This file is indexed.

/usr/share/perl5/MCE/Stream.pm is in libmce-perl 1.517-1.

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
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
###############################################################################
## ----------------------------------------------------------------------------
## MCE::Stream - Parallel stream model for chaining multiple maps and greps.
##
###############################################################################

package MCE::Stream;

use strict;
use warnings;

use Scalar::Util qw( looks_like_number );

use MCE;
use MCE::Util;

use MCE::Queue;

our $VERSION = '1.517'; $VERSION = eval $VERSION;

###############################################################################
## ----------------------------------------------------------------------------
## Import routine.
##
###############################################################################

our $DEFAULT_MODE = 'map';
our $MAX_WORKERS  = 'auto';
our $CHUNK_SIZE   = 'auto';

my ($_params, @_prev_c, @_prev_m, @_prev_n, @_prev_w, @_user_tasks, @_queue);
my ($_MCE, $_loaded); my $_tag = 'MCE::Stream';

sub import {

   my $_class = shift; return if ($_loaded++);

   ## Process module arguments.
   while (my $_arg = shift) {

      $DEFAULT_MODE = shift and next if ( $_arg =~ /^default_mode$/i );
      $MAX_WORKERS  = shift and next if ( $_arg =~ /^max_workers$/i );
      $CHUNK_SIZE   = shift and next if ( $_arg =~ /^chunk_size$/i );
      $MCE::TMP_DIR = shift and next if ( $_arg =~ /^tmp_dir$/i );
      $MCE::FREEZE  = shift and next if ( $_arg =~ /^freeze$/i );
      $MCE::THAW    = shift and next if ( $_arg =~ /^thaw$/i );

      if ( $_arg =~ /^sereal$/i ) {
         if (shift eq '1') {
            local $@; eval 'use Sereal qw(encode_sereal decode_sereal)';
            unless ($@) {
               $MCE::FREEZE = \&encode_sereal;
               $MCE::THAW   = \&decode_sereal;
            }
         }
         next;
      }

      _croak("$_tag::import: '$_arg' is not a valid module argument");
   }

   _croak("$_tag: 'DEFAULT_MODE' is not valid")
      if ($DEFAULT_MODE ne 'grep' && $DEFAULT_MODE ne 'map');

   $MAX_WORKERS = MCE::Util::_parse_max_workers($MAX_WORKERS);
   _validate_number($MAX_WORKERS, 'MAX_WORKERS');

   _validate_number($CHUNK_SIZE, 'CHUNK_SIZE')
      unless ($CHUNK_SIZE eq 'auto');

   ## Import functions.
   no strict 'refs'; no warnings 'redefine';
   my $_package = caller();

   *{ $_package . '::mce_stream_f' } = \&mce_stream_f;
   *{ $_package . '::mce_stream_s' } = \&mce_stream_s;
   *{ $_package . '::mce_stream'   } = \&mce_stream;

   return;
}

END {
   return if (defined $_MCE && $_MCE->wid);

   MCE::Stream::finish();
}

###############################################################################
## ----------------------------------------------------------------------------
## Gather callback to ensure chunk order is preserved during gathering.
## Also, the task end callback for when a task completes.
##
###############################################################################

my ($_gather_ref, $_order_id, %_tmp);

sub _preserve_order {

   $_tmp{$_[1]} = $_[0];

   if (defined $_gather_ref) {
      while (1) {
         last unless exists $_tmp{$_order_id};
         push @{ $_gather_ref }, @{ $_tmp{$_order_id} };
         delete $_tmp{$_order_id++};
      }
   }
   else {
      $_order_id++;
   }

   return;
}

sub _task_end {

   my ($_mce, $_task_id, $_task_name) = @_;

   if (defined $_mce->{user_tasks}->[$_task_id + 1]) {
      my $N_workers = $_mce->{user_tasks}->[$_task_id + 1]->{max_workers};
      my $_queue_id = @_queue - $_task_id - 1;

      $_queue[$_queue_id]->enqueue((undef) x $N_workers);
   }

   $_params->{task_end}->($_mce, $_task_id, $_task_name)
      if (exists $_params->{task_end} && ref $_params->{task_end} eq 'CODE');

   return;
}

###############################################################################
## ----------------------------------------------------------------------------
## Init and finish routines.
##
###############################################################################

sub init (@) {

   if (MCE->wid) {
      @_ = (); _croak(
         "$_tag: function cannot be called by the worker process"
      );
   }

