In writing
cross-stub, i need to write specs to ensure cross process stubbing indeed work as expected. This is achieved by building a simple server/client using eventmachine, here's how
echo_server.rb looks like:
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| require 'rubygems'
require 'eventmachine'
require 'logger'
require 'base64'
module EchoServer
ADDRESS = '127.0.0.1'
PORT = 10999
LOG_FILE = '/tmp/echo_server.log'
INIT_WAIT_TIME = 2 # may need to increase this depending on how slow is ur machine
class << self
def log(*msg)
(@logger ||= Logger.new(LOG_FILE)) << [msg, ""].flatten.join("\n")
end
def cleanup
@logger.close
end
def start(other_process=false)
unless other_process
print 'Starting echo service ... '
@process = IO.popen("ruby #{__FILE__}",'r')
sleep INIT_WAIT_TIME
puts 'done (pid#%s)' % @process.pid
else
log 'Echo service (pid#%s) listening at %s:%s' % [Process.pid, ADDRESS, PORT]
EventMachine::run { EventMachine::start_server(ADDRESS, PORT, EM) }
end
end
def stop
Process.kill('SIGHUP', @process.pid) if @process
end
end
private
module EM
def receive_data(data)
log 'Received client data: %s' % data.inspect
result = process_data(data)
log 'Processed to yield result: %s' % result.inspect
send_data(Base64.encode64(Marshal.dump(result)))
end
def process_data(data)
# do some meaningful processing to yield result
result = '~ processed %s ~ ' % data
end
def log(*msg)
EchoServer.log(*msg)
end
end
end
if $0 == __FILE__
begin
EchoServer.start(true)
rescue
EchoServer.log "#{$!.inspect}\n"
ensure
EchoServer.cleanup
end
end
|
And
echo_client.rb:
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| # Keeping things DRY, avoid repeated typing of requiring statements &
# server specific info (eg. address & port)
require File.join(File.dirname(__FILE__), 'echo_server')
module EchoClient
ADDRESS = EchoServer::ADDRESS
PORT = EchoServer::PORT
class << self
def get(data)
EventMachine::run do
EventMachine::connect(ADDRESS, PORT, EM).execute(data) do |data|
@result = Marshal.load(Base64.decode64(data))
end
end
@result
end
end
private
module EM
def receive_data(data)
@callback.call(data)
EventMachine::stop_event_loop # ends loop & resumes program flow
end
def execute(method, &callback)
@callback = callback
send_data(method)
end
end
end
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And finally the example usage:
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| require File.join(File.dirname(__FILE__), 'echo_server')
require File.join(File.dirname(__FILE__), 'echo_client')
EchoServer.start
10.times do |i|
puts EchoClient.get(i)
end
EchoServer.stop
|
Personally, i prefer placing the server & client code inside a single file
echo_service.rb, since the client code is pretty coupled with the server code. One gotcha i've encountered while working with this server/client thingy is that error in the server hangs the client, that's why having the server log file is really useful in debugging.
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