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[ID 20010506.049] Conteptual mistake in IO::Select
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From:
dLux
Date:
May 6, 2001 05:15
Subject:
[ID 20010506.049] Conteptual mistake in IO::Select
Message ID:
E14tHHb-0000o6-00@dl.sch.bme.hu
This is a bug report for perl from dlux@kapu.hu,
generated with the help of perlbug 1.28 running under perl v5.6.0.
-----------------------------------------------------------------
This bug is only a conceptual bug, and I don't understand how this problem
is not a problem for others. Let me see the manual of the IO::Select:
DESCRIPTION
The `IO::Select' package implements an object approach to
the system `select' function call. It allows the user to
see what IO handles, see the IO::Handle manpage, are ready
for reading, writing or have an error condition pending.
The implementation of the IO::Select does not cover the whole functionality
of the "select" system call and the "select" perl function, because it can
not handle multi-way connections. I can select to read, write _OR_ error
condition! This is not enough if you want to write a non-blocking one-process
server, which maintains keep-alive connections!
The module needs redesign to allow this functionality, e.g the separation of
the read, write and error-condition file-handles. It is not good if you
simply add a function:
sub can_do_anything {
my $vec = shift;
my $timeout = shift;
my $r = $vec->[VEC_BITS];
defined($r) && (select($r,$r,$r,$timeout) > 0)
? handles($vec, $r)
: ();
}
This is a bad solution, because it returns when we can write to a socket, and
I cannot tell the module: I don't want to write to this socket.
If you are adventurous, you can rewrite the module to handle that case also.
If you need my help, I can send a patch for it, you only need to apply this.
If you are not intend to change this module, then I will write another one
which will be the _real_ Object-approach of the select system-call in perl.
-----------------------------------------------------------------
---
Flags:
category=library
severity=low
---
Site configuration information for perl v5.6.0:
Configured by bod at Fri Mar 9 06:08:27 EST 2001.
Summary of my perl5 (revision 5.0 version 6 subversion 0) configuration:
Platform:
osname=linux, osvers=2.4.2, archname=i386-linux
uname='linux duende 2.4.2 #1 fri mar 2 13:52:32 est 2001 i686 unknown '
config_args='-Dccflags=-DDEBIAN -Darchname=i386-linux -Dprefix=/usr -Dprivlib=/usr/share/perl/5.6.0 -Darchlib=/usr/lib/perl/5.6.0 -Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.6.0 -Dsitearch=/usr/local/lib/perl/5.6.0 -Dman1dir=/usr/share/man/man1 -Dman3dir=/usr/share/man/man3 -Dman1ext=1 -Dman3ext=3perl -Dpager=/usr/bin/pager -Uafs -Ud_csh -Uusesfio -Duseshrplib -Dlibperl=libperl.so.5.6.0 -Dd_dosuid -des'
hint=recommended, useposix=true, d_sigaction=define
usethreads=undef use5005threads=undef useithreads=undef usemultiplicity=undef
useperlio=undef d_sfio=undef uselargefiles=define
use64bitint=undef use64bitall=undef uselongdouble=undef usesocks=undef
Compiler:
cc='cc', optimize='-O2', gccversion=2.95.3 20010219 (prerelease)
cppflags='-DDEBIAN -fno-strict-aliasing -I/usr/local/include'
ccflags ='-DDEBIAN -fno-strict-aliasing -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64'
stdchar='char', d_stdstdio=define, usevfork=false
intsize=4, longsize=4, ptrsize=4, doublesize=8
d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
alignbytes=4, usemymalloc=n, prototype=define
Linker and Libraries:
ld='cc', ldflags =' -L/usr/local/lib'
libpth=/usr/local/lib /lib /usr/lib
libs=-lnsl -ldl -lm -lc -lcrypt
libc=/lib/libc-2.2.2.so, so=so, useshrplib=true, libperl=libperl.so.5.6.0
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic'
cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib'
Locally applied patches:
---
@INC for perl v5.6.0:
/usr/local/lib/perl/5.6.0
/usr/local/share/perl/5.6.0
/usr/lib/perl5
/usr/share/perl5
/usr/lib/perl/5.6.0
/usr/share/perl/5.6.0
/usr/local/lib/site_perl
/usr/lib/perl5/5.6/i386-linux
/usr/lib/perl5/5.6
/usr/lib/perl5/5.005/i386-linux
.
---
Environment for perl v5.6.0:
HOME=/home/dlux
LANG=C
LANGUAGE (unset)
LD_LIBRARY_PATH=~/lib
LOGDIR (unset)
PATH=/opt/bin:/usr/bin:/usr/local/bin:/home/dlux/bin:/home/dlux/projects/shell:/opt/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/bin/X11
PERL_BADLANG (unset)
SHELL=/bin/bash
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