Class: Kafka::SSLSocketWithTimeout

Inherits:
Object
  • Object
show all
Defined in:
lib/kafka/ssl_socket_with_timeout.rb

Overview

Opens sockets in a non-blocking fashion, ensuring that we're not stalling for long periods of time.

It's possible to set timeouts for connecting to the server, for reading data, and for writing data. Whenever a timeout is exceeded, Errno::ETIMEDOUT is raised.

Instance Method Summary collapse

Constructor Details

#initialize(host, port, connect_timeout: nil, timeout: nil, ssl_context:) ⇒ SSLSocketWithTimeout

Opens a socket.

Parameters:

  • host (String)
  • port (Integer)
  • connect_timeout (Integer) (defaults to: nil) —

    the connection timeout, in seconds.

  • timeout (Integer) (defaults to: nil) —

    the read and write timeout, in seconds.

  • ssl_context (OpenSSL::SSL::SSLContext) —

    which SSLContext the ssl connection should use

Raises:

  • (Errno::ETIMEDOUT) —

    if the timeout is exceeded.



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# File 'lib/kafka/ssl_socket_with_timeout.rb', line 22

def initialize(host, port, connect_timeout: nil, timeout: nil, ssl_context:)
  addr = Socket.getaddrinfo(host, nil)
  sockaddr = Socket.pack_sockaddr_in(port, addr[0][3])

  @timeout = timeout

  @tcp_socket = Socket.new(Socket.const_get(addr[0][0]), Socket::SOCK_STREAM, 0)
  @tcp_socket.setsockopt(Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1)

  # first initiate the TCP socket
  begin
    # Initiate the socket connection in the background. If it doesn't fail 
    # immediately it will raise an IO::WaitWritable (Errno::EINPROGRESS) 
    # indicating the connection is in progress.
    @tcp_socket.connect_nonblock(sockaddr)
  rescue IO::WaitWritable
    # IO.select will block until the socket is writable or the timeout
    # is exceeded, whichever comes first.
    unless IO.select(nil, [@tcp_socket], nil, connect_timeout)
      # IO.select returns nil when the socket is not ready before timeout 
      # seconds have elapsed
      @tcp_socket.close
      raise Errno::ETIMEDOUT
    end

    begin
      # Verify there is now a good connection.
      @tcp_socket.connect_nonblock(sockaddr)
    rescue Errno::EISCONN
      # The socket is connected, we're good!
    end
  end

  # once that's connected, we can start initiating the ssl socket
  @ssl_socket = OpenSSL::SSL::SSLSocket.new(@tcp_socket, ssl_context)

  begin
    # Initiate the socket connection in the background. If it doesn't fail 
    # immediately it will raise an IO::WaitWritable (Errno::EINPROGRESS) 
    # indicating the connection is in progress.
    # Unlike waiting for a tcp socket to connect, you can't time out ssl socket
    # connections during the connect phase properly, because IO.select only partially works.
    # Instead, you have to retry.
    @ssl_socket.connect_nonblock
  rescue Errno::EAGAIN, Errno::EWOULDBLOCK, IO::WaitReadable
    IO.select([@ssl_socket])
    retry
  rescue IO::WaitWritable
    IO.select(nil, [@ssl_socket])
    retry
  end
end

Instance Method Details

#close ⇒ Object 



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# File 'lib/kafka/ssl_socket_with_timeout.rb', line 145

def close
  @tcp_socket.close
  @ssl_socket.close
end

#read(num_bytes) ⇒ String

Reads bytes from the socket, possible with a timeout.

Parameters:

  • num_bytes (Integer) —

    the number of bytes to read.

Returns:

  • (String) —

    the data that was read from the socket.

Raises:

  • (Errno::ETIMEDOUT) —

    if the timeout is exceeded.



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# File 'lib/kafka/ssl_socket_with_timeout.rb', line 80

def read(num_bytes)
  buffer = ''
  until buffer.length >= num_bytes
    begin
      # unlike plain tcp sockets, ssl sockets don't support IO.select
      # properly.
      # Instead, timeouts happen on a per read basis, and we have to
      # catch exceptions from read_nonblock, and gradually build up
      # our read buffer.
      buffer << @ssl_socket.read_nonblock(num_bytes - buffer.length)
    rescue IO::WaitReadable
      unless IO.select([@ssl_socket], nil, nil, @timeout)
        raise Errno::ETIMEDOUT
      end
      retry
    rescue IO::WaitWritable
      unless IO.select(nil, [@ssl_socket], nil, @timeout)
        raise Errno::ETIMEDOUT
      end
      retry
    end
  end
  buffer
end

#set_encoding(encoding) ⇒ Object 



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# File 'lib/kafka/ssl_socket_with_timeout.rb', line 150

def set_encoding(encoding)
  @tcp_socket.set_encoding(encoding)
end

#write(bytes) ⇒ Integer

Writes bytes to the socket, possible with a timeout.

Parameters:

  • bytes (String) —

    the data that should be written to the socket.

Returns:

  • (Integer) —

    the number of bytes written.

Raises:

  • (Errno::ETIMEDOUT) —

    if the timeout is exceeded.



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# File 'lib/kafka/ssl_socket_with_timeout.rb', line 110

def write(bytes)
  loop do
    written = 0
    begin
      # unlike plain tcp sockets, ssl sockets don't support IO.select
      # properly.
      # Instead, timeouts happen on a per write basis, and we have to
      # catch exceptions from write_nonblock, and gradually build up
      # our write buffer.
      written += @ssl_socket.write_nonblock(bytes)
    rescue Errno::EFAULT => error
        raise error
    rescue OpenSSL::SSL::SSLError, Errno::EAGAIN, Errno::EWOULDBLOCK, IO::WaitWritable => error
      if error.is_a?(OpenSSL::SSL::SSLError) && error.message == 'write would block'
        if IO.select(nil, [@ssl_socket], nil, @timeout)
          retry
        else
          raise Errno::ETIMEDOUT
        end
      else
        raise error
      end
    end

    # Fast, common case.
    break if written == bytes.size

    # This takes advantage of the fact that most ruby implementations
    # have Copy-On-Write strings. Thusly why requesting a subrange
    # of data, we actually don't copy data because the new string
    # simply references a subrange of the original.
    bytes = bytes[written, bytes.size]
  end
end