text: # -*- Mode: Python -*-
  #   Id: asyncore.py,v 2.51 2000/09/07 22:29:26 rushing Exp
  #   Author: Sam Rushing <rushing@nightmare.com>
  
  # ======================================================================
  # Copyright 1996 by Sam Rushing
  #
  #                         All Rights Reserved
  #
  # Permission to use, copy, modify, and distribute this software and
  # its documentation for any purpose and without fee is hereby
  # granted, provided that the above copyright notice appear in all
  # copies and that both that copyright notice and this permission
  # notice appear in supporting documentation, and that the name of Sam
  # Rushing not be used in advertising or publicity pertaining to
  # distribution of the software without specific, written prior
  # permission.
  #
  # SAM RUSHING DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  # INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN
  # NO EVENT SHALL SAM RUSHING BE LIABLE FOR ANY SPECIAL, INDIRECT OR
  # CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
  # OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
  # NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
  # CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  # ======================================================================
  
  """Basic infrastructure for asynchronous socket service clients and servers.
  
  There are only two ways to have a program on a single processor do "more
  than one thing at a time".  Multi-threaded programming is the simplest and
  most popular way to do it, but there is another very different technique,
  that lets you have nearly all the advantages of multi-threading, without
  actually using multiple threads. it's really only practical if your program
  is largely I/O bound. If your program is CPU bound, then pre-emptive
  scheduled threads are probably what you really need. Network servers are
  rarely CPU-bound, however.
  
  If your operating system supports the select() system call in its I/O
  library (and nearly all do), then you can use it to juggle multiple
  communication channels at once; doing other work while your I/O is taking
  place in the "background."  Although this strategy can seem strange and
  complex, especially at first, it is in many ways easier to understand and
  control than multi-threaded programming. The module documented here solves
  many of the difficult problems for you, making the task of building
  sophisticated high-performance network servers and clients a snap.
  """
  
  import select
  import socket
  import sys
  import time
  import warnings
  
  import os
  from errno import EALREADY, EINPROGRESS, EWOULDBLOCK, ECONNRESET, EINVAL, \
       ENOTCONN, ESHUTDOWN, EISCONN, EBADF, ECONNABORTED, EPIPE, EAGAIN, \
       errorcode
  
  _DISCONNECTED = frozenset({ECONNRESET, ENOTCONN, ESHUTDOWN, ECONNABORTED, EPIPE,
                             EBADF})
  
  try:
      socket_map
  except NameError:
      socket_map = {}
  
  def _strerror(err):
      try:
          return os.strerror(err)
      except (ValueError, OverflowError, NameError):
          if err in errorcode:
              return errorcode[err]
          return "Unknown error %s" %err
  
  class ExitNow(Exception):
      pass
  
  _reraised_exceptions = (ExitNow, KeyboardInterrupt, SystemExit)
  
  def read(obj):
      try:
          obj.handle_read_event()
      except _reraised_exceptions:
          raise
      except:
          obj.handle_error()
  
  def write(obj):
      try:
          obj.handle_write_event()
      except _reraised_exceptions:
          raise
      except:
          obj.handle_error()
  
  def _exception(obj):
      try:
          obj.handle_expt_event()
      except _reraised_exceptions:
          raise
      except:
          obj.handle_error()
  
  def readwrite(obj, flags):
      try:
          if flags & select.POLLIN:
              obj.handle_read_event()
          if flags & select.POLLOUT:
              obj.handle_write_event()
          if flags & select.POLLPRI:
              obj.handle_expt_event()
          if flags & (select.POLLHUP | select.POLLERR | select.POLLNVAL):
              obj.handle_close()
      except OSError as e:
          if e.args[0] not in _DISCONNECTED:
              obj.handle_error()
          else:
              obj.handle_close()
      except _reraised_exceptions:
          raise
      except:
          obj.handle_error()
  
  def poll(timeout=0.0, map=None):
      if map is None:
          map = socket_map
      if map:
          r = []; w = []; e = []
          for fd, obj in list(map.items()):
              is_r = obj.readable()
              is_w = obj.writable()
              if is_r:
                  r.append(fd)
              # accepting sockets should not be writable
              if is_w and not obj.accepting:
                  w.append(fd)
              if is_r or is_w:
                  e.append(fd)
          if [] == r == w == e:
              time.sleep(timeout)
              return
  
          r, w, e = select.select(r, w, e, timeout)
  
