representing "pure" functions; that is, blocks of
code which have no stateful effect on the process, and whose result depends
only on the arguments passed in. For a more general co-routine ability, see
also L<IO::Async::Routine>.

=cut

=head1 PARAMETERS

The following named parameters may be passed to C<new> or C<configure>:

=head2 code => CODE

The body of the function to execute.

=head2 model => "fork" | "thread"

Optional. Requests a specific C<IO::Async::Routine> model. If not supplied,
leaves the default choice up to Routine.

=head2 min_workers => INT

=head2 max_workers => INT

The lower and upper bounds of worker processes to try to keep running. The
actual number running at any time will be kept somewhere between these bounds
according to load.

=head2 max_worker_calls => INT

Optional. If provided, stop a worker process after it has processed this
number of calls. (New workers may be started to replace stopped ones, within
the bounds given above).

=head2 idle_timeout => NUM

Optional. If provided, idle worker processes will be shut down after this
amount of time, if there are more than C<min_workers> of them.

=head2 exit_on_die => BOOL

Optional boolean, controls what happens after the C<code> throws an
exception. If missing or false, the worker will continue running to process
more requests. If true, the worker will be shut down. A new worker might be
constructed by the C<call> method to replace it, if necessary.

=head2 setup => ARRAY

Optional array reference. Specifies the C<setup> key to pass to the underlying
L<IO::Async::Process> when setting up new worker processes.

=cut

sub _init
{
   my $self = shift;
   $self->SUPER::_init( @_ );

   $self->{min_workers} = 1;
   $self->{max_workers} = 8;

   $self->{workers} = {}; # {$id} => IaFunction:Worker

   $self->{pending_queue} = [];
}

sub configure
{
   my $self = shift;
   my %params = @_;

   my %worker_params;
   foreach (qw( model exit_on_die max_worker_calls )) {
      $self->{$_} = $worker_params{$_} = delete $params{$_} if exists $params{$_};
   }

   if( keys %worker_params ) {
      foreach my $worker ( $self->_worker_objects ) {
         $worker->configure( %worker_params );
      }
   }

   if( exists $params{idle_timeout} ) {
      my $timeout = delete $params{idle_timeout};
      if( !$timeout ) {
         $self->remove_child( delete $self->{idle_timer} ) if $self->{idle_timer};
      }
      elsif( my $idle_timer = $self->{idle_timer} ) {
         $idle_timer->configure( delay => $timeout );
      }
      else {
         $self->{idle_timer} = IO::Async::Timer::Countdown->new(
            delay => $timeout,
            on_expire => $self->_capture_weakself( sub {
               my $self = shift or return;
               my $workers = $self->{workers};

               # Shut down atmost one idle worker, starting from the highest
               # ID. Since we search from lowest to assign work, this tries
               # to ensure we'll shut down the least useful ones first,
               # keeping more useful ones in memory (page/cache warmth, etc..)
               foreach my $id ( reverse sort keys %$workers ) {
                  next if $workers->{$id}{busy};

                  $workers->{$id}->stop;
                  last;
               }

               # Still more?
               $self->{idle_timer}->start if $self->workers_idle > $self->{min_workers};
            } ),
         );
         $self->add_child( $self->{idle_timer} );
      }
   }

   foreach (qw( min_workers max_workers )) {
      $self->{$_} = delete $params{$_} if exists $params{$_};
      # TODO: something about retuning
   }

   my $need_restart;

   foreach (qw( code setup )) {
      $need_restart++, $self->{$_} = delete $params{$_} if exists $params{$_};
   }

   $self->SUPER::configure( %params );

   if( $need_restart and $self->loop ) {
      $self->stop;
      $self->start;
   }
}

sub _add_to_loop
{
   my $self = shift;
   $self->SUPER::_add_to_loop( @_ );

   $self->start;
}

sub _remove_from_loop
{
   my $self = shift;

   $self->stop;

   $self->SUPER::_remove_from_loop( @_ );
}

=head1 METHODS

The following methods documented with a trailing call to C<< ->get >> return
L<Future> instances.

=cut

=head2 $function->start

Start the worker processes

=cut

sub start
{
   my $self = shift;

   $self->_new_worker for 1 .. $self->{min_workers};
}

=head2 $function->stop

Stop the worker processes

=cut

sub stop
{
   my $self = shift;

   $self->{stopping} = 1;
   foreach my $worker ( $self->_worker_objects ) {
      $worker->stop;
   }
}

=head2 $function->restart

Gracefully stop and restart all the worker processes. 

