annotate mercurial/dispatch.py @ 26755:bb0b955d050d

streamclone: support for producing and consuming stream clone bundles

Up to this point, stream clones only existed as a dynamically generated
data format produced and consumed during streaming clones. In order to
support this efficient cloning format with the clone bundles feature, we
need a more formal, on disk representation of the streaming clone data.

This patch introduces a new "bundle" type for streaming clones. Unlike
existing bundles, it does not contain changegroup data. It does,
however, share the same concepts like the 4 byte header which identifies
the type of data that follows and the 2 byte abbreviation for
compression types (of which only "UN" is currently supported).

The new bundle format is essentially the existing stream clone version 1
data format with some headers at the beginning.

Content negotiation at stream clone request time checked for repository
format/requirements compatibility before initiating a stream clone. We
can't do active content negotiation when using clone bundles. So, we put
this set of requirements inside the payload so consumers have a built-in
mechanism for checking compatibility before reading and applying lots of
data. Of course, we will also advertise this requirements set in clone
bundles. But that's for another patch.

We currently don't have a mechanism to produce and consume this new
bundle format. This will be implemented in upcoming patches.

It's worth noting that if a legacy client attempts to `hg unbundle` a
stream clone bundle (with the "HGS1" header), it will abort with:
"unknown bundle version S1," which seems appropriate.

# dispatch.py - command dispatching for mercurial
#
# Copyright 2005-2007 Matt Mackall <[e-mail]>
#
# 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 atexit
import difflib
import errno
import os
import pdb
import re
import shlex
import signal
import socket
import sys
import time
import traceback


from .i18n import _

from . import (
    cmdutil,
    commands,
    demandimport,
    encoding,
    error,
    extensions,
    fancyopts,
    hg,
    hook,
    ui as uimod,
    util,
)

class request(object):
    def __init__(self, args, ui=None, repo=None, fin=None, fout=None,
                 ferr=None):
        self.args = args
        self.ui = ui
        self.repo = repo

        # input/output/error streams
        self.fin = fin
        self.fout = fout
        self.ferr = ferr

def run():
    "run the command in sys.argv"
    sys.exit((dispatch(request(sys.argv[1:])) or 0) & 255)

def _getsimilar(symbols, value):
    sim = lambda x: difflib.SequenceMatcher(None, value, x).ratio()
    # The cutoff for similarity here is pretty arbitrary. It should
    # probably be investigated and tweaked.
    return [s for s in symbols if sim(s) > 0.6]

def _formatparse(write, inst):
    similar = []
    if isinstance(inst, error.UnknownIdentifier):
        # make sure to check fileset first, as revset can invoke fileset
        similar = _getsimilar(inst.symbols, inst.function)
    if len(inst.args) > 1:
        write(_("hg: parse error at %s: %s\n") %
                         (inst.args[1], inst.args[0]))
        if (inst.args[0][0] == ' '):
            write(_("unexpected leading whitespace\n"))
    else:
        write(_("hg: parse error: %s\n") % inst.args[0])
        if similar:
            if len(similar) == 1:
                write(_("(did you mean %r?)\n") % similar[0])
            else:
                ss = ", ".join(sorted(similar))
                write(_("(did you mean one of %s?)\n") % ss)

def dispatch(req):
    "run the command specified in req.args"
    if req.ferr:
        ferr = req.ferr
    elif req.ui:
        ferr = req.ui.ferr
    else:
        ferr = sys.stderr

    try:
        if not req.ui:
            req.ui = uimod.ui()
        if '--traceback' in req.args:
            req.ui.setconfig('ui', 'traceback', 'on', '--traceback')

        # set ui streams from the request
        if req.fin:
            req.ui.fin = req.fin
        if req.fout:
            req.ui.fout = req.fout
        if req.ferr:
            req.ui.ferr = req.ferr
    except error.Abort as inst:
        ferr.write(_("abort: %s\n") % inst)
        if inst.hint:
            ferr.write(_("(%s)\n") % inst.hint)
        return -1
    except error.ParseError as inst:
        _formatparse(ferr.write, inst)
        return -1

    msg = ' '.join(' ' in a and repr(a) or a for a in req.args)
    starttime = time.time()
    ret = None
    try:
        ret = _runcatch(req)
        return ret
    finally:
        duration = time.time() - starttime
        req.ui.log("commandfinish", "%s exited %s after %0.2f seconds\n",
                   msg, ret or 0, duration)

def _runcatch(req):
    def catchterm(*args):
        raise error.SignalInterrupt

    ui = req.ui
    try:
        for name in 'SIGBREAK', 'SIGHUP', 'SIGTERM':
            num = getattr(signal, name, None)
            if num:
                signal.signal(num, catchterm)
    except ValueError:
        pass # happens if called in a thread

    try:
        try:
            debugger = 'pdb'
            debugtrace = {
                'pdb' : pdb.set_trace
            }
            debugmortem = {
                'pdb' : pdb.post_mortem
            }

