# -*- 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 os

from errno import EALREADY, EINPROGRESS, EWOULDBLOCK, ECONNRESET, \

     ENOTCONN, ESHUTDOWN, EINTR, EISCONN, EBADF, ECONNABORTED, errorcode

try:

    socket_map

except NameError:

    socket_map = {}

def _strerror(err):

    res = os.strerror(err)

    if res == 'Unknown error':

        res = errorcode[err]

    return res

class ExitNow(Exception):

    pass

def read(obj):

    try:

        obj.handle_read_event()

    except (ExitNow, KeyboardInterrupt, SystemExit):

        raise

    except:

        obj.handle_error()

def write(obj):

    try:

        obj.handle_write_event()

    except (ExitNow, KeyboardInterrupt, SystemExit):

        raise

    except:

        obj.handle_error()

def _exception(obj):

    try:

        obj.handle_expt_event()

    except (ExitNow, KeyboardInterrupt, SystemExit):

        raise

    except:

        obj.handle_error()

def readwrite(obj, flags):

    try:

        if flags & (select.POLLIN | select.POLLPRI):

            obj.handle_read_event()

        if flags & select.POLLOUT:

            obj.handle_write_event()

        if flags & (select.POLLERR | select.POLLNVAL):

            obj.handle_expt_event()

        if flags & select.POLLHUP:

            obj.handle_close()

    except (ExitNow, KeyboardInterrupt, SystemExit):

        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 map.items():

            is_r = obj.readable()

            is_w = obj.writable()

            if is_r:

                r.append(fd)

            if is_w:

                w.append(fd)

            if is_r or is_w:

                e.append(fd)

        if [] == r == w == e:

            time.sleep(timeout)

            return

        try:

            r, w, e = select.select(r, w, e, timeout)

        except select.error, err:

            if err.args[0] != EINTR:

                raise

            else:

                return

        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 map.items():

            flags = 0

            if obj.readable():

                flags |= select.POLLIN | select.POLLPRI

            if obj.writable():

                flags |= select.POLLOUT

            if flags:

                # Only check for exceptions if object was either readable

                # or writable.

                flags |= select.POLLERR | select.POLLHUP | select.POLLNVAL

                pollster.register(fd, flags)

        try:

            r = pollster.poll(timeout)

        except select.error, err:

            if err.args[0] != EINTR:

                raise

            r = []

        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

    closing = False

    addr = None

    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(0)

            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 socket.error, err:

                if err.args[0] == ENOTCONN:

                    # 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__.__name__]

        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, type):

        self.family_and_type = family, type

        sock = socket.socket(family, type)

        sock.setblocking(0)

        self.set_socket(sock)

    def set_socket(self, sock, map=None):

        self.socket = sock

##        self.__dict__['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 socket.error:

            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

        err = self.socket.connect_ex(address)

        # XXX Should interpret Winsock return values

        if err in (EINPROGRESS, EALREADY, EWOULDBLOCK):

            return

        if err in (0, EISCONN):

            self.addr = address

            self.handle_connect_event()

        else:

            raise socket.error(err, errorcode[err])

    def accept(self):

        # XXX can return either an address pair or None

        try:

            conn, addr = self.socket.accept()

            return conn, addr

        except socket.error, why:

            if why.args[0] == EWOULDBLOCK:

                pass

            else:

                raise

    def send(self, data):

        try:

            result = self.socket.send(data)

            return result

        except socket.error, why:

            if why.args[0] == EWOULDBLOCK:

                return 0

            elif why.args[0] in (ECONNRESET, ENOTCONN, ESHUTDOWN, ECONNABORTED):

                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 ''

            else:

                return data

        except socket.error, why:

            # winsock sometimes throws ENOTCONN

            if why.args[0] in [ECONNRESET, ENOTCONN, ESHUTDOWN, ECONNABORTED]:

                self.handle_close()

                return ''

            else:

                raise

    def close(self):

        self.connected = False

        self.accepting = False

        self.del_channel()

        try:

            self.socket.close()

        except socket.error, why:

            if why.args[0] not in (ENOTCONN, EBADF):

                raise

    # cheap inheritance, used to pass all other attribute

    # references to the underlying socket object.

    def __getattr__(self, attr):

        return getattr(self.socket, attr)

    # 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 __debug__ or type != 'info':

            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:

            self.handle_connect_event()

            self.handle_read()

        else:

            self.handle_read()

    def handle_connect_event(self):

        self.connected = True

        self.handle_connect()

    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:

            #check for errors

            err = self.socket.getsockopt(socket.SOL_SOCKET, socket.SO_ERROR)

            if err != 0:

                raise socket.error(err, _strerror(err))

            self.handle_connect_event()

        self.handle_write()

    def handle_expt_event(self):

        # if the handle_expt is the same default worthless method,

        # we'll not even bother calling it, we'll instead generate

        # a useful error

        x = True

        try:

            y1 = self.__class__.handle_expt.im_func

            y2 = dispatcher.handle_expt.im_func

            x = y1 is y2

        except AttributeError:

            pass

        if x:

            err = self.socket.getsockopt(socket.SOL_SOCKET, socket.SO_ERROR)

            msg = _strerror(err)

            raise socket.error(err, msg)

        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 exception', '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):

        self.log_info('unhandled accept 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 = ''

    def initiate_send(self):

        num_sent = 0

        num_sent = dispatcher.send(self, self.out_buffer[:512])

        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