Re: MP3 server with IO::Socket

[ryan]

Child reaping update:

After yet more experimentation with this fabulously educational node I did what was necessary to make it run via init.d based on this node.

I soon discovered that when a client was streaming and the parent was killed via the init.d script, the child serving the active client remained running and required manual killing.

To fix this problem I kept track of the children in the code and provided a clean-up routine when the script received a TERM signal. Below I list the $SIG{"TERM"} code to catch the TERM signal and 2 extra lines inside the main while loop to track the children as marked between the # >> tags:

# somewhere before the socket is used
my %kids;

$SIG{"TERM"} = "cleanup_and_exit";
        sub cleanup_and_exit {
                my $sig = @_;
                foreach my $kid (keys %kids) {
                  #reap them
                  warn("Failed to reap child pid: $kid\n") unless kill
+ 9, $kid;
                }
                # it's a good idea to exit when we are told to
                exit(0);
        }

# -- bits left out here --

#wait for connections at the accept call
while (my $connection = $listen_socket->accept)
{   
    my $child;
    # perform the fork or exit
    die "Can't fork: $!" unless defined ($child = fork());
    if ($child == 0)
    {   #i'm the child!
    
        #close the child's listen socket, we dont need it.
        $listen_socket->close;
        
        #call the main child rountine
        play_songs($connection);
        
        #if the child returns, then just exit;
# >> 
        undef $kids{$child};
# >>
        exit 0;
    } 
    else
    {   #i'm the parent!
# >>
        $kids{$child} = 1;
# >>    
        #who connected?
        warn "Connecton recieved ... ",$connection->peerhost,"\n";

        #close the connection, the parent has already passed
        #   it off to a child.
        $connection->close();
        
    }
    #go back and listen for the next connection!
} 

# -- bits left out here --

I'm not a great Perl programmer, but this works flawlessly on my Debian system and has provided my an exceptional motivational tool to start learning socket programming. I hope I havne't overlooked too much error checking or done anything dangerous with my reaping and this can be of some use to someone.

Thanks again.