            # read --config before doing anything else
            # (e.g. to change trust settings for reading .hg/hgrc)
            cfgs = _parseconfig(req.ui, _earlygetopt(['--config'], req.args))

            if req.repo:
                # copy configs that were passed on the cmdline (--config) to
                # the repo ui
                for sec, name, val in cfgs:
                    req.repo.ui.setconfig(sec, name, val, source='--config')

            # developer config: ui.debugger
            debugger = ui.config("ui", "debugger")
            debugmod = pdb
            if not debugger or ui.plain():
                # if we are in HGPLAIN mode, then disable custom debugging
                debugger = 'pdb'
            elif '--debugger' in req.args:
                # This import can be slow for fancy debuggers, so only
                # do it when absolutely necessary, i.e. when actual
                # debugging has been requested
                with demandimport.deactivated():
                    try:
                        debugmod = __import__(debugger)
                    except ImportError:
                        pass # Leave debugmod = pdb

            debugtrace[debugger] = debugmod.set_trace
            debugmortem[debugger] = debugmod.post_mortem

            # enter the debugger before command execution
            if '--debugger' in req.args:
                ui.warn(_("entering debugger - "
                        "type c to continue starting hg or h for help\n"))

                if (debugger != 'pdb' and
                    debugtrace[debugger] == debugtrace['pdb']):
                    ui.warn(_("%s debugger specified "
                              "but its module was not found\n") % debugger)
                with demandimport.deactivated():
                    debugtrace[debugger]()
            try:
                return _dispatch(req)
            finally:
                ui.flush()
        except: # re-raises
            # enter the debugger when we hit an exception
            if '--debugger' in req.args:
                traceback.print_exc()
                debugmortem[debugger](sys.exc_info()[2])
            ui.traceback()
            raise

