Sharing DB connections across objects using class methods in ruby? - ruby

Question

I am writing a ruby script to be used as Postfix SMTP access policy delegation. The script needs to access a Tokyo Tyrant database. I am using EventMachine to take care of network connections. EventMachine needs a EventMachine::Connection class that is instantiated by EventMachine‘s processing loop whenever a new connection is created. so for each connection a class is instantiated and destroyed.
I am creating a connection to Tokyo Tyrant from the post_init of the EventMachine::Connection (ie right after connection is setup) and tearing it down after connection is terminated.
My question is if this is the proper way to connect to db? ie making a connection every yime I need it and tearing it down after I am finished? Wouldn't be better to connect to DB once (when program is started) tear it down during program shutdown? If that is so how should I code that ?
My code is:
require 'rubygems'
require 'eventmachine'
require 'rufus/tokyo/tyrant'
class LineCounter < EM::Connection
ActionAllow = "action=dunno\n\n"
def post_init
puts "Received a new connection"
#tokyo = Rufus::Tokyo::Tyrant.new('server', 1978)
#data_received = ""
end
def receive_data data
#data_received << data
#data_received.lines do |line|
key = line.split('=')[0]
value = line.split('=')[1]
#reverse_client_name = value.strip() if key == 'reverse_client_name'
#client_address = value.strip() if key == 'client_address'
#tokyo[#client_address] = #reverse_client_name
end
puts #client_address, #reverse_client_name
send_data ActionAllow
end
def unbind
#tokyo.close
end
end
EventMachine::run {
host,port = "127.0.0.1", 9997
EventMachine::start_server host, port, LineCounter
puts "Now accepting connections on address #{host}, port #{port}..."
EventMachine::add_periodic_timer( 10 ) { $stderr.write "*" }
}
with regards,
raj

Answer 1

Surprising there's no answers to this question.
What you probably need is a connection pool where you can fetch, use, and return connections as they are required.
class ConnectionPool
def initialize(&block)
#pool = [ ]
#generator = block
end
def fetch
#pool.shift or #generator and #generator.call
end
def release(handle)
#pool.push(handle)
end
def use
if (block_given?)
handle = fetch
yield(handle)
release(handle)
end
end
end
# Declare a pool with an appropriate connection generator
tokyo_pool = ConnectionPool.new do
Rufus::Tokyo::Tyrant.new('server', 1978)
end
# Fetch/Release cycle
tokyo = tokyo_pool.fetch
tokyo[#client_address] = #reverse_client_name
tokyo_pool.release(tokyo)
# Simple block-method for use
tokyo_pool.use do |tokyo|
tokyo[#client_address] = #reverse_client_name
end