text: """Base class extended by connection adapters. This extends the
  connection.Connection class to encapsulate connection behavior but still
  isolate socket and low level communication.
  
  """
  import errno
  import logging
  import socket
  import ssl
  
  import pika.compat
  from pika import connection
  
  try:
      SOL_TCP = socket.SOL_TCP
  except AttributeError:
      SOL_TCP = 6
  
  
  if pika.compat.PY2:
      _SOCKET_ERROR = socket.error
  else:
      # socket.error was deprecated and replaced by OSError in python 3.3
      _SOCKET_ERROR = OSError
  
  
  LOGGER = logging.getLogger(__name__)
  
  
  class BaseConnection(connection.Connection):
      """BaseConnection class that should be extended by connection adapters"""
  
      # Use epoll's constants to keep life easy
      READ = 0x0001
      WRITE = 0x0004
      ERROR = 0x0008
  
      ERRORS_TO_ABORT = [errno.EBADF, errno.ECONNABORTED, errno.EPIPE]
      ERRORS_TO_IGNORE = [errno.EWOULDBLOCK, errno.EAGAIN, errno.EINTR]
      DO_HANDSHAKE = True
      WARN_ABOUT_IOLOOP = False
  
      def __init__(self,
                   parameters=None,
                   on_open_callback=None,
                   on_open_error_callback=None,
                   on_close_callback=None,
                   ioloop=None,
                   stop_ioloop_on_close=True):
          """Create a new instance of the Connection object.
  
          :param pika.connection.Parameters parameters: Connection parameters
          :param method on_open_callback: Method to call on connection open
          :param method on_open_error_callback: Called if the connection can't
              be established: on_open_error_callback(connection, str|exception)
          :param method on_close_callback: Called when the connection is closed:
              on_close_callback(connection, reason_code, reason_text)
          :param object ioloop: IOLoop object to use
          :param bool stop_ioloop_on_close: Call ioloop.stop() if disconnected
          :raises: RuntimeError
          :raises: ValueError
  
          """
          if parameters and not isinstance(parameters, connection.Parameters):
              raise ValueError('Expected instance of Parameters, not %r' %
                               parameters)
  
          # Let the developer know we could not import SSL
          if parameters and parameters.ssl and not ssl:
              raise RuntimeError("SSL specified but it is not available")
          self.base_events = self.READ | self.ERROR
          self.event_state = self.base_events
          self.ioloop = ioloop
          self.socket = None
          self.stop_ioloop_on_close = stop_ioloop_on_close
          self.write_buffer = None
          super(BaseConnection, self).__init__(parameters, on_open_callback,
                                               on_open_error_callback,
                                               on_close_callback)
  
      def __repr__(self):
          def get_socket_repr(sock):
              if sock is None:
                  return None
  
              sockname = sock.getsockname()
  
              peername = None
              try:
                  peername = sock.getpeername()
              except socket.error:
                  # not connected?
                  pass
  
              return '%s->%s' % (sockname, peername)
  
          return (
              '<%s state=%s socket=%s params=%s>' %
              (self.__class__.__name__,
               self.connection_state,
               get_socket_repr(self.socket),
               self.params))
  
      def add_timeout(self, deadline, callback_method):
          """Add the callback_method to the IOLoop timer to fire after deadline
          seconds. Returns a handle to the timeout
  
          :param int deadline: The number of seconds to wait to call callback
          :param method callback_method: The callback method
          :rtype: str
  
          """
          return self.ioloop.add_timeout(deadline, callback_method)
  
      def close(self, reply_code=200, reply_text='Normal shutdown'):
          """Disconnect from RabbitMQ. If there are any open channels, it will
          attempt to close them prior to fully disconnecting. Channels which
          have active consumers will attempt to send a Basic.Cancel to RabbitMQ
          to cleanly stop the delivery of messages prior to closing the channel.
  
          :param int reply_code: The code number for the close
          :param str reply_text: The text reason for the close
  
          """
          try:
              super(BaseConnection, self).close(reply_code, reply_text)
          finally:
              if self.is_closed:
                  self._handle_ioloop_stop()
  
      def remove_timeout(self, timeout_id):
          """Remove the timeout from the IOLoop by the ID returned from
          add_timeout.
  
