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1 | # IO::Select.pm |
2 | |
3 | package IO::Select; |
4 | |
5 | =head1 NAME |
6 | |
7 | IO::Select - OO interface to the system select call |
8 | |
9 | =head1 SYNOPSYS |
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 | |
34 | The constructor create a new object and optionally initialises it with a set |
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 | |
52 | Remove all the given handles from the object. |
53 | |
54 | =item can_read ( [ TIMEOUT ] ) |
55 | |
56 | Return an array of handles that are ready for reading. C<TIMEOUT> is the maximum |
57 | amount of time to wait before returning an empty list. If C<TIMEOUT> is |
58 | not given then the call will block. |
59 | |
60 | =item can_write ( [ TIMEOUT ] ) |
61 | |
62 | Same as C<can_read> except check for handles that can be written to. |
63 | |
64 | =item has_error ( [ TIMEOUT ] ) |
65 | |
66 | Same as C<can_read> except check for handles that have an error condition, for |
67 | example EOF. |
68 | |
69 | =item select ( READ, WRITE, ERROR [, TIMEOUT ] ) |
70 | |
71 | C<select> is a static method, that is you call it with the package name |
72 | like C<new>. C<READ>, C<WRITE> and C<ERROR> are either C<undef> or |
73 | C<IO::Select> objects. C<TIMEOUT> is optional and has the same effect as |
74 | before. |
75 | |
76 | The result will be an array of 3 elements, each a reference to an array |
77 | which will hold the handles that are ready for reading, writing and have |
78 | error conditions respectively. Upon error an empty array is returned. |
79 | |
80 | =back |
81 | |
82 | =head1 EXAMPLE |
83 | |
84 | Here is a short example which shows how C<IO::Select> could be used |
85 | to write a server which communicates with several sockets while also |
86 | listening for more connections on a listen socket |
87 | |
88 | use IO::Select; |
89 | use IO::Socket; |
90 | |
91 | $lsn = new IO::Socket::INET(Listen => 1, LocalPort => 8080); |
92 | $sel = new IO::Select( $lsn ); |
93 | |
94 | while(@ready = $sel->can_read) { |
95 | foreach $fh (@ready) { |
96 | if($fh == $lsn) { |
97 | # Create a new socket |
98 | $new = $lsn->accept; |
99 | $sel->add($new); |
100 | } |
101 | else { |
102 | # Process socket |
103 | |
104 | # Maybe we have finished with the socket |
105 | $sel->remove($fh); |
106 | $fh->close; |
107 | } |
108 | } |
109 | } |
110 | |
111 | =head1 AUTHOR |
112 | |
113 | Graham Barr <Graham.Barr@tiuk.ti.com> |
114 | |
115 | =head1 REVISION |
116 | |
117 | $Revision: 1.2 $ |
118 | |
119 | =head1 COPYRIGHT |
120 | |
121 | Copyright (c) 1995 Graham Barr. All rights reserved. This program is free |
122 | software; you can redistribute it and/or modify it under the same terms |
123 | as Perl itself. |
124 | |
125 | =cut |
126 | |
127 | use strict; |
128 | use vars qw($VERSION @ISA); |
129 | require Exporter; |
130 | |
131 | $VERSION = sprintf("%d.%02d", q$Revision: 1.2 $ =~ /(\d+)\.(\d+)/); |
132 | |
133 | @ISA = qw(Exporter); # This is only so we can do version checking |