   _croak("$_tag: 'argument' is not a HASH reference")
      unless (ref $_[0] eq 'HASH');

   MCE::Stream::finish(); $_params = shift;

   return;
}

sub finish () {

   if (defined $_MCE) {
      MCE::_save_state; $_MCE->shutdown(); MCE::_restore_state;
   }

   $_gather_ref = $_order_id = undef; undef %_tmp; @_user_tasks = ();
   @_prev_w = (); @_prev_n = (); @_prev_m = (); @_prev_c = ();

   $_->DESTROY() foreach (@_queue); @_queue = ();

   return;
}

###############################################################################
## ----------------------------------------------------------------------------
## Parallel stream with MCE -- file.
##
###############################################################################

sub mce_stream_f (@) {

   my ($_file, $_pos); my $_start_pos = (ref $_[0] eq 'HASH') ? 2 : 1;

   for ($_start_pos .. @_ - 1) {
      my $_r = ref $_[$_];
      if ($_r eq "" || $_r eq 'GLOB' || $_r eq 'SCALAR' || $_r =~ /^IO::/) {
         $_file = $_[$_]; $_pos = $_;
         last;
      }
   }

   if (defined $_params) {
      delete $_params->{input_data} if (exists $_params->{input_data});
      delete $_params->{sequence}   if (exists $_params->{sequence});
   }
   else {
      $_params = {};
   }

   if (defined $_file && ref $_file eq "" && $_file ne "") {
      _croak("$_tag: '$_file' does not exist") unless (-e $_file);
      _croak("$_tag: '$_file' is not readable") unless (-r $_file);
      _croak("$_tag: '$_file' is not a plain file") unless (-f $_file);
      $_params->{_file} = $_file;
   }
   elsif (ref $_file eq 'GLOB' || ref $_file eq 'SCALAR' || ref($_file) =~ /^IO::/) {
      $_params->{_file} = $_file;
   }
   else {
      _croak("$_tag: 'file' is not specified or valid");
   }

   if (defined $_pos) {
      pop @_ for ($_pos .. @_ - 1);
   }

   return mce_stream(@_);
}

###############################################################################
## ----------------------------------------------------------------------------
## Parallel stream with MCE -- sequence.
##
###############################################################################

sub mce_stream_s (@) {

   my ($_begin, $_end, $_pos); my $_start_pos = (ref $_[0] eq 'HASH') ? 2 : 1;

   delete $_params->{sequence}
      if (exists $_params->{sequence});

   for ($_start_pos .. @_ - 1) {
      my $_ref = ref $_[$_];

      if ($_ref eq "" || $_ref eq 'HASH' || $_ref eq 'ARRAY') {
         $_pos = $_;

         if ($_ref eq "") {
            $_begin = $_[$_pos]; $_end = $_[$_pos + 1];
            $_params->{sequence} = [
               $_[$_pos], $_[$_pos + 1], $_[$_pos + 2], $_[$_pos + 3]
            ];
         }
         elsif ($_ref eq 'HASH') {
            $_begin = $_[$_pos]->{begin}; $_end = $_[$_pos]->{end};
            $_params->{sequence} = $_[$_pos];
         }
         elsif ($_ref eq 'ARRAY') {
            $_begin = $_[$_pos]->[0]; $_end = $_[$_pos]->[1];
            $_params->{sequence} = $_[$_pos];
         }

         last;
      }
   }

   if (defined $_params) {
      delete $_params->{input_data} if (exists $_params->{input_data});
      delete $_params->{_file}      if (exists $_params->{_file});
   }
   else {
      $_params = {};
   }

   _croak("$_tag: 'sequence' is not specified or valid")
      unless (exists $_params->{sequence});

   _croak("$_tag: 'begin' is not specified for sequence")
      unless (defined $_begin);

   _croak("$_tag: 'end' is not specified for sequence")
      unless (defined $_end);

   if (defined $_pos) {
      pop @_ for ($_pos .. @_ - 1);
   }

   return mce_stream(@_);
}

###############################################################################
## ----------------------------------------------------------------------------
## Parallel stream with MCE.
##
###############################################################################

sub mce_stream (@) {

   if (MCE->wid) {
      @_ = (); _croak(
         "$_tag: function cannot be called by the worker process"
      );
   }

   if (ref $_[0] eq 'HASH' && !exists $_[0]->{code}) {
      $_params = {} unless defined $_params;
      $_params->{$_} = $_[0]->{$_} foreach (keys %{ $_[0] });

      shift;
   }

   my $_aref = shift if (ref $_[0] eq 'ARRAY');