    # Global exception handling, alphabetically
    # Mercurial-specific first, followed by built-in and library exceptions
    except error.AmbiguousCommand as inst:
        ui.warn(_("hg: command '%s' is ambiguous:\n    %s\n") %
                (inst.args[0], " ".join(inst.args[1])))
    except error.ParseError as inst:
        _formatparse(ui.warn, inst)
        return -1
    except error.LockHeld as inst:
        if inst.errno == errno.ETIMEDOUT:
            reason = _('timed out waiting for lock held by %s') % inst.locker
        else:
            reason = _('lock held by %s') % inst.locker
        ui.warn(_("abort: %s: %s\n") % (inst.desc or inst.filename, reason))
    except error.LockUnavailable as inst:
        ui.warn(_("abort: could not lock %s: %s\n") %
               (inst.desc or inst.filename, inst.strerror))
    except error.CommandError as inst:
        if inst.args[0]:
            ui.warn(_("hg %s: %s\n") % (inst.args[0], inst.args[1]))
            commands.help_(ui, inst.args[0], full=False, command=True)
        else:
            ui.warn(_("hg: %s\n") % inst.args[1])
            commands.help_(ui, 'shortlist')
    except error.OutOfBandError as inst:
        if inst.args:
            msg = _("abort: remote error:\n")
        else:
            msg = _("abort: remote error\n")
        ui.warn(msg)
        if inst.args:
            ui.warn(''.join(inst.args))
        if inst.hint:
            ui.warn('(%s)\n' % inst.hint)
    except error.RepoError as inst:
        ui.warn(_("abort: %s!\n") % inst)
        if inst.hint:
            ui.warn(_("(%s)\n") % inst.hint)
    except error.ResponseError as inst:
        ui.warn(_("abort: %s") % inst.args[0])
        if not isinstance(inst.args[1], basestring):
            ui.warn(" %r\n" % (inst.args[1],))
        elif not inst.args[1]:
            ui.warn(_(" empty string\n"))
        else:
            ui.warn("\n%r\n" % util.ellipsis(inst.args[1]))
    except error.CensoredNodeError as inst:
        ui.warn(_("abort: file censored %s!\n") % inst)
    except error.RevlogError as inst:
        ui.warn(_("abort: %s!\n") % inst)
    except error.SignalInterrupt:
        ui.warn(_("killed!\n"))
    except error.UnknownCommand as inst:
        ui.warn(_("hg: unknown command '%s'\n") % inst.args[0])
        try:
            # check if the command is in a disabled extension
            # (but don't check for extensions themselves)
            commands.help_(ui, inst.args[0], unknowncmd=True)
        except (error.UnknownCommand, error.Abort):
            suggested = False
            if len(inst.args) == 2:
                sim = _getsimilar(inst.args[1], inst.args[0])
                if sim:
                    ui.warn(_('(did you mean one of %s?)\n') %
                            ', '.join(sorted(sim)))
                    suggested = True
            if not suggested:
                commands.help_(ui, 'shortlist')
    except error.InterventionRequired as inst:
        ui.warn("%s\n" % inst)
        return 1
    except error.Abort as inst:
        ui.warn(_("abort: %s\n") % inst)
        if inst.hint:
            ui.warn(_("(%s)\n") % inst.hint)
    except ImportError as inst:
        ui.warn(_("abort: %s!\n") % inst)
        m = str(inst).split()[-1]
        if m in "mpatch bdiff".split():
            ui.warn(_("(did you forget to compile extensions?)\n"))
        elif m in "zlib".split():
            ui.warn(_("(is your Python install correct?)\n"))
    except IOError as inst:
        if util.safehasattr(inst, "code"):
            ui.warn(_("abort: %s\n") % inst)
        elif util.safehasattr(inst, "reason"):
            try: # usually it is in the form (errno, strerror)
                reason = inst.reason.args[1]
            except (AttributeError, IndexError):
                # it might be anything, for example a string
                reason = inst.reason
            if isinstance(reason, unicode):
                # SSLError of Python 2.7.9 contains a unicode
                reason = reason.encode(encoding.encoding, 'replace')
            ui.warn(_("abort: error: %s\n") % reason)
        elif (util.safehasattr(inst, "args")
              and inst.args and inst.args[0] == errno.EPIPE):
            pass
        elif getattr(inst, "strerror", None):
            if getattr(inst, "filename", None):
                ui.warn(_("abort: %s: %s\n") % (inst.strerror, inst.filename))
            else:
                ui.warn(_("abort: %s\n") % inst.strerror)
        else:
            raise
    except OSError as inst:
        if getattr(inst, "filename", None) is not None:
            ui.warn(_("abort: %s: '%s'\n") % (inst.strerror, inst.filename))
        else:
            ui.warn(_("abort: %s\n") % inst.strerror)
    except KeyboardInterrupt:
        try:
            ui.warn(_("interrupted!\n"))
        except IOError as inst:
            if inst.errno != errno.EPIPE:
                raise
    except MemoryError:
        ui.warn(_("abort: out of memory\n"))
    except SystemExit as inst:
        # Commands shouldn't sys.exit directly, but give a return code.
        # Just in case catch this and and pass exit code to caller.
        return inst.code
    except socket.error as inst:
        ui.warn(_("abort: %s\n") % inst.args[-1])
    except: # re-raises
        myver = util.version()
        # For compatibility checking, we discard the portion of the hg
        # version after the + on the assumption that if a "normal
        # user" is running a build with a + in it the packager
        # probably built from fairly close to a tag and anyone with a
        # 'make local' copy of hg (where the version number can be out
        # of date) will be clueful enough to notice the implausible
        # version number and try updating.
        compare = myver.split('+')[0]
        ct = tuplever(compare)
        worst = None, ct, ''
        if ui.config('ui', 'supportcontact', None) is None:
            for name, mod in extensions.extensions():
                testedwith = getattr(mod, 'testedwith', '')
                report = getattr(mod, 'buglink', _('the extension author.'))
                if not testedwith.strip():
                    # We found an untested extension. It's likely the culprit.
                    worst = name, 'unknown', report
                    break

                # Never blame on extensions bundled with Mercurial.
                if testedwith == 'internal':
                    continue

                tested = [tuplever(t) for t in testedwith.split()]
                if ct in tested:
                    continue