          :rtype: str
  
          """
          self.ioloop.remove_timeout(timeout_id)
  
      def _adapter_connect(self):
          """Connect to the RabbitMQ broker, returning True if connected.
  
          :returns: error string or exception instance on error; None on success
  
          """
          # Get the addresses for the socket, supporting IPv4 & IPv6
          while True:
              try:
                  addresses = socket.getaddrinfo(self.params.host,
                                                 self.params.port,
                                                 0, socket.SOCK_STREAM,
                                                 socket.IPPROTO_TCP)
                  break
              except _SOCKET_ERROR as error:
                  if error.errno == errno.EINTR:
                      continue
  
                  LOGGER.critical('Could not get addresses to use: %s (%s)', error,
                                  self.params.host)
                  return error
  
          # If the socket is created and connected, continue on
          error = "No socket addresses available"
          for sock_addr in addresses:
              error = self._create_and_connect_to_socket(sock_addr)
              if not error:
                  # Make the socket non-blocking after the connect
                  self.socket.setblocking(0)
                  return None
              self._cleanup_socket()
  
          # Failed to connect
          return error
  
      def _adapter_disconnect(self):
          """Invoked if the connection is being told to disconnect"""
          try:
              self._cleanup_socket()
          finally:
              self._handle_ioloop_stop()
  
      def _cleanup_socket(self):
          """Close the socket cleanly"""
          if self.socket:
              try:
                  self.socket.shutdown(socket.SHUT_RDWR)
              except _SOCKET_ERROR:
                  pass
              self.socket.close()
              self.socket = None
  
      def _create_and_connect_to_socket(self, sock_addr_tuple):
          """Create socket and connect to it, using SSL if enabled.
  
          :returns: error string on failure; None on success
          """
          self.socket = socket.socket(sock_addr_tuple[0], socket.SOCK_STREAM, 0)
          self.socket.setsockopt(SOL_TCP, socket.TCP_NODELAY, 1)
          self.socket.settimeout(self.params.socket_timeout)
  
          # Wrap socket if using SSL
          if self.params.ssl:
              self.socket = self._wrap_socket(self.socket)
              ssl_text = " with SSL"
          else:
              ssl_text = ""
  
          LOGGER.info('Connecting to %s:%s%s', sock_addr_tuple[4][0],
                      sock_addr_tuple[4][1], ssl_text)
  
          # Connect to the socket
          try:
              self.socket.connect(sock_addr_tuple[4])
          except socket.timeout:
              error = 'Connection to %s:%s failed: timeout' % (
                  sock_addr_tuple[4][0], sock_addr_tuple[4][1]
              )
              LOGGER.error(error)
              return error
          except _SOCKET_ERROR as error:
              error = 'Connection to %s:%s failed: %s' % (sock_addr_tuple[4][0],
                                                          sock_addr_tuple[4][1],
                                                          error)
              LOGGER.warning(error)
              return error
  
          # Handle SSL Connection Negotiation
          if self.params.ssl and self.DO_HANDSHAKE:
              try:
                  self._do_ssl_handshake()
              except ssl.SSLError as error:
                  error = 'SSL connection to %s:%s failed: %s' % (
                      sock_addr_tuple[4][0], sock_addr_tuple[4][1], error
                  )
                  LOGGER.error(error)
                  return error
          # Made it this far
          return None
  
      def _do_ssl_handshake(self):
          """Perform SSL handshaking, copied from python stdlib test_ssl.py.
  
          """
          if not self.DO_HANDSHAKE:
              return
          while True:
              try:
                  self.socket.do_handshake()
                  break
              except ssl.SSLError as err:
                  if err.args[0] == ssl.SSL_ERROR_WANT_READ:
                      self.event_state = self.READ
                  elif err.args[0] == ssl.SSL_ERROR_WANT_WRITE:
                      self.event_state = self.WRITE
                  else:
                      raise
                  self._manage_event_state()
  
      @staticmethod
      def _get_error_code(error_value):
          """Get the error code from the error_value accounting for Python
          version differences.
  