   $_order_id = 1; undef %_tmp;

   if (defined $_aref) {
      $_gather_ref = $_aref; @$_aref = ();
   }

   ## -------------------------------------------------------------------------

   my (@_code, @_mode, @_name, @_wrks); my $_init_mce = 0; my $_pos = 0;

   while (ref $_[0] eq 'CODE' || ref $_[0] eq 'HASH') {
      if (ref $_[0] eq 'CODE') {
         push @_code, $_[0];
         push @_mode, $DEFAULT_MODE;
      }
      else {
         push @_code, exists $_[0]->{code} ? $_[0]->{code} : undef;
         push @_mode, exists $_[0]->{mode} ? $_[0]->{mode} : $DEFAULT_MODE;

         unless (ref $_code[-1] eq 'CODE') {
            @_ = (); _croak("$_tag: 'code' is not valid");
         }
         if ($_mode[-1] ne 'grep' && $_mode[-1] ne 'map') {
            @_ = (); _croak("$_tag: 'mode' is not valid");
         }
      }

      push @_name, (defined $_params && ref $_params->{task_name} eq 'ARRAY')
         ? $_params->{task_name}->[$_pos] : undef;
      push @_wrks, (defined $_params && ref $_params->{max_workers} eq 'ARRAY')
         ? $_params->{max_workers}->[$_pos] : undef;

      $_init_mce = 1
         if (!defined $_prev_c[$_pos] || $_prev_c[$_pos] != $_code[$_pos]);
      $_init_mce = 1
         if (!defined $_prev_m[$_pos] || $_prev_m[$_pos] ne $_mode[$_pos]);

      {
         no warnings;
         $_init_mce = 1 if ($_prev_n[$_pos] ne $_name[$_pos]);
         $_init_mce = 1 if ($_prev_w[$_pos] ne $_wrks[$_pos]);
      }

      $_prev_c[$_pos] = $_code[$_pos];
      $_prev_m[$_pos] = $_mode[$_pos];
      $_prev_n[$_pos] = $_name[$_pos];
      $_prev_w[$_pos] = $_wrks[$_pos];

      shift; $_pos++;
   }

   if (defined $_prev_c[$_pos]) {
      pop @_prev_c for ($_pos .. @_prev_c - 1);
      pop @_prev_m for ($_pos .. @_prev_m - 1);
      pop @_prev_n for ($_pos .. @_prev_n - 1);
      pop @_prev_w for ($_pos .. @_prev_w - 1);

      $_init_mce = 1;
   }

   return unless (scalar @_code);

   ## -------------------------------------------------------------------------

   my $_input_data; my $_max_workers = $MAX_WORKERS; my $_r = ref $_[0];

   if ($_r eq 'ARRAY' || $_r eq 'GLOB' || $_r eq 'SCALAR' || $_r =~ /^IO::/) {
      $_input_data = shift;
   }

   if (defined $_params) { my $_p = $_params;
      $_max_workers = MCE::Util::_parse_max_workers($_p->{max_workers})
         if (exists $_p->{max_workers} && ref $_p->{max_workers} ne 'ARRAY');

      delete $_p->{sequence}    if (defined $_input_data || scalar @_);
      delete $_p->{user_func}   if (exists $_p->{user_func});
      delete $_p->{user_tasks}  if (exists $_p->{user_tasks});
      delete $_p->{use_slurpio} if (exists $_p->{use_slurpio});
      delete $_p->{bounds_only} if (exists $_p->{bounds_only});
      delete $_p->{gather}      if (exists $_p->{gather});
   }

   $_max_workers = int($_max_workers / @_code + 0.5) + 1
      if (@_code > 1);

   my $_chunk_size = MCE::Util::_parse_chunk_size(
      $CHUNK_SIZE, $_max_workers, $_params, $_input_data, scalar @_
   );

   if (defined $_params) {
      $_input_data = $_params->{input_data} if (exists $_params->{input_data});

      if (exists $_params->{_file}) {
         $_input_data = $_params->{_file}; delete $_params->{_file};
      }
   }

   MCE::_save_state;

