Display error logs if write fails due to a bad socket

[abicky]

I want to display error logs so that I can notice that write fails, but currently no logs are displayed even if write fails due to a bad socket.
I confirmed the behavior using the following script:

require 'logger'
require 'socket'
require 'datadog/statsd'

socket_path = '/tmp/datadog/dsd.socket'
Thread.new do
  2.times do
    sock = Socket.new(:UNIX, :DGRAM, 0)
    sock.bind(Addrinfo.unix(socket_path))

    3.times do
      puts "Received: #{sock.recvfrom_nonblock(128).first}"
    rescue IO::WaitReadable
      sleep 0.1
      retry
    end
    puts "Close socket"
    sock.close
    File.unlink(socket_path)
    sleep 2
  end
end

logger = Logger.new($stdout)
logger.level = Logger::INFO
statsd = Datadog::Statsd.new(nil, nil, socket_path: socket_path, logger: logger)
while true
  print 'increment: '
  p statsd.increment("page.views")
  sleep 1
end

Before

$ ruby /path/to/script
increment: 14
Received: page.views:1|c
increment: 14
Received: page.views:1|c
increment: 14
Received: page.views:1|c
Close socket
increment: nil
increment: nil
increment: 14
Received: page.views:1|c

After

$ ruby /path/to/script
increment: 14
Received: page.views:1|c
increment: 14
Received: page.views:1|c
increment: 14
Received: page.views:1|c
Close socket
increment: E, [2018-07-30T18:58:03.582215 #41583] ERROR -- : Statsd: Datadog::Statsd::UDSConnection::BadSocketError Errno::ECONNRESET: Connection reset by peer - sendmsg(2)
nil
increment: E, [2018-07-30T18:58:04.583728 #41583] ERROR -- : Statsd: Datadog::Statsd::UDSConnection::BadSocketError Errno::ENOENT: No such file or directory - connect(2) for /tmp/datadog/dsd.socket
nil
increment: 14
Received: page.views:1|c

[albertvaka]

Thanks for the patch! This makes sense and the code looks better after splitting the Connection in two.

I had to fix a small conflict, but it's good to merge 😄

Sorry it took a year to review this... and thanks again!