filelog: wrap revlog instead of inheriting it (API)
The revlog base class exposes a ton of methods. Inheriting the
revlog class for filelog will make it difficult to expose a
clean interface. There will be abstraction violations.
This commit breaks the inheritance of revlog by the filelog
class. Filelog instances now contain a reference to a revlog
instance. Various properties and methods are now proxied to
that instance.
There is precedence for doing this: manifestlog does something
similar. Although, manifestlog has a cleaner interface than
filelog. We'll get there with filelog...
The new filelog class exposes a handful of extra properties and
methods that aren't part of the declared filelog interface.
Every extra item was added in order to get a test to pass. The
set of tests that failed without these extra proxies has
significant overlap with the set of tests that don't work with
the simple store repo. There should be no surprise there.
Hopefully the hardest part about this commit to review are the
changes to bundlerepo and unionrepo. Both repository types
define a custom revlog or revlog-like class and then have a
custom filelog that inherits from both filelog and their custom
revlog. This code has been changed so the filelog types don't
inherit from revlog. Instead, they replace the revlog instance
on the created filelog. This is super hacky. I plan to fix this
in a future commit by parameterizing filelog.__init__.
Because Python function call overhead is a thing, this change
could impact performance by introducing a nearly empty proxy
function for various methods and properties. I would gladly
measure the performance impact of it, but I'm not sure what
operations have tight loops over filelog attribute lookups
or function calls. I know some of the DAG traversal code can
be sensitive about the performance of e.g. parentrevs(). However,
many of these functions are implemented on the revlog class and
therefore have direct access to self.parentrevs() and aren't
going through a proxy.
.. api::
filelog.filelog is now a standalone class and doesn't inherit
from revlog. Instead, it wraps a revlog instance at self._revlog.
This change was made in an attempt to formalize storage APIs and
prevent revlog implementation details leaking through to callers.
Differential Revision: https://phab.mercurial-scm.org/D3154
# repoview.py - Filtered view of a localrepo object
#
# Copyright 2012 Pierre-Yves David <pierre-yves.david@ens-lyon.org>
# Logilab SA <contact@logilab.fr>
#
# 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 copy
import weakref
from .node import nullrev
from . import (
obsolete,
phases,
pycompat,
tags as tagsmod,
)
def hideablerevs(repo):
"""Revision candidates to be hidden
This is a standalone function to allow extensions to wrap it.
Because we use the set of immutable changesets as a fallback subset in
branchmap (see mercurial.branchmap.subsettable), you cannot set "public"
changesets as "hideable". Doing so would break multiple code assertions and
lead to crashes."""
return obsolete.getrevs(repo, 'obsolete')
def pinnedrevs(repo):
"""revisions blocking hidden changesets from being filtered
"""
cl = repo.changelog
pinned = set()
pinned.update([par.rev() for par in repo[None].parents()])
pinned.update([cl.rev(bm) for bm in repo._bookmarks.values()])
tags = {}
tagsmod.readlocaltags(repo.ui, repo, tags, {})
if tags:
rev, nodemap = cl.rev, cl.nodemap
pinned.update(rev(t[0]) for t in tags.values() if t[0] in nodemap)
return pinned
def _revealancestors(pfunc, hidden, revs):
"""reveals contiguous chains of hidden ancestors of 'revs' by removing them
from 'hidden'
- pfunc(r): a funtion returning parent of 'r',
- hidden: the (preliminary) hidden revisions, to be updated
- revs: iterable of revnum,
(Ancestors are revealed exclusively, i.e. the elements in 'revs' are
*not* revealed)
"""
stack = list(revs)
while stack:
for p in pfunc(stack.pop()):
if p != nullrev and p in hidden:
hidden.remove(p)
stack.append(p)
def computehidden(repo, visibilityexceptions=None):
"""compute the set of hidden revision to filter
During most operation hidden should be filtered."""
assert not repo.changelog.filteredrevs
hidden = hideablerevs(repo)
if hidden:
hidden = set(hidden - pinnedrevs(repo))
if visibilityexceptions:
hidden -= visibilityexceptions
pfunc = repo.changelog.parentrevs
mutablephases = (phases.draft, phases.secret)
mutable = repo._phasecache.getrevset(repo, mutablephases)
visible = mutable - hidden
_revealancestors(pfunc, hidden, visible)
return frozenset(hidden)
def computeunserved(repo, visibilityexceptions=None):
"""compute the set of revision that should be filtered when used a server
Secret and hidden changeset should not pretend to be here."""
assert not repo.changelog.filteredrevs
# fast path in simple case to avoid impact of non optimised code
hiddens = filterrevs(repo, 'visible')
if phases.hassecret(repo):
cl = repo.changelog
secret = phases.secret
getphase = repo._phasecache.phase
first = min(cl.rev(n) for n in repo._phasecache.phaseroots[secret])
revs = cl.revs(start=first)
secrets = set(r for r in revs if getphase(repo, r) >= secret)
return frozenset(hiddens | secrets)
else:
return hiddens
def computemutable(repo, visibilityexceptions=None):
assert not repo.changelog.filteredrevs
# fast check to avoid revset call on huge repo
if any(repo._phasecache.phaseroots[1:]):
getphase = repo._phasecache.phase
maymutable = filterrevs(repo, 'base')
return frozenset(r for r in maymutable if getphase(repo, r))
return frozenset()
def computeimpactable(repo, visibilityexceptions=None):
"""Everything impactable by mutable revision
The immutable filter still have some chance to get invalidated. This will
happen when:
- you garbage collect hidden changeset,
- public phase is moved backward,
- something is changed in the filtering (this could be fixed)
This filter out any mutable changeset and any public changeset that may be
impacted by something happening to a mutable revision.