   ## -------------------------------------------------------------------------

   if ($_init_mce) {
      $_MCE->shutdown() if (defined $_MCE);

      pop( @_queue )->DESTROY for (@_code .. @_queue);
      push @_queue, MCE::Queue->new for (@_queue .. @_code - 2);

      _gen_user_tasks(\@_queue, \@_code, \@_mode, \@_name, \@_wrks);

      my %_options = (
         use_threads => 0, max_workers => $_max_workers, task_name => $_tag,
         user_tasks => \@_user_tasks, task_end => \&_task_end,
         use_slurpio => 0
      );

      if (defined $_params) {
         my $_p = $_params;

         foreach (keys %{ $_p }) {
            next if ($_ eq 'max_workers' && ref $_p->{max_workers} eq 'ARRAY');
            next if ($_ eq 'task_name' && ref $_p->{task_name} eq 'ARRAY');
            next if ($_ eq 'input_data');
            next if ($_ eq 'chunk_size');
            next if ($_ eq 'task_end');

            _croak("MCE::Stream: '$_' is not a valid constructor argument")
               unless (exists $MCE::_valid_fields_new{$_});

            $_options{$_} = $_p->{$_};
         }
      }

      $_MCE = MCE->new(%_options);
   }
   else {
      ## Workers may persist after running. MCE::Stream allows options
      ## to be passed using an anonymous hash. Therefore, lets update
      ## the MCE instance. These options do not require respawning.

      for (qw(
         RS interval stderr_file stdout_file user_error user_output
         job_delay submit_delay on_post_exit on_post_run user_args
         flush_file flush_stderr flush_stdout
      )) {
         $_MCE->{$_} = $_params->{$_} if (exists $_params->{$_});
      }
   }

   ## -------------------------------------------------------------------------

   if (defined $_input_data) {
      @_ = (); $_MCE->process({ chunk_size => $_chunk_size }, $_input_data);
   }
   elsif (scalar @_) {
      $_MCE->process({ chunk_size => $_chunk_size }, \@_);
   }
   else {
      $_MCE->run({ chunk_size => $_chunk_size }, 0)
         if (defined $_params && exists $_params->{sequence});
   }

   MCE::_restore_state;

   return map { @{ $_ } } delete @_tmp{ 1 .. $_order_id - 1 }
      unless (defined $_aref);

   $_gather_ref = undef;

   return;
}

###############################################################################
## ----------------------------------------------------------------------------
## Private methods.
##
###############################################################################

sub _croak {

   goto &MCE::_croak;
}

sub _gen_user_tasks {

   my ($_queue_ref, $_code_ref, $_mode_ref, $_name_ref, $_wrks_ref) = @_;

   @_user_tasks = ();

   ## For the code block farthest to the right.

   push @_user_tasks, {
      task_name => $_name_ref->[-1],
      max_workers => $_wrks_ref->[-1],

      gather => (@{ $_code_ref } > 1)
         ? $_queue_ref->[-1] : \&_preserve_order,

      user_func => sub {
         my ($_mce, $_chunk_ref, $_chunk_id) = @_;
         my @_a; my $_code = $_code_ref->[-1];

         if (ref $_chunk_ref) {
            push @_a, ($_mode_ref->[-1] eq 'map')
               ?  map { &$_code } @{ $_chunk_ref }
               : grep { &$_code } @{ $_chunk_ref };
         }
         else {
            push @_a, ($_mode_ref->[-1] eq 'map')
               ?  map { &$_code } $_chunk_ref
               : grep { &$_code } $_chunk_ref;
         }

         MCE->gather( (@{ $_code_ref } > 1)
            ? MCE->freeze([ \@_a, $_chunk_id ])
            : (\@_a, $_chunk_id)
         );
      }
   };

   ## For in-between code blocks (processed from right to left).

   for (my $_i = @{ $_code_ref } - 2; $_i > 0; $_i--) {
      my $_pos = $_i;

      push @_user_tasks, {
         task_name => $_name_ref->[$_pos],
         max_workers => $_wrks_ref->[$_pos],
         gather => $_queue_ref->[$_pos - 1],

         user_func => sub {
            my $_q = $_queue_ref->[$_pos];

            while (1) {
               my $_chunk = $_q->dequeue;
               last unless (defined $_chunk);

               my @_a; my $_code = $_code_ref->[$_pos];
               $_chunk = MCE->thaw($_chunk);

               push @_a, ($_mode_ref->[$_pos] eq 'map')
                  ?  map { &$_code } @{ $_chunk->[0] }
                  : grep { &$_code } @{ $_chunk->[0] };

