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1 | # IO::Select.pm |
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2 | # |
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3 | # Copyright (c) 1997-8 Graham Barr <gbarr@pobox.com>. All rights reserved. |
4 | # This program is free software; you can redistribute it and/or |
5 | # modify it under the same terms as Perl itself. |
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6 | |
7 | package IO::Select; |
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); |
12 | require Exporter; |
13 | |
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14 | $VERSION = "1.15"; |
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15 | |
16 | @ISA = qw(Exporter); # This is only so we can do version checking |
17 | |
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18 | sub VEC_BITS () {0} |
19 | sub FD_COUNT () {1} |
20 | sub FIRST_FD () {2} |
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21 | |
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22 | sub new |
23 | { |
24 | my $self = shift; |
25 | my $type = ref($self) || $self; |
26 | |
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27 | my $vec = bless [undef,0], $type; |
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28 | |
29 | $vec->add(@_) |
30 | if @_; |
31 | |
32 | $vec; |
33 | } |
34 | |
35 | sub add |
36 | { |
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37 | shift->_update('add', @_); |
38 | } |
39 | |
40 | |
41 | sub remove |
42 | { |
43 | shift->_update('remove', @_); |
44 | } |
45 | |
46 | |
47 | sub exists |
48 | { |
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49 | my $vec = shift; |
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50 | my $fno = $vec->_fileno(shift); |
51 | return undef unless defined $fno; |
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 |
57 | { |
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'; |
61 | ($f =~ /^\d+$/) ? $f : fileno($f); |
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62 | } |
63 | |
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64 | sub _update |
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65 | { |
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]; |
70 | $bits = '' unless defined $bits; |
71 | |
72 | my $count = 0; |
73 | my $f; |
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74 | foreach $f (@_) |
75 | { |
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76 | my $fn = $vec->_fileno($f); |
77 | next unless defined $fn; |
78 | my $i = $fn + FIRST_FD; |
79 | if ($add) { |
80 | if (defined $vec->[$i]) { |
81 | $vec->[$i] = $f; # if array rest might be different, so we update |
82 | next; |
83 | } |
84 | $vec->[FD_COUNT]++; |
85 | vec($bits, $fn, 1) = 1; |
86 | $vec->[$i] = $f; |
87 | } else { # remove |
88 | next unless defined $vec->[$i]; |
89 | $vec->[FD_COUNT]--; |
90 | vec($bits, $fn, 1) = 0; |
91 | $vec->[$i] = undef; |
92 | } |
93 | $count++; |
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94 | } |
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95 | $vec->[VEC_BITS] = $vec->[FD_COUNT] ? $bits : undef; |
96 | $count; |
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97 | } |
98 | |
99 | sub can_read |
100 | { |
101 | my $vec = shift; |
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 | : (); |
108 | } |
109 | |
110 | sub can_write |
111 | { |
112 | my $vec = shift; |
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 | : (); |
119 | } |
120 | |
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121 | sub has_exception |
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122 | { |
123 | my $vec = shift; |
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 | : (); |
130 | } |
131 | |
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132 | sub has_error |
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; |
137 | } |
138 | |
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139 | sub count |
140 | { |
141 | my $vec = shift; |
142 | $vec->[FD_COUNT]; |
143 | } |
144 | |
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145 | sub bits |
146 | { |
147 | my $vec = shift; |
148 | $vec->[VEC_BITS]; |
149 | } |
150 | |
151 | sub as_string # for debugging |
152 | { |
153 | my $vec = shift; |
154 | my $str = ref($vec) . ": "; |
155 | my $bits = $vec->bits; |
156 | my $count = $vec->count; |
157 | $str .= defined($bits) ? unpack("b*", $bits) : "undef"; |
158 | $str .= " $count"; |
159 | my @handles = @$vec; |
160 | splice(@handles, 0, FIRST_FD); |
161 | for (@handles) { |
162 | $str .= " " . (defined($_) ? "$_" : "-"); |
163 | } |
164 | $str; |
165 | } |
166 | |
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167 | sub _max |
168 | { |
169 | my($a,$b,$c) = @_; |
170 | $a > $b |
171 | ? $a > $c |
172 | ? $a |
173 | : $c |
174 | : $b > $c |
175 | ? $b |
176 | : $c; |
177 | } |
178 | |
179 | sub select |
180 | { |
181 | shift |
182 | if defined $_[0] && !ref($_[0]); |
183 | |
184 | my($r,$w,$e,$t) = @_; |
185 | my @result = (); |
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; |
189 | my $eb = defined $e ? $e->[VEC_BITS] : undef; |
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190 | |
191 | if(select($rb,$wb,$eb,$t) > 0) |
192 | { |
193 | my @r = (); |
194 | my @w = (); |
195 | my @e = (); |
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196 | my $i = _max(defined $r ? scalar(@$r)-1 : 0, |
197 | defined $w ? scalar(@$w)-1 : 0, |
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 | } |
