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1 | # IO::Select.pm |
7a4c00b4 |
2 | # |
3 | # Copyright (c) 1995 Graham Barr. All rights reserved. This program is free |
4 | # software; you can redistribute it and/or modify it under the same terms |
5 | # as Perl itself. |
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6 | |
7 | package IO::Select; |
8 | |
9 | =head1 NAME |
10 | |
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11 | IO::Select - OO interface to the select system call |
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12 | |
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13 | =head1 SYNOPSIS |
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14 | |
15 | use IO::Select; |
16 | |
17 | $s = IO::Select->new(); |
18 | |
19 | $s->add(\*STDIN); |
20 | $s->add($some_handle); |
21 | |
22 | @ready = $s->can_read($timeout); |
23 | |
24 | @ready = IO::Select->new(@handles)->read(0); |
25 | |
26 | =head1 DESCRIPTION |
27 | |
28 | The C<IO::Select> package implements an object approach to the system C<select> |
29 | function call. It allows the user to see what IO handles, see L<IO::Handle>, |
30 | are ready for reading, writing or have an error condition pending. |
31 | |
32 | =head1 CONSTRUCTOR |
33 | |
34 | =over 4 |
35 | |
36 | =item new ( [ HANDLES ] ) |
37 | |
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38 | The constructor creates a new object and optionally initialises it with a set |
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39 | of handles. |
40 | |
41 | =back |
42 | |
43 | =head1 METHODS |
44 | |
45 | =over 4 |
46 | |
47 | =item add ( HANDLES ) |
48 | |
49 | Add the list of handles to the C<IO::Select> object. It is these values that |
50 | will be returned when an event occurs. C<IO::Select> keeps these values in a |
51 | cache which is indexed by the C<fileno> of the handle, so if more than one |
52 | handle with the same C<fileno> is specified then only the last one is cached. |
53 | |
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54 | Each handle can be an C<IO::Handle> object, an integer or an array |
55 | reference where the first element is a C<IO::Handle> or an integer. |
56 | |
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57 | =item remove ( HANDLES ) |
58 | |
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59 | Remove all the given handles from the object. This method also works |
60 | by the C<fileno> of the handles. So the exact handles that were added |
61 | need not be passed, just handles that have an equivalent C<fileno> |
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62 | |
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63 | =item exists ( HANDLE ) |
64 | |
65 | Returns a true value (actually the handle itself) if it is present. |
66 | Returns undef otherwise. |
67 | |
68 | =item handles |
69 | |
70 | Return an array of all registered handles. |
71 | |
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72 | =item can_read ( [ TIMEOUT ] ) |
73 | |
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74 | Return an array of handles that are ready for reading. C<TIMEOUT> is |
75 | the maximum amount of time to wait before returning an empty list. If |
76 | C<TIMEOUT> is not given and any handles are registered then the call |
77 | will block. |
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78 | |
79 | =item can_write ( [ TIMEOUT ] ) |
80 | |
81 | Same as C<can_read> except check for handles that can be written to. |
82 | |
83 | =item has_error ( [ TIMEOUT ] ) |
84 | |
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85 | Same as C<can_read> except check for handles that have an error |
86 | condition, for example EOF. |
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87 | |
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88 | =item count () |
89 | |
90 | Returns the number of handles that the object will check for when |
91 | one of the C<can_> methods is called or the object is passed to |
92 | the C<select> static method. |
93 | |
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94 | =item bits() |
95 | |
96 | Return the bit string suitable as argument to the core select() call. |
97 | |
98 | =item bits() |
99 | |
100 | Return the bit string suitable as argument to the core select() call. |
101 | |
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102 | =item select ( READ, WRITE, ERROR [, TIMEOUT ] ) |
103 | |
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104 | C<select> is a static method, that is you call it with the package |
105 | name like C<new>. C<READ>, C<WRITE> and C<ERROR> are either C<undef> |
106 | or C<IO::Select> objects. C<TIMEOUT> is optional and has the same |
107 | effect as for the core select call. |
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108 | |
