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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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gnuarch.py
355 lines | 12.7 KiB | text/x-python | PythonLexer
# gnuarch.py - GNU Arch support for the convert extension
#
# Copyright 2008, 2009 Aleix Conchillo Flaque <aleix@member.fsf.org>
# 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 email.parser as emailparser
import os
import shutil
import stat
import tempfile
from mercurial.i18n import _
from mercurial import (
encoding,
error,
)
from mercurial.utils import (
dateutil,
procutil,
)
from . import common
class gnuarch_source(common.converter_source, common.commandline):
class gnuarch_rev(object):
def __init__(self, rev):
self.rev = rev
self.summary = ''
self.date = None
self.author = ''
self.continuationof = None
self.add_files = []
self.mod_files = []
self.del_files = []
self.ren_files = {}
self.ren_dirs = {}
def __init__(self, ui, repotype, path, revs=None):
super(gnuarch_source, self).__init__(ui, repotype, path, revs=revs)
if not os.path.exists(os.path.join(path, '{arch}')):
raise common.NoRepo(_("%s does not look like a GNU Arch repository")
% path)
# Could use checktool, but we want to check for baz or tla.
self.execmd = None
if procutil.findexe('baz'):
self.execmd = 'baz'
else:
if procutil.findexe('tla'):
self.execmd = 'tla'
else:
raise error.Abort(_('cannot find a GNU Arch tool'))
common.commandline.__init__(self, ui, self.execmd)
self.path = os.path.realpath(path)
self.tmppath = None
self.treeversion = None
self.lastrev = None
self.changes = {}
self.parents = {}
self.tags = {}
self.catlogparser = emailparser.Parser()
self.encoding = encoding.encoding
self.archives = []
def before(self):
# Get registered archives
self.archives = [i.rstrip('\n')
for i in self.runlines0('archives', '-n')]
if self.execmd == 'tla':
output = self.run0('tree-version', self.path)
else:
output = self.run0('tree-version', '-d', self.path)
self.treeversion = output.strip()
# Get name of temporary directory
version = self.treeversion.split('/')
self.tmppath = os.path.join(tempfile.gettempdir(),
'hg-%s' % version[1])
# Generate parents dictionary
self.parents[None] = []
treeversion = self.treeversion
child = None
while treeversion:
self.ui.status(_('analyzing tree version %s...\n') % treeversion)
archive = treeversion.split('/')[0]
if archive not in self.archives:
self.ui.status(_('tree analysis stopped because it points to '
'an unregistered archive %s...\n') % archive)
break
# Get the complete list of revisions for that tree version
output, status = self.runlines('revisions', '-r', '-f', treeversion)
self.checkexit(status, 'failed retrieving revisions for %s'
% treeversion)
# No new iteration unless a revision has a continuation-of header
treeversion = None
for l in output:
rev = l.strip()
self.changes[rev] = self.gnuarch_rev(rev)
self.parents[rev] = []
# Read author, date and summary
catlog, status = self.run('cat-log', '-d', self.path, rev)
if status:
catlog = self.run0('cat-archive-log', rev)
self._parsecatlog(catlog, rev)
# Populate the parents map
self.parents[child].append(rev)
# Keep track of the current revision as the child of the next
# revision scanned
child = rev
# Check if we have to follow the usual incremental history
# or if we have to 'jump' to a different treeversion given
# by the continuation-of header.
if self.changes[rev].continuationof:
treeversion = '--'.join(
self.changes[rev].continuationof.split('--')[:-1])
break
# If we reached a base-0 revision w/o any continuation-of
# header, it means the tree history ends here.
if rev[-6:] == 'base-0':
break
def after(self):
self.ui.debug('cleaning up %s\n' % self.tmppath)
shutil.rmtree(self.tmppath, ignore_errors=True)
def getheads(self):
return self.parents[None]
def getfile(self, name, rev):
if rev != self.lastrev:
raise error.Abort(_('internal calling inconsistency'))
if not os.path.lexists(os.path.join(self.tmppath, name)):
return None, None
return self._getfile(name, rev)
def getchanges(self, rev, full):
if full:
raise error.Abort(_("convert from arch does not support --full"))
self._update(rev)
changes = []
copies = {}
for f in self.changes[rev].add_files:
changes.append((f, rev))
for f in self.changes[rev].mod_files:
changes.append((f, rev))
for f in self.changes[rev].del_files:
changes.append((f, rev))
for src in self.changes[rev].ren_files:
to = self.changes[rev].ren_files[src]
changes.append((src, rev))
changes.append((to, rev))
copies[to] = src
for src in self.changes[rev].ren_dirs:
to = self.changes[rev].ren_dirs[src]
chgs, cps = self._rendirchanges(src, to)
changes += [(f, rev) for f in chgs]
copies.update(cps)
self.lastrev = rev
return sorted(set(changes)), copies, set()
def getcommit(self, rev):
changes = self.changes[rev]
