branchcache: add a "pure topological head" fast path
In a narrow but actually quick common case, all topological heads are all on
the same branch and all open. In this case, computing the branch map is very
simple. We can quickly detect situation where this situation will not change.
So we update the V3 format to be able to express this situation and upgrade the
update code to detect we remains in that mode.
The branch cache is populated with the actual value when the branch map is
accessed, but the update_disk method can do the update without needing to
populate it.
#!/usr/bin/env python3
#
# check-py3-compat - check Python 3 compatibility of Mercurial files
#
# Copyright 2015 Gregory Szorc <gregory.szorc@gmail.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
import ast
import importlib
import os
import sys
import traceback
import warnings
def check_compat_py3(f):
"""Check Python 3 compatibility of a file with Python 3."""
with open(f, 'rb') as fh:
content = fh.read()
try:
ast.parse(content, filename=f)
except SyntaxError as e:
print('%s: invalid syntax: %s' % (f, e))
return
# Try to import the module.
# For now we only support modules in packages because figuring out module
# paths for things not in a package can be confusing.
if f.startswith(
('hgdemandimport/', 'hgext/', 'mercurial/')
) and not f.endswith('__init__.py'):
assert f.endswith('.py')
name = f.replace('/', '.')[:-3]
try:
importlib.import_module(name)
except Exception as e:
exc_type, exc_value, tb = sys.exc_info()
# We walk the stack and ignore frames from our custom importer,
# import mechanisms, and stdlib modules. This kinda/sorta
# emulates CPython behavior in import.c while also attempting
# to pin blame on a Mercurial file.
for frame in reversed(traceback.extract_tb(tb)):
if frame.name == '_call_with_frames_removed':
continue
if 'importlib' in frame.filename:
continue
if 'mercurial/__init__.py' in frame.filename:
continue
if frame.filename.startswith(sys.prefix):
continue
break
if frame.filename:
filename = os.path.basename(frame.filename)
print(
'%s: error importing: <%s> %s (error at %s:%d)'
% (f, type(e).__name__, e, filename, frame.lineno)
)
else:
print(
'%s: error importing module: <%s> %s (line %d)'
% (f, type(e).__name__, e, frame.lineno)
)
if __name__ == '__main__':
# check_compat_py3 will import every filename we specify as long as it
# starts with one of a few prefixes. It does this by converting
# specified filenames like 'mercurial/foo.py' to 'mercurial.foo' and
# importing that. When running standalone (not as part of a test), this
# means we actually import the installed versions, not the files we just
# specified. When running as test-check-py3-compat.t, we technically
# would import the correct paths, but it's cleaner to have both cases
# use the same import logic.
sys.path.insert(0, os.getcwd())
for f in sys.argv[1:]:
with warnings.catch_warnings(record=True) as warns:
check_compat_py3(f)
for w in warns:
print(
warnings.formatwarning(
w.message, w.category, w.filename, w.lineno
).rstrip()
)
sys.exit(0)