view hgext/convert/git.py @ 33800:f257943e47ab

repository: formalize peer interface with abstract base class

There are various interfaces for interacting with repositories
and peers. They form a contract for how one should interact with
a repo or peer object.

The contracts today aren't very well-defined or enforced. There
have been several bugs over the years where peers or repo types
have forgotten to implement certain methods. In addition, the
inheritance of some classes is wonky. For example, localrepository
doesn't inherit from an interface and the god-object nature of
that class means the repository interface isn't well-defined. Other
repository types inherit from localrepository then stub out
methods that don't make sense (e.g. statichttprepository
re-defining locking methods to fail fast).

Not having well-defined interfaces makes implementing alternate
storage backends, wire protocol transports, and repository types
difficult because it isn't clear what exactly needs to be
implemented.

This patch starts the process of attempting to establish more
order to the type system around repositories and peers.

Our first patch starts with a problem space that already has a
partial solution: peers. The peer.peerrepository class already
somewhat defines a peer interface. But it is missing a few things
and the total interface isn't well-defined because it is combined
with wireproto.wirepeer.

Our newly-established basepeer class uses the abc module to
declare an abstract base class with the properties and methods that
a generic peer must implement.

We create a new class that inherits from it. This class will hold
our other future abstract base classes / interfaces so we can expose
a unified base class/interface.

We don't yet use the new interface because subsequent additions
will break existing code without some refactoring first.

A new module (repository.py) was created to hold the interfaces.
I could have put things in peer.py. However, I have plans to
eventually add interfaces to define repository and storage types.
These almost certainly require a new module. And I figured having
all the interfaces live in one module makes sense. So I created
repository.py to be that future home.

Differential Revision: https://phab.mercurial-scm.org/D332

# git.py - git support for the convert extension
#
#  Copyright 2005-2009 Matt Mackall <[e-mail]> 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 os

from mercurial.i18n import _
from mercurial import (
    config,
    error,
    node as nodemod,
)

from . import (
    common,
)

class submodule(object):
    def __init__(self, path, node, url):
        self.path = path
        self.node = node
        self.url = url

    def hgsub(self):
        return "%s = [git]%s" % (self.path, self.url)

    def hgsubstate(self):
        return "%s %s" % (self.node, self.path)

# Keys in extra fields that should not be copied if the user requests.
bannedextrakeys = {
    # Git commit object built-ins.
    'tree',
    'parent',
    'author',
    'committer',
    # Mercurial built-ins.
    'branch',
    'close',
}

class convert_git(common.converter_source, common.commandline):
    # Windows does not support GIT_DIR= construct while other systems
    # cannot remove environment variable. Just assume none have
    # both issues.

    def _gitcmd(self, cmd, *args, **kwargs):
        return cmd('--git-dir=%s' % self.path, *args, **kwargs)

    def gitrun0(self, *args, **kwargs):
        return self._gitcmd(self.run0, *args, **kwargs)

    def gitrun(self, *args, **kwargs):
        return self._gitcmd(self.run, *args, **kwargs)

    def gitrunlines0(self, *args, **kwargs):
        return self._gitcmd(self.runlines0, *args, **kwargs)

    def gitrunlines(self, *args, **kwargs):
        return self._gitcmd(self.runlines, *args, **kwargs)

    def gitpipe(self, *args, **kwargs):
        return self._gitcmd(self._run3, *args, **kwargs)

    def __init__(self, ui, path, revs=None):
        super(convert_git, self).__init__(ui, path, revs=revs)
        common.commandline.__init__(self, ui, 'git')

        # Pass an absolute path to git to prevent from ever being interpreted
        # as a URL
        path = os.path.abspath(path)

        if os.path.isdir(path + "/.git"):
            path += "/.git"
        if not os.path.exists(path + "/objects"):
            raise common.NoRepo(_("%s does not look like a Git repository") %
                                path)