                lower = [t for t in tested if t < ct]
                nearest = max(lower or tested)
                if worst[0] is None or nearest < worst[1]:
                    worst = name, nearest, report
        if worst[0] is not None:
            name, testedwith, report = worst
            if not isinstance(testedwith, str):
                testedwith = '.'.join([str(c) for c in testedwith])
            warning = (_('** Unknown exception encountered with '
                         'possibly-broken third-party extension %s\n'
                         '** which supports versions %s of Mercurial.\n'
                         '** Please disable %s and try your action again.\n'
                         '** If that fixes the bug please report it to %s\n')
                       % (name, testedwith, name, report))
        else:
            bugtracker = ui.config('ui', 'supportcontact', None)
            if bugtracker is None:
                bugtracker = _("https://mercurial-scm.org/wiki/BugTracker")
            warning = (_("** unknown exception encountered, "
                         "please report by visiting\n** ") + bugtracker + '\n')
        warning += ((_("** Python %s\n") % sys.version.replace('\n', '')) +
                    (_("** Mercurial Distributed SCM (version %s)\n") % myver) +
                    (_("** Extensions loaded: %s\n") %
                     ", ".join([x[0] for x in extensions.extensions()])))
        ui.log("commandexception", "%s\n%s\n", warning, traceback.format_exc())
        ui.warn(warning)
        raise

    return -1

def tuplever(v):
    try:
        # Assertion: tuplever is only used for extension compatibility
        # checking. Otherwise, the discarding of extra version fields is
        # incorrect.
        return tuple([int(i) for i in v.split('.')[0:2]])
    except ValueError:
        return tuple()

def aliasargs(fn, givenargs):
    args = getattr(fn, 'args', [])
    if args:
        cmd = ' '.join(map(util.shellquote, args))

        nums = []
        def replacer(m):
            num = int(m.group(1)) - 1
            nums.append(num)
            if num < len(givenargs):
                return givenargs[num]
            raise error.Abort(_('too few arguments for command alias'))
        cmd = re.sub(r'\$(\d+|\$)', replacer, cmd)
        givenargs = [x for i, x in enumerate(givenargs)
                     if i not in nums]
        args = shlex.split(cmd)
    return args + givenargs

def aliasinterpolate(name, args, cmd):
    '''interpolate args into cmd for shell aliases

    This also handles $0, $@ and "$@".
    '''
    # util.interpolate can't deal with "$@" (with quotes) because it's only
    # built to match prefix + patterns.
    replacemap = dict(('$%d' % (i + 1), arg) for i, arg in enumerate(args))
    replacemap['$0'] = name
    replacemap['$$'] = '$'
    replacemap['$@'] = ' '.join(args)
    # Typical Unix shells interpolate "$@" (with quotes) as all the positional
    # parameters, separated out into words. Emulate the same behavior here by
    # quoting the arguments individually. POSIX shells will then typically
    # tokenize each argument into exactly one word.
    replacemap['"$@"'] = ' '.join(util.shellquote(arg) for arg in args)
    # escape '\$' for regex
    regex = '|'.join(replacemap.keys()).replace('$', r'\$')
    r = re.compile(regex)
    return r.sub(lambda x: replacemap[x.group()], cmd)

class cmdalias(object):
    def __init__(self, name, definition, cmdtable):
        self.name = self.cmd = name
        self.cmdname = ''
        self.definition = definition
        self.fn = None
        self.args = []
        self.opts = []
        self.help = ''
        self.norepo = True
        self.optionalrepo = False
        self.badalias = None
        self.unknowncmd = False

        try:
            aliases, entry = cmdutil.findcmd(self.name, cmdtable)
            for alias, e in cmdtable.iteritems():
                if e is entry:
                    self.cmd = alias
                    break
            self.shadows = True
        except error.UnknownCommand:
            self.shadows = False

        if not self.definition:
            self.badalias = _("no definition for alias '%s'") % self.name
            return

        if self.definition.startswith('!'):
            self.shell = True
            def fn(ui, *args):
                env = {'HG_ARGS': ' '.join((self.name,) + args)}
                def _checkvar(m):
                    if m.groups()[0] == '$':
                        return m.group()
                    elif int(m.groups()[0]) <= len(args):
                        return m.group()
                    else:
                        ui.debug("No argument found for substitution "
                                 "of %i variable in alias '%s' definition."
                                 % (int(m.groups()[0]), self.name))
                        return ''
                cmd = re.sub(r'\$(\d+|\$)', _checkvar, self.definition[1:])
                cmd = aliasinterpolate(self.name, args, cmd)
                return ui.system(cmd, environ=env)
            self.fn = fn
            return

        try:
            args = shlex.split(self.definition)
        except ValueError as inst:
            self.badalias = (_("error in definition for alias '%s': %s")
                             % (self.name, inst))
            return
        self.cmdname = cmd = args.pop(0)
        args = map(util.expandpath, args)

        for invalidarg in ("--cwd", "-R", "--repository", "--repo", "--config"):
            if _earlygetopt([invalidarg], args):
                self.badalias = (_("error in definition for alias '%s': %s may "
                                   "only be given on the command line")
                                 % (self.name, invalidarg))
                return