return common.commit(author=changes.author, date=changes.date,
desc=changes.summary, parents=self.parents[rev],
rev=rev)
def gettags(self):
return self.tags
def _execute(self, cmd, *args, **kwargs):
cmdline = [self.execmd, cmd]
cmdline += args
cmdline = [procutil.shellquote(arg) for arg in cmdline]
cmdline += ['>', os.devnull, '2>', os.devnull]
cmdline = procutil.quotecommand(' '.join(cmdline))
self.ui.debug(cmdline, '\n')
return os.system(cmdline)
def _update(self, rev):
self.ui.debug('applying revision %s...\n' % rev)
changeset, status = self.runlines('replay', '-d', self.tmppath,
rev)
if status:
# Something went wrong while merging (baz or tla
# issue?), get latest revision and try from there
shutil.rmtree(self.tmppath, ignore_errors=True)
self._obtainrevision(rev)
else:
old_rev = self.parents[rev][0]
self.ui.debug('computing changeset between %s and %s...\n'
% (old_rev, rev))
self._parsechangeset(changeset, rev)
def _getfile(self, name, rev):
mode = os.lstat(os.path.join(self.tmppath, name)).st_mode
if stat.S_ISLNK(mode):
data = os.readlink(os.path.join(self.tmppath, name))
if mode:
mode = 'l'
else:
mode = ''
else:
data = open(os.path.join(self.tmppath, name), 'rb').read()
mode = (mode & 0o111) and 'x' or ''
return data, mode
def _exclude(self, name):
exclude = ['{arch}', '.arch-ids', '.arch-inventory']
for exc in exclude:
if name.find(exc) != -1:
return True
return False
def _readcontents(self, path):
files = []
contents = os.listdir(path)
while len(contents) > 0:
c = contents.pop()
p = os.path.join(path, c)
# os.walk could be used, but here we avoid internal GNU
# Arch files and directories, thus saving a lot time.
if not self._exclude(p):
if os.path.isdir(p):
contents += [os.path.join(c, f) for f in os.listdir(p)]
else:
files.append(c)
return files
def _rendirchanges(self, src, dest):
changes = []
copies = {}
files = self._readcontents(os.path.join(self.tmppath, dest))
for f in files:
s = os.path.join(src, f)
d = os.path.join(dest, f)
changes.append(s)
changes.append(d)
copies[d] = s
return changes, copies
def _obtainrevision(self, rev):
self.ui.debug('obtaining revision %s...\n' % rev)
output = self._execute('get', rev, self.tmppath)
self.checkexit(output)
self.ui.debug('analyzing revision %s...\n' % rev)
files = self._readcontents(self.tmppath)
self.changes[rev].add_files += files
def _stripbasepath(self, path):
if path.startswith('./'):
return path[2:]
return path
def _parsecatlog(self, data, rev):
try:
catlog = self.catlogparser.parsestr(data)
# Commit date
self.changes[rev].date = dateutil.datestr(
dateutil.strdate(catlog['Standard-date'],
'%Y-%m-%d %H:%M:%S'))
# Commit author
self.changes[rev].author = self.recode(catlog['Creator'])
# Commit description
self.changes[rev].summary = '\n\n'.join((catlog['Summary'],
catlog.get_payload()))
self.changes[rev].summary = self.recode(self.changes[rev].summary)
# Commit revision origin when dealing with a branch or tag
if 'Continuation-of' in catlog:
self.changes[rev].continuationof = self.recode(
catlog['Continuation-of'])
except Exception:
raise error.Abort(_('could not parse cat-log of %s') % rev)
def _parsechangeset(self, data, rev):
for l in data:
l = l.strip()
# Added file (ignore added directory)
if l.startswith('A') and not l.startswith('A/'):
file = self._stripbasepath(l[1:].strip())
if not self._exclude(file):
self.changes[rev].add_files.append(file)
# Deleted file (ignore deleted directory)
elif l.startswith('D') and not l.startswith('D/'):
file = self._stripbasepath(l[1:].strip())
if not self._exclude(file):
self.changes[rev].del_files.append(file)
# Modified binary file
elif l.startswith('Mb'):
file = self._stripbasepath(l[2:].strip())
if not self._exclude(file):
self.changes[rev].mod_files.append(file)
# Modified link
elif l.startswith('M->'):
file = self._stripbasepath(l[3:].strip())
if not self._exclude(file):
self.changes[rev].mod_files.append(file)
# Modified file
elif l.startswith('M'):
file = self._stripbasepath(l[1:].strip())
if not self._exclude(file):
self.changes[rev].mod_files.append(file)
# Renamed file (or link)
elif l.startswith('=>'):
files = l[2:].strip().split(' ')
if len(files) == 1:
files = l[2:].strip().split('\t')
src = self._stripbasepath(files[0])
dst = self._stripbasepath(files[1])
if not self._exclude(src) and not self._exclude(dst):
self.changes[rev].ren_files[src] = dst
# Conversion from file to link or from link to file (modified)
elif l.startswith('ch'):
file = self._stripbasepath(l[2:].strip())
if not self._exclude(file):
self.changes[rev].mod_files.append(file)
# Renamed directory
elif l.startswith('/>'):
dirs = l[2:].strip().split(' ')
if len(dirs) == 1:
dirs = l[2:].strip().split('\t')
src = self._stripbasepath(dirs[0])
dst = self._stripbasepath(dirs[1])
if not self._exclude(src) and not self._exclude(dst):
self.changes[rev].ren_dirs[src] = dst