               MCE->gather(MCE->freeze([ \@_a, $_chunk->[1] ]));
            }

            return;
         }
      };
   }

   ## For the left-most code block.

   if (@{ $_code_ref } > 1) {

      push @_user_tasks, {
         task_name => $_name_ref->[0],
         max_workers => $_wrks_ref->[0],
         gather => \&_preserve_order,

         user_func => sub {
            my $_q = $_queue_ref->[0];

            while (1) {
               my $_chunk = $_q->dequeue;
               last unless (defined $_chunk);

               my @_a; my $_code = $_code_ref->[0];
               $_chunk = MCE->thaw($_chunk);

               push @_a, ($_mode_ref->[0] eq 'map')
                  ?  map { &$_code } @{ $_chunk->[0] }
                  : grep { &$_code } @{ $_chunk->[0] };

               MCE->gather(\@_a, $_chunk->[1]);
            }

            return;
         }
      };
   }

   return;
}

sub _validate_number {

   my $_n = $_[0]; my $_key = $_[1];

   $_n =~ s/K\z//i; $_n =~ s/M\z//i;

   _croak("$_tag: '$_key' is not valid")
      if (!looks_like_number($_n) || int($_n) != $_n || $_n < 1);

   return;
}

1;

__END__

###############################################################################
## ----------------------------------------------------------------------------
## Module usage.
##
###############################################################################

=head1 NAME

MCE::Stream - Parallel stream model for chaining multiple maps and greps

=head1 VERSION

This document describes MCE::Stream version 1.517

=head1 SYNOPSIS

   ## Exports mce_stream, mce_stream_f, mce_stream_s
   use MCE::Stream;

   my (@m1, @m2, @m3);

   ## Default mode is map and processed from right-to-left
   @m1 = mce_stream sub { $_ * 3 }, sub { $_ * 2 }, 1..10000;
   mce_stream \@m2, sub { $_ * 3 }, sub { $_ * 2 }, 1..10000;

   ## Native Perl
   @m3 = map { $_ * $_ } grep { $_ % 5 == 0 } 1..10000;

   ## Streaming grep and map in parallel
   mce_stream \@m3,
      { mode => 'map',  code => sub { $_ * $_ } },
      { mode => 'grep', code => sub { $_ % 5 == 0 } }, 1..10000;

   ## Array or array_ref
   my @a = mce_stream sub { $_ * $_ }, 1..10000;
   my @b = mce_stream sub { $_ * $_ }, [ 1..10000 ];

   ## File_path, glob_ref, or scalar_ref
   my @c = mce_stream_f sub { chomp; $_ }, "/path/to/file";
   my @d = mce_stream_f sub { chomp; $_ }, $file_handle;
   my @e = mce_stream_f sub { chomp; $_ }, \$scalar;

   ## Sequence of numbers (begin, end [, step, format])
   my @f = mce_stream_s sub { $_ * $_ }, 1, 10000, 5;
   my @g = mce_stream_s sub { $_ * $_ }, [ 1, 10000, 5 ];

   my @h = mce_stream_s sub { $_ * $_ }, {
      begin => 1, end => 10000, step => 5, format => undef
   };

=head1 DESCRIPTION

This module allows one to stream multiple map and/or grep operations in
parallel. Code blocks run simultaneously from right-to-left. Chunk data are
sent immediately to the next code block during processing. The results are
appended immediately as well when passing the reference to the array.

   ## Appends are serialized, even out-of-order ok, but immediately.
   ## Out-of-order chunks are held temporarily until ordered chunks
   ## arrive before appending.

   mce_stream \@a, sub { $_ }, sub { $_ }, sub { $_ }, 1..10000;

   ##                                                    input
   ##                                        chunk1      input
   ##                            chunk3      chunk2      input
   ##                chunk2      chunk2      chunk3      input
   ##   append1      chunk3      chunk1      chunk4      input
   ##   append2      chunk1      chunk5      chunk5      input
   ##   append3      chunk5      chunk4      chunk6      ...
   ##   append4      chunk4      chunk6      ...
   ##   append5      chunk6      ...
   ##   append6      ...
   ##   ...
   ##

MCE incurs a small overhead due to passing of data. Therefore, a fast code
block will likely run faster when chaining multiple map functions natively in
Perl. However, the overhead quickly diminishes as the complexity of the code
increases.