        # The default value (50) is based on the default for 'git diff'.
        similarity = ui.configint('convert', 'git.similarity', default=50)
        if similarity < 0 or similarity > 100:
            raise error.Abort(_('similarity must be between 0 and 100'))
        if similarity > 0:
            self.simopt = ['-C%d%%' % similarity]
            findcopiesharder = ui.configbool('convert', 'git.findcopiesharder',
                                             False)
            if findcopiesharder:
                self.simopt.append('--find-copies-harder')

            renamelimit = ui.configint('convert', 'git.renamelimit',
                                       default=400)
            self.simopt.append('-l%d' % renamelimit)
        else:
            self.simopt = []

        common.checktool('git', 'git')

        self.path = path
        self.submodules = []

        self.catfilepipe = self.gitpipe('cat-file', '--batch')

        self.copyextrakeys = self.ui.configlist('convert', 'git.extrakeys')
        banned = set(self.copyextrakeys) & bannedextrakeys
        if banned:
            raise error.Abort(_('copying of extra key is forbidden: %s') %
                              _(', ').join(sorted(banned)))

        committeractions = self.ui.configlist('convert', 'git.committeractions',
                                              'messagedifferent')

        messagedifferent = None
        messagealways = None
        for a in committeractions:
            if a.startswith(('messagedifferent', 'messagealways')):
                k = a
                v = None
                if '=' in a:
                    k, v = a.split('=', 1)

                if k == 'messagedifferent':
                    messagedifferent = v or 'committer:'
                elif k == 'messagealways':
                    messagealways = v or 'committer:'

        if messagedifferent and messagealways:
            raise error.Abort(_('committeractions cannot define both '
                                'messagedifferent and messagealways'))

        dropcommitter = 'dropcommitter' in committeractions
        replaceauthor = 'replaceauthor' in committeractions

        if dropcommitter and replaceauthor:
            raise error.Abort(_('committeractions cannot define both '
                                'dropcommitter and replaceauthor'))

        if dropcommitter and messagealways:
            raise error.Abort(_('committeractions cannot define both '
                                'dropcommitter and messagealways'))

        if not messagedifferent and not messagealways:
            messagedifferent = 'committer:'

        self.committeractions = {
            'dropcommitter': dropcommitter,
            'replaceauthor': replaceauthor,
            'messagedifferent': messagedifferent,
            'messagealways': messagealways,
        }

    def after(self):
        for f in self.catfilepipe:
            f.close()

    def getheads(self):
        if not self.revs:
            output, status = self.gitrun('rev-parse', '--branches', '--remotes')
            heads = output.splitlines()
            if status:
                raise error.Abort(_('cannot retrieve git heads'))
        else:
            heads = []
            for rev in self.revs:
                rawhead, ret = self.gitrun('rev-parse', '--verify', rev)
                heads.append(rawhead[:-1])
                if ret:
                    raise error.Abort(_('cannot retrieve git head "%s"') % rev)
        return heads

    def catfile(self, rev, type):
        if rev == nodemod.nullhex:
            raise IOError
        self.catfilepipe[0].write(rev+'\n')
        self.catfilepipe[0].flush()
        info = self.catfilepipe[1].readline().split()
        if info[1] != type:
            raise error.Abort(_('cannot read %r object at %s') % (type, rev))
        size = int(info[2])
        data = self.catfilepipe[1].read(size)
        if len(data) < size:
            raise error.Abort(_('cannot read %r object at %s: unexpected size')
                             % (type, rev))
        # read the trailing newline
        self.catfilepipe[1].read(1)
        return data

    def getfile(self, name, rev):
        if rev == nodemod.nullhex:
            return None, None
        if name == '.hgsub':
            data = '\n'.join([m.hgsub() for m in self.submoditer()])
            mode = ''
        elif name == '.hgsubstate':
            data = '\n'.join([m.hgsubstate() for m in self.submoditer()])
            mode = ''
        else:
            data = self.catfile(rev, "blob")
            mode = self.modecache[(name, rev)]
        return data, mode

    def submoditer(self):
        null = nodemod.nullhex
        for m in sorted(self.submodules, key=lambda p: p.path):
            if m.node != null:
                yield m