134 | |
135 | sub new |
136 | { |
137 | my $self = shift; |
138 | my $type = ref($self) || $self; |
139 | |
140 | my $vec = bless [''], $type; |
141 | |
142 | $vec->add(@_) |
143 | if @_; |
144 | |
145 | $vec; |
146 | } |
147 | |
148 | sub add |
149 | { |
150 | my $vec = shift; |
151 | my $f; |
152 | |
153 | foreach $f (@_) |
154 | { |
155 | my $fn = $f =~ /^\d+$/ ? $f : fileno($f); |
156 | next |
157 | unless defined $fn; |
158 | vec($vec->[0],$fn++,1) = 1; |
159 | $vec->[$fn] = $f; |
160 | } |
161 | } |
162 | |
163 | sub remove |
164 | { |
165 | my $vec = shift; |
166 | my $f; |
167 | |
168 | foreach $f (@_) |
169 | { |
170 | my $fn = $f =~ /^\d+$/ ? $f : fileno($f); |
171 | next |
172 | unless defined $fn; |
173 | vec($vec->[0],$fn++,1) = 0; |
174 | $vec->[$fn] = undef; |
175 | } |
176 | } |
177 | |
178 | sub can_read |
179 | { |
180 | my $vec = shift; |
181 | my $timeout = shift; |
182 | |
183 | my $r = $vec->[0]; |
184 | |
185 | select($r,undef,undef,$timeout) > 0 |
186 | ? _handles($vec, $r) |
187 | : (); |
188 | } |
189 | |
190 | sub can_write |
191 | { |
192 | my $vec = shift; |
193 | my $timeout = shift; |
194 | |
195 | my $w = $vec->[0]; |
196 | |
197 | select(undef,$w,undef,$timeout) > 0 |
198 | ? _handles($vec, $w) |
199 | : (); |
200 | } |
201 | |
202 | sub has_error |
203 | { |
204 | my $vec = shift; |
205 | my $timeout = shift; |
206 | |
207 | my $e = $vec->[0]; |
208 | |
209 | select(undef,undef,$e,$timeout) > 0 |
210 | ? _handles($vec, $e) |
211 | : (); |
212 | } |
213 | |
214 | sub _max |
215 | { |
216 | my($a,$b,$c) = @_; |
217 | $a > $b |
218 | ? $a > $c |
219 | ? $a |
220 | : $c |
221 | : $b > $c |
222 | ? $b |
223 | : $c; |
224 | } |
225 | |
226 | sub select |
227 | { |
228 | shift |
229 | if defined $_[0] && !ref($_[0]); |
230 | |
231 | my($r,$w,$e,$t) = @_; |
232 | my @result = (); |
233 | |
234 | my $rb = defined $r ? $r->[0] : undef; |
235 | my $wb = defined $w ? $e->[0] : undef; |
236 | my $eb = defined $e ? $w->[0] : undef; |
237 | |
238 | if(select($rb,$wb,$eb,$t) > 0) |
239 | { |
240 | my @r = (); |
241 | my @w = (); |
242 | my @e = (); |
243 | my $i = _max(defined $r ? scalar(@$r) : 0, |
244 | defined $w ? scalar(@$w) : 0, |
245 | defined $e ? scalar(@$e) : 0); |
246 | |
247 | for( ; $i > 0 ; $i--) |
248 | { |
249 | my $j = $i - 1; |
250 | push(@r, $r->[$i]) |
251 | if defined $r->[$i] && vec($rb, $j, 1); |
252 | push(@w, $w->[$i]) |
253 | if defined $w->[$i] && vec($wb, $j, 1); |
254 | push(@e, $e->[$i]) |
255 | if defined $e->[$i] && vec($eb, $j, 1); |
256 | } |
257 | |
258 | @result = (\@r, \@w, \@e); |
259 | } |
260 | @result; |
261 | } |
262 | |
263 | sub _handles |
264 | { |
265 | my $vec = shift; |
266 | my $bits = shift; |
267 | my @h = (); |
268 | my $i; |
269 | |
270 | for($i = scalar(@$vec) - 1 ; $i > 0 ; $i--) |
271 | { |
272 | next unless defined $vec->[$i]; |
273 | push(@h, $vec->[$i]) |
274 | if vec($bits,$i - 1,1); |
275 | } |
276 | |
277 | @h; |
278 | } |
279 | |
280 | 1; |