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"""
This file contains extensions of the multiprocessing module to be used with gem5
Some code inspired by the Python standard library implementation of the
multiprocessing module (i.e., cpython/Lib/multiprocessing/).
"""

from multiprocessing import context, process
from multiprocessing.context import DefaultContext

# The `_start_method` must be `None` for the `Spawn_gem5Process` class.
# Otherwise, in `_bootstrap` in the `BaseProcess` it will try to force the
# `_start_method` to be gem5-specific, which the `multiprocessing` module
# doesn't understand.
class Spawn_gem5Process(process.BaseProcess):
    _start_method = None

    @staticmethod
    def _Popen(process_obj):
        from .popen_spawn_gem5 import Popen

        return Popen(process_obj)


class Process(process.BaseProcess):
    _start_method = None

    @staticmethod
    def _Popen(process_obj):
        return _default_context.get_context().Process._Popen(process_obj)


class gem5Context(context.BaseContext):
    _name = "spawn_gem5"
    Process = Spawn_gem5Process

    def get_context(self, method=None):
        if method is None:
            return self
        try:
            ctx = _concrete_contexts[method]
        except KeyError:
            raise ValueError("cannot find context for %r" % method) from None
        ctx._check_available()
        return ctx


_concrete_contexts = {"spawn_gem5": gem5Context()}

_default_context = DefaultContext(_concrete_contexts["spawn_gem5"])