Mercurial > hg
view mercurial/config.py @ 32697:19b9fc40cc51
revlog: skeleton support for version 2 revlogs
There are a number of improvements we want to make to revlogs
that will require a new version - version 2. It is unclear what the
full set of improvements will be or when we'll be done with them.
What I do know is that the process will likely take longer than a
single release, will require input from various stakeholders to
evaluate changes, and will have many contentious debates and
bikeshedding.
It is unrealistic to develop revlog version 2 up front: there
are just too many uncertainties that we won't know until things
are implemented and experiments are run. Some changes will also
be invasive and prone to bit rot, so sitting on dozens of patches
is not practical.
This commit introduces skeleton support for version 2 revlogs in
a way that is flexible and not bound by backwards compatibility
concerns.
An experimental repo requirement for denoting revlog v2 has been
added. The requirement string has a sub-version component to it.
This will allow us to declare multiple requirements in the course
of developing revlog v2. Whenever we change the in-development
revlog v2 format, we can tweak the string, creating a new
requirement and locking out old clients. This will allow us to
make as many backwards incompatible changes and experiments to
revlog v2 as we want. In other words, we can land code and make
meaningful progress towards revlog v2 while still maintaining
extreme format flexibility up until the point we freeze the
format and remove the experimental labels.
To enable the new repo requirement, you must supply an experimental
and undocumented config option. But not just any boolean flag
will do: you need to explicitly use a value that no sane person
should ever type. This is an additional guard against enabling
revlog v2 on an installation it shouldn't be enabled on. The
specific scenario I'm trying to prevent is say a user with a
4.4 client with a frozen format enabling the option but then
downgrading to 4.3 and accidentally creating repos with an
outdated and unsupported repo format. Requiring a "challenge"
string should prevent this.
Because the format is not yet finalized and I don't want to take
any chances, revlog v2's version is currently 0xDEAD. I figure
squatting on a value we're likely never to use as an actual revlog
version to mean "internal testing only" is acceptable. And
"dead" is easily recognized as something meaningful.
There is a bunch of cleanup that is needed before work on revlog
v2 begins in earnest. I plan on doing that work once this patch
is accepted and we're comfortable with the idea of starting down
this path.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Fri, 19 May 2017 20:29:11 -0700 |
parents | 6a773d3050c9 |
children | 0fa781320203 |
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# config.py - configuration parsing for Mercurial # # Copyright 2009 Matt Mackall <mpm@selenic.com> and others # # 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 errno import os from .i18n import _ from . import ( error, pycompat, util, ) class config(object): def __init__(self, data=None, includepaths=None): self._data = {} self._source = {} self._unset = [] self._includepaths = includepaths or [] if data: for k in data._data: self._data[k] = data[k].copy() self._source = data._source.copy() def copy(self): return config(self) def __contains__(self, section): return section in self._data def hasitem(self, section, item): return item in self._data.get(section, {}) def __getitem__(self, section): return self._data.get(section, {}) def __iter__(self): for d in self.sections(): yield d def update(self, src): for s, n in src._unset: if s in self and n in self._data[s]: del self._data[s][n] del self._source[(s, n)] for s in src: if s not in self: self._data[s] = util.sortdict() self._data[s].update(src._data[s]) self._source.update(src._source) def get(self, section, item, default=None): return self._data.get(section, {}).get(item, default) def backup(self, section, item): """return a tuple allowing restore to reinstall a previous value The main reason we need it is because it handles the "no data" case. """ try: value = self._data[section][item] source = self.source(section, item) return (section, item, value, source) except KeyError: return (section, item) def source(self, section, item): return self._source.get((section, item), "") def sections(self): return sorted(self._data.keys()) def items(self, section): return list(self._data.get(section, {}).iteritems()) def set(self, section, item, value, source=""): if pycompat.ispy3: assert not isinstance(value, str), ( 'config values may not be unicode strings on Python 3') if section not in self: self._data[section] = util.sortdict() self._data[section][item] = value if source: self._source[(section, item)] = source def restore(self, data): """restore data returned by self.backup""" if len(data) == 4: # restore old data section, item, value, source = data self._data[section][item] = value self._source[(section, item)] = source else: # no data before, remove everything section, item = data if section in self._data: self._data[section].pop(item, None) self._source.pop((section, item), None) def parse(self, src, data, sections=None, remap=None, include=None): sectionre = util.re.compile(br'\[([^\[]+)\]') itemre = util.re.compile(br'([^=\s][^=]*?)