Mercurial > hg
view mercurial/filelog.py @ 17774:0496d4f73cf4
obsolete: cheap detection of nullid as successors
Nullid as successors create multiple issues:
- Nullid revnum is -1, confusing algorithm that use revnum unless you add
special handling in all of them.
- Nullid confuses "divergent" changeset detection and resolution. As you can't
add any successors to Nullid without being in even more troubles
Fortunately, there is no good reason to use nullid as a successor. The only
sensible meaning of "succeed by nullid" is "dropped" and this meaning is already
covered by obsolescence marker with empty successors set.
However, letting some nullid successors to slip in may cause terrible damage in
such algorithm difficult to debug. So I prefer to perform and clear detection of
of such pathological changeset. We could be much smarter by cleaning up nullid
successors on the fly but it would be much for expensive. As core Mercurial does
not create any such changeset, I think it is fine to just abort when suspicious
situation is detected.
Earlier experimental version created such changesets, so there are some out
there. The evolve extension added the necessary logic to clean up its mess.
author | Pierre-Yves David <pierre-yves.david@logilab.fr> |
---|---|
date | Mon, 15 Oct 2012 00:12:06 +0200 |
parents | 7c231754a621 |
children | 3bda242bf244 |
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# filelog.py - file history class for mercurial # # Copyright 2005-2007 Matt Mackall <mpm@selenic.com> # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. import revlog import re _mdre = re.compile('\1\n') def _parsemeta(text): """return (metadatadict, keylist, metadatasize)""" # text can be buffer, so we can't use .startswith or .index if text[:2] != '\1\n': return None, None, None s = _mdre.search(text, 2).start() mtext = text[2:s] meta = {} keys = [] for l in mtext.splitlines(): k, v = l.split(": ", 1) meta[k] = v keys.append(k) return meta, keys, (s + 2) def _packmeta(meta, keys=None): if not keys: keys = sorted(meta.iterkeys()) return "".join("%s: %s\n" % (k, meta[k]) for k in keys) class filelog(revlog.revlog): def __init__(self, opener, path): revlog.revlog.__init__(self, opener, "/".join(("data", path + ".i"))) def read(self, node): t = self.revision(node) if not t.startswith('\1\n'): return t s = t.index('\1\n', 2) return t[s + 2:] def add(self, text, meta, transaction, link, p1=None, p2=None): if meta or text.startswith('\1\n'): text = "\1\n%s\1\n%s" % (_packmeta(meta), text) return self.addrevision(text, transaction, link, p1, p2) def renamed(self, node): if self.parents(node)[0] != revlog.nullid: return False t = self.revision(node) m = _parsemeta(t)[0] if m and "copy" in m: return (m["copy"], revlog.bin(m["copyrev"])) return False def size(self, rev): """return the size of a given revision""" # for revisions with renames, we have to go the slow way node = self.node(rev) if self.renamed(node): return len(self.read(node)) # XXX if self.read(node).startswith("\1\n"), this returns (size+4) return revlog.revlog.size(self, rev) def cmp(self, node, text): """compare text with a given file revision returns True if text is different than what is stored. """ t = text if text.startswith('\1\n'): t = '\1\n\1\n' + text samehashes = not revlog.revlog.cmp(self, node, t) if samehashes: return False # renaming a file produces a different hash, even if the data # remains unchanged. Check if it's the case (slow): if self.renamed(node): t2 = self.read(node) return t2 != text return True def _file(self, f): return filelog(self.opener, f)