Viewing file:  contexts.py (3.4 KB) -rw-r--r--
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import contextlib
import io
import os
import shutil
import site
import sys
import tempfile
from filelock import FileLock
@contextlib.contextmanager
def tempdir(cd=lambda dir: None, **kwargs):
temp_dir = tempfile.mkdtemp(**kwargs)
orig_dir = os.getcwd()
try:
cd(temp_dir)
yield temp_dir
finally:
cd(orig_dir)
shutil.rmtree(temp_dir)
@contextlib.contextmanager
def environment(**replacements):
"""
In a context, patch the environment with replacements. Pass None values
to clear the values.
"""
saved = dict((key, os.environ[key]) for key in replacements if key in os.environ)
# remove values that are null
remove = (key for (key, value) in replacements.items() if value is None)
for key in list(remove):
os.environ.pop(key, None)
replacements.pop(key)
os.environ.update(replacements)
try:
yield saved
finally:
for key in replacements:
os.environ.pop(key, None)
os.environ.update(saved)
@contextlib.contextmanager
def quiet():
"""
Redirect stdout/stderr to StringIO objects to prevent console output from
distutils commands.
"""
old_stdout = sys.stdout
old_stderr = sys.stderr
new_stdout = sys.stdout = io.StringIO()
new_stderr = sys.stderr = io.StringIO()
try:
yield new_stdout, new_stderr
finally:
new_stdout.seek(0)
new_stderr.seek(0)
sys.stdout = old_stdout
sys.stderr = old_stderr
@contextlib.contextmanager
def save_user_site_setting():
saved = site.ENABLE_USER_SITE
try:
yield saved
finally:
site.ENABLE_USER_SITE = saved
@contextlib.contextmanager
def save_pkg_resources_state():
import pkg_resources
pr_state = pkg_resources.__getstate__()
# also save sys.path
sys_path = sys.path[:]
try:
yield pr_state, sys_path
finally:
sys.path[:] = sys_path
pkg_resources.__setstate__(pr_state)
@contextlib.contextmanager
def suppress_exceptions(*excs):
try:
yield
except excs:
pass
def multiproc(request):
"""
Return True if running under xdist and multiple
workers are used.
"""
try:
worker_id = request.getfixturevalue('worker_id')
except Exception:
return False
return worker_id != 'master'
@contextlib.contextmanager
def session_locked_tmp_dir(request, tmp_path_factory, name):
"""Uses a file lock to guarantee only one worker can access a temp dir"""
# get the temp directory shared by all workers
base = tmp_path_factory.getbasetemp()
shared_dir = base.parent if multiproc(request) else base
locked_dir = shared_dir / name
with FileLock(locked_dir.with_suffix(".lock")):
# ^-- prevent multiple workers to access the directory at once
locked_dir.mkdir(exist_ok=True, parents=True)
yield locked_dir
@contextlib.contextmanager
def save_paths():
"""Make sure ``sys.path``, ``sys.meta_path`` and ``sys.path_hooks`` are preserved"""
prev = sys.path[:], sys.meta_path[:], sys.path_hooks[:]
try:
yield
finally:
sys.path, sys.meta_path, sys.path_hooks = prev
@contextlib.contextmanager
def save_sys_modules():
"""Make sure initial ``sys.modules`` is preserved"""
prev_modules = sys.modules
try:
sys.modules = sys.modules.copy()
yield
finally:
sys.modules = prev_modules
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