    def parsegitmodules(self, content):
        """Parse the formatted .gitmodules file, example file format:
        [submodule "sub"]\n
        \tpath = sub\n
        \turl = git://giturl\n
        """
        self.submodules = []
        c = config.config()
        # Each item in .gitmodules starts with whitespace that cant be parsed
        c.parse('.gitmodules', '\n'.join(line.strip() for line in
                               content.split('\n')))
        for sec in c.sections():
            s = c[sec]
            if 'url' in s and 'path' in s:
                self.submodules.append(submodule(s['path'], '', s['url']))

    def retrievegitmodules(self, version):
        modules, ret = self.gitrun('show', '%s:%s' % (version, '.gitmodules'))
        if ret:
            # This can happen if a file is in the repo that has permissions
            # 160000, but there is no .gitmodules file.
            self.ui.warn(_("warning: cannot read submodules config file in "
                           "%s\n") % version)
            return

        try:
            self.parsegitmodules(modules)
        except error.ParseError:
            self.ui.warn(_("warning: unable to parse .gitmodules in %s\n")
                         % version)
            return

        for m in self.submodules:
            node, ret = self.gitrun('rev-parse', '%s:%s' % (version, m.path))
            if ret:
                continue
            m.node = node.strip()

    def getchanges(self, version, full):
        if full:
            raise error.Abort(_("convert from git does not support --full"))
        self.modecache = {}
        cmd = ['diff-tree','-z', '--root', '-m', '-r'] + self.simopt + [version]
        output, status = self.gitrun(*cmd)
        if status:
            raise error.Abort(_('cannot read changes in %s') % version)
        changes = []
        copies = {}
        seen = set()
        entry = None
        subexists = [False]
        subdeleted = [False]
        difftree = output.split('\x00')
        lcount = len(difftree)
        i = 0

        skipsubmodules = self.ui.configbool('convert', 'git.skipsubmodules',
                                            False)
        def add(entry, f, isdest):
            seen.add(f)
            h = entry[3]
            p = (entry[1] == "100755")
            s = (entry[1] == "120000")
            renamesource = (not isdest and entry[4][0] == 'R')

            if f == '.gitmodules':
                if skipsubmodules:
                    return

                subexists[0] = True
                if entry[4] == 'D' or renamesource:
                    subdeleted[0] = True
                    changes.append(('.hgsub', nodemod.nullhex))
                else:
                    changes.append(('.hgsub', ''))
            elif entry[1] == '160000' or entry[0] == ':160000':
                if not skipsubmodules:
                    subexists[0] = True
            else:
                if renamesource:
                    h = nodemod.nullhex
                self.modecache[(f, h)] = (p and "x") or (s and "l") or ""
                changes.append((f, h))

        while i < lcount:
            l = difftree[i]
            i += 1
            if not entry:
                if not l.startswith(':'):
                    continue
                entry = l.split()
                continue
            f = l
            if entry[4][0] == 'C':
                copysrc = f
                copydest = difftree[i]
                i += 1
                f = copydest
                copies[copydest] = copysrc
            if f not in seen:
                add(entry, f, False)
            # A file can be copied multiple times, or modified and copied
            # simultaneously. So f can be repeated even if fdest isn't.
            if entry[4][0] == 'R':
                # rename: next line is the destination
                fdest = difftree[i]
                i += 1
                if fdest not in seen:
                    add(entry, fdest, True)
                    # .gitmodules isn't imported at all, so it being copied to
                    # and fro doesn't really make sense
                    if f != '.gitmodules' and fdest != '.gitmodules':
                        copies[fdest] = f
            entry = None

        if subexists[0]:
            if subdeleted[0]:
                changes.append(('.hgsubstate', nodemod.nullhex))
            else:
                self.retrievegitmodules(version)
                changes.append(('.hgsubstate', ''))
        return (changes, copies, set())

    def getcommit(self, version):
        c = self.catfile(version, "commit") # read the commit hash
        end = c.find("\n\n")
        message = c[end + 2:]
        message = self.recode(message)
        l = c[:end].splitlines()
        parents = []
        author = committer = None
        extra = {}
        for e in l[1:]:
            n, v = e.split(" ", 1)
            if n == "author":
                p = v.split()
                tm, tz = p[-2:]
                author = " ".join(p[:-2])
                if author[0] == "<": author = author[1:-1]
                author = self.recode(author)
            if n == "committer":
                p = v.split()
                tm, tz = p[-2:]
                committer = " ".join(p[:-2])
                if committer[0] == "<": committer = committer[1:-1]
                committer = self.recode(committer)
            if n == "parent":
                parents.append(v)
            if n in self.copyextrakeys:
                extra[n] = v

