# Copyright 2010-2020 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2

from _emerge.AbstractPollTask import AbstractPollTask

from portage import os
from portage.cache.mappings import slot_dict_class


class FifoIpcDaemon(AbstractPollTask):

    __slots__ = ("input_fifo", "output_fifo", "_files")

    _file_names = ("pipe_in",)
    _files_dict = slot_dict_class(_file_names, prefix="")

    def _start(self):
        self._files = self._files_dict()

        # File streams are in unbuffered mode since we do atomic
        # read and write of whole pickles.
        self._files.pipe_in = os.open(self.input_fifo, os.O_RDONLY | os.O_NONBLOCK)

        self.scheduler.add_reader(self._files.pipe_in, self._input_handler)

        self._registered = True

    def _reopen_input(self):
        """
        Re-open the input stream, in order to suppress
        POLLHUP events (bug #339976).
        """
        self.scheduler.remove_reader(self._files.pipe_in)
        os.close(self._files.pipe_in)
        self._files.pipe_in = os.open(self.input_fifo, os.O_RDONLY | os.O_NONBLOCK)

        self.scheduler.add_reader(self._files.pipe_in, self._input_handler)

    def _cancel(self):
        if self.returncode is None:
            self.returncode = 1
        self._unregister()
        # notify exit listeners
        self._async_wait()

    def _input_handler(self):
        raise NotImplementedError(self)

    def _unregister(self):
        """
        Unregister from the scheduler and close open files.
        """

        self._registered = False

        if self._files is not None:
            for f in self._files.values():
                self.scheduler.remove_reader(f)
                os.close(f)
            self._files = None