NAME

Server::Starter - a superdaemon for hot-deploying server programs

SYNOPSIS

# from command line
% start_server --port=80 my_httpd

# in my_httpd
use Server::Starter qw(server_ports);

my $listen_sock = IO::Socket::INET->new(
    Proto => 'tcp',
);
$listen_sock->fdopen((values %{server_ports()})[0], 'w')
    or die "failed to bind to listening socket:$!";

while (1) {
    if (my $conn = $listen_sock->accept) {
        ....
    }
}

DESCRIPTION

It is often a pain to write a server program that supports graceful restarts, with no resource leaks. Server::Starter, solves the problem by splitting the task into two. One is start_server, a script provided as a part of the module, which works as a superdaemon that binds to one or more TCP ports, and repeatedly spawns the server program that actually handles the incomming commenctions. The spawned server programs under Server::Starter call accept(2) and handle the requests.

To gracefully restart the server program, send SIGHUP to the superdaemon. The superdaemon spawns a new server program, and if (and only if) it starts up successfully, sends SIGTERM to the old server program.

By using Server::Starter it is much easier to write a hot-deployable server. Following are the only requirements a server program to be run under Server::Starter should conform to:

- receive file descriptors to listen to through an environment variable - perform a graceful shutdown when receiving SIGTERM

A Net::Server personality that can be run under Server::Starter exists under the name Net::Server::SS::PreFork.

METHODS

server_ports

Returns one or more file descriptors on which the server program should call accept(2) in a hashref. Each element of the hashref is: (host:port|port)=file_descriptor.

start_server

Starts the superdaemon. Used by the strat_server scirpt.

AUTHOR

Kazuho Oku <kazuhooku@gmail.com> Copyright (C) 2009 Cybozu Labs, Inc.

SEE ALSO

Net::Server::SS::PreFork

LICENSE

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.