        if self.committeractions['dropcommitter']:
            committer = None
        elif self.committeractions['replaceauthor']:
            author = committer

        if committer:
            messagealways = self.committeractions['messagealways']
            messagedifferent = self.committeractions['messagedifferent']
            if messagealways:
                message += '\n%s %s\n' % (messagealways, committer)
            elif messagedifferent and author != committer:
                message += '\n%s %s\n' % (messagedifferent, committer)

        tzs, tzh, tzm = tz[-5:-4] + "1", tz[-4:-2], tz[-2:]
        tz = -int(tzs) * (int(tzh) * 3600 + int(tzm))
        date = tm + " " + str(tz)
        saverev = self.ui.configbool('convert', 'git.saverev', True)

        c = common.commit(parents=parents, date=date, author=author,
                          desc=message,
                          rev=version,
                          extra=extra,
                          saverev=saverev)
        return c

    def numcommits(self):
        output, ret = self.gitrunlines('rev-list', '--all')
        if ret:
            raise error.Abort(_('cannot retrieve number of commits in %s') \
                              % self.path)
        return len(output)

    def gettags(self):
        tags = {}
        alltags = {}
        output, status = self.gitrunlines('ls-remote', '--tags', self.path)

        if status:
            raise error.Abort(_('cannot read tags from %s') % self.path)
        prefix = 'refs/tags/'

        # Build complete list of tags, both annotated and bare ones
        for line in output:
            line = line.strip()
            if line.startswith("error:") or line.startswith("fatal:"):
                raise error.Abort(_('cannot read tags from %s') % self.path)
            node, tag = line.split(None, 1)
            if not tag.startswith(prefix):
                continue
            alltags[tag[len(prefix):]] = node

        # Filter out tag objects for annotated tag refs
        for tag in alltags:
            if tag.endswith('^{}'):
                tags[tag[:-3]] = alltags[tag]
            else:
                if tag + '^{}' in alltags:
                    continue
                else:
                    tags[tag] = alltags[tag]

        return tags

    def getchangedfiles(self, version, i):
        changes = []
        if i is None:
            output, status = self.gitrunlines('diff-tree', '--root', '-m',
                                              '-r', version)
            if status:
                raise error.Abort(_('cannot read changes in %s') % version)
            for l in output:
                if "\t" not in l:
                    continue
                m, f = l[:-1].split("\t")
                changes.append(f)
        else:
            output, status = self.gitrunlines('diff-tree', '--name-only',
                                              '--root', '-r', version,
                                              '%s^%s' % (version, i + 1), '--')
            if status:
                raise error.Abort(_('cannot read changes in %s') % version)
            changes = [f.rstrip('\n') for f in output]

        return changes

    def getbookmarks(self):
        bookmarks = {}

        # Handle local and remote branches
        remoteprefix = self.ui.config('convert', 'git.remoteprefix', 'remote')
        reftypes = [
            # (git prefix, hg prefix)
            ('refs/remotes/origin/', remoteprefix + '/'),
            ('refs/heads/', '')
        ]

        exclude = {
            'refs/remotes/origin/HEAD',
        }

        try:
            output, status = self.gitrunlines('show-ref')
            for line in output:
                line = line.strip()
                rev, name = line.split(None, 1)
                # Process each type of branch
                for gitprefix, hgprefix in reftypes:
                    if not name.startswith(gitprefix) or name in exclude:
                        continue
                    name = '%s%s' % (hgprefix, name[len(gitprefix):])
                    bookmarks[name] = rev
        except Exception:
            pass

        return bookmarks

    def checkrevformat(self, revstr, mapname='splicemap'):
        """ git revision string is a 40 byte hex """
        self.checkhexformat(revstr, mapname)