eventmachine defer sample.

eventmachine-defer.rb

require 'bundler/setup'
require 'eventmachine'
require 'open-uri'

EM.run do
  puts "main: #{Thread.current}"

  operation = proc {
    puts "defer operation: #{Thread.current}"
    sleep(20)
    open('http://google.co.jp/').status
    //raise "errrrrrooooooorrrrrr"  ## raise error
  }

  callback = proc {|result|
    puts '--- callback # ------------------------------------------------------------------------------'
    puts "defer callback: #{result}"
    puts "defer callback: #{Thread.current}"
    EM.stop
  }

  errorback = proc {|error|
    puts '--- error # ------------------------------------------------------------------------------'
    #puts "defer error: #{error}"
    puts "defer error: #{error}"
    puts "defer error: #{Thread.current}"
    EM.stop
  }

  puts '--- calling defer'
  EM.defer(operation, callback, errorback)
  puts '--- called defer'

end

result console: callback

main: #<Thread:0x007ffe3a8bc3c0>
--- calling defer
--- called defer
defer operation: #<Thread:0x007ffe3b136cd0>
--- callback # ------------------------------------------------------------------------------
defer callback: ["200", "OK"]
defer callback: #<Thread:0x007ffe3a8bc3c0>

result console: error callback (raise error)

main: #<Thread:0x007fb3e40bc3a0>
--- calling defer
--- called defer
defer operation: #<Thread:0x007fb3e427ae80>
--- error # ------------------------------------------------------------------------------
defer error: errrrrrooooooorrrrrr
defer error: #<Thread:0x007fb3e40bc3a0>