        try:
            tableentry = cmdutil.findcmd(cmd, cmdtable, False)[1]
            if len(tableentry) > 2:
                self.fn, self.opts, self.help = tableentry
            else:
                self.fn, self.opts = tableentry

            self.args = aliasargs(self.fn, args)
            if cmd not in commands.norepo.split(' '):
                self.norepo = False
            if cmd in commands.optionalrepo.split(' '):
                self.optionalrepo = True
            if self.help.startswith("hg " + cmd):
                # drop prefix in old-style help lines so hg shows the alias
                self.help = self.help[4 + len(cmd):]
            self.__doc__ = self.fn.__doc__

        except error.UnknownCommand:
            self.badalias = (_("alias '%s' resolves to unknown command '%s'")
                             % (self.name, cmd))
            self.unknowncmd = True
        except error.AmbiguousCommand:
            self.badalias = (_("alias '%s' resolves to ambiguous command '%s'")
                             % (self.name, cmd))

    def __call__(self, ui, *args, **opts):
        if self.badalias:
            hint = None
            if self.unknowncmd:
                try:
                    # check if the command is in a disabled extension
                    cmd, ext = extensions.disabledcmd(ui, self.cmdname)[:2]
                    hint = _("'%s' is provided by '%s' extension") % (cmd, ext)
                except error.UnknownCommand:
                    pass
            raise error.Abort(self.badalias, hint=hint)
        if self.shadows:
            ui.debug("alias '%s' shadows command '%s'\n" %
                     (self.name, self.cmdname))

        if util.safehasattr(self, 'shell'):
            return self.fn(ui, *args, **opts)
        else:
            try:
                return util.checksignature(self.fn)(ui, *args, **opts)
            except error.SignatureError:
                args = ' '.join([self.cmdname] + self.args)
                ui.debug("alias '%s' expands to '%s'\n" % (self.name, args))
                raise

def addaliases(ui, cmdtable):
    # aliases are processed after extensions have been loaded, so they
    # may use extension commands. Aliases can also use other alias definitions,
    # but only if they have been defined prior to the current definition.
    for alias, definition in ui.configitems('alias'):
        aliasdef = cmdalias(alias, definition, cmdtable)

        try:
            olddef = cmdtable[aliasdef.cmd][0]
            if olddef.definition == aliasdef.definition:
                continue
        except (KeyError, AttributeError):
            # definition might not exist or it might not be a cmdalias
            pass

        cmdtable[aliasdef.name] = (aliasdef, aliasdef.opts, aliasdef.help)
        if aliasdef.norepo:
            commands.norepo += ' %s' % alias
        if aliasdef.optionalrepo:
            commands.optionalrepo += ' %s' % alias

def _parse(ui, args):
    options = {}
    cmdoptions = {}

    try:
        args = fancyopts.fancyopts(args, commands.globalopts, options)
    except fancyopts.getopt.GetoptError as inst:
        raise error.CommandError(None, inst)

    if args:
        cmd, args = args[0], args[1:]
        aliases, entry = cmdutil.findcmd(cmd, commands.table,
                                         ui.configbool("ui", "strict"))
        cmd = aliases[0]
        args = aliasargs(entry[0], args)
        defaults = ui.config("defaults", cmd)
        if defaults:
            args = map(util.expandpath, shlex.split(defaults)) + args
        c = list(entry[1])
    else:
        cmd = None
        c = []

    # combine global options into local
    for o in commands.globalopts:
        c.append((o[0], o[1], options[o[1]], o[3]))

    try:
        args = fancyopts.fancyopts(args, c, cmdoptions, True)
    except fancyopts.getopt.GetoptError as inst:
        raise error.CommandError(cmd, inst)

    # separate global options back out
    for o in commands.globalopts:
        n = o[1]
        options[n] = cmdoptions[n]
        del cmdoptions[n]

    return (cmd, cmd and entry[0] or None, args, options, cmdoptions)

def _parseconfig(ui, config):
    """parse the --config options from the command line"""
    configs = []

    for cfg in config:
        try:
            name, value = cfg.split('=', 1)
            section, name = name.split('.', 1)
            if not section or not name:
                raise IndexError
            ui.setconfig(section, name, value, '--config')
            configs.append((section, name, value))
        except (IndexError, ValueError):
            raise error.Abort(_('malformed --config option: %r '
                               '(use --config section.name=value)') % cfg)

    return configs

def _earlygetopt(aliases, args):
    """Return list of values for an option (or aliases).

    The values are listed in the order they appear in args.
    The options and values are removed from args.

