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Filename : Map.pm
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###############################################################################
## ----------------------------------------------------------------------------
## Parallel map model similar to the native map function.
##
###############################################################################

package MCE::Map;

use strict;
use warnings;

no warnings qw( threads recursion uninitialized );

our $VERSION = '1.835';

## no critic (BuiltinFunctions::ProhibitStringyEval)
## no critic (Subroutines::ProhibitSubroutinePrototypes)
## no critic (TestingAndDebugging::ProhibitNoStrict)

use Scalar::Util qw( looks_like_number weaken );
use MCE;

our @CARP_NOT = qw( MCE );

my $_has_threads = $INC{'threads.pm'} ? 1 : 0;
my $_tid = $_has_threads ? threads->tid() : 0;

sub CLONE {
   $_tid = threads->tid() if $_has_threads;
}

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

my ($_MCE, $_def, $_params, $_prev_c, $_tag) = ({}, {}, {}, {}, 'MCE::Map');

sub import {
   my ($_class, $_pkg) = (shift, caller);

   my $_p = $_def->{$_pkg} = {
      MAX_WORKERS => 'auto',
      CHUNK_SIZE  => 'auto',
   };

   ## Import functions.
   no strict 'refs'; no warnings 'redefine';

   *{ $_pkg.'::mce_map_f' } = \&run_file;
   *{ $_pkg.'::mce_map_s' } = \&run_seq;
   *{ $_pkg.'::mce_map'   } = \&run;

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

      $_p->{MAX_WORKERS} = shift, next if ( $_arg eq 'max_workers' );
      $_p->{CHUNK_SIZE}  = shift, next if ( $_arg eq 'chunk_size' );
      $_p->{TMP_DIR}     = shift, next if ( $_arg eq 'tmp_dir' );
      $_p->{FREEZE}      = shift, next if ( $_arg eq 'freeze' );
      $_p->{THAW}        = shift, next if ( $_arg eq 'thaw' );

      ## Sereal 3.015+, if available, is used automatically by MCE 1.8+.
      if ( $_arg eq 'sereal' ) {
         if ( shift eq '0' ) {
            require Storable;
            $_p->{FREEZE} = \&Storable::freeze;
            $_p->{THAW}   = \&Storable::thaw;
         }
         next;
      }

      _croak("Error: ($_argument) invalid module option");
   }

   $_p->{MAX_WORKERS} = MCE::Util::_parse_max_workers($_p->{MAX_WORKERS});

   _validate_number($_p->{MAX_WORKERS}, 'MAX_WORKERS');
   _validate_number($_p->{CHUNK_SIZE}, 'CHUNK_SIZE')
      unless ($_p->{CHUNK_SIZE} eq 'auto');

   return;
}

###############################################################################
## ----------------------------------------------------------------------------
## Gather callback for storing by chunk_id => chunk_ref into a hash.
##
###############################################################################

my ($_total_chunks, %_tmp);

sub _gather {

   my ($_chunk_id, $_data_ref) = @_;

   $_tmp{$_chunk_id} = $_data_ref;
   $_total_chunks++;

   return;
}

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

sub init (@) {

   shift if (defined $_[0] && $_[0] eq 'MCE::Map');
   my $_pkg = "$$.$_tid.".caller();

   $_params->{$_pkg} = (ref $_[0] eq 'HASH') ? shift : { @_ };

   _croak("$_tag: (HASH) not allowed as input by this MCE model")
      if ( ref $_params->{$_pkg}{input_data} eq 'HASH' );

   @_ = ();

   return;
}

sub finish (@) {

   shift if (defined $_[0] && $_[0] eq 'MCE::Map');
   my $_pkg = (defined $_[0]) ? shift : "$$.$_tid.".caller();

   if ( $_pkg eq 'MCE' ) {
      for my $_k ( keys %{ $_MCE } ) { MCE::Map->finish($_k, 1); }
   }
   elsif ( $_MCE->{$_pkg} && $_MCE->{$_pkg}{_init_pid} eq "$$.$_tid" ) {
      $_MCE->{$_pkg}->shutdown(@_) if $_MCE->{$_pkg}{_spawned};
      $_total_chunks = undef, undef %_tmp;

      delete $_prev_c->{$_pkg};
      delete $_MCE->{$_pkg};
   }

   @_ = ();

   return;
}

###############################################################################
## ----------------------------------------------------------------------------
## Parallel map with MCE -- file.
##
###############################################################################

sub run_file (&@) {

   shift if (defined $_[0] && $_[0] eq 'MCE::Map');

   my $_code = shift; my $_file = shift;
   my $_pid  = "$$.$_tid.".caller();

