Mercurial > hg
view mercurial/fancyopts.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outdated and unsupported repo format.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 | bd872f64a8ba |
children | db8531c45953 |
line wrap: on
line source
# fancyopts.py - better command line parsing # # Copyright 2005-2009 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 from .i18n import _ from . import ( error, pycompat, ) # Set of flags to not apply boolean negation logic on nevernegate = { # avoid --no-noninteractive 'noninteractive', # These two flags are special because they cause hg to do one # thing and then exit, and so aren't suitable for use in things # like aliases anyway. 'help', 'version', } def gnugetopt(args, options, longoptions): """Parse options mostly like getopt.gnu_getopt. This is different from getopt.gnu_getopt in that an argument of - will become an argument of - instead of vanishing completely. """ extraargs = [] if '--' in args: stopindex = args.index('--') extraargs = args[stopindex + 1:] args = args[:stopindex] opts, parseargs = pycompat.getoptb(args, options, longoptions) args = [] while parseargs: arg = parseargs.pop(0) if arg and arg[0] == '-' and len(arg) > 1: parseargs.insert(0, arg) topts, newparseargs = pycompat.getoptb(parseargs,\ options, longoptions) opts = opts + topts parseargs = newparseargs else: args.append(arg) args.extend(extraargs) return opts, args def fancyopts(args, options, state, gnu=False): """ read args, parse options, and store options in state each option is a tuple of: short option or '' long option default value description option value label(optional) option types include: boolean or none - option sets variable in state to true string - parameter string is stored in state list - parameter string is added to a list integer - parameter strings is stored as int function - call function with parameter non-option args are returned """ namelist = [] shortlist = '' argmap = {} defmap = {} negations = {} alllong = set(o[1] for o in options) for option in options: if len(option) == 5: short, name, default, comment, dummy = option else: short, name, default, comment = option # convert opts to getopt format oname = name name = name.replace('-', '_') argmap['-' + short] = argmap['--' + oname] = name defmap[name] = default # copy defaults to state if isinstance(default, list): state[name] = default[:] elif callable(default): state[name] = None else: state[name] = default # does it take a parameter? if not (default is None or default is True or default is False): if short: short += ':' if oname: oname += '=' elif oname not in nevernegate: if oname.startswith('no-'): insert = oname[3:] else: insert = 'no-' + oname # backout (as a practical example) has both --commit and # --no-commit options, so we don't want to allow the # negations of those flags. if insert not in alllong: assert ('--' + oname) not in negations negations['--' + insert] = '--' + oname namelist.append(insert) if short: shortlist += short if name: namelist.append(oname) # parse arguments if gnu: parse = gnugetopt else: parse = pycompat.getoptb opts, args = parse(args, shortlist, namelist) # transfer result to state for opt, val in opts: boolval = True negation = negations.get(opt, False) if negation: opt = negation boolval = False name = argmap[opt] obj = defmap[name] t = type(obj) if callable(obj): state[name] = defmap[name](val) elif t is type(1): try: state[name] = int(val) except ValueError: raise error.Abort(_('invalid value %r for option %s, ' 'expected int') % (val, opt)) elif t is type(''): state[name] = val elif t is type([]): state[name].append(val) elif t is type(None) or t is type(False): state[name] = boolval # return unparsed args return args