=cut

sub restart
{
   my $self = shift;

   $self->stop;
   $self->start;
}

=head2 @result = $function->call( %params )->get

Schedules an invocation of the contained function to be executed on one of the
worker processes. If a non-busy worker is available now, it will be called
immediately. If not, it will be queued and sent to the next free worker that
becomes available.

The request will already have been serialised by the marshaller, so it will be
safe to modify any referenced data structures in the arguments after this call
returns.

The C<%params> hash takes the following keys:

=over 8

=item args => ARRAY

A reference to the array of arguments to pass to the code.

=back

=head2 $function->call( %params )

When not returning a future, the C<on_result>, C<on_return> and C<on_error>
arguments give continuations to handle successful results or failure.

=over 8

=item on_result => CODE

A continuation that is invoked when the code has been executed. If the code
returned normally, it is called as:

 $on_result->( 'return', @values )

If the code threw an exception, or some other error occured such as a closed
connection or the process died, it is called as:

 $on_result->( 'error', $exception_name )

=item on_return => CODE and on_error => CODE

An alternative to C<on_result>. Two continuations to use in either of the
circumstances given above. They will be called directly, without the leading
'return' or 'error' value.

=back

=cut

sub call
{
   my $self = shift;
   my %params = @_;

   # TODO: possibly just queue this?
   $self->loop or croak "Cannot ->call on a Function not yet in a Loop";

   my $args = delete $params{args};
   ref $args eq "ARRAY" or croak "Expected 'args' to be an array";

   my ( $on_done, $on_fail );
   if( defined $params{on_result} ) {
      my $on_result = delete $params{on_result};
      ref $on_result or croak "Expected 'on_result' to be a reference";

      $on_done = $self->_capture_weakself( sub {
         my $self = shift or return;
         $self->debug_printf( "CONT on_result return" );
         $on_result->( return => @_ );
      } );
      $on_fail = $self->_capture_weakself( sub {
         my $self = shift or return;
         my ( $err, @values ) = @_;
         $self->debug_printf( "CONT on_result error" );
         $on_result->( error => @values );
      } );
   }
   elsif( defined $params{on_return} and defined $params{on_error} ) {
      my $on_return = delete $params{on_return};
      ref $on_return or croak "Expected 'on_return' to be a reference";
      my $on_error  = delete $params{on_error};
      ref $on_error or croak "Expected 'on_error' to be a reference";

      $on_done = $self->_capture_weakself( sub {
         my $self = shift or return;
         $self->debug_printf( "CONT on_return" );
         $on_return->( @_ );
      } );
      $on_fail = $self->_capture_weakself( sub {
         my $self = shift or return;
         $self->debug_printf( "CONT on_error" );
         $on_error->( @_ );
      } );
   }
   elsif( !defined wantarray ) {
      croak "Expected either 'on_result' or 'on_return' and 'on_error' keys, or to return a Future";
   }

   my $request = freeze( $args );

   my $future;
   if( my $worker = $self->_get_worker ) {
      $self->debug_printf( "CALL" );
      $future = $self->_call_worker( $worker, $request );
   }
   else {
      $self->debug_printf( "QUEUE" );
      push @{ $self->{pending_queue} }, my $wait_f = $self->loop->new_future;

      $future = $wait_f->then( sub {
         my ( $self, $worker ) = @_;
         $self->_call_worker( $worker, $request );
      });
   }

   $future->on_done( $on_done ) if $on_done;
   $future->on_fail( $on_fail ) if $on_fail;

   return $future if defined wantarray;

   # Caller is not going to keep hold of the Future, so we have to ensure it
   # stays alive somehow
   $future->on_ready( sub { undef $future } ); # intentional cycle
}

sub _worker_objects
{
   my $self = shift;
   return values %{ $self->{workers} };
}

=head2 $count = $function->workers

Returns the total number of worker processes available

=cut

sub workers
{
   my $self = shift;
   return scalar keys %{ $self->{workers} };
}

=head2 $count = $function->workers_busy

Returns the number of worker processes that are currently busy

=cut

sub workers_busy
{
   my $self = shift;
   return scalar grep { $_->{busy} } $self->_worker_objects;
}

=head2 $count = $function->workers_idle

Returns the number of worker processes that are currently idle

=cut

sub workers_idle
{
   my $self = shift;
   return scalar grep { !$_->{busy} } $self->_worker_objects;
}

sub _new_worker
{
   my $self = shift;

   my $worker = IO::Async::Function::Worker->new(
      ( map { $_ => $self->{$_} } qw( model code setup exit_on_die ) ),
      max_calls => $self->{max_worker_calls},

      on_finish => $self->_capture_weakself( sub {
         my $self = shift or return;
         my ( $worker ) = @_;

         return if $self->{stopping};