210 | |
211 | @result = (\@r, \@w, \@e); |
212 | } |
213 | @result; |
214 | } |
215 | |
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216 | |
217 | sub handles |
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218 | { |
219 | my $vec = shift; |
220 | my $bits = shift; |
221 | my @h = (); |
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 | { |
227 | next unless defined $vec->[$i]; |
228 | push(@h, $vec->[$i]) |
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229 | if !defined($bits) || vec($bits, $i - FIRST_FD, 1); |
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230 | } |
231 | |
232 | @h; |
233 | } |
234 | |
235 | 1; |
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236 | __END__ |
237 | |
238 | =head1 NAME |
239 | |
240 | IO::Select - OO interface to the select system call |
241 | |
242 | =head1 SYNOPSIS |
243 | |
244 | use IO::Select; |
245 | |
246 | $s = IO::Select->new(); |
247 | |
248 | $s->add(\*STDIN); |
249 | $s->add($some_handle); |
250 | |
251 | @ready = $s->can_read($timeout); |
252 | |
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253 | @ready = IO::Select->new(@handles)->can_read(0); |
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254 | |
255 | =head1 DESCRIPTION |
256 | |
257 | The C<IO::Select> package implements an object approach to the system C<select> |
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 | |
261 | =head1 CONSTRUCTOR |
262 | |
263 | =over 4 |
264 | |
265 | =item new ( [ HANDLES ] ) |
266 | |
267 | The constructor creates a new object and optionally initialises it with a set |
268 | of handles. |
269 | |
270 | =back |
271 | |
272 | =head1 METHODS |
273 | |
274 | =over 4 |
275 | |
276 | =item add ( HANDLES ) |
277 | |
278 | Add the list of handles to the C<IO::Select> object. It is these values that |
279 | will be returned when an event occurs. C<IO::Select> keeps these values in a |
280 | cache which is indexed by the C<fileno> of the handle, so if more than one |
281 | handle with the same C<fileno> is specified then only the last one is cached. |
282 | |
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 | |
286 | =item remove ( HANDLES ) |
287 | |
288 | Remove all the given handles from the object. This method also works |
289 | by the C<fileno> of the handles. So the exact handles that were added |
290 | need not be passed, just handles that have an equivalent C<fileno> |
291 | |
292 | =item exists ( HANDLE ) |
293 | |
294 | Returns a true value (actually the handle itself) if it is present. |
295 | Returns undef otherwise. |
296 | |
297 | =item handles |
298 | |
299 | Return an array of all registered handles. |
300 | |
301 | =item can_read ( [ TIMEOUT ] ) |
302 | |
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 |
305 | seconds, possibly fractional. If C<TIMEOUT> is not given and any |
306 | handles are registered then the call will block. |
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307 | |
308 | =item can_write ( [ TIMEOUT ] ) |
309 | |
310 | Same as C<can_read> except check for handles that can be written to. |
311 | |
312 | =item has_exception ( [ TIMEOUT ] ) |
313 | |
314 | Same as C<can_read> except check for handles that have an exception |
315 | condition, for example pending out-of-band data. |
316 | |
317 | =item count () |
318 | |
319 | Returns the number of handles that the object will check for when |
320 | one of the C<can_> methods is called or the object is passed to |
321 | the C<select> static method. |
322 | |
323 | =item bits() |
324 | |
325 | Return the bit string suitable as argument to the core select() call. |
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 |
330 | like C<new>. C<READ>, C<WRITE> and C<EXCEPTION> are either C<undef> or |
331 | C<IO::Select> objects. C<TIMEOUT> is optional and has the same effect as |
332 | for the core select call. |
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333 | |
334 | The result will be an array of 3 elements, each a reference to an array |
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 | |
338 | =back |
339 | |
340 | =head1 EXAMPLE |
341 | |
342 | Here is a short example which shows how C<IO::Select> could be used |
343 | to write a server which communicates with several sockets while also |
344 | listening for more connections on a listen socket |
345 | |
346 | use IO::Select; |
347 | use IO::Socket; |
348 | |
349 | $lsn = new IO::Socket::INET(Listen => 1, LocalPort => 8080); |
350 | $sel = new IO::Select( $lsn ); |
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351 | |
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352 | while(@ready = $sel->can_read) { |
353 | foreach $fh (@ready) { |
354 | if($fh == $lsn) { |
355 | # Create a new socket |
356 | $new = $lsn->accept; |
357 | $sel->add($new); |
358 | } |
359 | else { |
360 | # Process socket |
361 | |
362 | # Maybe we have finished with the socket |
363 | $sel->remove($fh); |
364 | $fh->close; |
365 | } |
366 | } |
367 | } |
368 | |
369 | =head1 AUTHOR |
370 | |
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371 | Graham Barr. Currently maintained by the Perl Porters. Please report all |
372 | bugs to <perl5-porters@perl.org>. |
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373 | |
374 | =head1 COPYRIGHT |
375 | |
376 | Copyright (c) 1997-8 Graham Barr <gbarr@pobox.com>. All rights reserved. |
377 | This program is free software; you can redistribute it and/or |
378 | modify it under the same terms as Perl itself. |
379 | |
380 | =cut |
381 | |