Mercurial > hg
view mercurial/policy.py @ 44593:496868f1030c
rust-matchers: use the `regex` crate
Instead of falling back to Python when a code path with "ignore" functionality
is reached and `Re2` is not installed, the default compilation (i.e. without
the `with-re2` feature) will use the `regex` crate for all regular expressions
business.
As with the introduction of `Re2` in a previous series, this yields a big
performance boost compared to the Python + C code in `status`, `diff`, `commit`,
`update`, and maybe others.
For now `Re2` looks to be faster at compiling the DFA (1.5ms vs 5ms for
Netbeans' `.hgignore`) and a bit faster in actual use: (123ms vs 137ms for
the parallel traversal of Netbeans' clean repo). I am in talks with the author
of `regex` to see whether that performance difference is a bug, a "won't fix",
or a tuning issue.
The `regex` crate is already one of our dependencies and using this code does
not require any additional work from the end-user than to use the Rust
extensions.
Differential Revision: https://phab.mercurial-scm.org/D8323
author | Raphaël Gomès <rgomes@octobus.net> |
---|---|
date | Tue, 24 Mar 2020 17:55:59 +0100 |
parents | b56de57c45ce |
children | 61e7464477ac |
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# policy.py - module policy logic for Mercurial. # # 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. from __future__ import absolute_import import os import sys from .pycompat import getattr # Rules for how modules can be loaded. Values are: # # c - require C extensions # rust+c - require Rust and C extensions # rust+c-allow - allow Rust and C extensions with fallback to pure Python # for each # allow - allow pure Python implementation when C loading fails # cffi - required cffi versions (implemented within pure module) # cffi-allow - allow pure Python implementation if cffi version is missing # py - only load pure Python modules # # By default, fall back to the pure modules so the in-place build can # run without recompiling the C extensions. This will be overridden by # __modulepolicy__ generated by setup.py. policy = b'allow' _packageprefs = { # policy: (versioned package, pure package) b'c': ('cext', None), b'allow': ('cext', 'pure'), b'cffi': ('cffi', None), b'cffi-allow': ('cffi', 'pure'), b'py': (None, 'pure'), # For now, rust policies impact importrust only b'rust+c': ('cext', None), b'rust+c-allow': ('cext', 'pure'), } try: from . import __modulepolicy__ policy = __modulepolicy__.modulepolicy except ImportError: pass # PyPy doesn't load C extensions. # # The canonical way to do this is to test platform.python_implementation(). # But we don't import platform and don't bloat for it here. if '__pypy__' in sys.builtin_module_names: policy = b'cffi' # Environment variable can always force settings. if sys.version_info[0] >= 3: if 'HGMODULEPOLICY' in os.environ: policy = os.environ['HGMODULEPOLICY'].encode('utf-8') else: policy = os.environ.get('HGMODULEPOLICY', policy) def _importfrom(pkgname, modname): # from .<pkgname> import <modname> (where . is looked through this module) fakelocals = {} pkg = __import__(pkgname, globals(), fakelocals, [modname], level=1) try: fakelocals[modname] = mod = getattr(pkg, modname) except AttributeError: raise ImportError('cannot import name %s' % modname) # force import; fakelocals[modname] may be replaced with the real module getattr(mod, '__doc__', None) return fakelocals[modname] # keep in sync with "version" in C modules _cextversions = { ('cext', 'base85'): 1, ('cext', 'bdiff'): 3, ('cext', 'mpatch'): 1, ('cext', 'osutil'): 4, ('cext', 'parsers'): 16, } # map import request to other package or module _modredirects = { ('cext', 'charencode'): ('cext', 'parsers'), ('cffi', 'base85'): ('pure', 'base85'), ('cffi', 'charencode'): ('pure', 'charencode'), ('cffi', 'parsers'): ('pure', 'parsers'), } def _checkmod(pkgname, modname, mod): expected = _cextversions.get((pkgname, modname)) actual = getattr(mod, 'version', None) if actual != expected: raise ImportError( 'cannot import module %s.%s ' '(expected version: %d, actual: %r)' % (pkgname, modname, expected, actual) ) def importmod(modname): """Import module according to policy and check API version""" try: verpkg, purepkg = _packageprefs[policy] except KeyError: raise ImportError('invalid HGMODULEPOLICY %r' % policy) assert verpkg or purepkg if verpkg: pn, mn = _modredirects.get((verpkg, modname), (verpkg, modname)) try: mod = _importfrom(pn, mn) if pn == verpkg: _checkmod(pn, mn, mod) return mod except ImportError: if not purepkg: raise pn, mn = _modredirects.get((purepkg, modname), (purepkg, modname)) return _importfrom(pn, mn) def _isrustpermissive(): """Assuming the policy is a Rust one, tell if it's permissive.""" return policy.endswith(b'-allow') def importrust(modname, member=None, default=None): """Import Rust module according to policy and availability. If policy isn't a Rust one, this returns `default`. If either the module or its member is not available, this returns `default` if policy is permissive and raises `ImportError` if not. """ if not policy.startswith(b'rust'): return default try: mod = _importfrom('rustext', modname) except ImportError: if _isrustpermissive(): return default raise if member is None: return mod try: return getattr(mod, member) except AttributeError: if _isrustpermissive(): return default raise ImportError("Cannot import name %s" % member)