module TCPSocketExt

def self.prepended(base)

base.prepend Initializer

end

module Initializer

CONNECTION_TIMEOUT = 5

IPV4_DELAY_SECONDS = 0.1

def initialize(host, serv, *rest)

mutex = Thread::Mutex.new

addrs = []

threads = []

cond_var = Thread::ConditionVariable.new

Addrinfo.foreach(host, serv, nil, :STREAM) do |addr|

Thread.report_on_exception = false

threads << Thread.new(addr) do

# give head start to ipv6 addresses

sleep IPV4_DELAY_SECONDS if addr.ipv4?

# raises Errno::ECONNREFUSED when ip:port is unreachable

Socket.tcp(addr.ip_address, serv, connect_timeout: CONNECTION_TIMEOUT).close

mutex.synchronize do

addrs << addr.ip_address

cond_var.signal

end

end

end

mutex.synchronize do

timeout_time = CONNECTION_TIMEOUT + Time.now.to_f

while addrs.empty? && (remaining_time = timeout_time - Time.now.to_f) > 0

cond_var.wait(mutex, remaining_time)

end

host = addrs.shift unless addrs.empty?

end

threads.each {|t| t.kill.join if t.alive? }

super(host, serv, *rest)

end

end

end