109 | The result will be an array of 3 elements, each a reference to an array |
110 | which will hold the handles that are ready for reading, writing and have |
111 | error conditions respectively. Upon error an empty array is returned. |
112 | |
113 | =back |
114 | |
115 | =head1 EXAMPLE |
116 | |
117 | Here is a short example which shows how C<IO::Select> could be used |
118 | to write a server which communicates with several sockets while also |
119 | listening for more connections on a listen socket |
120 | |
121 | use IO::Select; |
122 | use IO::Socket; |
123 | |
124 | $lsn = new IO::Socket::INET(Listen => 1, LocalPort => 8080); |
125 | $sel = new IO::Select( $lsn ); |
126 | |
127 | while(@ready = $sel->can_read) { |
128 | foreach $fh (@ready) { |
129 | if($fh == $lsn) { |
130 | # Create a new socket |
131 | $new = $lsn->accept; |
132 | $sel->add($new); |
133 | } |
134 | else { |
135 | # Process socket |
136 | |
137 | # Maybe we have finished with the socket |
138 | $sel->remove($fh); |
139 | $fh->close; |
140 | } |
141 | } |
142 | } |
143 | |
144 | =head1 AUTHOR |
145 | |
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146 | Graham Barr E<lt>F<Graham.Barr@tiuk.ti.com>E<gt> |
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147 | |
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148 | =head1 COPYRIGHT |
149 | |
150 | Copyright (c) 1995 Graham Barr. All rights reserved. This program is free |
151 | software; you can redistribute it and/or modify it under the same terms |
152 | as Perl itself. |
153 | |
154 | =cut |
155 | |
156 | use strict; |
157 | use vars qw($VERSION @ISA); |
158 | require Exporter; |
159 | |
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160 | $VERSION = "1.10"; |
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161 | |
162 | @ISA = qw(Exporter); # This is only so we can do version checking |
163 | |
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164 | sub VEC_BITS () {0} |
165 | sub FD_COUNT () {1} |
166 | sub FIRST_FD () {2} |
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167 | |
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168 | sub new |
169 | { |
170 | my $self = shift; |
171 | my $type = ref($self) || $self; |
172 | |
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173 | my $vec = bless [undef,0], $type; |
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174 | |
175 | $vec->add(@_) |
176 | if @_; |
177 | |
178 | $vec; |
179 | } |
180 | |
181 | sub add |
182 | { |
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183 | shift->_update('add', @_); |
184 | } |
185 | |
186 | |
187 | sub remove |
188 | { |
189 | shift->_update('remove', @_); |
190 | } |
191 | |
192 | |
193 | sub exists |
194 | { |
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195 | my $vec = shift; |
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196 | $vec->[$vec->_fileno(shift) + FIRST_FD]; |
197 | } |
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198 | |
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199 | |
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200 | sub _fileno |
201 | { |
202 | my($self, $f) = @_; |
203 | $f = $f->[0] if ref($f) eq 'ARRAY'; |
204 | ($f =~ /^\d+$/) ? $f : fileno($f); |
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205 | } |
206 | |
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207 | sub _update |
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208 | { |
209 | my $vec = shift; |
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210 | my $add = shift eq 'add'; |
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211 | |
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212 | my $bits = $vec->[VEC_BITS]; |
213 | $bits = '' unless defined $bits; |
214 | |
215 | my $count = 0; |
216 | my $f; |
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217 | foreach $f (@_) |
218 | { |
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219 | my $fn = $vec->_fileno($f); |
220 | next unless defined $fn; |
221 | my $i = $fn + FIRST_FD; |
222 | if ($add) { |
223 | if (defined $vec->[$i]) { |
224 | $vec->[$i] = $f; # if array rest might be different, so we update |
225 | next; |
226 | } |
227 | $vec->[FD_COUNT]++; |
228 | vec($bits, $fn, 1) = 1; |
229 | $vec->[$i] = $f; |
230 | } else { # remove |
231 | next unless defined $vec->[$i]; |
232 | $vec->[FD_COUNT]--; |
233 | vec($bits, $fn, 1) = 0; |
234 | $vec->[$i] = undef; |
235 | } |
236 | $count++; |
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237 | } |
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238 | $vec->[VEC_BITS] = $vec->[FD_COUNT] ? $bits : undef; |
239 | $count; |
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240 | } |
241 | |
242 | sub can_read |
243 | { |
244 | my $vec = shift; |
245 | my $timeout = shift; |
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246 | my $r = $vec->[VEC_BITS]; |