\s*=\s*(.*\S|)') contre = util.re.compile(br'\s+(\S|\S.*\S)\s*$') emptyre = util.re.compile(br'(;|#|\s*$)') commentre = util.re.compile(br'(;|#)') unsetre = util.re.compile(br'%unset\s+(\S+)') includere = util.re.compile(br'%include\s+(\S|\S.*\S)\s*$') section = "" item = None line = 0 cont = False for l in data.splitlines(True): line += 1 if line == 1 and l.startswith('\xef\xbb\xbf'): # Someone set us up the BOM l = l[3:] if cont: if commentre.match(l): continue m = contre.match(l) if m: if sections and section not in sections: continue v = self.get(section, item) + "\n" + m.group(1) self.set(section, item, v, "%s:%d" % (src, line)) continue item = None cont = False m = includere.match(l) if m and include: expanded = util.expandpath(m.group(1)) includepaths = [os.path.dirname(src)] + self._includepaths for base in includepaths: inc = os.path.normpath(os.path.join(base, expanded)) try: include(inc, remap=remap, sections=sections) break except IOError as inst: if inst.errno != errno.ENOENT: raise error.ParseError(_("cannot include %s (%s)") % (inc, inst.strerror), "%s:%s" % (src, line)) continue if emptyre.match(l): continue m = sectionre.match(l) if m: section = m.group(1) if remap: section = remap.get(section, section) if section not in self: self._data[section] = util.sortdict() continue m = itemre.match(l) if m: item = m.group(1) cont = True if sections and section not in sections: continue self.set(section, item, m.group(2), "%s:%d" % (src, line)) continue m = unsetre.match(l) if m: name = m.group(1) if sections and section not in sections: continue if self.get(section, name) is not None: del self._data[section][name] self._unset.append((section, name)) continue raise error.ParseError(l.rstrip(), ("%s:%s" % (src, line))) def read(self, path, fp=None, sections=None, remap=None): if not fp: fp = util.posixfile(path, 'rb') assert getattr(fp, 'mode', r'rb') == r'rb', ( 'config files must be opened in binary mode, got fp=%r mode=%r' % ( fp, fp.mode)) self.parse(path, fp.read(), sections=sections, remap=remap, include=self.read) def parselist(value): """parse a configuration value as a list of comma/space separated strings >>> parselist('this,is "a small" ,test') ['this', 'is', 'a small', 'test'] """ def _parse_plain(parts, s, offset): whitespace = False while offset < len(s) and (s[offset:offset + 1].isspace() or s[offset:offset + 1] == ','): whitespace = True offset += 1 if offset >= len(s): return None, parts, offset if whitespace: parts.append('') if s[offset:offset + 1] == '"' and not parts[-1]: return _parse_quote, parts, offset + 1 elif s[offset:offset + 1] == '"' and parts[-1][-1] == '\\': parts[-1] = parts[-1][:-1] + s[offset:offset + 1] return _parse_plain, parts, offset + 1 parts[-1] += s[offset:offset + 1] return _parse_plain, parts, offset + 1 def _parse_quote(parts, s, offset): if offset < len(s) and s[offset:offset + 1] == '"': # "" parts.append('') offset += 1 while offset < len(s) and (s[offset:offset + 1].isspace() or s[offset:offset + 1] == ','): offset += 1 return _parse_plain, parts, offset while offset < len(s) and s[offset:offset + 1] != '"': if (s[offset:offset + 1] == '\\' and offset + 1 < len(s) and s[offset + 1:offset + 2] == '"'): offset += 1 parts[-1] += '"' else: parts[-1] += s[offset:offset + 1] offset += 1 if offset >= len(s): real_parts = _configlist(parts[-1]) if not real_parts: parts[-1] = '"' else: real_parts[0] = '"' + real_parts[0] parts = parts[:-1] parts.extend(real_parts) return None, parts, offset offset += 1 while offset < len(s) and s[offset:offset + 1] in [' ', ',']: offset += 1 if offset < len(s): if offset + 1 == len(s) and s[offset:offset + 1] == '"': parts[-1] += '"' offset += 1 else: parts.append('') else: return None, parts, offset return _parse_plain, parts, offset def _configlist(s): s = s.rstrip(' ,') if not s: return [] parser, parts, offset = _parse_plain, [''], 0 while parser: parser, parts, offset = parser(parts, s, offset) return parts if value is not None and isinstance(value, bytes): result = _configlist(value.lstrip(' ,\n')) else: result = value return result or []