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# Copyright 2010 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
import array
import pickle
from portage import os
from _emerge.AbstractPollTask import AbstractPollTask
from _emerge.PollConstants import PollConstants
from portage.cache.mappings import slot_dict_class
class FifoIpcDaemon(AbstractPollTask):
"""
This class serves as an IPC daemon, which ebuild processes can use
to communicate with portage's main python process.
Here are a few possible uses:
1) Robust subshell/subprocess die support. This allows the ebuild
environment to reliably die without having to rely on signal IPC.
2) Delegation of portageq calls to the main python process, eliminating
performance and userpriv permission issues.
3) Reliable ebuild termination in cases when the ebuild has accidentally
left orphan processes running in the backgraound (as in bug 278895).
"""
__slots__ = ("input_fifo", "output_fifo",) + \
("_files", "_reg_id",)
_file_names = ("pipe_in",)
_files_dict = slot_dict_class(_file_names, prefix="")
def _start(self):
self._files = self._files_dict()
input_fd = os.open(self.input_fifo, os.O_RDONLY|os.O_NONBLOCK)
self._files.pipe_in = os.fdopen(input_fd, 'rb')
self._reg_id = self.scheduler.register(
self._files.pipe_in.fileno(),
self._registered_events, self._input_handler)
self._registered = True
def isAlive(self):
return self._registered
def cancel(self):
if self.returncode is None:
self.returncode = 1
self.cancelled = True
self._unregister()
self.wait()
def _wait(self):
if self.returncode is not None:
return self.returncode
if self._registered:
self.scheduler.schedule(self._reg_id)
self._unregister()
if self.returncode is None:
self.returncode = os.EX_OK
return self.returncode
def _input_handler(self, fd, event):
if event & PollConstants.POLLIN:
buf = array.array('B')
try:
buf.fromfile(self._files.pipe_in, self._bufsize)
except (EOFError, IOError):
pass
if buf:
obj = pickle.loads(buf.tostring())
if isinstance(obj, list) and \
obj and \
obj[0] == 'exit':
output_fd = os.open(self.output_fifo, os.O_WRONLY|os.O_NONBLOCK)
output_file = os.fdopen(output_fd, 'wb')
pickle.dump('OK', output_file)
output_file.close()
self._unregister()
self.wait()
self._unregister_if_appropriate(event)
return self._registered
def _unregister(self):
"""
Unregister from the scheduler and close open files.
"""
self._registered = False
if self._reg_id is not None:
self.scheduler.unregister(self._reg_id)
self._reg_id = None
if self._files is not None:
for f in self._files.values():
f.close()
self._files = None
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