    >>> args = ['x', '--cwd', 'foo', 'y']
    >>> _earlygetopt(['--cwd'], args), args
    (['foo'], ['x', 'y'])

    >>> args = ['x', '--cwd=bar', 'y']
    >>> _earlygetopt(['--cwd'], args), args
    (['bar'], ['x', 'y'])

    >>> args = ['x', '-R', 'foo', 'y']
    >>> _earlygetopt(['-R'], args), args
    (['foo'], ['x', 'y'])

    >>> args = ['x', '-Rbar', 'y']
    >>> _earlygetopt(['-R'], args), args
    (['bar'], ['x', 'y'])
    """
    try:
        argcount = args.index("--")
    except ValueError:
        argcount = len(args)
    shortopts = [opt for opt in aliases if len(opt) == 2]
    values = []
    pos = 0
    while pos < argcount:
        fullarg = arg = args[pos]
        equals = arg.find('=')
        if equals > -1:
            arg = arg[:equals]
        if arg in aliases:
            del args[pos]
            if equals > -1:
                values.append(fullarg[equals + 1:])
                argcount -= 1
            else:
                if pos + 1 >= argcount:
                    # ignore and let getopt report an error if there is no value
                    break
                values.append(args.pop(pos))
                argcount -= 2
        elif arg[:2] in shortopts:
            # short option can have no following space, e.g. hg log -Rfoo
            values.append(args.pop(pos)[2:])
            argcount -= 1
        else:
            pos += 1
    return values

def runcommand(lui, repo, cmd, fullargs, ui, options, d, cmdpats, cmdoptions):
    # run pre-hook, and abort if it fails
    hook.hook(lui, repo, "pre-%s" % cmd, True, args=" ".join(fullargs),
              pats=cmdpats, opts=cmdoptions)
    ret = _runcommand(ui, options, cmd, d)
    # run post-hook, passing command result
    hook.hook(lui, repo, "post-%s" % cmd, False, args=" ".join(fullargs),
              result=ret, pats=cmdpats, opts=cmdoptions)
    return ret

def _getlocal(ui, rpath):
    """Return (path, local ui object) for the given target path.

    Takes paths in [cwd]/.hg/hgrc into account."
    """
    try:
        wd = os.getcwd()
    except OSError as e:
        raise error.Abort(_("error getting current working directory: %s") %
                         e.strerror)
    path = cmdutil.findrepo(wd) or ""
    if not path:
        lui = ui
    else:
        lui = ui.copy()
        lui.readconfig(os.path.join(path, ".hg", "hgrc"), path)

    if rpath and rpath[-1]:
        path = lui.expandpath(rpath[-1])
        lui = ui.copy()
        lui.readconfig(os.path.join(path, ".hg", "hgrc"), path)

    return path, lui

def _checkshellalias(lui, ui, args, precheck=True):
    """Return the function to run the shell alias, if it is required

    'precheck' is whether this function is invoked before adding
    aliases or not.
    """
    options = {}

    try:
        args = fancyopts.fancyopts(args, commands.globalopts, options)
    except fancyopts.getopt.GetoptError:
        return

    if not args:
        return

    if precheck:
        strict = True
        norepo = commands.norepo
        optionalrepo = commands.optionalrepo
        def restorecommands():
            commands.norepo = norepo
            commands.optionalrepo = optionalrepo
        cmdtable = commands.table.copy()
        addaliases(lui, cmdtable)
    else:
        strict = False
        def restorecommands():
            pass
        cmdtable = commands.table

    cmd = args[0]
    try:
        aliases, entry = cmdutil.findcmd(cmd, cmdtable, strict)
    except (error.AmbiguousCommand, error.UnknownCommand):
        restorecommands()
        return

    cmd = aliases[0]
    fn = entry[0]

    if cmd and util.safehasattr(fn, 'shell'):
        d = lambda: fn(ui, *args[1:])
        return lambda: runcommand(lui, None, cmd, args[:1], ui, options, d,
                                  [], {})

    restorecommands()

_loaded = set()
def _dispatch(req):
    args = req.args
    ui = req.ui

    # check for cwd
    cwd = _earlygetopt(['--cwd'], args)
    if cwd:
        os.chdir(cwd[-1])

    rpath = _earlygetopt(["-R", "--repository", "--repo"], args)
    path, lui = _getlocal(ui, rpath)

    # Now that we're operating in the right directory/repository with
    # the right config settings, check for shell aliases
    shellaliasfn = _checkshellalias(lui, ui, args)
    if shellaliasfn:
        return shellaliasfn()