This is achieved by filtered everything with a revision number egal or
higher than the first mutable changeset is filtered."""
assert not repo.changelog.filteredrevs
cl = repo.changelog
firstmutable = len(cl)
for roots in repo._phasecache.phaseroots[1:]:
if roots:
firstmutable = min(firstmutable, min(cl.rev(r) for r in roots))
# protect from nullrev root
firstmutable = max(0, firstmutable)
return frozenset(xrange(firstmutable, len(cl)))
# function to compute filtered set
#
# When adding a new filter you MUST update the table at:
# mercurial.branchmap.subsettable
# Otherwise your filter will have to recompute all its branches cache
# from scratch (very slow).
filtertable = {'visible': computehidden,
'visible-hidden': computehidden,
'served': computeunserved,
'immutable': computemutable,
'base': computeimpactable}
def filterrevs(repo, filtername, visibilityexceptions=None):
"""returns set of filtered revision for this filter name
visibilityexceptions is a set of revs which must are exceptions for
hidden-state and must be visible. They are dynamic and hence we should not
cache it's result"""
if filtername not in repo.filteredrevcache:
func = filtertable[filtername]
if visibilityexceptions:
return func(repo.unfiltered, visibilityexceptions)
repo.filteredrevcache[filtername] = func(repo.unfiltered())
return repo.filteredrevcache[filtername]
class repoview(object):
"""Provide a read/write view of a repo through a filtered changelog
This object is used to access a filtered version of a repository without
altering the original repository object itself. We can not alter the
original object for two main reasons:
- It prevents the use of a repo with multiple filters at the same time. In
particular when multiple threads are involved.
- It makes scope of the filtering harder to control.
This object behaves very closely to the original repository. All attribute
operations are done on the original repository:
- An access to `repoview.someattr` actually returns `repo.someattr`,
- A write to `repoview.someattr` actually sets value of `repo.someattr`,
- A deletion of `repoview.someattr` actually drops `someattr`
from `repo.__dict__`.
The only exception is the `changelog` property. It is overridden to return
a (surface) copy of `repo.changelog` with some revisions filtered. The
`filtername` attribute of the view control the revisions that need to be
filtered. (the fact the changelog is copied is an implementation detail).
Unlike attributes, this object intercepts all method calls. This means that
all methods are run on the `repoview` object with the filtered `changelog`
property. For this purpose the simple `repoview` class must be mixed with
the actual class of the repository. This ensures that the resulting
`repoview` object have the very same methods than the repo object. This
leads to the property below.
repoview.method() --> repo.__class__.method(repoview)
The inheritance has to be done dynamically because `repo` can be of any
subclasses of `localrepo`. Eg: `bundlerepo` or `statichttprepo`.
"""
def __init__(self, repo, filtername, visibilityexceptions=None):
object.__setattr__(self, r'_unfilteredrepo', repo)
object.__setattr__(self, r'filtername', filtername)
object.__setattr__(self, r'_clcachekey', None)
object.__setattr__(self, r'_clcache', None)
# revs which are exceptions and must not be hidden
object.__setattr__(self, r'_visibilityexceptions',
visibilityexceptions)
# not a propertycache on purpose we shall implement a proper cache later
@property
def changelog(self):
"""return a filtered version of the changeset
this changelog must not be used for writing"""
# some cache may be implemented later
unfi = self._unfilteredrepo
unfichangelog = unfi.changelog
# bypass call to changelog.method
unfiindex = unfichangelog.index
unfilen = len(unfiindex) - 1
unfinode = unfiindex[unfilen - 1][7]
revs = filterrevs(unfi, self.filtername, self._visibilityexceptions)
cl = self._clcache
newkey = (unfilen, unfinode, hash(revs), unfichangelog._delayed)
# if cl.index is not unfiindex, unfi.changelog would be
# recreated, and our clcache refers to garbage object
if (cl is not None and
(cl.index is not unfiindex or newkey != self._clcachekey)):
cl = None
# could have been made None by the previous if
if cl is None:
cl = copy.copy(unfichangelog)
cl.filteredrevs = revs
object.__setattr__(self, r'_clcache', cl)
object.__setattr__(self, r'_clcachekey', newkey)
return cl
def unfiltered(self):
"""Return an unfiltered version of a repo"""
return self._unfilteredrepo
def filtered(self, name, visibilityexceptions=None):
"""Return a filtered version of a repository"""
if name == self.filtername and not visibilityexceptions:
return self
return self.unfiltered().filtered(name, visibilityexceptions)
def __repr__(self):
return r'<%s:%s %r>' % (self.__class__.__name__,
pycompat.sysstr(self.filtername),
self.unfiltered())
# everything access are forwarded to the proxied repo
def __getattr__(self, attr):
return getattr(self._unfilteredrepo, attr)
def __setattr__(self, attr, value):
return setattr(self._unfilteredrepo, attr, value)
def __delattr__(self, attr):
return delattr(self._unfilteredrepo, attr)
# Python <3.4 easily leaks types via __mro__. See
# https://bugs.python.org/issue17950. We cache dynamically created types
# so they won't be leaked on every invocation of repo.filtered().
_filteredrepotypes = weakref.WeakKeyDictionary()
def newtype(base):
"""Create a new type with the repoview mixin and the given base class"""
if base not in _filteredrepotypes:
class filteredrepo(repoview, base):
pass
_filteredrepotypes[base] = filteredrepo
return _filteredrepotypes[base]