Mercurial > hg
view mercurial/repoview.py @ 39638:d292328e0143
exchangev2: fetch manifest revisions
Now that the server has support for retrieving manifest data, we can
implement the client bits to call it.
We teach the changeset fetching code to capture the manifest revisions
that are encountered on incoming changesets. We then feed this into a
new function which filters out known manifests and then batches up
manifest data requests to the server.
This is different from the previous wire protocol in a few notable
ways.
First, the client fetches manifest data separately and explicitly.
Before, we'd ask the server for data pertaining to some changesets
(via a "getbundle" command) and manifests (and files) would be sent
automatically. Providing an API for looking up just manifest data
separately gives clients much more flexibility for manifest management.
For example, a client may choose to only fetch manifest data on demand
instead of prefetching it (i.e. partial clone).
Second, we send N commands to the server for manifest retrieval instead
of 1. This property has a few nice side-effects. One is that the
deterministic nature of the requests lends itself to server-side
caching. For example, say the remote has 50,000 manifests. If the
server is configured to cache responses, each time a new commit
arrives, you will have a cache miss and need to regenerate all outgoing
data. But if you makes N requests requesting 10,000 manifests each,
a new commit will still yield cache hits on the initial, unchanged
manifest batches/requests.
A derived benefit from these properties is that resumable clone is
conceptually simpler to implement. When making a monolithic request
for all of the repository data, recovering from an interrupted clone
is hard because the server was in the driver's seat and was maintaining
state about all the data that needed transferred. With the client
driving fetching, the client can persist the set of unfetched entities
and retry/resume a fetch if something goes wrong. Or we can fetch all
data N changesets at a time and slowly build up a repository. This
approach is drastically easier to implement when we have server APIs
exposing low-level repository primitives (such as manifests and files).
We don't yet support tree manifests. But it should be possible to
implement that with the existing wire protocol command.
Differential Revision: https://phab.mercurial-scm.org/D4489
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Wed, 05 Sep 2018 09:09:57 -0700 |
parents | 06c976acc581 |
children | bc15e37ecc16 |
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# 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.""" obsoletes = obsolete.getrevs(repo, 'obsolete') internals = repo._phasecache.getrevset(repo, phases.localhiddenphases) internals = frozenset(internals) return obsoletes | internals 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 mutable = repo._phasecache.getrevset(repo, phases.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): secrets = repo._phasecache.getrevset(repo, phases.remotehiddenphases) return frozenset(hiddens | frozenset(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(pycompat.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) 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]