Hi Monks,
I'm writing a daemon that will listen on UNIX socket, accept connections, take a request, crunch a bit on it, and spit out a response.
A problem arises when server closes connection after writing out on socket what it had to say. Somehow the data gets lost and client never receives it.
A kludge is to add sleep(1) just before the close. But, this is not acceptable in "production" application because it severely limits throughput to less than 1 msg/sec.
Is there a way to make IO::Socket::UNIX do a REAL FLUSH on that UNIX socket so client could read the data that's been written to it?
Here is the server's code:
#!/usr/bin/perl -w
use IO::Socket::UNIX;
use strict;
my $sockfile = '/tmp/mysocket';
my $r;
unlink($sockfile);
my $usock = new IO::Socket::UNIX(
Type => SOCK_STREAM,
Local => $sockfile,
Listen => 1)
|| die "ERROR: $!\n";
while (1) {
if (($r) = $usock->accept) {
my $out = do_something($r);
$r->printflush($out);
# sleep 1; # this makes it work
$r->close;
}
}
sub do_something {
my ($fh) = @_;
my ($l) = <$fh>;
return uc($l);
}
And here is my sample UNIX socket client:
#!/usr/bin/perl -w
use IO::Socket::UNIX;
my ($sockfile) = shift
|| die "$0: Socket address required\n";
my $r;
my $usock = new IO::Socket::UNIX (Type => SOCK_STREAM,
Peer => $sockfile)
|| die "ERROR: $!\n";
# read stdin and write to socket
while(<>) {
print $usock $_;
}
# shut down writing side (server receives EOF)
$usock->shutdown(1);
$sock->blocking(1); # this does not help
# read socket (blocking) and write to stdout
while(<$usock>) {
print $_;
}
# shut down reading side
$usock->shutdown(0);
I've tried SO_LINGER stuff (snippet found on google/groups) in server...
my $linger = pack('ii', 1, 120); # BSD struct
$usock->sockopt(SO_LINGER, $linger);
But to no avail.
PLEASE HELP!!™ :)
Damir Dzeko -- PGP keyID: 38ED4CFF
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