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
11 IO::Select - OO interface to the select system call
17 $s = IO::Select->new();
20 $s->add($some_handle);
22 @ready = $s->can_read($timeout);
24 @ready = IO::Select->new(@handles)->read(0);
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.
36 =item new ( [ HANDLES ] )
38 The constructor creates a new object and optionally initialises it with a set
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.
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.
57 =item remove ( HANDLES )
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>
63 =item exists ( HANDLE )
65 Returns a true value (actually the handle itself) if it is present.
66 Returns undef otherwise.
70 Return an array of all registered handles.
72 =item can_read ( [ TIMEOUT ] )
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
79 =item can_write ( [ TIMEOUT ] )
81 Same as C<can_read> except check for handles that can be written to.
83 =item has_error ( [ TIMEOUT ] )
85 Same as C<can_read> except check for handles that have an error
86 condition, for example EOF.
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.
96 Return the bit string suitable as argument to the core select() call.
100 Return the bit string suitable as argument to the core select() call.
102 =item select ( READ, WRITE, ERROR [, TIMEOUT ] )
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.
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.
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
124 $lsn = new IO::Socket::INET(Listen => 1, LocalPort => 8080);
125 $sel = new IO::Select( $lsn );
127 while(@ready = $sel->can_read) {
128 foreach $fh (@ready) {
130 # Create a new socket
137 # Maybe we have finished with the socket
146 Graham Barr E<lt>F<Graham.Barr@tiuk.ti.com>E<gt>
150 Copyright (c) 1995 Graham Barr. All rights reserved. This program is free
151 software; you can redistribute it and/or modify it under the same terms
157 use vars qw($VERSION @ISA);
162 @ISA = qw(Exporter); # This is only so we can do version checking
171 my $type = ref($self) || $self;
173 my $vec = bless [undef,0], $type;
183 shift->_update('add', @_);
189 shift->_update('remove', @_);
196 $vec->[$vec->_fileno(shift) + FIRST_FD];
203 $f = $f->[0] if ref($f) eq 'ARRAY';
204 ($f =~ /^\d+$/) ? $f : fileno($f);
210 my $add = shift eq 'add';
212 my $bits = $vec->[VEC_BITS];
213 $bits = '' unless defined $bits;
219 my $fn = $vec->_fileno($f);
220 next unless defined $fn;
221 my $i = $fn + FIRST_FD;
223 if (defined $vec->[$i]) {
224 $vec->[$i] = $f; # if array rest might be different, so we update
228 vec($bits, $fn, 1) = 1;
231 next unless defined $vec->[$i];
233 vec($bits, $fn, 1) = 0;
238 $vec->[VEC_BITS] = $vec->[FD_COUNT] ? $bits : undef;
246 my $r = $vec->[VEC_BITS];
248 defined($r) && (select($r,undef,undef,$timeout) > 0)
257 my $w = $vec->[VEC_BITS];
259 defined($w) && (select(undef,$w,undef,$timeout) > 0)
268 my $e = $vec->[VEC_BITS];
270 defined($e) && (select(undef,undef,$e,$timeout) > 0)
287 sub as_string # for debugging
290 my $str = ref($vec) . ": ";
291 my $bits = $vec->bits;
292 my $count = $vec->count;
293 $str .= defined($bits) ? unpack("b*", $bits) : "undef";
296 splice(@handles, 0, FIRST_FD);
298 $str .= " " . (defined($_) ? "$_" : "-");
318 if defined $_[0] && !ref($_[0]);
320 my($r,$w,$e,$t) = @_;
323 my $rb = defined $r ? $r->[VEC_BITS] : undef;
324 my $wb = defined $w ? $w->[VEC_BITS] : undef;
325 my $eb = defined $e ? $e->[VEC_BITS] : undef;
327 if(select($rb,$wb,$eb,$t) > 0)
332 my $i = _max(defined $r ? scalar(@$r)-1 : 0,
333 defined $w ? scalar(@$w)-1 : 0,
334 defined $e ? scalar(@$e)-1 : 0);
336 for( ; $i >= FIRST_FD ; $i--)
338 my $j = $i - FIRST_FD;
340 if defined $rb && defined $r->[$i] && vec($rb, $j, 1);
342 if defined $wb && defined $w->[$i] && vec($wb, $j, 1);
344 if defined $eb && defined $e->[$i] && vec($eb, $j, 1);
347 @result = (\@r, \@w, \@e);
359 my $max = scalar(@$vec) - 1;
361 for ($i = FIRST_FD; $i <= $max; $i++)
363 next unless defined $vec->[$i];
365 if !defined($bits) || vec($bits, $i - FIRST_FD, 1);