#
# Module to allow connection and socket objects to be transferred
# between processes
#
# multiprocessing/reduction.py
#
# Copyright (c) 2006-2008, R Oudkerk
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# 1. Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
# 3. Neither the name of author nor the names of any contributors may be
# used to endorse or promote products derived from this software
# without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#

__all__ = []

import os
import sys
import socket
import threading

import _multiprocessing
from multiprocessing import current_process
from multiprocessing.forking import Popen, duplicate, close, ForkingPickler
from multiprocessing.util import register_after_fork, debug, sub_debug
from multiprocessing.connection import Client, Listener


#
#
#

if not(sys.platform == 'win32' or hasattr(_multiprocessing, 'recvfd')):
raise ImportError('pickling of connections not supported')

#
# Platform specific definitions
#

if sys.platform == 'win32':
import _subprocess
from _multiprocessing import win32

def send_handle(conn, handle, destination_pid):
process_handle = win32.OpenProcess(
win32.PROCESS_ALL_ACCESS, False, destination_pid
)
try:
new_handle = duplicate(handle, process_handle)
conn.send(new_handle)
finally:
close(process_handle)

def recv_handle(conn):
return conn.recv()

else:
def send_handle(conn, handle, destination_pid):
_multiprocessing.sendfd(conn.fileno(), handle)

def recv_handle(conn):
return _multiprocessing.recvfd(conn.fileno())

#
# Support for a per-process server thread which caches pickled handles
#

_cache = set()

def _reset(obj):
global _lock, _listener, _cache
for h in _cache:
close(h)
_cache.clear()
_lock = threading.Lock()
_listener = None

_reset(None)
register_after_fork(_reset, _reset)

def _get_listener():
global _listener

if _listener is None:
_lock.acquire()
try:
if _listener is None:
debug('starting listener and thread for sending handles')
_listener = Listener(authkey=current_process().authkey)
t = threading.Thread(target=_serve)
t.daemon = True
t.start()
finally:
_lock.release()

return _listener

def _serve():
from .util import is_exiting, sub_warning

while 1:
try:
conn = _listener.accept()
handle_wanted, destination_pid = conn.recv()
_cache.remove(handle_wanted)
send_handle(conn, handle_wanted, destination_pid)
close(handle_wanted)
conn.close()
except:
if not is_exiting():
import traceback
sub_warning(
'thread for sharing handles raised exception :\n' +
'-'*79 + '\n' + traceback.format_exc() + '-'*79
)

#
# Functions to be used for pickling/unpickling objects with handles
#

def reduce_handle(handle):
if Popen.thread_is_spawning():
return (None, Popen.duplicate_for_child(handle), True)
dup_handle = duplicate(handle)
_cache.add(dup_handle)
sub_debug('reducing handle %d', handle)
return (_get_listener().address, dup_handle, False)

def rebuild_handle(pickled_data):
address, handle, inherited = pickled_data
if inherited:
return handle
sub_debug('rebuilding handle %d', handle)
conn = Client(address, authkey=current_process().authkey)
conn.send((handle, os.getpid()))
new_handle = recv_handle(conn)
conn.close()
return new_handle

#
# Register `_multiprocessing.Connection` with `ForkingPickler`
#

def reduce_connection(conn):
rh = reduce_handle(conn.fileno())
return rebuild_connection, (rh, conn.readable, conn.writable)

def rebuild_connection(reduced_handle, readable, writable):
handle = rebuild_handle(reduced_handle)
return _multiprocessing.Connection(
handle, readable=readable, writable=writable
)

ForkingPickler.register(_multiprocessing.Connection, reduce_connection)

#
# Register `socket.socket` with `ForkingPickler`
#

def fromfd(fd, family, type_, proto=0):
s = socket.fromfd(fd, family, type_, proto)
if s.__class__ is not socket.socket:
s = socket.socket(_sock=s)
return s

def reduce_socket(s):
reduced_handle = reduce_handle(s.fileno())
return rebuild_socket, (reduced_handle, s.family, s.type, s.proto)

def rebuild_socket(reduced_handle, family, type_, proto):
fd = rebuild_handle(reduced_handle)
_sock = fromfd(fd, family, type_, proto)
close(fd)
return _sock

ForkingPickler.register(socket.socket, reduce_socket)

#
# Register `_multiprocessing.PipeConnection` with `ForkingPickler`
#

if sys.platform == 'win32':

def reduce_pipe_connection(conn):
rh = reduce_handle(conn.fileno())
return rebuild_pipe_connection, (rh, conn.readable, conn.writable)

def rebuild_pipe_connection(reduced_handle, readable, writable):
handle = rebuild_handle(reduced_handle)
return _multiprocessing.PipeConnection(
handle, readable=readable, writable=writable
)

ForkingPickler.register(_multiprocessing.PipeConnection, reduce_pipe_connection)