          for fd in r:
              obj = map.get(fd)
              if obj is None:
                  continue
              read(obj)
  
          for fd in w:
              obj = map.get(fd)
              if obj is None:
                  continue
              write(obj)
  
          for fd in e:
              obj = map.get(fd)
              if obj is None:
                  continue
              _exception(obj)
  
  def poll2(timeout=0.0, map=None):
      # Use the poll() support added to the select module in Python 2.0
      if map is None:
          map = socket_map
      if timeout is not None:
          # timeout is in milliseconds
          timeout = int(timeout*1000)
      pollster = select.poll()
      if map:
          for fd, obj in list(map.items()):
              flags = 0
              if obj.readable():
                  flags |= select.POLLIN | select.POLLPRI
              # accepting sockets should not be writable
              if obj.writable() and not obj.accepting:
                  flags |= select.POLLOUT
              if flags:
                  pollster.register(fd, flags)
  
          r = pollster.poll(timeout)
          for fd, flags in r:
              obj = map.get(fd)
              if obj is None:
                  continue
              readwrite(obj, flags)
  
  poll3 = poll2                           # Alias for backward compatibility
  
  def loop(timeout=30.0, use_poll=False, map=None, count=None):
      if map is None:
          map = socket_map
  
      if use_poll and hasattr(select, 'poll'):
          poll_fun = poll2
      else:
          poll_fun = poll
  
      if count is None:
          while map:
              poll_fun(timeout, map)
  
      else:
          while map and count > 0:
              poll_fun(timeout, map)
              count = count - 1
  
  class dispatcher:
  
      debug = False
      connected = False
      accepting = False
      connecting = False
      closing = False
      addr = None
      ignore_log_types = frozenset({'warning'})
  
      def __init__(self, sock=None, map=None):
          if map is None:
              self._map = socket_map
          else:
              self._map = map
  
          self._fileno = None
  
          if sock:
              # Set to nonblocking just to make sure for cases where we
              # get a socket from a blocking source.
              sock.setblocking(False)
              self.set_socket(sock, map)
              self.connected = True
              # The constructor no longer requires that the socket
              # passed be connected.
              try:
                  self.addr = sock.getpeername()
              except OSError as err:
                  if err.args[0] in (ENOTCONN, EINVAL):
                      # To handle the case where we got an unconnected
                      # socket.
                      self.connected = False
                  else:
                      # The socket is broken in some unknown way, alert
                      # the user and remove it from the map (to prevent
                      # polling of broken sockets).
                      self.del_channel(map)
                      raise
          else:
              self.socket = None
  
      def __repr__(self):
          status = [self.__class__.__module__+"."+self.__class__.__qualname__]
          if self.accepting and self.addr:
              status.append('listening')
          elif self.connected:
              status.append('connected')
          if self.addr is not None:
              try:
                  status.append('%s:%d' % self.addr)
              except TypeError:
                  status.append(repr(self.addr))
          return '<%s at %#x>' % (' '.join(status), id(self))
  
      def add_channel(self, map=None):
          #self.log_info('adding channel %s' % self)
          if map is None:
              map = self._map
          map[self._fileno] = self
  
      def del_channel(self, map=None):
          fd = self._fileno
          if map is None:
              map = self._map
          if fd in map:
              #self.log_info('closing channel %d:%s' % (fd, self))
              del map[fd]
          self._fileno = None
  
      def create_socket(self, family=socket.AF_INET, type=socket.SOCK_STREAM):
          self.family_and_type = family, type
          sock = socket.socket(family, type)
          sock.setblocking(False)
          self.set_socket(sock)
  
      def set_socket(self, sock, map=None):
          self.socket = sock
          self._fileno = sock.fileno()
          self.add_channel(map)
  
      def set_reuse_addr(self):
          # try to re-use a server port if possible
          try:
              self.socket.setsockopt(
                  socket.SOL_SOCKET, socket.SO_REUSEADDR,
                  self.socket.getsockopt(socket.SOL_SOCKET,
                                         socket.SO_REUSEADDR) | 1
                  )
          except OSError:
              pass
  
