emitrevision: consider ancestors revision to emit as available base
This should make more delta base valid. This notably affects:
* case where we skipped some parent with empty delta to directly delta against
an ancestors
* case where an intermediate snapshots is stored.
This change means we could sent largish intermediate snapshots over the wire.
However this is actually a sub goal here. Sending snapshots over the wire means
the client have a high odd of simply storing the pre-computed delta instead of
doing a lengthy process that will… end up doing the same intermediate snapshot.
In addition the overall size of snapshot (or any level) is "only" some or the
overall delta size. (0.17% for my mercurial clone, 20% for my clone of Mozilla
try). So Sending them other the wire is unlikely to change large impact on the
bandwidth used.
If we decide that minimising the bandwidth is an explicit goal, we should
introduce new logic to filter-out snapshot as delta. The current code has no
notion explicite of snapshot so far, they just tended to fall into the wobbly
filtering options.
In some cases, this patch can yield large improvement to the bundling time:
### data-env-vars.name = mozilla-try-2019-02-18-zstd-sparse-revlog
# benchmark.name = perf-bundle
# benchmark.variants.revs = last-100000
before: 68.787066 seconds
after: 47.552677 seconds (-30.87%)
That translate to large improvement to the pull time :
### data-env-vars.name = mozilla-try-2019-02-18-zstd-sparse-revlog
# benchmark.name = pull
# benchmark.variants.
issue6528 = disabled
# benchmark.variants.revs = last-100000
before: 142.186625 seconds
after: 75.897745 seconds (-46.62%)
No significant negative impact have been observed.
# hgdemandimport - global demand-loading of modules for Mercurial
#
# Copyright 2017 Facebook Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
'''demandimport - automatic demand-loading of modules'''
# This is in a separate package from mercurial because in Python 3,
# demand loading is per-package. Keeping demandimport in the mercurial package
# would disable demand loading for any modules in mercurial.
import os
import sys
from . import demandimportpy3 as demandimport
# Full module names which can't be lazy imported.
# Extensions can add to this set.
IGNORES = {
'__future__',
'_hashlib',
# ImportError during pkg_resources/__init__.py:fixup_namespace_package
'_imp',
'_xmlplus',
'fcntl',
'nt', # pathlib2 tests the existence of built-in 'nt' module
'win32com.gen_py',
'win32com.shell', # 'appdirs' tries to import win32com.shell
'_winreg', # 2.7 mimetypes needs immediate ImportError
'pythoncom',
# imported by tarfile, not available under Windows
'pwd',
'grp',
# imported by profile, itself imported by hotshot.stats,
# not available under Windows
'resource',
# this trips up many extension authors
'gtk',
# setuptools' pkg_resources.py expects "from __main__ import x" to
# raise ImportError if x not defined
'__main__',
'_ast', # https://bugs.python.org/issue41631
'_ssl', # conditional imports in the stdlib, issue1964
'_sre', # issue4920
'rfc822',
'mimetools',
'sqlalchemy.events', # has import-time side effects (issue5085)
'sqlalchemy.dialects', # similar problems as above
# setuptools 8 expects this module to explode early when not on windows
'distutils.msvc9compiler',
'__builtin__',
'builtins',
'urwid.command_map', # for pudb
'lzma',
}
_pypy = '__pypy__' in sys.builtin_module_names
if _pypy:
# _ctypes.pointer is shadowed by "from ... import pointer" (PyPy 5)
IGNORES.add('_ctypes.pointer')
# pure Python module on PyPy, must be loaded to raise ModuleNotFoundError
# on non-Windows platforms
IGNORES.add('msvcrt')
demandimport.init(IGNORES)
# Re-export.
isenabled = demandimport.isenabled
disable = demandimport.disable
deactivated = demandimport.deactivated
def enable():
# chg pre-imports modules so do not enable demandimport for it
if (
'CHGINTERNALMARK' not in os.environ
and os.environ.get('HGDEMANDIMPORT') != 'disable'
):
demandimport.enable()