##// END OF EJS Templates
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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darcs.py
224 lines | 8.3 KiB | text/x-python | PythonLexer
# darcs.py - darcs support for the convert extension
#
# Copyright 2007-2009 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
import re
import shutil
from mercurial.i18n import _
from mercurial import (
error,
pycompat,
util,
)
from mercurial.utils import dateutil
from . import common
NoRepo = common.NoRepo
# The naming drift of ElementTree is fun!
try:
import xml.etree.cElementTree.ElementTree as ElementTree
import xml.etree.cElementTree.XMLParser as XMLParser
except ImportError:
try:
import xml.etree.ElementTree.ElementTree as ElementTree
import xml.etree.ElementTree.XMLParser as XMLParser
except ImportError:
try:
import elementtree.cElementTree.ElementTree as ElementTree
import elementtree.cElementTree.XMLParser as XMLParser
except ImportError:
try:
import elementtree.ElementTree.ElementTree as ElementTree
import elementtree.ElementTree.XMLParser as XMLParser
except ImportError:
pass
class darcs_source(common.converter_source, common.commandline):
def __init__(self, ui, repotype, path, revs=None):
common.converter_source.__init__(self, ui, repotype, path, revs=revs)
common.commandline.__init__(self, ui, 'darcs')
# check for _darcs, ElementTree so that we can easily skip
# test-convert-darcs if ElementTree is not around
if not os.path.exists(os.path.join(path, '_darcs')):
raise NoRepo(_("%s does not look like a darcs repository") % path)
common.checktool('darcs')
version = self.run0('--version').splitlines()[0].strip()
if version < '2.1':
raise error.Abort(_('darcs version 2.1 or newer needed (found %r)')
% version)
if "ElementTree" not in globals():
raise error.Abort(_("Python ElementTree module is not available"))
self.path = os.path.realpath(path)
self.lastrev = None
self.changes = {}
self.parents = {}
self.tags = {}
# Check darcs repository format
format = self.format()
if format:
if format in ('darcs-1.0', 'hashed'):
raise NoRepo(_("%s repository format is unsupported, "
"please upgrade") % format)
else:
self.ui.warn(_('failed to detect repository format!'))
def before(self):
self.tmppath = pycompat.mkdtemp(
prefix='convert-' + os.path.basename(self.path) + '-')
output, status = self.run('init', repodir=self.tmppath)
self.checkexit(status)
tree = self.xml('changes', xml_output=True, summary=True,
repodir=self.path)
tagname = None
child = None
for elt in tree.findall('patch'):
node = elt.get('hash')
name = elt.findtext('name', '')
if name.startswith('TAG '):
tagname = name[4:].strip()
elif tagname is not None:
self.tags[tagname] = node
tagname = None
self.changes[node] = elt
self.parents[child] = [node]
child = node
self.parents[child] = []
def after(self):
self.ui.debug('cleaning up %s\n' % self.tmppath)
shutil.rmtree(self.tmppath, ignore_errors=True)
def recode(self, s, encoding=None):
if isinstance(s, pycompat.unicode):
# XMLParser returns unicode objects for anything it can't
# encode into ASCII. We convert them back to str to get
# recode's normal conversion behavior.
s = s.encode('latin-1')
return super(darcs_source, self).recode(s, encoding)
def xml(self, cmd, **kwargs):
# NOTE: darcs is currently encoding agnostic and will print
# patch metadata byte-for-byte, even in the XML changelog.
etree = ElementTree()
# While we are decoding the XML as latin-1 to be as liberal as
# possible, etree will still raise an exception if any
# non-printable characters are in the XML changelog.
parser = XMLParser(encoding='latin-1')
p = self._run(cmd, **kwargs)
etree.parse(p.stdout, parser=parser)
p.wait()
self.checkexit(p.returncode)
return etree.getroot()
def format(self):
output, status = self.run('show', 'repo', repodir=self.path)
self.checkexit(status)
m = re.search(r'^\s*Format:\s*(.*)$', output, re.MULTILINE)
if not m:
return None
return ','.join(sorted(f.strip() for f in m.group(1).split(',')))
def manifest(self):
man = []
output, status = self.run('show', 'files', no_directories=True,
repodir=self.tmppath)
self.checkexit(status)
for line in output.split('\n'):
path = line[2:]
if path:
man.append(path)
return man
def getheads(self):
return self.parents[None]
def getcommit(self, rev):
elt = self.changes[rev]
dateformat = '%a %b %d %H:%M:%S %Z %Y'
date = dateutil.strdate(elt.get('local_date'), dateformat)
desc = elt.findtext('name') + '\n' + elt.findtext('comment', '')
# etree can return unicode objects for name, comment, and author,
# so recode() is used to ensure str objects are emitted.
newdateformat = '%Y-%m-%d %H:%M:%S %1%2'
return common.commit(author=self.recode(elt.get('author')),
date=dateutil.datestr(date, newdateformat),
desc=self.recode(desc).strip(),
parents=self.parents[rev])
def pull(self, rev):
output, status = self.run('pull', self.path, all=True,
match='hash %s' % rev,
no_test=True, no_posthook=True,
external_merge='/bin/false',
repodir=self.tmppath)
if status:
if output.find('We have conflicts in') == -1:
self.checkexit(status, output)
output, status = self.run('revert', all=True, repodir=self.tmppath)
self.checkexit(status, output)
def getchanges(self, rev, full):
if full:
raise error.Abort(_("convert from darcs does not support --full"))
copies = {}
changes = []
man = None
for elt in self.changes[rev].find('summary').getchildren():
if elt.tag in ('add_directory', 'remove_directory'):
continue
if elt.tag == 'move':
if man is None:
man = self.manifest()
source, dest = elt.get('from'), elt.get('to')
if source in man:
# File move
changes.append((source, rev))
changes.append((dest, rev))
copies[dest] = source
else:
# Directory move, deduce file moves from manifest
source = source + '/'
for f in man:
if not f.startswith(source):
continue
fdest = dest + '/' + f[len(source):]
changes.append((f, rev))
changes.append((fdest, rev))
copies[fdest] = f
else:
changes.append((elt.text.strip(), rev))
self.pull(rev)
self.lastrev = rev
return sorted(changes), copies, set()
def getfile(self, name, rev):
if rev != self.lastrev:
raise error.Abort(_('internal calling inconsistency'))
path = os.path.join(self.tmppath, name)
try:
data = util.readfile(path)
mode = os.lstat(path).st_mode
except IOError as inst:
if inst.errno == errno.ENOENT:
return None, None
raise
mode = (mode & 0o111) and 'x' or ''
return data, mode
def gettags(self):
return self.tags