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

   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);
      $_params->{$_pid}{_file} = $_file;
   }
   elsif (ref $_file eq 'SCALAR' || ref($_file) =~ /^(?:GLOB|FileHandle|IO::)/) {
      $_params->{$_pid}{_file} = $_file;
   }
   else {
      _croak("$_tag: (file) is not specified or valid");
   }

   @_ = ();

   return run($_code);
}

###############################################################################
## ----------------------------------------------------------------------------
## Parallel map with MCE -- sequence.
##
###############################################################################

sub run_seq (&@) {

   shift if (defined $_[0] && $_[0] eq 'MCE::Map');

   my $_code = shift;
   my $_pid  = "$$.$_tid.".caller();

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

   my ($_begin, $_end);

   if (ref $_[0] eq 'HASH') {
      $_begin = $_[0]->{begin}; $_end = $_[0]->{end};
      $_params->{$_pid}{sequence} = $_[0];
   }
   elsif (ref $_[0] eq 'ARRAY') {
      $_begin = $_[0]->[0]; $_end = $_[0]->[1];
      $_params->{$_pid}{sequence} = $_[0];
   }
   elsif (ref $_[0] eq '' || ref($_[0]) =~ /^Math::/) {
      $_begin = $_[0]; $_end = $_[1];
      $_params->{$_pid}{sequence} = [ @_ ];
   }
   else {
      _croak("$_tag: (sequence) is not specified or valid");
   }

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

   $_params->{$_pid}{sequence_run} = undef;

   @_ = ();

   return run($_code);
}

###############################################################################
## ----------------------------------------------------------------------------
## Parallel map with MCE.
##
###############################################################################

sub run (&@) {

   shift if (defined $_[0] && $_[0] eq 'MCE::Map');

   my $_code = shift;  $_total_chunks = 0; undef %_tmp;
   my $_pkg  = caller() eq 'MCE::Map' ? caller(1) : caller();
   my $_pid  = "$$.$_tid.$_pkg";

   my $_input_data; my $_max_workers = $_def->{$_pkg}{MAX_WORKERS};
   my $_r = ref $_[0];

   if (@_ == 1 && $_r =~ /^(?:ARRAY|HASH|SCALAR|CODE|GLOB|FileHandle|IO::)/) {
      _croak("$_tag: (HASH) not allowed as input by this MCE model")
         if $_r eq 'HASH';
      $_input_data = shift;
   }

   if (defined (my $_p = $_params->{$_pid})) {
      $_max_workers = MCE::Util::_parse_max_workers($_p->{max_workers})
         if (exists $_p->{max_workers});

      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});
   }

   my $_chunk_size = MCE::Util::_parse_chunk_size(
      $_def->{$_pkg}{CHUNK_SIZE}, $_max_workers, $_params->{$_pid},
      $_input_data, scalar @_
   );

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

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

   MCE::_save_state($_MCE->{$_pid});

   if (!defined $_prev_c->{$_pid} || $_prev_c->{$_pid} != $_code) {
      $_MCE->{$_pid}->shutdown() if (defined $_MCE->{$_pid});
      $_prev_c->{$_pid} = $_code;

      my %_opts = (
         max_workers => $_max_workers, task_name => $_tag,
         user_func => sub {

            my ($_mce, $_chunk_ref, $_chunk_id) = @_;
            my $_wantarray = $_mce->{user_args}[0];

            if ($_wantarray) {
               my @_a;

               if (ref $_chunk_ref eq 'SCALAR') {
                  local $/ = $_mce->{RS} if defined $_mce->{RS};
                  open my $_MEM_FH, '<', $_chunk_ref;
                  binmode $_MEM_FH, ':raw';
                  while (<$_MEM_FH>) { push @_a, &{ $_code }; }
                  close   $_MEM_FH;
                  weaken  $_MEM_FH;
               }
               else {
                  if (ref $_chunk_ref) {
                     push @_a, map { &{ $_code } } @{ $_chunk_ref };
                  } else {
                     push @_a, map { &{ $_code } } $_chunk_ref;
                  }
               }