    # Configure extensions in phases: uisetup, extsetup, cmdtable, and
    # reposetup. Programs like TortoiseHg will call _dispatch several
    # times so we keep track of configured extensions in _loaded.
    extensions.loadall(lui)
    exts = [ext for ext in extensions.extensions() if ext[0] not in _loaded]
    # Propagate any changes to lui.__class__ by extensions
    ui.__class__ = lui.__class__

    # (uisetup and extsetup are handled in extensions.loadall)

    for name, module in exts:
        cmdtable = getattr(module, 'cmdtable', {})
        overrides = [cmd for cmd in cmdtable if cmd in commands.table]
        if overrides:
            ui.warn(_("extension '%s' overrides commands: %s\n")
                    % (name, " ".join(overrides)))
        commands.table.update(cmdtable)
        _loaded.add(name)

    # (reposetup is handled in hg.repository)

    addaliases(lui, commands.table)

    if not lui.configbool("ui", "strict"):
        # All aliases and commands are completely defined, now.
        # Check abbreviation/ambiguity of shell alias again, because shell
        # alias may cause failure of "_parse" (see issue4355)
        shellaliasfn = _checkshellalias(lui, ui, args, precheck=False)
        if shellaliasfn:
            return shellaliasfn()

    # check for fallback encoding
    fallback = lui.config('ui', 'fallbackencoding')
    if fallback:
        encoding.fallbackencoding = fallback

    fullargs = args
    cmd, func, args, options, cmdoptions = _parse(lui, args)

    if options["config"]:
        raise error.Abort(_("option --config may not be abbreviated!"))
    if options["cwd"]:
        raise error.Abort(_("option --cwd may not be abbreviated!"))
    if options["repository"]:
        raise error.Abort(_(
            "option -R has to be separated from other options (e.g. not -qR) "
            "and --repository may only be abbreviated as --repo!"))

    if options["encoding"]:
        encoding.encoding = options["encoding"]
    if options["encodingmode"]:
        encoding.encodingmode = options["encodingmode"]
    if options["time"]:
        def get_times():
            t = os.times()
            if t[4] == 0.0: # Windows leaves this as zero, so use time.clock()
                t = (t[0], t[1], t[2], t[3], time.clock())
            return t
        s = get_times()
        def print_time():
            t = get_times()
            ui.warn(_("time: real %.3f secs (user %.3f+%.3f sys %.3f+%.3f)\n") %
                (t[4]-s[4], t[0]-s[0], t[2]-s[2], t[1]-s[1], t[3]-s[3]))
        atexit.register(print_time)

    uis = set([ui, lui])

    if req.repo:
        uis.add(req.repo.ui)

    if options['verbose'] or options['debug'] or options['quiet']:
        for opt in ('verbose', 'debug', 'quiet'):
            val = str(bool(options[opt]))
            for ui_ in uis:
                ui_.setconfig('ui', opt, val, '--' + opt)

    if options['traceback']:
        for ui_ in uis:
            ui_.setconfig('ui', 'traceback', 'on', '--traceback')

    if options['noninteractive']:
        for ui_ in uis:
            ui_.setconfig('ui', 'interactive', 'off', '-y')

    if cmdoptions.get('insecure', False):
        for ui_ in uis:
            ui_.setconfig('web', 'cacerts', '!', '--insecure')

    if options['version']:
        return commands.version_(ui)
    if options['help']:
        return commands.help_(ui, cmd, command=True)
    elif not cmd:
        return commands.help_(ui, 'shortlist')

    repo = None
    cmdpats = args[:]
    if cmd not in commands.norepo.split():
        # use the repo from the request only if we don't have -R
        if not rpath and not cwd:
            repo = req.repo

        if repo:
            # set the descriptors of the repo ui to those of ui
            repo.ui.fin = ui.fin
            repo.ui.fout = ui.fout
            repo.ui.ferr = ui.ferr
        else:
            try:
                repo = hg.repository(ui, path=path)
                if not repo.local():
                    raise error.Abort(_("repository '%s' is not local") % path)
                repo.ui.setconfig("bundle", "mainreporoot", repo.root, 'repo')
            except error.RequirementError:
                raise
            except error.RepoError:
                if rpath and rpath[-1]: # invalid -R path
                    raise
                if cmd not in commands.optionalrepo.split():
                    if (cmd in commands.inferrepo.split() and
                        args and not path): # try to infer -R from command args
                        repos = map(cmdutil.findrepo, args)
                        guess = repos[0]
                        if guess and repos.count(guess) == len(repos):
                            req.args = ['--repository', guess] + fullargs
                            return _dispatch(req)
                    if not path:
                        raise error.RepoError(_("no repository found in '%s'"
                                                " (.hg not found)")
                                              % os.getcwd())
                    raise
        if repo:
            ui = repo.ui
            if options['hidden']:
                repo = repo.unfiltered()
        args.insert(0, repo)
    elif rpath:
        ui.warn(_("warning: --repository ignored\n"))

