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
# remotenames.py - extension to display remotenames
#
# Copyright 2017 Augie Fackler <raf@durin42.com>
# Copyright 2017 Sean Farley <sean@farley.io>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
""" showing remotebookmarks and remotebranches in UI (EXPERIMENTAL)
By default both remotebookmarks and remotebranches are turned on. Config knob to
control the individually are as follows.
Config options to tweak the default behaviour:
remotenames.bookmarks
Boolean value to enable or disable showing of remotebookmarks (default: True)
remotenames.branches
Boolean value to enable or disable showing of remotebranches (default: True)
remotenames.hoistedpeer
Name of the peer whose remotebookmarks should be hoisted into the top-level
namespace (default: 'default')
"""
from __future__ import absolute_import
from mercurial.i18n import _
from mercurial.node import (
bin,
)
from mercurial import (
bookmarks,
extensions,
logexchange,
namespaces,
pycompat,
registrar,
revsetlang,
smartset,
templateutil,
)
if pycompat.ispy3:
import collections.abc
mutablemapping = collections.abc.MutableMapping
else:
import collections
mutablemapping = collections.MutableMapping
# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = 'ships-with-hg-core'
configtable = {}
configitem = registrar.configitem(configtable)
templatekeyword = registrar.templatekeyword()
revsetpredicate = registrar.revsetpredicate()
configitem('remotenames', 'bookmarks',
default=True,
)
configitem('remotenames', 'branches',
default=True,
)
configitem('remotenames', 'hoistedpeer',
default='default',
)
class lazyremotenamedict(mutablemapping):
"""
Read-only dict-like Class to lazily resolve remotename entries
We are doing that because remotenames startup was slow.
We lazily read the remotenames file once to figure out the potential entries
and store them in self.potentialentries. Then when asked to resolve an
entry, if it is not in self.potentialentries, then it isn't there, if it
is in self.potentialentries we resolve it and store the result in
self.cache. We cannot be lazy is when asked all the entries (keys).
"""
def __init__(self, kind, repo):
self.cache = {}
self.potentialentries = {}
self._kind = kind # bookmarks or branches
self._repo = repo
self.loaded = False
def _load(self):
""" Read the remotenames file, store entries matching selected kind """
self.loaded = True
repo = self._repo
for node, rpath, rname in logexchange.readremotenamefile(repo,
self._kind):
name = rpath + '/' + rname
self.potentialentries[name] = (node, rpath, name)
def _resolvedata(self, potentialentry):
""" Check that the node for potentialentry exists and return it """
if not potentialentry in self.potentialentries:
return None
node, remote, name = self.potentialentries[potentialentry]
repo = self._repo
binnode = bin(node)
# if the node doesn't exist, skip it
try:
repo.changelog.rev(binnode)
except LookupError:
return None
# Skip closed branches
if (self._kind == 'branches' and repo[binnode].closesbranch()):
return None
return [binnode]
def __getitem__(self, key):
if not self.loaded:
self._load()
val = self._fetchandcache(key)
if val is not None:
return val
else:
raise KeyError()
def __iter__(self):
return iter(self.potentialentries)
def __len__(self):
return len(self.potentialentries)
def __setitem__(self):
raise NotImplementedError
def __delitem__(self):
raise NotImplementedError
def _fetchandcache(self, key):
if key in self.cache:
return self.cache[key]
val = self._resolvedata(key)
if val is not None:
self.cache[key] = val
return val
else:
return None
def keys(self):
""" Get a list of bookmark or branch names """
if not self.loaded:
self._load()
return self.potentialentries.keys()
def iteritems(self):
""" Iterate over (name, node) tuples """
if not self.loaded:
self._load()
for k, vtup in self.potentialentries.iteritems():
yield (k, [bin(vtup[0])])
class remotenames(object):
"""
This class encapsulates all the remotenames state. It also contains
methods to access that state in convenient ways. Remotenames are lazy
loaded. Whenever client code needs to ensure the freshest copy of
remotenames, use the `clearnames` method to force an eventual load.