               MCE->gather($_chunk_id, \@_a);
            }
            else {
               my $_cnt = 0;

               if (ref $_chunk_ref eq 'SCALAR') {
                  local $/ = $_mce->{RS} if defined $_mce->{RS};
                  open my $_MEM_FH, '<', $_chunk_ref;
                  binmode $_MEM_FH, ':raw';
                  while (<$_MEM_FH>) { $_cnt++; &{ $_code }; }
                  close   $_MEM_FH;
                  weaken  $_MEM_FH;
               }
               else {
                  if (ref $_chunk_ref) {
                     $_cnt += map { &{ $_code } } @{ $_chunk_ref };
                  } else {
                     $_cnt += map { &{ $_code } } $_chunk_ref;
                  }
               }

               MCE->gather($_cnt) if defined $_wantarray;
            }
         },
      );

      if (defined (my $_p = $_params->{$_pid})) {
         for my $_k (keys %{ $_p }) {
            next if ($_k eq 'sequence_run');
            next if ($_k eq 'input_data');
            next if ($_k eq 'chunk_size');

            _croak("$_tag: ($_k) is not a valid constructor argument")
               unless (exists $MCE::_valid_fields_new{$_k});

            $_opts{$_k} = $_p->{$_k};
         }
      }

      for my $_k (qw/ tmp_dir freeze thaw /) {
         $_opts{$_k} = $_def->{$_pkg}{uc($_k)}
            if (exists $_def->{$_pkg}{uc($_k)} && !exists $_opts{$_k});
      }

      $_MCE->{$_pid} = MCE->new(pkg => $_pkg, %_opts);
   }

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

   my $_cnt = 0; my $_wantarray = wantarray;

   $_MCE->{$_pid}{use_slurpio} = ($_chunk_size > &MCE::MAX_RECS_SIZE) ? 1 : 0;
   $_MCE->{$_pid}{user_args}   = [ $_wantarray ];

   $_MCE->{$_pid}{gather} = $_wantarray
      ? \&_gather : sub { $_cnt += $_[0]; return; };

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

   MCE::_restore_state();

   if ($_wantarray) {
      return map { @{ $_ } } delete @_tmp{ 1 .. $_total_chunks };
   }
   elsif (defined $_wantarray) {
      return $_cnt;
   }

   return;
}

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

sub _croak {

   goto &MCE::_croak;
}

sub _validate_number {

   my ($_n, $_key) = @_;

   _croak("$_tag: ($_key) is not valid") if (!defined $_n);

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

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

   return;
}

1;

__END__

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

=head1 NAME

MCE::Map - Parallel map model similar to the native map function

=head1 VERSION

This document describes MCE::Map version 1.835

=head1 SYNOPSIS

 ## Exports mce_map, mce_map_f, and mce_map_s
 use MCE::Map;

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

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

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

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

=head1 DESCRIPTION

This module provides a parallel map implementation via Many-Core Engine.
MCE incurs a small overhead due to passing of data. A fast code block will
run faster natively. However, the overhead will likely diminish as the
complexity increases for the code.

 my @m1 =     map { $_ * $_ } 1..1000000;               ## 0.127 secs
 my @m2 = mce_map { $_ * $_ } 1..1000000;               ## 0.304 secs

Chunking, enabled by default, greatly reduces the overhead behind the scene.
The time for mce_map below also includes the time for data exchanges between
the manager and worker processes. More parallelization will be seen when the
code incurs additional CPU time.

 sub calc {
    sqrt $_ * sqrt $_ / 1.3 * 1.5 / 3.2 * 1.07
 }

 my @m1 =     map { calc } 1..1000000;                  ## 0.367 secs
 my @m2 = mce_map { calc } 1..1000000;                  ## 0.365 secs