      # ==================================================
      # predicates for select()
      # these are used as filters for the lists of sockets
      # to pass to select().
      # ==================================================
  
      def readable(self):
          return True
  
      def writable(self):
          return True
  
      # ==================================================
      # socket object methods.
      # ==================================================
  
      def listen(self, num):
          self.accepting = True
          if os.name == 'nt' and num > 5:
              num = 5
          return self.socket.listen(num)
  
      def bind(self, addr):
          self.addr = addr
          return self.socket.bind(addr)
  
      def connect(self, address):
          self.connected = False
          self.connecting = True
          err = self.socket.connect_ex(address)
          if err in (EINPROGRESS, EALREADY, EWOULDBLOCK) \
          or err == EINVAL and os.name == 'nt':
              self.addr = address
              return
          if err in (0, EISCONN):
              self.addr = address
              self.handle_connect_event()
          else:
              raise OSError(err, errorcode[err])
  
      def accept(self):
          # XXX can return either an address pair or None
          try:
              conn, addr = self.socket.accept()
          except TypeError:
              return None
          except OSError as why:
              if why.args[0] in (EWOULDBLOCK, ECONNABORTED, EAGAIN):
                  return None
              else:
                  raise
          else:
              return conn, addr
  
      def send(self, data):
          try:
              result = self.socket.send(data)
              return result
          except OSError as why:
              if why.args[0] == EWOULDBLOCK:
                  return 0
              elif why.args[0] in _DISCONNECTED:
                  self.handle_close()
                  return 0
              else:
                  raise
  
      def recv(self, buffer_size):
          try:
              data = self.socket.recv(buffer_size)
              if not data:
                  # a closed connection is indicated by signaling
                  # a read condition, and having recv() return 0.
                  self.handle_close()
                  return b''
              else:
                  return data
          except OSError as why:
              # winsock sometimes raises ENOTCONN
              if why.args[0] in _DISCONNECTED:
                  self.handle_close()
                  return b''
              else:
                  raise
  
      def close(self):
          self.connected = False
          self.accepting = False
          self.connecting = False
          self.del_channel()
          if self.socket is not None:
              try:
                  self.socket.close()
              except OSError as why:
                  if why.args[0] not in (ENOTCONN, EBADF):
                      raise
  
      # log and log_info may be overridden to provide more sophisticated
      # logging and warning methods. In general, log is for 'hit' logging
      # and 'log_info' is for informational, warning and error logging.
  
      def log(self, message):
          sys.stderr.write('log: %s\n' % str(message))
  
      def log_info(self, message, type='info'):
          if type not in self.ignore_log_types:
              print('%s: %s' % (type, message))
  
      def handle_read_event(self):
          if self.accepting:
              # accepting sockets are never connected, they "spawn" new
              # sockets that are connected
              self.handle_accept()
          elif not self.connected:
              if self.connecting:
                  self.handle_connect_event()
              self.handle_read()
          else:
              self.handle_read()
  
      def handle_connect_event(self):
          err = self.socket.getsockopt(socket.SOL_SOCKET, socket.SO_ERROR)
          if err != 0:
              raise OSError(err, _strerror(err))
          self.handle_connect()
          self.connected = True
          self.connecting = False
  
      def handle_write_event(self):
          if self.accepting:
              # Accepting sockets shouldn't get a write event.
              # We will pretend it didn't happen.
              return
  
          if not self.connected:
              if self.connecting:
                  self.handle_connect_event()
          self.handle_write()
  
      def handle_expt_event(self):
          # handle_expt_event() is called if there might be an error on the
          # socket, or if there is OOB data
          # check for the error condition first
          err = self.socket.getsockopt(socket.SOL_SOCKET, socket.SO_ERROR)
          if err != 0:
              # we can get here when select.select() says that there is an
              # exceptional condition on the socket
              # since there is an error, we'll go ahead and close the socket
              # like we would in a subclassed handle_read() that received no
              # data
              self.handle_close()
          else:
              self.handle_expt()
  
      def handle_error(self):
          nil, t, v, tbinfo = compact_traceback()
  
          # sometimes a user repr method will crash.
          try:
              self_repr = repr(self)
          except:
              self_repr = '<__repr__(self) failed for object at %0x>' % id(self)
  
          self.log_info(
              'uncaptured python exception, closing channel %s (%s:%s %s)' % (
                  self_repr,
                  t,
                  v,
                  tbinfo
                  ),
              'error'
              )
          self.handle_close()
  
      def handle_expt(self):
          self.log_info('unhandled incoming priority event', 'warning')
  
      def handle_read(self):
          self.log_info('unhandled read event', 'warning')
  
      def handle_write(self):
          self.log_info('unhandled write event', 'warning')
  
      def handle_connect(self):
          self.log_info('unhandled connect event', 'warning')
  
      def handle_accept(self):
          pair = self.accept()
          if pair is not None:
              self.handle_accepted(*pair)
  
      def handle_accepted(self, sock, addr):
          sock.close()
          self.log_info('unhandled accepted event', 'warning')
  
      def handle_close(self):
          self.log_info('unhandled close event', 'warning')
          self.close()
  
