1 | # IO::Select.pm
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2 | #
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3 | # Copyright (c) 1997-8 Graham Barr <[email protected]>. All rights reserved.
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4 | # This program is free software; you can redistribute it and/or
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5 | # modify it under the same terms as Perl itself.
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6 |
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7 | package IO::Select;
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8 |
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9 | use strict;
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10 | use warnings::register;
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11 | use vars qw($VERSION @ISA);
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12 | require Exporter;
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13 |
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14 | $VERSION = "1.17";
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15 |
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16 | @ISA = qw(Exporter); # This is only so we can do version checking
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17 |
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18 | sub VEC_BITS () {0}
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19 | sub FD_COUNT () {1}
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20 | sub FIRST_FD () {2}
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21 |
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22 | sub new
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23 | {
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24 | my $self = shift;
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25 | my $type = ref($self) || $self;
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26 |
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27 | my $vec = bless [undef,0], $type;
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28 |
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29 | $vec->add(@_)
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30 | if @_;
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31 |
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32 | $vec;
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33 | }
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34 |
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35 | sub add
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36 | {
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37 | shift->_update('add', @_);
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38 | }
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39 |
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40 |
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41 | sub remove
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42 | {
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43 | shift->_update('remove', @_);
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44 | }
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45 |
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46 |
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47 | sub exists
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48 | {
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49 | my $vec = shift;
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50 | my $fno = $vec->_fileno(shift);
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51 | return undef unless defined $fno;
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52 | $vec->[$fno + FIRST_FD];
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53 | }
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54 |
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55 |
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56 | sub _fileno
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57 | {
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58 | my($self, $f) = @_;
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59 | return unless defined $f;
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60 | $f = $f->[0] if ref($f) eq 'ARRAY';
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61 | ($f =~ /^\d+$/) ? $f : fileno($f);
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62 | }
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63 |
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64 | sub _update
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65 | {
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66 | my $vec = shift;
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67 | my $add = shift eq 'add';
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68 |
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69 | my $bits = $vec->[VEC_BITS];
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70 | $bits = '' unless defined $bits;
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71 |
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72 | my $count = 0;
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73 | my $f;
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74 | foreach $f (@_)
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75 | {
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76 | my $fn = $vec->_fileno($f);
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77 | next unless defined $fn;
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78 | my $i = $fn + FIRST_FD;
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79 | if ($add) {
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80 | if (defined $vec->[$i]) {
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81 | $vec->[$i] = $f; # if array rest might be different, so we update
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82 | next;
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83 | }
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84 | $vec->[FD_COUNT]++;
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85 | vec($bits, $fn, 1) = 1;
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86 | $vec->[$i] = $f;
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87 | } else { # remove
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88 | next unless defined $vec->[$i];
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89 | $vec->[FD_COUNT]--;
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90 | vec($bits, $fn, 1) = 0;
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91 | $vec->[$i] = undef;
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92 | }
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93 | $count++;
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94 | }
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95 | $vec->[VEC_BITS] = $vec->[FD_COUNT] ? $bits : undef;
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96 | $count;
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97 | }
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98 |
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99 | sub can_read
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100 | {
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101 | my $vec = shift;
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102 | my $timeout = shift;
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103 | my $r = $vec->[VEC_BITS];
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104 |
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105 | defined($r) && (select($r,undef,undef,$timeout) > 0)
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106 | ? handles($vec, $r)
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107 | : ();
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108 | }
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109 |
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110 | sub can_write
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111 | {
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112 | my $vec = shift;
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113 | my $timeout = shift;
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114 | my $w = $vec->[VEC_BITS];
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115 |
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116 | defined($w) && (select(undef,$w,undef,$timeout) > 0)
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117 | ? handles($vec, $w)
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118 | : ();
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119 | }
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120 |
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121 | sub has_exception
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122 | {
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123 | my $vec = shift;
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124 | my $timeout = shift;
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125 | my $e = $vec->[VEC_BITS];
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126 |
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127 | defined($e) && (select(undef,undef,$e,$timeout) > 0)
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128 | ? handles($vec, $e)
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129 | : ();
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130 | }
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131 |
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132 | sub has_error
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133 | {
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134 | warnings::warn("Call to deprecated method 'has_error', use 'has_exception'")
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135 | if warnings::enabled();
