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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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scmwindows.py
61 lines | 1.9 KiB | text/x-python | PythonLexer
Gregory Szorc
scmwindows: use absolute_import
r27481 from __future__ import absolute_import
Kevin Bullock
scmutil: split platform-specific bits into their own modules...
r18690 import os
Gregory Szorc
scmwindows: use absolute_import
r27481
from . import (
Pulkit Goyal
py3: replace os.environ with encoding.environ (part 4 of 5)
r30637 encoding,
Pulkit Goyal
py3: replace os.pathsep with pycompat.ospathsep...
r30612 pycompat,
Gregory Szorc
scmwindows: use absolute_import
r27481 util,
Yuya Nishihara
scmutil: move util.termwidth()...
r30309 win32,
Gregory Szorc
scmwindows: use absolute_import
r27481 )
Kevin Bullock
scmutil: split platform-specific bits into their own modules...
r18690
Pulkit Goyal
py3: conditionalize _winreg import...
r29760 try:
import _winreg as winreg
winreg.CloseKey
except ImportError:
import winreg
Yuya Nishihara
pager: use less as a fallback on Unix...
r32078 # MS-DOS 'more' is the only pager available by default on Windows.
fallbackpager = 'more'
Kevin Bullock
scmutil: split platform-specific bits into their own modules...
r18690 def systemrcpath():
'''return default os-specific hgrc search path'''
rcpath = []
Yuya Nishihara
rcutil: directly call win32.executablepath()...
r37113 filename = win32.executablepath()
Kevin Bullock
scmutil: split platform-specific bits into their own modules...
r18690 # Use mercurial.ini found in directory with hg.exe
progrc = os.path.join(os.path.dirname(filename), 'mercurial.ini')
Mads Kiilerich
windows: read all global config files, not just the first (issue4491) (BC)...
r26625 rcpath.append(progrc)
Kevin Bullock
scmutil: split platform-specific bits into their own modules...
r18690 # Use hgrc.d found in directory with hg.exe
progrcd = os.path.join(os.path.dirname(filename), 'hgrc.d')
if os.path.isdir(progrcd):
Yuya Nishihara
osutil: proxy through util (and platform) modules (API)...
r32203 for f, kind in util.listdir(progrcd):
Kevin Bullock
scmutil: split platform-specific bits into their own modules...
r18690 if f.endswith('.rc'):
rcpath.append(os.path.join(progrcd, f))
# else look for a system rcpath in the registry
value = util.lookupreg('SOFTWARE\\Mercurial', None,
Pulkit Goyal
py3: conditionalize _winreg import...
r29760 winreg.HKEY_LOCAL_MACHINE)
Kevin Bullock
scmutil: split platform-specific bits into their own modules...
r18690 if not isinstance(value, str) or not value:
return rcpath
value = util.localpath(value)
Pulkit Goyal
py3: replace os.pathsep with pycompat.ospathsep...
r30612 for p in value.split(pycompat.ospathsep):
Kevin Bullock
scmutil: split platform-specific bits into their own modules...
r18690 if p.lower().endswith('mercurial.ini'):
rcpath.append(p)
elif os.path.isdir(p):
Yuya Nishihara
osutil: proxy through util (and platform) modules (API)...
r32203 for f, kind in util.listdir(p):
Kevin Bullock
scmutil: split platform-specific bits into their own modules...
r18690 if f.endswith('.rc'):
rcpath.append(os.path.join(p, f))
return rcpath
def userrcpath():
'''return os-specific hgrc search path to the user dir'''
home = os.path.expanduser('~')
path = [os.path.join(home, 'mercurial.ini'),
os.path.join(home, '.hgrc')]
Pulkit Goyal
py3: replace os.environ with encoding.environ (part 4 of 5)
r30637 userprofile = encoding.environ.get('USERPROFILE')
Mads Kiilerich
config: don't read the same config file twice...
r22583 if userprofile and userprofile != home:
Kevin Bullock
scmutil: split platform-specific bits into their own modules...
r18690 path.append(os.path.join(userprofile, 'mercurial.ini'))
path.append(os.path.join(userprofile, '.hgrc'))
return path
Yuya Nishihara
scmutil: move util.termwidth()...
r30309
Yuya Nishihara
scmutil: extend termwidth() to return terminal height, renamed to termsize()...
r30314 def termsize(ui):
return win32.termsize()