# -*- 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)