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1 | # IO::Select.pm |
2 | |
3 | package IO::Select; |
4 | |
5 | =head1 NAME |
6 | |
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7 | IO::Select - OO interface to the select system call |
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8 | |
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9 | =head1 SYNOPSIS |
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10 | |
11 | use IO::Select; |
12 | |
13 | $s = IO::Select->new(); |
14 | |
15 | $s->add(\*STDIN); |
16 | $s->add($some_handle); |
17 | |
18 | @ready = $s->can_read($timeout); |
19 | |
20 | @ready = IO::Select->new(@handles)->read(0); |
21 | |
22 | =head1 DESCRIPTION |
23 | |
24 | The C<IO::Select> package implements an object approach to the system C<select> |
25 | function call. It allows the user to see what IO handles, see L<IO::Handle>, |
26 | are ready for reading, writing or have an error condition pending. |
27 | |
28 | =head1 CONSTRUCTOR |
29 | |
30 | =over 4 |
31 | |
32 | =item new ( [ HANDLES ] ) |
33 | |
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34 | The constructor creates a new object and optionally initialises it with a set |
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35 | of handles. |
36 | |
37 | =back |
38 | |
39 | =head1 METHODS |
40 | |
41 | =over 4 |
42 | |
43 | =item add ( HANDLES ) |
44 | |
45 | Add the list of handles to the C<IO::Select> object. It is these values that |
46 | will be returned when an event occurs. C<IO::Select> keeps these values in a |
47 | cache which is indexed by the C<fileno> of the handle, so if more than one |
48 | handle with the same C<fileno> is specified then only the last one is cached. |
49 | |
50 | =item remove ( HANDLES ) |
51 | |
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52 | Remove all the given handles from the object. This method also works |
53 | by the C<fileno> of the handles. So the exact handles that were added |
54 | need not be passed, just handles that have an equivalent C<fileno> |
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55 | |
56 | =item can_read ( [ TIMEOUT ] ) |
57 | |
58 | Return an array of handles that are ready for reading. C<TIMEOUT> is the maximum |
59 | amount of time to wait before returning an empty list. If C<TIMEOUT> is |
60 | not given then the call will block. |
61 | |
62 | =item can_write ( [ TIMEOUT ] ) |
63 | |
64 | Same as C<can_read> except check for handles that can be written to. |
65 | |
66 | =item has_error ( [ TIMEOUT ] ) |
67 | |
68 | Same as C<can_read> except check for handles that have an error condition, for |
69 | example EOF. |
70 | |
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71 | =item count () |
72 | |
73 | Returns the number of handles that the object will check for when |
74 | one of the C<can_> methods is called or the object is passed to |
75 | the C<select> static method. |
76 | |
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77 | =item select ( READ, WRITE, ERROR [, TIMEOUT ] ) |
78 | |
79 | C<select> is a static method, that is you call it with the package name |
80 | like C<new>. C<READ>, C<WRITE> and C<ERROR> are either C<undef> or |
81 | C<IO::Select> objects. C<TIMEOUT> is optional and has the same effect as |
82 | before. |
83 | |
84 | The result will be an array of 3 elements, each a reference to an array |
85 | which will hold the handles that are ready for reading, writing and have |
86 | error conditions respectively. Upon error an empty array is returned. |
87 | |
88 | =back |
89 | |
90 | =head1 EXAMPLE |
91 | |
92 | Here is a short example which shows how C<IO::Select> could be used |
93 | to write a server which communicates with several sockets while also |
94 | listening for more connections on a listen socket |
95 | |
96 | use IO::Select; |
97 | use IO::Socket; |
98 | |
99 | $lsn = new IO::Socket::INET(Listen => 1, LocalPort => 8080); |
100 | $sel = new IO::Select( $lsn ); |
101 | |
102 | while(@ready = $sel->can_read) { |
103 | foreach $fh (@ready) { |
104 | if($fh == $lsn) { |
105 | # Create a new socket |
106 | $new = $lsn->accept; |
107 | $sel->add($new); |
108 | } |
109 | else { |
110 | # Process socket |
111 | |
112 | # Maybe we have finished with the socket |
113 | $sel->remove($fh); |
114 | $fh->close; |
115 | } |
116 | } |
117 | } |
118 | |
119 | =head1 AUTHOR |
120 | |
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121 | Graham Barr E<lt>F<Graham.Barr@tiuk.ti.com>E<gt> |
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122 | |
123 | =head1 REVISION |
124 | |
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125 | $Revision: 1.9 $ |
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126 | |
127 | =head1 COPYRIGHT |
128 | |
129 | Copyright (c) 1995 Graham Barr. All rights reserved. This program is free |
130 | software; you can redistribute it and/or modify it under the same terms |
131 | as Perl itself. |
132 | |
133 | =cut |
134 | |
135 | use strict; |
136 | use vars qw($VERSION @ISA); |
137 | require Exporter; |
138 | |
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139 | $VERSION = sprintf("%d.%02d", q$Revision: 1.9 $ =~ /(\d+)\.(\d+)/); |
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140 | |
141 | @ISA = qw(Exporter); # This is only so we can do version checking |
142 | |
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143 | sub VEC_BITS {0} |
144 | sub FD_COUNT {1} |
145 | sub FIRST_FD {2} |
146 | |
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147 | sub new |
148 | { |
149 | my $self = shift; |
150 | my $type = ref($self) || $self; |
151 | |
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152 | my $vec = bless [undef,0], $type; |