          :rtype: int
  
          """
          if not error_value:
              return None
  
          if hasattr(error_value, 'errno'):  # Python >= 2.6
              return error_value.errno
          else:
              # TODO: this doesn't look right; error_value.args[0] ??? Could
              # probably remove this code path since pika doesn't test against
              # Python 2.5
              return error_value[0]  # Python <= 2.5
  
      def _flush_outbound(self):
          """Have the state manager schedule the necessary I/O.
          """
          # NOTE: We don't call _handle_write() from this context, because pika
          # code was not designed to be writing to (or reading from) the socket
          # from any methods, except from ioloop handler callbacks. Many methods
          # in pika core and adapters do not deal gracefully with connection
          # errors occurring in their context; e.g., Connection.channel (pika
          # issue #659), Connection._on_connection_tune (if connection loss is
          # detected in _send_connection_tune_ok, before _send_connection_open is
          # called), etc., etc., etc.
          self._manage_event_state()
  
      def _handle_ioloop_stop(self):
          """Invoked when the connection is closed to determine if the IOLoop
          should be stopped or not.
  
          """
          if self.stop_ioloop_on_close and self.ioloop:
              self.ioloop.stop()
          elif self.WARN_ABOUT_IOLOOP:
              LOGGER.warning('Connection is closed but not stopping IOLoop')
  
      def _handle_error(self, error_value):
          """Internal error handling method. Here we expect a socket.error
          coming in and will handle different socket errors differently.
  
          :param int|object error_value: The inbound error
  
          """
          # TODO: doesn't seem right: docstring defines error_value as int|object,
          # but _get_error_code expects a falsie or an exception-like object
          error_code = self._get_error_code(error_value)
  
          if not error_code:
              LOGGER.critical("Tried to handle an error where no error existed")
              return
  
          # Ok errors, just continue what we were doing before
          if error_code in self.ERRORS_TO_IGNORE:
              LOGGER.debug("Ignoring %s", error_code)
              return
  
          # Socket is no longer connected, abort
          elif error_code in self.ERRORS_TO_ABORT:
              LOGGER.error("Fatal Socket Error: %r", error_value)
  
          elif self.params.ssl and isinstance(error_value, ssl.SSLError):
  
              if error_value.args[0] == ssl.SSL_ERROR_WANT_READ:
                  # TODO: doesn't seem right: this logic updates event state, but
                  # the logic at the bottom unconditionaly disconnects anyway.
                  self.event_state = self.READ
              elif error_value.args[0] == ssl.SSL_ERROR_WANT_WRITE:
                  self.event_state = self.WRITE
              else:
                  LOGGER.error("SSL Socket error: %r", error_value)
  
          else:
              # Haven't run into this one yet, log it.
              LOGGER.error("Socket Error: %s", error_code)
  
          # Disconnect from our IOLoop and let Connection know what's up
          self._on_terminate(connection.InternalCloseReasons.SOCKET_ERROR,
                             repr(error_value))
  
      def _handle_timeout(self):
          """Handle a socket timeout in read or write.
          We don't do anything in the non-blocking handlers because we
          only have the socket in a blocking state during connect."""
          LOGGER.warning("Unexpected socket timeout")
  
      def _handle_events(self, fd, events, error=None, write_only=False):
          """Handle IO/Event loop events, processing them.
  
          :param int fd: The file descriptor for the events
          :param int events: Events from the IO/Event loop
          :param int error: Was an error specified; TODO none of the current
            adapters appear to be able to pass the `error` arg - is it needed?
          :param bool write_only: Only handle write events
  
