Mercurial > hg
view mercurial/repoview.py @ 31793:69d8fcf20014
help: document bundle specifications
I softly formalized the concept of a "bundle specification" a while
ago when I was working on clone bundles and stream clone bundles and
wanted a more robust way to define what exactly is in a bundle file.
The concept has existed for a while. Since it is part of the clone
bundles feature and exposed to the user via the "-t" argument to
`hg bundle`, it is something we need to support for the long haul.
After the 4.1 release, I heard a few people comment that they didn't
realize you could generate zstd bundles with `hg bundle`. I'm
partially to blame for not documenting it in bundle's docstring.
Additionally, I added a hacky, experimental feature for controlling
the compression level of bundles in 76104a4899ad. As the commit
message says, I went with a quick and dirty solution out of time
constraints. Furthermore, I wanted to eventually store this
configuration in the "bundlespec" so it could be made more flexible.
Given:
a) bundlespecs are here to stay
b) we don't have great documentation over what they are, despite being
a user-facing feature
c) the list of available compression engines and their behavior isn't
exposed
d) we need an extensible place to modify behavior of compression
engines
I want to move forward with formalizing bundlespecs as a user-facing
feature. This commit does that by introducing a "bundlespec" help
page. Leaning on the just-added compression engine documentation
and API, the topic also conveniently lists available compression
engines and details about them. This makes features like zstd
bundle compression more discoverable. e.g. you can now
`hg help -k zstd` and it lists the "bundlespec" topic.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Sat, 01 Apr 2017 13:42:06 -0700 |
parents | 55390e97fdd2 |
children | 06aa645e2372 |
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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 hashlib import heapq import struct from .node import nullrev from . import ( error, obsolete, phases, 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 _getstatichidden(repo): """Revision to be hidden (disregarding dynamic blocker) To keep a consistent graph, we cannot hide any revisions with non-hidden descendants. This function computes the set of revisions that could be hidden while keeping the graph consistent. A second pass will be done to apply "dynamic blocker" like bookmarks or working directory parents. """ assert not repo.changelog.filteredrevs hidden = set(hideablerevs(repo)) if hidden: getphase = repo._phasecache.phase getparentrevs = repo.changelog.parentrevs # Skip heads which are public (guaranteed to not be hidden) heap = [-r for r in repo.changelog.headrevs() if getphase(repo, r)] heapq.heapify(heap) heappop = heapq.heappop heappush = heapq.heappush seen = set() # no need to init it with heads, they have no children while heap: rev = -heappop(heap) # All children have been processed so at that point, if no children # removed 'rev' from the 'hidden' set, 'rev' is going to be hidden. blocker = rev not in hidden for parent in getparentrevs(rev): if parent == nullrev: continue if blocker: # If visible, ensure parent will be visible too hidden.discard(parent) # - Avoid adding the same revision twice # - Skip nodes which are public (guaranteed to not be hidden) pre = len(seen) seen.add(parent) if pre < len(seen) and getphase(repo, rev): heappush(heap, -parent) return hidden def _getdynamicblockers(repo): """Non-cacheable revisions blocking hidden changesets from being filtered. Get revisions that will block hidden changesets and are likely to change, but unlikely to create hidden blockers. They won't be cached, so be careful with adding additional computation.""" cl = repo.changelog blockers = set() blockers.update([par.rev() for par in repo[None].parents()]) blockers.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 blockers.update(rev(t[0]) for t in tags.values() if t[0] in nodemap) return blockers cacheversion = 1 cachefile = 'cache/hidden' def cachehash(repo, hideable): """return sha1 hash of repository data to identify a valid cache. We calculate a sha1 of repo heads and the content of the obsstore and write it to the cache. Upon reading we can easily validate by checking the hash against the stored one and discard the cache in case the hashes don't match. """ h = hashlib.sha1() h.update(''.join(repo.heads())) h.update('%d' % hash(frozenset(hideable))) return h.digest() def _writehiddencache(cachefile, cachehash, hidden): """write hidden data to a cache file""" data = struct.pack('>%ii' % len(hidden), *sorted(hidden)) cachefile.write(struct.pack(">H", cacheversion)) cachefile.write(cachehash) cachefile.write(data) def trywritehiddencache(repo, hideable, hidden): """write cache of hidden changesets to disk Will not write the cache if a wlock cannot be obtained lazily. The cache consists of a head of 22byte: 2 byte version number of the cache 20 byte sha1 to validate the cache n*4 byte hidden revs """ wlock = fh = None try: wlock = repo.wlock(wait=False) # write cache to file newhash = cachehash(repo, hideable) fh = repo.vfs.open(cachefile, 'w+b', atomictemp=True) _writehiddencache(fh, newhash, hidden) fh.close() except (IOError, OSError): repo.ui.debug('error writing hidden changesets cache\n') except error.LockHeld: repo.ui.debug('cannot obtain lock to write hidden changesets cache\n') finally: if wlock: wlock.release() def _readhiddencache(repo, cachefilename, newhash): hidden = fh = None try: if repo.vfs.exists(cachefile): fh = repo.vfs.open(cachefile, 'rb') version, = struct.unpack(">H", fh.read(2)) oldhash = fh.read(20) if (cacheversion, oldhash) == (version, newhash): # cache is valid, so we can start reading the hidden revs data = fh.read() count = len(data) / 4 hidden = frozenset(struct.unpack('>%ii' % count, data)) return hidden except struct.error: repo.ui.debug('corrupted hidden cache\n') # No need to fix the content as it will get rewritten return None except (IOError, OSError): repo.ui.debug('cannot read hidden cache\n') return None finally: if fh: fh.close() def tryreadcache(repo, hideable): """read a cache if the cache exists and is valid, otherwise returns None.""" newhash = cachehash(repo, hideable) return _readhiddencache(repo, cachefile, newhash) def computehidden(repo): """compute the set of hidden revision to filter During most operation hidden should be filtered.""" assert not repo.changelog.filteredrevs hidden = frozenset() hideable = hideablerevs(repo) if hideable: cl = repo.changelog hidden = tryreadcache(repo, hideable) if hidden is None: hidden = frozenset(_getstatichidden(repo)) trywritehiddencache(repo, hideable, hidden) # check if we have wd parents, bookmarks or tags pointing to hidden # changesets and remove those. dynamic = hidden & _getdynamicblockers(repo) if dynamic: blocked = cl.ancestors(dynamic, inclusive=True) hidden = frozenset(r for r in hidden if r not in blocked) return hidden def computeunserved(repo): """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): """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 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): """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, 'served': computeunserved, 'immutable': computemutable, 'base': computeimpactable} def filterrevs(repo, filtername): """returns set of filtered revision for this filter name""" if filtername not in repo.filteredrevcache: func = filtertable[filtername] 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): object.__setattr__(self, r'_unfilteredrepo', repo) object.__setattr__(self, r'filtername', filtername) object.__setattr__(self, r'_clcachekey', None) object.__setattr__(self, r'_clcache', None) # 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) 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): """Return a filtered version of a repository""" if name == self.filtername: return self return self.unfiltered().filtered(name) # 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) # The `requirements` attribute is initialized during __init__. But # __getattr__ won't be called as it also exists on the class. We need # explicit forwarding to main repo here @property def requirements(self): return self._unfilteredrepo.requirements