Mercurial > hg
view mercurial/filelog.py @ 17682:829919ef894a stable
lock: fixed race condition in trylock/testlock (issue3506)
Suppose the following scenario:
1. Process A takes the lock (e.g. on commit).
2. Process B wants to grab the lock. Since lock file exists
the exception is raised. In the catch block the testlock
function is called.
3. Process A releases the lock.
4. Process B tries to read the lock file as a part of testlock
function. This results in OSError (ENOENT) and since we're
not inside the exception handler function this is propagated
and aborts the whole operation.
To fix this we now check in testlock function whether lock file
actually exists and if not (i.e. if readlock fails) we just return.
author | Tomasz Kleczek <tomasz.kleczek@fb.com> |
---|---|
date | Thu, 27 Sep 2012 14:38:03 -0700 |
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)