# Copyright Spack Project Developers. See COPYRIGHT file for details.
#
# SPDX-License-Identifier: (Apache-2.0 OR MIT)
"""
This module handles transmission of Spack state to child processes started
using the 'spawn' start method. Notably, installations are performed in a
subprocess and require transmitting the Package object (in such a way
that the repository is available for importing when it is deserialized);
installations performed in Spack unit tests may include additional
modifications to global state in memory that must be replicated in the
child process.
"""
import importlib
import io
import multiprocessing
import pickle
import pydoc
from types import ModuleType
import spack.config
import spack.environment
import spack.paths
import spack.platforms
import spack.repo
import spack.store
patches = None
[docs]
def append_patch(patch):
global patches
if not patches:
patches = list()
patches.append(patch)
[docs]
def serialize(obj):
serialized_obj = io.BytesIO()
pickle.dump(obj, serialized_obj)
serialized_obj.seek(0)
return serialized_obj
[docs]
class SpackTestProcess:
def __init__(self, fn):
self.fn = fn
def _restore_and_run(self, fn, test_state):
test_state.restore()
fn()
[docs]
def create(self):
test_state = GlobalStateMarshaler()
return multiprocessing.Process(target=self._restore_and_run, args=(self.fn, test_state))
[docs]
class PackageInstallContext:
"""Captures the in-memory process state of a package installation that
needs to be transmitted to a child process.
"""
def __init__(self, pkg, *, ctx=None):
ctx = ctx or multiprocessing.get_context()
self.serialize = ctx.get_start_method() != "fork"
if self.serialize:
self.serialized_pkg = serialize(pkg)
self.global_state = GlobalStateMarshaler()
self.serialized_env = serialize(spack.environment.active_environment())
else:
self.pkg = pkg
self.global_state = None
self.env = spack.environment.active_environment()
self.spack_working_dir = spack.paths.spack_working_dir
[docs]
def restore(self):
spack.paths.spack_working_dir = self.spack_working_dir
env = pickle.load(self.serialized_env) if self.serialize else self.env
# Activating the environment modifies the global configuration, so globals have to
# be restored afterward, in case other modifications were applied on top (e.g. from
# command line)
if env:
spack.environment.activate(env)
if self.serialize:
self.global_state.restore()
# Order of operation is important, since the package might be retrieved
# from a repo defined within the environment configuration
pkg = pickle.load(self.serialized_pkg) if self.serialize else self.pkg
return pkg
[docs]
class GlobalStateMarshaler:
"""Class to serialize and restore global state for child processes.
Spack may modify state that is normally read from disk or command line in memory;
this object is responsible for properly serializing that state to be applied to a subprocess.
"""
def __init__(self):
self.config = spack.config.CONFIG.ensure_unwrapped()
self.platform = spack.platforms.host
self.test_patches = store_patches()
self.store = spack.store.STORE
[docs]
def restore(self):
spack.config.CONFIG = self.config
spack.repo.PATH = spack.repo.create(self.config)
spack.platforms.host = self.platform
spack.store.STORE = self.store
self.test_patches.restore()
[docs]
class TestPatches:
def __init__(self, module_patches, class_patches):
self.module_patches = list((x, y, serialize(z)) for (x, y, z) in module_patches)
self.class_patches = list((x, y, serialize(z)) for (x, y, z) in class_patches)
[docs]
def restore(self):
for module_name, attr_name, value in self.module_patches:
value = pickle.load(value)
module = importlib.import_module(module_name)
setattr(module, attr_name, value)
for class_fqn, attr_name, value in self.class_patches:
value = pickle.load(value)
cls = pydoc.locate(class_fqn)
setattr(cls, attr_name, value)
[docs]
def store_patches():
global patches
module_patches = list()
class_patches = list()
if not patches:
return TestPatches(list(), list())
for target, name, _ in patches:
if isinstance(target, ModuleType):
new_val = getattr(target, name)
module_name = target.__name__
module_patches.append((module_name, name, new_val))
elif isinstance(target, type):
new_val = getattr(target, name)
class_fqn = ".".join([target.__module__, target.__name__])
class_patches.append((class_fqn, name, new_val))
return TestPatches(module_patches, class_patches)
[docs]
def clear_patches():
global patches
patches = None