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# Copyright 2015 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
import pickle
import traceback
from portage import os
from portage.util._async.ForkProcess import ForkProcess
from _emerge.PipeReader import PipeReader
class AsyncFunction(ForkProcess):
"""
Execute a function call in a fork, and retrieve the function
return value via pickling/unpickling, accessible as the
"result" attribute after the forked process has exited.
"""
__slots__ = ('args', 'kwargs', 'result', 'target',
'_async_func_reader', '_async_func_reader_pw')
def _start(self):
pr, pw = os.pipe()
self.fd_pipes = {}
self.fd_pipes[pw] = pw
self._async_func_reader_pw = pw
self._async_func_reader = PipeReader(
input_files={"input":pr},
scheduler=self.scheduler)
self._async_func_reader.addExitListener(self._async_func_reader_exit)
self._async_func_reader.start()
ForkProcess._start(self)
os.close(pw)
def _run(self):
try:
result = self.target(*(self.args or []), **(self.kwargs or {}))
os.write(self._async_func_reader_pw, pickle.dumps(result))
except Exception:
traceback.print_exc()
return 1
return os.EX_OK
def _pipe_logger_exit(self, pipe_logger):
# Ignore this event, since we want to ensure that we exit
# only after _async_func_reader_exit has reached EOF.
self._pipe_logger = None
def _async_func_reader_exit(self, pipe_reader):
try:
self.result = pickle.loads(pipe_reader.getvalue())
except Exception:
# The child process will have printed a traceback in this case,
# and returned an unsuccessful returncode.
pass
self._async_func_reader = None
self._unregister()
self.wait()
def _unregister(self):
ForkProcess._unregister(self)
pipe_reader = self._async_func_reader
if pipe_reader is not None:
self._async_func_reader = None
pipe_reader.removeExitListener(self._async_func_reader_exit)
pipe_reader.cancel()
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