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247 | |
27d4819a |
248 | defined($r) && (select($r,undef,undef,$timeout) > 0) |
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249 | ? handles($vec, $r) |
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250 | : (); |
251 | } |
252 | |
253 | sub can_write |
254 | { |
255 | my $vec = shift; |
256 | my $timeout = shift; |
27d4819a |
257 | my $w = $vec->[VEC_BITS]; |
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258 | |
27d4819a |
259 | defined($w) && (select(undef,$w,undef,$timeout) > 0) |
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260 | ? handles($vec, $w) |
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261 | : (); |
262 | } |
263 | |
264 | sub has_error |
265 | { |
266 | my $vec = shift; |
267 | my $timeout = shift; |
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268 | my $e = $vec->[VEC_BITS]; |
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269 | |
27d4819a |
270 | defined($e) && (select(undef,undef,$e,$timeout) > 0) |
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271 | ? handles($vec, $e) |
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272 | : (); |
273 | } |
274 | |
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275 | sub count |
276 | { |
277 | my $vec = shift; |
278 | $vec->[FD_COUNT]; |
279 | } |
280 | |
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281 | sub bits |
282 | { |
283 | my $vec = shift; |
284 | $vec->[VEC_BITS]; |
285 | } |
286 | |
287 | sub as_string # for debugging |
288 | { |
289 | my $vec = shift; |
290 | my $str = ref($vec) . ": "; |
291 | my $bits = $vec->bits; |
292 | my $count = $vec->count; |
293 | $str .= defined($bits) ? unpack("b*", $bits) : "undef"; |
294 | $str .= " $count"; |
295 | my @handles = @$vec; |
296 | splice(@handles, 0, FIRST_FD); |
297 | for (@handles) { |
298 | $str .= " " . (defined($_) ? "$_" : "-"); |
299 | } |
300 | $str; |
301 | } |
302 | |
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303 | sub _max |
304 | { |
305 | my($a,$b,$c) = @_; |
306 | $a > $b |
307 | ? $a > $c |
308 | ? $a |
309 | : $c |
310 | : $b > $c |
311 | ? $b |
312 | : $c; |
313 | } |
314 | |
315 | sub select |
316 | { |
317 | shift |
318 | if defined $_[0] && !ref($_[0]); |
319 | |
320 | my($r,$w,$e,$t) = @_; |
321 | my @result = (); |
322 | |
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323 | my $rb = defined $r ? $r->[VEC_BITS] : undef; |
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324 | my $wb = defined $w ? $w->[VEC_BITS] : undef; |
325 | my $eb = defined $e ? $e->[VEC_BITS] : undef; |
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326 | |
327 | if(select($rb,$wb,$eb,$t) > 0) |
328 | { |
329 | my @r = (); |
330 | my @w = (); |
331 | my @e = (); |
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332 | my $i = _max(defined $r ? scalar(@$r)-1 : 0, |
333 | defined $w ? scalar(@$w)-1 : 0, |
334 | defined $e ? scalar(@$e)-1 : 0); |
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335 | |
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336 | for( ; $i >= FIRST_FD ; $i--) |
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337 | { |
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338 | my $j = $i - FIRST_FD; |
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339 | push(@r, $r->[$i]) |
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340 | if defined $rb && defined $r->[$i] && vec($rb, $j, 1); |
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341 | push(@w, $w->[$i]) |
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342 | if defined $wb && defined $w->[$i] && vec($wb, $j, 1); |
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343 | push(@e, $e->[$i]) |
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344 | if defined $eb && defined $e->[$i] && vec($eb, $j, 1); |
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345 | } |
346 | |
347 | @result = (\@r, \@w, \@e); |
348 | } |
349 | @result; |
350 | } |
351 | |
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352 | |
353 | sub handles |
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354 | { |
355 | my $vec = shift; |
356 | my $bits = shift; |
357 | my @h = (); |
358 | my $i; |
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359 | my $max = scalar(@$vec) - 1; |
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360 | |
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361 | for ($i = FIRST_FD; $i <= $max; $i++) |
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362 | { |
363 | next unless defined $vec->[$i]; |
364 | push(@h, $vec->[$i]) |
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365 | if !defined($bits) || vec($bits, $i - FIRST_FD, 1); |
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366 | } |
367 | |
368 | @h; |
369 | } |
370 | |
371 | 1; |