   ## 0.542 secs -- baseline using the native map function
   my @m1 = map { $_ * 4 } map { $_ * 3 } map { $_ * 2 } 1..1000000;

   ## 0.765 secs -- this is quite amazing considering data passing
   my @m2 = mce_stream
         sub { $_ * 4 }, sub { $_ * 3 }, sub { $_ * 2 }, 1..1000000;

   ## 0.592 secs -- appends to @m3 are immediate
   my @m3; mce_stream \@m3,
         sub { $_ * 4 }, sub { $_ * 3 }, sub { $_ * 2 }, 1..1000000;

The mce_stream_s function will provide better times, useful when the input data
is simply a range of numbers. Workers generate sequences mathematically among
themselves without any interaction from the manager process. Two arguments are
required for mce_stream_s (begin, end). Step defaults to 1 if begin is smaller
than end, otherwise -1.

   ## 0.447 secs -- numbers are generated mathematically via sequence
   my @m4; mce_stream_s \@m4,
         sub { $_ * 4 }, sub { $_ * 3 }, sub { $_ * 2 }, 1, 1000000;

=head1 OVERRIDING DEFAULTS

The following list 6 options which may be overridden when loading the module.

   use Sereal qw(encode_sereal decode_sereal);

   use MCE::Stream
         default_mode => 'grep',               ## Default 'map'
         max_workers  => 8,                    ## Default 'auto'
         chunk_size   => 500,                  ## Default 'auto'
         tmp_dir      => "/path/to/app/tmp",   ## $MCE::Signal::tmp_dir
         freeze       => \&encode_sereal,      ## \&Storable::freeze
         thaw         => \&decode_sereal       ## \&Storable::thaw
   ;

There is a simpler way to enable Sereal with MCE 1.5. The following will
attempt to use Sereal if available, otherwise will default back to using
Storable for serialization.

   use MCE::Stream Sereal => 1;

   ## Serialization is through Sereal if available.
   my @m2 = mce_stream sub { $_ * $_ }, 1..10000;

=head1 CUSTOMIZING MCE

=over 3

=item init

The init function accepts a hash of MCE options. The gather and bounds_only
options, if specified, will be ignored due to being used internally by the
module (not shown below).

   use MCE::Stream;

   MCE::Stream::init {
      chunk_size => 1, max_workers => 4,

      user_begin => sub {
         print "## ", MCE->wid, " started\n";
      },

      user_end => sub {
         print "## ", MCE->wid, " completed\n";
      }
   };

   my @a = mce_stream sub { $_ * $_ }, 1..100;

   print "\n", "@a", "\n";

   -- Output

   ## 1 started
   ## 2 started
   ## 3 started
   ## 4 started
   ## 3 completed
   ## 1 completed
   ## 2 completed
   ## 4 completed

   1 4 9 16 25 36 49 64 81 100 121 144 169 196 225 256 289 324 361
   400 441 484 529 576 625 676 729 784 841 900 961 1024 1089 1156
   1225 1296 1369 1444 1521 1600 1681 1764 1849 1936 2025 2116 2209
   2304 2401 2500 2601 2704 2809 2916 3025 3136 3249 3364 3481 3600
   3721 3844 3969 4096 4225 4356 4489 4624 4761 4900 5041 5184 5329
   5476 5625 5776 5929 6084 6241 6400 6561 6724 6889 7056 7225 7396
   7569 7744 7921 8100 8281 8464 8649 8836 9025 9216 9409 9604 9801
   10000

=back

Like with MCE::Stream::init above, MCE options may be specified using an
anonymous hash for the first argument. Notice how both max_workers and
task_name can take an anonymous array for setting values individually
for each code block. Remember that MCE::Stream processes from
right-to-left when setting the individual values.

   use MCE::Stream;

   my @a = mce_stream {
      max_workers => [ 2, 4, 3, ], task_name => [ 'c', 'b', 'a' ],

      user_end => sub {
         my ($task_id, $task_name) = (MCE->task_id, MCE->task_name);
         print "$task_id - $task_name completed\n";
      },

      task_end => sub {
         my ($mce, $task_id, $task_name) = @_;
         MCE->print("$task_id - $task_name ended\n");
      }
   },
   sub { $_ * 4 },             ## 2 workers, named c
   sub { $_ * 3 },             ## 4 workers, named b
   sub { $_ * 2 }, 1..10000;   ## 3 workers, named a