          """
          if not self.socket:
              LOGGER.error('Received events on closed socket: %r', fd)
              return
  
          if self.socket and (events & self.WRITE):
              self._handle_write()
              self._manage_event_state()
  
          if self.socket and not write_only and (events & self.READ):
              self._handle_read()
  
          if (self.socket and write_only and (events & self.READ) and
                  (events & self.ERROR)):
              error_msg = ('BAD libc:  Write-Only but Read+Error. '
                           'Assume socket disconnected.')
              LOGGER.error(error_msg)
              self._on_terminate(connection.InternalCloseReasons.SOCKET_ERROR,
                                 error_msg)
  
          if self.socket and (events & self.ERROR):
              LOGGER.error('Error event %r, %r', events, error)
              self._handle_error(error)
  
      def _handle_read(self):
          """Read from the socket and call our on_data_available with the data."""
          try:
              while True:
                  try:
                      if self.params.ssl:
                          data = self.socket.read(self._buffer_size)
                      else:
                          data = self.socket.recv(self._buffer_size)
  
                      break
                  except _SOCKET_ERROR as error:
                      if error.errno == errno.EINTR:
                          continue
                      else:
                          raise
  
          except socket.timeout:
              self._handle_timeout()
              return 0
  
          except ssl.SSLError as error:
              if error.args[0] == ssl.SSL_ERROR_WANT_READ:
                  # ssl wants more data but there is nothing currently
                  # available in the socket, wait for it to become readable.
                  return 0
              return self._handle_error(error)
  
          except _SOCKET_ERROR as error:
              if error.errno in (errno.EAGAIN, errno.EWOULDBLOCK):
                  return 0
              return self._handle_error(error)
  
          # Empty data, should disconnect
          if not data or data == 0:
              LOGGER.error('Read empty data, calling disconnect')
              return self._on_terminate(
                  connection.InternalCloseReasons.SOCKET_ERROR,
                  "EOF")
  
          # Pass the data into our top level frame dispatching method
          self._on_data_available(data)
          return len(data)
  
      def _handle_write(self):
          """Try and write as much as we can, if we get blocked requeue
          what's left"""
          total_bytes_sent = 0
          try:
              while self.outbound_buffer:
                  frame = self.outbound_buffer.popleft()
                  while True:
                      try:
                          num_bytes_sent = self.socket.send(frame)
                          break
                      except _SOCKET_ERROR as error:
                          if error.errno == errno.EINTR:
                              continue
                          else:
                              raise
  
                  total_bytes_sent += num_bytes_sent
                  if num_bytes_sent < len(frame):
                      LOGGER.debug("Partial write, requeing remaining data")
                      self.outbound_buffer.appendleft(frame[num_bytes_sent:])
                      break
  
          except socket.timeout:
              # Will only come here if the socket is blocking
              LOGGER.debug("socket timeout, requeuing frame")
              self.outbound_buffer.appendleft(frame)
              self._handle_timeout()
  
          except _SOCKET_ERROR as error:
              if error.errno in (errno.EAGAIN, errno.EWOULDBLOCK):
                  LOGGER.debug("Would block, requeuing frame")
                  self.outbound_buffer.appendleft(frame)
              else:
                  return self._handle_error(error)
  
          return total_bytes_sent
  
  
      def _init_connection_state(self):
          """Initialize or reset all of our internal state variables for a given
          connection. If we disconnect and reconnect, all of our state needs to
          be wiped.
  
          """
          super(BaseConnection, self)._init_connection_state()
          self.base_events = self.READ | self.ERROR
          self.event_state = self.base_events
          self.socket = None
  
      def _manage_event_state(self):
          """Manage the bitmask for reading/writing/error which is used by the
          io/event handler to specify when there is an event such as a read or
          write.
  
          """
          if self.outbound_buffer:
              if not self.event_state & self.WRITE:
                  self.event_state |= self.WRITE
                  self.ioloop.update_handler(self.socket.fileno(),
                                             self.event_state)
          elif self.event_state & self.WRITE:
              self.event_state = self.base_events
              self.ioloop.update_handler(self.socket.fileno(), self.event_state)
  
      def _wrap_socket(self, sock):
          """Wrap the socket for connecting over SSL.
  
          :rtype: ssl.SSLSocket
  
          """
          return ssl.wrap_socket(sock,
                                 do_handshake_on_connect=self.DO_HANDSHAKE,
                                 **self.params.ssl_options)
  