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136 | goto &has_exception;
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137 | }
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138 |
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139 | sub count
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140 | {
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141 | my $vec = shift;
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142 | $vec->[FD_COUNT];
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143 | }
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144 |
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145 | sub bits
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146 | {
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147 | my $vec = shift;
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148 | $vec->[VEC_BITS];
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149 | }
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150 |
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151 | sub as_string # for debugging
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152 | {
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153 | my $vec = shift;
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154 | my $str = ref($vec) . ": ";
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155 | my $bits = $vec->bits;
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156 | my $count = $vec->count;
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157 | $str .= defined($bits) ? unpack("b*", $bits) : "undef";
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158 | $str .= " $count";
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159 | my @handles = @$vec;
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160 | splice(@handles, 0, FIRST_FD);
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161 | for (@handles) {
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162 | $str .= " " . (defined($_) ? "$_" : "-");
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163 | }
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164 | $str;
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165 | }
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166 |
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167 | sub _max
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168 | {
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169 | my($a,$b,$c) = @_;
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170 | $a > $b
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171 | ? $a > $c
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172 | ? $a
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173 | : $c
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174 | : $b > $c
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175 | ? $b
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176 | : $c;
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177 | }
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178 |
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179 | sub select
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180 | {
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181 | shift
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182 | if defined $_[0] && !ref($_[0]);
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183 |
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184 | my($r,$w,$e,$t) = @_;
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185 | my @result = ();
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186 |
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187 | my $rb = defined $r ? $r->[VEC_BITS] : undef;
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188 | my $wb = defined $w ? $w->[VEC_BITS] : undef;
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189 | my $eb = defined $e ? $e->[VEC_BITS] : undef;
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190 |
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191 | if(select($rb,$wb,$eb,$t) > 0)
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192 | {
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193 | my @r = ();
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194 | my @w = ();
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195 | my @e = ();
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196 | my $i = _max(defined $r ? scalar(@$r)-1 : 0,
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197 | defined $w ? scalar(@$w)-1 : 0,
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198 | defined $e ? scalar(@$e)-1 : 0);
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199 |
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200 | for( ; $i >= FIRST_FD ; $i--)
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201 | {
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202 | my $j = $i - FIRST_FD;
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203 | push(@r, $r->[$i])
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204 | if defined $rb && defined $r->[$i] && vec($rb, $j, 1);
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205 | push(@w, $w->[$i])
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206 | if defined $wb && defined $w->[$i] && vec($wb, $j, 1);
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207 | push(@e, $e->[$i])
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208 | if defined $eb && defined $e->[$i] && vec($eb, $j, 1);
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209 | }
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210 |
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211 | @result = (\@r, \@w, \@e);
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212 | }
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213 | @result;
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214 | }
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215 |
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216 |
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217 | sub handles
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218 | {
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219 | my $vec = shift;
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220 | my $bits = shift;
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221 | my @h = ();
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222 | my $i;
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223 | my $max = scalar(@$vec) - 1;
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224 |
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225 | for ($i = FIRST_FD; $i <= $max; $i++)
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226 | {
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227 | next unless defined $vec->[$i];
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228 | push(@h, $vec->[$i])
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229 | if !defined($bits) || vec($bits, $i - FIRST_FD, 1);
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230 | }
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231 |
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232 | @h;
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233 | }
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234 |
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235 | 1;
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236 | __END__
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237 |
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238 | =head1 NAME
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239 |
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240 | IO::Select - OO interface to the select system call
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241 |
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242 | =head1 SYNOPSIS
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243 |
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244 | use IO::Select;
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245 |
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246 | $s = IO::Select->new();
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247 |
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248 | $s->add(\*STDIN);
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249 | $s->add($some_handle);
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250 |
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251 | @ready = $s->can_read($timeout);
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252 |
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253 | @ready = IO::Select->new(@handles)->can_read(0);
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254 |
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255 | =head1 DESCRIPTION
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256 |
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257 | The C<IO::Select> package implements an object approach to the system C<select>
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258 | function call. It allows the user to see what IO handles, see L<IO::Handle>,
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259 | are ready for reading, writing or have an exception pending.
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260 |
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261 | =head1 CONSTRUCTOR
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262 |
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263 | =over 4
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264 |
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265 | =item new ( [ HANDLES ] )
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266 |
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267 | The constructor creates a new object and optionally initialises it with a set
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268 | of handles.