    msg = ' '.join(' ' in a and repr(a) or a for a in fullargs)
    ui.log("command", '%s\n', msg)
    d = lambda: util.checksignature(func)(ui, *args, **cmdoptions)
    try:
        return runcommand(lui, repo, cmd, fullargs, ui, options, d,
                          cmdpats, cmdoptions)
    finally:
        if repo and repo != req.repo:
            repo.close()

def lsprofile(ui, func, fp):
    format = ui.config('profiling', 'format', default='text')
    field = ui.config('profiling', 'sort', default='inlinetime')
    limit = ui.configint('profiling', 'limit', default=30)
    climit = ui.configint('profiling', 'nested', default=0)

    if format not in ['text', 'kcachegrind']:
        ui.warn(_("unrecognized profiling format '%s'"
                    " - Ignored\n") % format)
        format = 'text'

    try:
        from . import lsprof
    except ImportError:
        raise error.Abort(_(
            'lsprof not available - install from '
            'http://codespeak.net/svn/user/arigo/hack/misc/lsprof/'))
    p = lsprof.Profiler()
    p.enable(subcalls=True)
    try:
        return func()
    finally:
        p.disable()

        if format == 'kcachegrind':
            from . import lsprofcalltree
            calltree = lsprofcalltree.KCacheGrind(p)
            calltree.output(fp)
        else:
            # format == 'text'
            stats = lsprof.Stats(p.getstats())
            stats.sort(field)
            stats.pprint(limit=limit, file=fp, climit=climit)

def flameprofile(ui, func, fp):
    try:
        from flamegraph import flamegraph
    except ImportError:
        raise error.Abort(_(
            'flamegraph not available - install from '
            'https://github.com/evanhempel/python-flamegraph'))
    # developer config: profiling.freq
    freq = ui.configint('profiling', 'freq', default=1000)
    filter_ = None
    collapse_recursion = True
    thread = flamegraph.ProfileThread(fp, 1.0 / freq,
                                      filter_, collapse_recursion)
    start_time = time.clock()
    try:
        thread.start()
        func()
    finally:
        thread.stop()
        thread.join()
        print 'Collected %d stack frames (%d unique) in %2.2f seconds.' % (
            time.clock() - start_time, thread.num_frames(),
            thread.num_frames(unique=True))


def statprofile(ui, func, fp):
    try:
        import statprof
    except ImportError:
        raise error.Abort(_(
            'statprof not available - install using "easy_install statprof"'))

    freq = ui.configint('profiling', 'freq', default=1000)
    if freq > 0:
        statprof.reset(freq)
    else:
        ui.warn(_("invalid sampling frequency '%s' - ignoring\n") % freq)

    statprof.start()
    try:
        return func()
    finally:
        statprof.stop()
        statprof.display(fp)

def _runcommand(ui, options, cmd, cmdfunc):
    """Enables the profiler if applicable.

    ``profiling.enabled`` - boolean config that enables or disables profiling
    """
    def checkargs():
        try:
            return cmdfunc()
        except error.SignatureError:
            raise error.CommandError(cmd, _("invalid arguments"))

    if options['profile'] or ui.configbool('profiling', 'enabled'):
        profiler = os.getenv('HGPROF')
        if profiler is None:
            profiler = ui.config('profiling', 'type', default='ls')
        if profiler not in ('ls', 'stat', 'flame'):
            ui.warn(_("unrecognized profiler '%s' - ignored\n") % profiler)
            profiler = 'ls'

        output = ui.config('profiling', 'output')

        if output == 'blackbox':
            import StringIO
            fp = StringIO.StringIO()
        elif output:
            path = ui.expandpath(output)
            fp = open(path, 'wb')
        else:
            fp = sys.stderr

        try:
            if profiler == 'ls':
                return lsprofile(ui, checkargs, fp)
            elif profiler == 'flame':
                return flameprofile(ui, checkargs, fp)
            else:
                return statprofile(ui, checkargs, fp)
        finally:
            if output:
                if output == 'blackbox':
                    val = "Profile:\n%s" % fp.getvalue()
                    # ui.log treats the input as a format string,
                    # so we need to escape any % signs.
                    val = val.replace('%', '%%')
                    ui.log('profile', val)
                fp.close()
    else:
        return checkargs()