   -- Output

   0 - a completed
   0 - a completed
   0 - a completed
   0 - a ended
   1 - b completed
   1 - b completed
   1 - b completed
   1 - b completed
   1 - b ended
   2 - c completed
   2 - c completed
   2 - c ended

Note that the anonymous hash, for specifying options, also comes first when
passing the array reference.

   my @a; mce_stream {
      ...
   }, \@a, sub { ... }, sub { ... }, 1..10000;

=head1 API DOCUMENTATION

Scripts using MCE::Stream can be written using the long or short form. The long
form becomes relavant when mixing modes. Processing occurs from right-to-left.

   my @m3 = mce_stream
      { mode => 'map',  code => sub { $_ * $_ } },
      { mode => 'grep', code => sub { $_ % 5 == 0 } }, 1..10000;

   my @m4; mce_stream \@m4,
      { mode => 'map',  code => sub { $_ * $_ } },
      { mode => 'grep', code => sub { $_ % 5 == 0 } }, 1..10000;

For multiple grep blocks, the short form can be used. Simply specify the
default mode for the module. The two valid values for default_mode is 'grep'
and 'map'.

   use MCE::Stream default_mode => 'grep';

   my @f = mce_stream_f sub { /ending$/ }, sub { /^starting/ }, $file;

The following assumes 'map' for default_mode in order to demonstrate all the
possibilities of passing input data into the code block.

=over 3

=item mce_stream sub { code }, list

Input data can be defined using a list or passing a reference to an array.

   my @a = mce_stream sub { $_ * 2 }, 1..1000;
   my @b = mce_stream sub { $_ * 2 }, [ 1..1000 ];

=item mce_stream_f sub { code }, file

The fastest of these is the /path/to/file. Workers communicate the next offset
position among themselves without any interaction from the manager process.

   my @c = mce_stream_f sub { chomp; $_ . "\r\n" }, "/path/to/file";
   my @d = mce_stream_f sub { chomp; $_ . "\r\n" }, $file_handle;
   my @e = mce_stream_f sub { chomp; $_ . "\r\n" }, \$scalar;

=item mce_stream_s sub { code }, sequence

Sequence can be defined as a list, an array reference, or a hash reference.
The functions require both begin and end values to run. Step and format are
optional. The format is passed to sprintf (% may be omitted below).

   my ($beg, $end, $step, $fmt) = (10, 20, 0.1, "%4.1f");

   my @f = mce_stream_s sub { $_ }, $beg, $end, $step, $fmt;
   my @g = mce_stream_s sub { $_ }, [ $beg, $end, $step, $fmt ];

   my @h = mce_stream_s sub { $_ }, {
      begin => $beg, end => $end, step => $step, format => $fmt
   };

=item mce_stream { input_data => iterator }, sub { code }

An iterator reference can by specified for input data. Notice the anonymous
hash as the first argument to mce_stream. The only other way is to specify
input_data via MCE::Stream::init. This prevents MCE::Stream from configuring
the iterator reference as another user task which will not work.

Iterators are described under "SYNTAX for INPUT_DATA" at L<MCE::Core>.

   MCE::Stream::init {
      input_data => iterator
   };

   my @a = mce_stream sub { $_ * 3 }, sub { $_ * 2 };

=back

=head1 MANUAL SHUTDOWN

=over 3

=item finish

MCE workers remain persistent as much as possible after running. Shutdown
occurs when the script exits. One can manually shutdown MCE by simply calling
finish after running. This resets the MCE instance.

   use MCE::Stream;

   MCE::Stream::init {
      chunk_size => 20, max_workers => 'auto'
   };

   my @a = mce_stream { ... } 1..100;

   MCE::Stream::finish;

=back

=head1 INDEX

L<MCE>

=head1 AUTHOR

Mario E. Roy, S<E<lt>marioeroy AT gmail DOT comE<gt>>

=head1 LICENSE

This program is free software; you can redistribute it and/or modify it
under the terms of either: the GNU General Public License as published
by the Free Software Foundation; or the Artistic License.

See L<http://dev.perl.org/licenses/> for more information.

=cut