echo-server.rb

#
# A simple pre-forking server that tests to make sure the MySQL server
# is available.
#
# Based so heavily on the following article by Ryan Tomakyo that it's
# practically a verbatim copy.
#
#  http://tomayko.com/writings/unicorn-is-unix
#
# Pasted at http://gist.github.com/213990
#

require 'socket'
require 'mysql'

# configuration
BIND_ADDRESS = '127.0.0.1'
BIND_PORT = '9999'
NUM_PROCESSES = 5
MYSQL_HOST = 'beatrix.escapecs.com'
MYSQL_USER = 'someone'
MYSQL_PASSWORD = 'pa$$w0rd'
MYSQL_DATABASE = 'testdb'

# create a socket and bind to port
acceptor = Socket.new(Socket::AF_INET, Socket::SOCK_STREAM, 0)
address = Socket.pack_sockaddr_in(BIND_PORT, BIND_ADDRESS)
acceptor.bind(address)

# start listening on the socket
acceptor.listen(10)

# trap for a process exit and stop listening
trap('EXIT') {

  acceptor.close
}

# fork the child processes
NUM_PROCESSES.times do

  fork do

    # trap for process break and exit
    trap('INT') { exit }

    puts "child #$$ accepting on shared socket (localhost:9999)"

    loop {

      # block until a new connection is ready to be de-queued
      socket, addr = acceptor.accept      

      # get the incoming message
      incoming_message = socket.gets
      
      # flag to indicate successful connection
      mysql_server_connect = false
      
      begin

        # connect to the MySQL server begin connect = connection =
        connection = Mysql.real_connect(MYSQL_HOST, MYSQL_USER, MYSQL_PASSWORD,
                                        MYSQL_DATABASE)

        server_version = connection.get_server_info

        message = "MySQL Server (version #{server_version}) is A-Okay!\n\n"
        mysql_server_connect = true
      rescue

        message = "Uh-oh! The MySQL Server did not respond. :(\n\n"
      ensure

        connection.close if connection
      end

      # send our status
      if mysql_server_connect

        socket.write "HTTP/1.1 200 OK\n"
      else

        socket.write "HTTP/1.1 503 Service Unavailable\n"
      end

      # send the header
      socket.write "Date: #{Time.now}\r\n"
      socket.write "Server: Simple Ruby Server\r\n"
      socket.write "Expires: #{Time.now}\r\n"
      socket.write "Content-Type: text/html; charset=UTF-8\r\n"
      socket.write "\r\n"

      # send out message
      socket.write message
           
      # close the socket
      socket.flush
      socket.close

      puts "child #$$ invoked with: '#{incoming_message.strip}'"
    }
  end
end

# trap interrupt and exit
trap('INT') {

  puts "Exiting..."
  exit
}

# wait for all child processes to exit
Process.waitall