Even faster is mce_map_s; useful when input data is a range of numbers.
Workers generate sequences mathematically among themselves without any
interaction from the manager process. Two arguments are required for
mce_map_s (begin, end). Step defaults to 1 if begin is smaller than end,
otherwise -1.

 my @m3 = mce_map_s { calc } 1, 1000000;                ## 0.270 secs

Although this document is about MCE::Map, the L<MCE::Stream> module can write
results immediately without waiting for all chunks to complete. This is made
possible by passing the reference to an array (in this case @m4 and @m5).

 use MCE::Stream;

 sub calc {
    sqrt $_ * sqrt $_ / 1.3 * 1.5 / 3.2 * 1.07
 }

 my @m4; mce_stream \@m4, sub { calc }, 1..1000000;

    ## Completes in 0.272 secs. This is amazing considering the
    ## overhead for passing data between the manager and workers.

 my @m5; mce_stream_s \@m5, sub { calc }, 1, 1000000;

    ## Completed in 0.176 secs. Like with mce_map_s, specifying a
    ## sequence specification turns out to be faster due to lesser
    ## overhead for the manager process.

=head1 OVERRIDING DEFAULTS

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

 use Sereal qw( encode_sereal decode_sereal );
 use CBOR::XS qw( encode_cbor decode_cbor );
 use JSON::XS qw( encode_json decode_json );

 use MCE::Map
     max_workers => 4,                # Default 'auto'
     chunk_size => 100,               # Default 'auto'
     tmp_dir => "/path/to/app/tmp",   # $MCE::Signal::tmp_dir
     freeze => \&encode_sereal,       # \&Storable::freeze
     thaw => \&decode_sereal          # \&Storable::thaw
 ;

From MCE 1.8 onwards, Sereal 3.015+ is loaded automatically if available.
Specify C<Sereal => 0> to use Storable instead.

 use MCE::Map Sereal => 0;

=head1 CUSTOMIZING MCE

=over 3

=item MCE::Map->init ( options )

=item MCE::Map::init { options }

The init function accepts a hash of MCE options. The gather option, if
specified, is ignored due to being used internally by the module.

 use MCE::Map;

 MCE::Map::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_map { $_ * $_ } 1..100;

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

 -- Output

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

=head1 API DOCUMENTATION

=over 3

=item MCE::Map->run ( sub { code }, list )

=item mce_map { code } list

Input data may be defined using a list or an array reference. Unlike MCE::Loop,
Flow, and Step, specifying a hash reference as input data isn't allowed.

 my @a = mce_map { $_ * 2 } 1..1000;
 my @b = mce_map { $_ * 2 } \@list;

 my @z = mce_map { $_ * 2 } \%hash;  # not supported

=item MCE::Map->run_file ( sub { code }, file )

=item mce_map_f { code } file

The fastest of these is the /path/to/file. Workers communicate the next offset
position among themselves with zero interaction by the manager process.

 my @c = mce_map_f { chomp; $_ . "\r\n" } "/path/to/file";  # faster
 my @d = mce_map_f { chomp; $_ . "\r\n" } $file_handle;
 my @e = mce_map_f { chomp; $_ . "\r\n" } \$scalar;

=item MCE::Map->run_seq ( sub { code }, $beg, $end [, $step, $fmt ] )

=item mce_map_s { code } $beg, $end [, $step, $fmt ]

Sequence may 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_map_s { $_ } $beg, $end, $step, $fmt;
 my @g = mce_map_s { $_ } [ $beg, $end, $step, $fmt ];

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

=item MCE::Map->run ( sub { code }, iterator )

=item mce_map { code } iterator

An iterator reference may be specified for input_data. Iterators are described
under section "SYNTAX for INPUT_DATA" at L<MCE::Core>.

 my @a = mce_map { $_ * 2 } make_iterator(10, 30, 2);

=back

=head1 MANUAL SHUTDOWN

=over 3

=item MCE::Map->finish

=item MCE::Map::finish

Workers remain persistent as much as possible after running. Shutdown occurs
automatically when the script terminates. Call finish when workers are no
longer needed.

 use MCE::Map;

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

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

 MCE::Map::finish;

=back

=head1 INDEX

L<MCE|MCE>, L<MCE::Core>

=head1 AUTHOR

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

=cut