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localrepo: iteratively derive local repository type...
localrepo: iteratively derive local repository type This commit implements the dynamic local repository type derivation that was explained in the recent commit bfeab472e3c0 "localrepo: create new function for instantiating a local repo object." Instead of a static localrepository class/type which must be customized after construction, we now dynamically construct a type by building up base classes/types to represent specific repository interfaces. Conceptually, the end state is similar to what was happening when various extensions would monkeypatch the __class__ of newly-constructed repo instances. However, the approach is inverted. Instead of making the instance then customizing it, we do the customization up front by influencing the behavior of the type then we instantiate that custom type. This approach gives us much more flexibility. For example, we can use completely separate classes for implementing different aspects of the repository. For example, we could have one class representing revlog-based file storage and another representing non-revlog based file storage. When then choose which implementation to use based on the presence of repo requirements. A concern with this approach is that it creates a lot more types and complexity and that complexity adds overhead. Yes, it is true that this approach will result in more types being created. Yes, this is more complicated than traditional "instantiate a static type." However, I believe the alternatives to supporting alternate storage backends are just as complicated. (Before I arrived at this solution, I had patches storing factory functions on local repo instances for e.g. constructing a file storage instance. We ended up having a handful of these. And this was logically identical to assigning custom methods. Since we were logically changing the type of the instance, I figured it would be better to just use specialized types instead of introducing levels of abstraction at run-time.) On the performance front, I don't believe that having N base classes has any significant performance overhead compared to just a single base class. Intuition says that Python will need to iterate the base classes to find an attribute. However, CPython caches method lookups: as long as the __class__ or MRO isn't changing, method attribute lookup should be constant time after first access. And non-method attributes are stored in __dict__, of which there is only 1 per object, so the number of base classes for __dict__ is irrelevant. Anyway, this commit splits up the monolithic completelocalrepository interface into sub-interfaces: 1 for file storage and 1 representing everything else. We've taught ``makelocalrepository()`` to call a series of factory functions which will produce types implementing specific interfaces. It then calls type() to create a new type from the built-up list of base types. This commit should be considered a start and not the end state. I suspect we'll hit a number of problems as we start to implement alternate storage backends: * Passing custom arguments to __init__ and setting custom attributes on __dict__. * Customizing the set of interfaces that are needed. e.g. the "readonly" intent could translate to not requesting an interface providing methods related to writing. * More ergonomic way for extensions to insert themselves so their callbacks aren't unconditionally called. * Wanting to modify vfs instances, other arguments passed to __init__. That being said, this code is usable in its current state and I'm convinced future commits will demonstrate the value in this approach. Differential Revision: https://phab.mercurial-scm.org/D4642

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git.py
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# git.py - git support for the convert extension
#
# 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
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, repotype, path, revs=None):
super(convert_git, self).__init__(ui, repotype, 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')
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')
if findcopiesharder:
self.simopt.append('--find-copies-harder')
renamelimit = ui.configint('convert', 'git.renamelimit')
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 = 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, ftype):
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] != ftype:
raise error.Abort(_('cannot read %r object at %s') % (ftype, 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')
% (ftype, 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')
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 + " " + (b"%d" % tz)
saverev = self.ui.configbool('convert', 'git.saverev')
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^%d' % (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')
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)