Implement #15

PythonHome/Lib/multiprocessing/reduction.py

@@ -0,0 +1,215 @@
+#
+# 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)