  # ---------------------------------------------------------------------------
  # adds simple buffered output capability, useful for simple clients.
  # [for more sophisticated usage use asynchat.async_chat]
  # ---------------------------------------------------------------------------
  
  class dispatcher_with_send(dispatcher):
  
      def __init__(self, sock=None, map=None):
          dispatcher.__init__(self, sock, map)
          self.out_buffer = b''
  
      def initiate_send(self):
          num_sent = 0
          num_sent = dispatcher.send(self, self.out_buffer[:65536])
          self.out_buffer = self.out_buffer[num_sent:]
  
      def handle_write(self):
          self.initiate_send()
  
      def writable(self):
          return (not self.connected) or len(self.out_buffer)
  
      def send(self, data):
          if self.debug:
              self.log_info('sending %s' % repr(data))
          self.out_buffer = self.out_buffer + data
          self.initiate_send()
  
  # ---------------------------------------------------------------------------
  # used for debugging.
  # ---------------------------------------------------------------------------
  
  def compact_traceback():
      t, v, tb = sys.exc_info()
      tbinfo = []
      if not tb: # Must have a traceback
          raise AssertionError("traceback does not exist")
      while tb:
          tbinfo.append((
              tb.tb_frame.f_code.co_filename,
              tb.tb_frame.f_code.co_name,
              str(tb.tb_lineno)
              ))
          tb = tb.tb_next
  
      # just to be safe
      del tb
  
      file, function, line = tbinfo[-1]
      info = ' '.join(['[%s|%s|%s]' % x for x in tbinfo])
      return (file, function, line), t, v, info
  
  def close_all(map=None, ignore_all=False):
      if map is None:
          map = socket_map
      for x in list(map.values()):
          try:
              x.close()
          except OSError as x:
              if x.args[0] == EBADF:
                  pass
              elif not ignore_all:
                  raise
          except _reraised_exceptions:
              raise
          except:
              if not ignore_all:
                  raise
      map.clear()
  
  # Asynchronous File I/O:
  #
  # After a little research (reading man pages on various unixen, and
  # digging through the linux kernel), I've determined that select()
  # isn't meant for doing asynchronous file i/o.
  # Heartening, though - reading linux/mm/filemap.c shows that linux
  # supports asynchronous read-ahead.  So _MOST_ of the time, the data
  # will be sitting in memory for us already when we go to read it.
  #
  # What other OS's (besides NT) support async file i/o?  [VMS?]
  #
  # Regardless, this is useful for pipes, and stdin/stdout...
  
  if os.name == 'posix':
      class file_wrapper:
          # Here we override just enough to make a file
          # look like a socket for the purposes of asyncore.
          # The passed fd is automatically os.dup()'d
  
          def __init__(self, fd):
              self.fd = os.dup(fd)
  
          def __del__(self):
              if self.fd >= 0:
                  warnings.warn("unclosed file %r" % self, ResourceWarning,
                                source=self)
              self.close()
  
          def recv(self, *args):
              return os.read(self.fd, *args)
  
          def send(self, *args):
              return os.write(self.fd, *args)
  
          def getsockopt(self, level, optname, buflen=None):
              if (level == socket.SOL_SOCKET and
                  optname == socket.SO_ERROR and
                  not buflen):
                  return 0
              raise NotImplementedError("Only asyncore specific behaviour "
                                        "implemented.")
  
          read = recv
          write = send
  
          def close(self):
              if self.fd < 0:
                  return
              fd = self.fd
              self.fd = -1
              os.close(fd)
  
          def fileno(self):
              return self.fd
  
      class file_dispatcher(dispatcher):
  
          def __init__(self, fd, map=None):
              dispatcher.__init__(self, None, map)
              self.connected = True
              try:
                  fd = fd.fileno()
              except AttributeError:
                  pass
              self.set_file(fd)
              # set it to non-blocking mode
              os.set_blocking(fd, False)
  
          def set_file(self, fd):
              self.socket = file_wrapper(fd)
              self._fileno = self.socket.fileno()
              self.add_channel()
  