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153 | |
154 | $vec->add(@_) |
155 | if @_; |
156 | |
157 | $vec; |
158 | } |
159 | |
160 | sub add |
161 | { |
162 | my $vec = shift; |
163 | my $f; |
164 | |
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165 | $vec->[VEC_BITS] = '' unless defined $vec->[VEC_BITS]; |
166 | |
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167 | foreach $f (@_) |
168 | { |
169 | my $fn = $f =~ /^\d+$/ ? $f : fileno($f); |
170 | next |
171 | unless defined $fn; |
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172 | vec($vec->[VEC_BITS],$fn,1) = 1; |
173 | $vec->[FD_COUNT] += 1 |
174 | unless defined $vec->[$fn+FIRST_FD]; |
175 | $vec->[$fn+FIRST_FD] = $f; |
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176 | } |
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177 | $vec->[VEC_BITS] = undef unless $vec->count; |
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178 | } |
179 | |
180 | sub remove |
181 | { |
182 | my $vec = shift; |
183 | my $f; |
184 | |
185 | foreach $f (@_) |
186 | { |
187 | my $fn = $f =~ /^\d+$/ ? $f : fileno($f); |
188 | next |
189 | unless defined $fn; |
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190 | vec($vec->[VEC_BITS],$fn,1) = 0; |
191 | $vec->[$fn+FIRST_FD] = undef; |
192 | $vec->[FD_COUNT] -= 1; |
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193 | } |
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194 | $vec->[VEC_BITS] = undef unless $vec->count; |
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195 | } |
196 | |
197 | sub can_read |
198 | { |
199 | my $vec = shift; |
200 | my $timeout = shift; |
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201 | my $r = $vec->[VEC_BITS]; |
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202 | |
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203 | defined($r) && (select($r,undef,undef,$timeout) > 0) |
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204 | ? _handles($vec, $r) |
205 | : (); |
206 | } |
207 | |
208 | sub can_write |
209 | { |
210 | my $vec = shift; |
211 | my $timeout = shift; |
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212 | my $w = $vec->[VEC_BITS]; |
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213 | |
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214 | defined($w) && (select(undef,$w,undef,$timeout) > 0) |
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215 | ? _handles($vec, $w) |
216 | : (); |
217 | } |
218 | |
219 | sub has_error |
220 | { |
221 | my $vec = shift; |
222 | my $timeout = shift; |
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223 | my $e = $vec->[VEC_BITS]; |
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224 | |
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225 | defined($e) && (select(undef,undef,$e,$timeout) > 0) |
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226 | ? _handles($vec, $e) |
227 | : (); |
228 | } |
229 | |
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230 | sub count |
231 | { |
232 | my $vec = shift; |
233 | $vec->[FD_COUNT]; |
234 | } |
235 | |
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236 | sub _max |
237 | { |
238 | my($a,$b,$c) = @_; |
239 | $a > $b |
240 | ? $a > $c |
241 | ? $a |
242 | : $c |
243 | : $b > $c |
244 | ? $b |
245 | : $c; |
246 | } |
247 | |
248 | sub select |
249 | { |
250 | shift |
251 | if defined $_[0] && !ref($_[0]); |
252 | |
253 | my($r,$w,$e,$t) = @_; |
254 | my @result = (); |
255 | |
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256 | my $rb = defined $r ? $r->[VEC_BITS] : undef; |
257 | my $wb = defined $w ? $e->[VEC_BITS] : undef; |
258 | my $eb = defined $e ? $w->[VEC_BITS] : undef; |
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259 | |
260 | if(select($rb,$wb,$eb,$t) > 0) |
261 | { |
262 | my @r = (); |
263 | my @w = (); |
264 | my @e = (); |
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265 | my $i = _max(defined $r ? scalar(@$r)-1 : 0, |
266 | defined $w ? scalar(@$w)-1 : 0, |
267 | defined $e ? scalar(@$e)-1 : 0); |
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268 | |
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269 | for( ; $i >= FIRST_FD ; $i--) |
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270 | { |
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271 | my $j = $i - FIRST_FD; |
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272 | push(@r, $r->[$i]) |
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273 | if defined $rb && defined $r->[$i] && vec($rb, $j, 1); |
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274 | push(@w, $w->[$i]) |
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275 | if defined $wb && defined $w->[$i] && vec($wb, $j, 1); |
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276 | push(@e, $e->[$i]) |
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277 | if defined $eb && defined $e->[$i] && vec($eb, $j, 1); |
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278 | } |
279 | |
280 | @result = (\@r, \@w, \@e); |
281 | } |
282 | @result; |
283 | } |
284 | |
285 | sub _handles |
286 | { |
287 | my $vec = shift; |
288 | my $bits = shift; |
289 | my @h = (); |
290 | my $i; |
291 | |
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292 | for($i = scalar(@$vec) - 1 ; $i >= FIRST_FD ; $i--) |
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293 | { |
294 | next unless defined $vec->[$i]; |
295 | push(@h, $vec->[$i]) |
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296 | if vec($bits,$i - FIRST_FD,1); |
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297 | } |
298 | |
299 | @h; |
300 | } |
301 | |
302 | 1; |