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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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transport.py
132 lines | 4.9 KiB | text/x-python | PythonLexer
Daniel Holth
convert extension: stripped-down svn transport module
r4764 # -*- coding: utf-8 -*-
# Copyright (C) 2007 Daniel Holth <dholth@fastmail.fm>
# This is a stripped-down version of the original bzr-svn transport.py,
# Copyright (C) 2006 Jelmer Vernooij <jelmer@samba.org>
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
# You should have received a copy of the GNU General Public License
Martin Geisler
Remove FSF mailing address from GPL headers...
r15782 # along with this program; if not, see <http://www.gnu.org/licenses/>.
timeless
convert: transport use absolute_import
r28412 from __future__ import absolute_import
Daniel Holth
convert extension: stripped-down svn transport module
r4764
Bryan O'Sullivan
convert/subversion: get converter working against plain HTTP.
r4938 import svn.client
Daniel Holth
convert extension: stripped-down svn transport module
r4764 import svn.core
timeless
convert: transport use absolute_import
r28412 import svn.ra
Pool = svn.core.Pool
SubversionException = svn.core.SubversionException
Daniel Holth
convert extension: stripped-down svn transport module
r4764
FUJIWARA Katsunori
convert: fix "stdlib import follows local import" problem in transport...
r28461 from mercurial import (
util,
)
Thomas Arendsen Hein
removed trailing whitespace
r4957 # Some older versions of the Python bindings need to be
Daniel Holth
convert extension: stripped-down svn transport module
r4764 # explicitly initialized. But what we want to do probably
# won't work worth a darn against those libraries anyway!
svn.ra.initialize()
Durham Goode
convert: move svn config initializer out of the module level...
r29668 svn_config = None
Daniel Holth
convert extension: stripped-down svn transport module
r4764
def _create_auth_baton(pool):
"""Create a Subversion authentication baton. """
import svn.client
# Give the client context baton a suite of authentication
# providers.h
providers = [
svn.client.get_simple_provider(pool),
svn.client.get_username_provider(pool),
svn.client.get_ssl_client_cert_file_provider(pool),
svn.client.get_ssl_client_cert_pw_file_provider(pool),
svn.client.get_ssl_server_trust_file_provider(pool),
]
timeless@mozdev.org
spelling: dependent
r17481 # Platform-dependent authentication methods
Patrick Mezard
convert/svn: support more OS specific auth providers via svn 1.6 API
r8120 getprovider = getattr(svn.core, 'svn_auth_get_platform_specific_provider',
None)
if getprovider:
# Available in svn >= 1.6
for name in ('gnome_keyring', 'keychain', 'kwallet', 'windows'):
for type in ('simple', 'ssl_client_cert_pw', 'ssl_server_trust'):
p = getprovider(name, type, pool)
if p:
providers.append(p)
else:
Augie Fackler
hgext: replace uses of hasattr with util.safehasattr
r14945 if util.safehasattr(svn.client, 'get_windows_simple_provider'):
Patrick Mezard
convert/svn: support more OS specific auth providers via svn 1.6 API
r8120 providers.append(svn.client.get_windows_simple_provider(pool))
Patrick Mezard
convert: support windows SVN simple auth provider
r5126
Daniel Holth
convert extension: stripped-down svn transport module
r4764 return svn.core.svn_auth_open(providers, pool)
class NotBranchError(SubversionException):
pass
class SvnRaTransport(object):
"""
Open an ra connection to a Subversion repository.
"""
def __init__(self, url="", ra=None):
self.pool = Pool()
self.svn_url = url
Bryan O'Sullivan
convert/subversion: get converter working against plain HTTP.
r4938 self.username = ''
self.password = ''
Daniel Holth
convert extension: stripped-down svn transport module
r4764
# Only Subversion 1.4 has reparent()
Augie Fackler
hgext: replace uses of hasattr with util.safehasattr
r14945 if ra is None or not util.safehasattr(svn.ra, 'reparent'):
Bryan O'Sullivan
convert/subversion: get converter working against plain HTTP.
r4938 self.client = svn.client.create_context(self.pool)
ab = _create_auth_baton(self.pool)
self.client.auth_baton = ab
Durham Goode
convert: move svn config initializer out of the module level...
r29668 global svn_config
if svn_config is None:
svn_config = svn.core.svn_config_get_config(None)
Bryan O'Sullivan
convert/subversion: get converter working against plain HTTP.
r4938 self.client.config = svn_config
Daniel Holth
convert extension: stripped-down svn transport module
r4764 try:
Bryan O'Sullivan
convert/subversion: get converter working against plain HTTP.
r4938 self.ra = svn.client.open_ra_session(
Patrick Mezard
convert/svn: fix URL quoting issue with svn 1.7...
r15599 self.svn_url,
Bryan O'Sullivan
convert/subversion: get converter working against plain HTTP.
r4938 self.client, self.pool)
Gregory Szorc
global: mass rewrite to use modern exception syntax...
r25660 except SubversionException as xxx_todo_changeme:
(inst, num) = xxx_todo_changeme.args
Bryan O'Sullivan
convert/subversion: get converter working against plain HTTP.
r4938 if num in (svn.core.SVN_ERR_RA_ILLEGAL_URL,
svn.core.SVN_ERR_RA_LOCAL_REPOS_OPEN_FAILED,
svn.core.SVN_ERR_BAD_URL):
Daniel Holth
convert extension: stripped-down svn transport module
r4764 raise NotBranchError(url)
raise
else:
self.ra = ra
svn.ra.reparent(self.ra, self.svn_url.encode('utf8'))
Benoit Boissinot
use new style classes
r8778 class Reporter(object):
Renato Cunha
convert: tuple parameter unpacking is deprecated in py3k
r11498 def __init__(self, reporter_data):
self._reporter, self._baton = reporter_data
Daniel Holth
convert extension: stripped-down svn transport module
r4764
def set_path(self, path, revnum, start_empty, lock_token, pool=None):
svn.ra.reporter2_invoke_set_path(self._reporter, self._baton,
path, revnum, start_empty, lock_token, pool)
def delete_path(self, path, pool=None):
svn.ra.reporter2_invoke_delete_path(self._reporter, self._baton,
path, pool)
def link_path(self, path, url, revision, start_empty, lock_token,
pool=None):
svn.ra.reporter2_invoke_link_path(self._reporter, self._baton,
path, url, revision, start_empty, lock_token,
pool)
def finish_report(self, pool=None):
svn.ra.reporter2_invoke_finish_report(self._reporter,
self._baton, pool)
def abort_report(self, pool=None):
svn.ra.reporter2_invoke_abort_report(self._reporter,
self._baton, pool)
def do_update(self, revnum, path, *args, **kwargs):
Matt Mackall
many, many trivial check-code fixups
r10282 return self.Reporter(svn.ra.do_update(self.ra, revnum, path,
*args, **kwargs))