import io
import os

from . import context
from . import popen_fork
from . import reduction
from . import spawn
from . import util

__all__ = ['Popen']


#
# Wrapper for an fd used while launching a process
#

class _DupFd(object):
def __init__(self, fd):
self.fd = fd
def detach(self):
return self.fd

#
# Start child process using a fresh interpreter
#

class Popen(popen_fork.Popen):
method = 'spawn'
DupFd = _DupFd

def __init__(self, process_obj):
self._fds = []
super().__init__(process_obj)

def duplicate_for_child(self, fd):
self._fds.append(fd)
return fd

def _launch(self, process_obj):
from . import semaphore_tracker
tracker_fd = semaphore_tracker.getfd()
self._fds.append(tracker_fd)
prep_data = spawn.get_preparation_data(process_obj._name)
fp = io.BytesIO()
context.set_spawning_popen(self)
try:
reduction.dump(prep_data, fp)
reduction.dump(process_obj, fp)
finally:
context.set_spawning_popen(None)

parent_r = child_w = child_r = parent_w = None
try:
parent_r, child_w = os.pipe()
child_r, parent_w = os.pipe()
cmd = spawn.get_command_line(tracker_fd=tracker_fd,
pipe_handle=child_r)
self._fds.extend([child_r, child_w])
self.pid = util.spawnv_passfds(spawn.get_executable(),
cmd, self._fds)
self.sentinel = parent_r
with open(parent_w, 'wb', closefd=False) as f:
f.write(fp.getbuffer())
finally:
if parent_r is not None:
util.Finalize(self, os.close, (parent_r,))
for fd in (child_r, child_w, parent_w):
if fd is not None:
os.close(fd)