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269 |
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270 | =back
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271 |
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272 | =head1 METHODS
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273 |
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274 | =over 4
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275 |
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276 | =item add ( HANDLES )
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277 |
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278 | Add the list of handles to the C<IO::Select> object. It is these values that
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279 | will be returned when an event occurs. C<IO::Select> keeps these values in a
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280 | cache which is indexed by the C<fileno> of the handle, so if more than one
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281 | handle with the same C<fileno> is specified then only the last one is cached.
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282 |
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283 | Each handle can be an C<IO::Handle> object, an integer or an array
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284 | reference where the first element is an C<IO::Handle> or an integer.
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285 |
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286 | =item remove ( HANDLES )
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287 |
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288 | Remove all the given handles from the object. This method also works
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289 | by the C<fileno> of the handles. So the exact handles that were added
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290 | need not be passed, just handles that have an equivalent C<fileno>
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291 |
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292 | =item exists ( HANDLE )
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293 |
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294 | Returns a true value (actually the handle itself) if it is present.
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295 | Returns undef otherwise.
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296 |
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297 | =item handles
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298 |
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299 | Return an array of all registered handles.
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300 |
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301 | =item can_read ( [ TIMEOUT ] )
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302 |
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303 | Return an array of handles that are ready for reading. C<TIMEOUT> is
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304 | the maximum amount of time to wait before returning an empty list, in
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305 | seconds, possibly fractional. If C<TIMEOUT> is not given and any
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306 | handles are registered then the call will block.
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307 |
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308 | =item can_write ( [ TIMEOUT ] )
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309 |
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310 | Same as C<can_read> except check for handles that can be written to.
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311 |
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312 | =item has_exception ( [ TIMEOUT ] )
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313 |
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314 | Same as C<can_read> except check for handles that have an exception
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315 | condition, for example pending out-of-band data.
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316 |
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317 | =item count ()
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318 |
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319 | Returns the number of handles that the object will check for when
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320 | one of the C<can_> methods is called or the object is passed to
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321 | the C<select> static method.
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322 |
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323 | =item bits()
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324 |
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325 | Return the bit string suitable as argument to the core select() call.
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326 |
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327 | =item select ( READ, WRITE, EXCEPTION [, TIMEOUT ] )
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328 |
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329 | C<select> is a static method, that is you call it with the package name
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330 | like C<new>. C<READ>, C<WRITE> and C<EXCEPTION> are either C<undef> or
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331 | C<IO::Select> objects. C<TIMEOUT> is optional and has the same effect as
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332 | for the core select call.
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333 |
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334 | The result will be an array of 3 elements, each a reference to an array
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335 | which will hold the handles that are ready for reading, writing and have
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336 | exceptions respectively. Upon error an empty list is returned.
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337 |
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338 | =back
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339 |
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340 | =head1 EXAMPLE
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341 |
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342 | Here is a short example which shows how C<IO::Select> could be used
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343 | to write a server which communicates with several sockets while also
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344 | listening for more connections on a listen socket
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345 |
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346 | use IO::Select;
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347 | use IO::Socket;
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348 |
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349 | $lsn = new IO::Socket::INET(Listen => 1, LocalPort => 8080);
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350 | $sel = new IO::Select( $lsn );
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351 |
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352 | while(@ready = $sel->can_read) {
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353 | foreach $fh (@ready) {
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354 | if($fh == $lsn) {
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355 | # Create a new socket
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356 | $new = $lsn->accept;
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357 | $sel->add($new);
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358 | }
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359 | else {
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360 | # Process socket
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361 |
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362 | # Maybe we have finished with the socket
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363 | $sel->remove($fh);
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364 | $fh->close;
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365 | }
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366 | }
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367 | }
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368 |
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369 | =head1 AUTHOR
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370 |
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371 | Graham Barr. Currently maintained by the Perl Porters. Please report all
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372 | bugs to <[email protected]>.
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373 |
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374 | =head1 COPYRIGHT
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375 |
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376 | Copyright (c) 1997-8 Graham Barr <[email protected]>. All rights reserved.
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377 | This program is free software; you can redistribute it and/or
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378 | modify it under the same terms as Perl itself.
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379 |
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380 | =cut
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381 |
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