"""
def __init__(self, repo, *args):
self._repo = repo
self.clearnames()
def clearnames(self):
""" Clear all remote names state """
self.bookmarks = lazyremotenamedict("bookmarks", self._repo)
self.branches = lazyremotenamedict("branches", self._repo)
self._invalidatecache()
def _invalidatecache(self):
self._nodetobmarks = None
self._nodetobranch = None
self._hoisttonodes = None
self._nodetohoists = None
def bmarktonodes(self):
return self.bookmarks
def nodetobmarks(self):
if not self._nodetobmarks:
bmarktonodes = self.bmarktonodes()
self._nodetobmarks = {}
for name, node in bmarktonodes.iteritems():
self._nodetobmarks.setdefault(node[0], []).append(name)
return self._nodetobmarks
def branchtonodes(self):
return self.branches
def nodetobranch(self):
if not self._nodetobranch:
branchtonodes = self.branchtonodes()
self._nodetobranch = {}
for name, nodes in branchtonodes.iteritems():
for node in nodes:
self._nodetobranch.setdefault(node, []).append(name)
return self._nodetobranch
def hoisttonodes(self, hoist):
if not self._hoisttonodes:
marktonodes = self.bmarktonodes()
self._hoisttonodes = {}
hoist += '/'
for name, node in marktonodes.iteritems():
if name.startswith(hoist):
name = name[len(hoist):]
self._hoisttonodes[name] = node
return self._hoisttonodes
def nodetohoists(self, hoist):
if not self._nodetohoists:
marktonodes = self.bmarktonodes()
self._nodetohoists = {}
hoist += '/'
for name, node in marktonodes.iteritems():
if name.startswith(hoist):
name = name[len(hoist):]
self._nodetohoists.setdefault(node[0], []).append(name)
return self._nodetohoists
def wrapprintbookmarks(orig, ui, repo, fm, bmarks):
if 'remotebookmarks' not in repo.names:
return
ns = repo.names['remotebookmarks']
for name in ns.listnames(repo):
nodes = ns.nodes(repo, name)
if not nodes:
continue
node = nodes[0]
bmarks[name] = (node, ' ', '')
return orig(ui, repo, fm, bmarks)
def extsetup(ui):
extensions.wrapfunction(bookmarks, '_printbookmarks', wrapprintbookmarks)
def reposetup(ui, repo):
# set the config option to store remotenames
repo.ui.setconfig('experimental', 'remotenames', True, 'remotenames-ext')
if not repo.local():
return
repo._remotenames = remotenames(repo)
ns = namespaces.namespace
if ui.configbool('remotenames', 'bookmarks'):
remotebookmarkns = ns(
'remotebookmarks',
templatename='remotebookmarks',
colorname='remotebookmark',
logfmt='remote bookmark: %s\n',
listnames=lambda repo: repo._remotenames.bmarktonodes().keys(),
namemap=lambda repo, name:
repo._remotenames.bmarktonodes().get(name, []),
nodemap=lambda repo, node:
repo._remotenames.nodetobmarks().get(node, []))
repo.names.addnamespace(remotebookmarkns)
# hoisting only works if there are remote bookmarks
hoist = ui.config('remotenames', 'hoistedpeer')
if hoist:
hoistednamens = ns(
'hoistednames',
templatename='hoistednames',
colorname='hoistedname',
logfmt='hoisted name: %s\n',
listnames = lambda repo:
repo._remotenames.hoisttonodes(hoist).keys(),
namemap = lambda repo, name:
repo._remotenames.hoisttonodes(hoist).get(name, []),
nodemap = lambda repo, node:
repo._remotenames.nodetohoists(hoist).get(node, []))
repo.names.addnamespace(hoistednamens)
if ui.configbool('remotenames', 'branches'):
remotebranchns = ns(
'remotebranches',
templatename='remotebranches',
colorname='remotebranch',
logfmt='remote branch: %s\n',
listnames = lambda repo: repo._remotenames.branchtonodes().keys(),
namemap = lambda repo, name:
repo._remotenames.branchtonodes().get(name, []),
nodemap = lambda repo, node:
repo._remotenames.nodetobranch().get(node, []))
repo.names.addnamespace(remotebranchns)
@templatekeyword('remotenames', requires={'repo', 'ctx'})
def remotenameskw(context, mapping):
"""List of strings. Remote names associated with the changeset."""
repo = context.resource(mapping, 'repo')
ctx = context.resource(mapping, 'ctx')
remotenames = []
if 'remotebookmarks' in repo.names:
remotenames = repo.names['remotebookmarks'].names(repo, ctx.node())
if 'remotebranches' in repo.names:
remotenames += repo.names['remotebranches'].names(repo, ctx.node())
return templateutil.compatlist(context, mapping, 'remotename', remotenames,
plural='remotenames')
@templatekeyword('remotebookmarks', requires={'repo', 'ctx'})
def remotebookmarkskw(context, mapping):
"""List of strings. Remote bookmarks associated with the changeset."""
repo = context.resource(mapping, 'repo')
ctx = context.resource(mapping, 'ctx')
remotebmarks = []
if 'remotebookmarks' in repo.names:
remotebmarks = repo.names['remotebookmarks'].names(repo, ctx.node())
return templateutil.compatlist(context, mapping, 'remotebookmark',
remotebmarks, plural='remotebookmarks')
@templatekeyword('remotebranches', requires={'repo', 'ctx'})
def remotebrancheskw(context, mapping):
"""List of strings. Remote branches associated with the changeset."""
repo = context.resource(mapping, 'repo')
ctx = context.resource(mapping, 'ctx')
remotebranches = []
if 'remotebranches' in repo.names:
remotebranches = repo.names['remotebranches'].names(repo, ctx.node())
return templateutil.compatlist(context, mapping, 'remotebranch',
remotebranches, plural='remotebranches')
def _revsetutil(repo, subset, x, rtypes):
"""utility function to return a set of revs based on the rtypes"""
revs = set()
cl = repo.changelog
for rtype in rtypes:
if rtype in repo.names:
ns = repo.names[rtype]
for name in ns.listnames(repo):
revs.update(ns.nodes(repo, name))
results = (cl.rev(n) for n in revs if cl.hasnode(n))
return subset & smartset.baseset(sorted(results))
@revsetpredicate('remotenames()')
def remotenamesrevset(repo, subset, x):
"""All changesets which have a remotename on them."""
revsetlang.getargs(x, 0, 0, _("remotenames takes no arguments"))
return _revsetutil(repo, subset, x, ('remotebookmarks', 'remotebranches'))
@revsetpredicate('remotebranches()')
def remotebranchesrevset(repo, subset, x):
"""All changesets which are branch heads on remotes."""
revsetlang.getargs(x, 0, 0, _("remotebranches takes no arguments"))
return _revsetutil(repo, subset, x, ('remotebranches',))
@revsetpredicate('remotebookmarks()')
def remotebmarksrevset(repo, subset, x):
"""All changesets which have bookmarks on remotes."""
revsetlang.getargs(x, 0, 0, _("remotebookmarks takes no arguments"))
return _revsetutil(repo, subset, x, ('remotebookmarks',))