         $self->_new_worker if $self->workers < $self->{min_workers};

         $self->_dispatch_pending;
      } ),
   );

   $self->add_child( $worker );

   return $self->{workers}{$worker->id} = $worker;
}

sub _get_worker
{
   my $self = shift;

   foreach ( sort keys %{ $self->{workers} } ) {
      return $self->{workers}{$_} if !$self->{workers}{$_}{busy};
   }

   if( $self->workers < $self->{max_workers} ) {
      return $self->_new_worker;
   }

   return undef;
}

sub _call_worker
{
   my $self = shift;
   my ( $worker, $type, $args ) = @_;

   my $future = $worker->call( $type, $args );

   if( $self->workers_idle == 0 ) {
      $self->{idle_timer}->stop if $self->{idle_timer};
   }

   return $future;
}

sub _dispatch_pending
{
   my $self = shift;

   while( my $next = shift @{ $self->{pending_queue} } ) {
      my $worker = $self->_get_worker or return;

      next if $next->is_cancelled;

      $self->debug_printf( "UNQUEUE" );
      $next->done( $self, $worker );
      return;
   }

   if( $self->workers_idle > $self->{min_workers} ) {
      $self->{idle_timer}->start if $self->{idle_timer} and !$self->{idle_timer}->is_running;
   }
}

package # hide from indexer
   IO::Async::Function::Worker;

use base qw( IO::Async::Routine );

use IO::Async::Channel;

sub new
{
   my $class = shift;
   my %params = @_;

   my $arg_channel = IO::Async::Channel->new;
   my $ret_channel = IO::Async::Channel->new;

   my $code = delete $params{code};
   $params{code} = sub {
      while( my $args = $arg_channel->recv ) {
         my @ret;
         my $ok = eval { @ret = $code->( @$args ); 1 };

         if( $ok ) {
            $ret_channel->send( [ r => @ret ] );
         }
         else {
            chomp( my $e = "$@" );
            $ret_channel->send( [ e => $e, error => ] );
         }
      }
   };

   my $worker = $class->SUPER::new(
      %params,
      channels_in  => [ $arg_channel ],
      channels_out => [ $ret_channel ],
   );

   $worker->{arg_channel} = $arg_channel;
   $worker->{ret_channel} = $ret_channel;

   return $worker;
}

sub configure
{
   my $self = shift;
   my %params = @_;

   exists $params{$_} and $self->{$_} = delete $params{$_} for qw( exit_on_die max_calls );

   $self->SUPER::configure( %params );
}

sub stop
{
   my $worker = shift;
   $worker->{arg_channel}->close;

   if( my $function = $worker->parent ) {
      delete $function->{workers}{$worker->id};

      if( $worker->{busy} ) {
         $worker->{remove_on_idle}++;
      }
      else {
         $function->remove_child( $worker );
      }
   }
}

sub call
{
   my $worker = shift;
   my ( $args ) = @_;

   $worker->{arg_channel}->send_frozen( $args );

   $worker->{busy} = 1;
   $worker->{max_calls}--;

   return $worker->{ret_channel}->recv->then(
      # on recv
      $worker->_capture_weakself( sub {
         my ( $worker, $result ) = @_;
         my ( $type, @values ) = @$result;

         $worker->stop if !$worker->{max_calls} or
                          $worker->{exit_on_die} && $type eq "e";

         if( $type eq "r" ) {
            return Future->new->done( @values );
         }
         elsif( $type eq "e" ) {
            return Future->new->fail( @values );
         }
         else {
            die "Unrecognised type from worker - $type\n";
         }
      } ),
      # on EOF
      $worker->_capture_weakself( sub {
         my ( $worker ) = @_;

         $worker->stop;

         return Future->new->fail( "closed", "closed" );
      } )
   )->on_ready( $worker->_capture_weakself( sub {
      my ( $worker, $f ) = @_;
      $worker->{busy} = 0;

      my $function = $worker->parent;
      $function->_dispatch_pending if $function;

      $function->remove_child( $worker ) if $function and $worker->{remove_on_idle};
   }));
}

=head1 NOTES

For the record, 123454321 is 11111 * 11111, a square number, and therefore not
prime.

=head1 AUTHOR

Paul Evans <leonerd@leonerd.org.uk>

=cut

0x55AA;