Mercurial > hg
view mercurial/changelog.py @ 45059:79f6f9fa18c1
documentation: add some internals documentation about bid merge
This is an important algorithm that was only documented on the wiki so far.
Some update to the algorithm (and associated doc) is to expected in the future
since the bid merge algorithm is bug-ridden when it comes to file deletion comes
to play.
Differential Revision: https://phab.mercurial-scm.org/D8711
author | Pierre-Yves David <pierre-yves.david@octobus.net> |
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date | Mon, 22 Jun 2020 13:32:20 +0200 |
parents | 4c1d39215034 |
children | b3040b6739ce |
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# changelog.py - changelog 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. from __future__ import absolute_import from .i18n import _ from .node import ( bin, hex, nullid, ) from .thirdparty import attr from . import ( encoding, error, metadata, pycompat, revlog, ) from .utils import ( dateutil, stringutil, ) from .revlogutils import sidedata as sidedatamod _defaultextra = {b'branch': b'default'} def _string_escape(text): """ >>> from .pycompat import bytechr as chr >>> d = {b'nl': chr(10), b'bs': chr(92), b'cr': chr(13), b'nul': chr(0)} >>> s = b"ab%(nl)scd%(bs)s%(bs)sn%(nul)s12ab%(cr)scd%(bs)s%(nl)s" % d >>> s 'ab\\ncd\\\\\\\\n\\x0012ab\\rcd\\\\\\n' >>> res = _string_escape(s) >>> s == _string_unescape(res) True """ # subset of the string_escape codec text = ( text.replace(b'\\', b'\\\\') .replace(b'\n', b'\\n') .replace(b'\r', b'\\r') ) return text.replace(b'\0', b'\\0') def _string_unescape(text): if b'\\0' in text: # fix up \0 without getting into trouble with \\0 text = text.replace(b'\\\\', b'\\\\\n') text = text.replace(b'\\0', b'\0') text = text.replace(b'\n', b'') return stringutil.unescapestr(text) def decodeextra(text): """ >>> from .pycompat import bytechr as chr >>> sorted(decodeextra(encodeextra({b'foo': b'bar', b'baz': chr(0) + b'2'}) ... ).items()) [('baz', '\\x002'), ('branch', 'default'), ('foo', 'bar')] >>> sorted(decodeextra(encodeextra({b'foo': b'bar', ... b'baz': chr(92) + chr(0) + b'2'}) ... ).items()) [('baz', '\\\\\\x002'), ('branch', 'default'), ('foo', 'bar')] """ extra = _defaultextra.copy() for l in text.split(b'\0'): if l: k, v = _string_unescape(l).split(b':', 1) extra[k] = v return extra def encodeextra(d): # keys must be sorted to produce a deterministic changelog entry items = [_string_escape(b'%s:%s' % (k, d[k])) for k in sorted(d)] return b"\0".join(items) def stripdesc(desc): """strip trailing whitespace and leading and trailing empty lines""" return b'\n'.join([l.rstrip() for l in desc.splitlines()]).strip(b'\n') class appender(object): '''the changelog index must be updated last on disk, so we use this class to delay writes to it''' def __init__(self, vfs, name, mode, buf): self.data = buf fp = vfs(name, mode) self.fp = fp self.offset = fp.tell() self.size = vfs.fstat(fp).st_size self._end = self.size def end(self): return self._end def tell(self): return self.offset def flush(self): pass @property def closed(self): return self.fp.closed def close(self): self.fp.close() def seek(self, offset, whence=0): '''virtual file offset spans real file and data''' if whence == 0: self.offset = offset elif whence == 1: self.offset += offset elif whence == 2: self.offset = self.end() + offset if self.offset < self.size: self.fp.seek(self.offset) def read(self, count=-1): '''only trick here is reads that span real file and data''' ret = b"" if self.offset < self.size: s = self.fp.read(count) ret = s self.offset += len(s) if count > 0: count -= len(s) if count != 0: doff = self.offset - self.size self.data.insert(0, b"".join(self.data)) del self.data[1:] s = self.data[0][doff : doff + count] self.offset += len(s) ret += s return ret def write(self, s): self.data.append(bytes(s)) self.offset += len(s) self._end += len(s) def __enter__(self): self.fp.__enter__() return self def __exit__(self, *args): return self.fp.__exit__(*args) class _divertopener(object): def __init__(self, opener, target): self._opener = opener self._target = target def __call__(self, name, mode=b'r', checkambig=False, **kwargs): if name != self._target: return self._opener(name, mode, **kwargs) return self._opener(name + b".a", mode, **kwargs) def __getattr__(self, attr): return getattr(self._opener, attr) def _delayopener(opener, target, buf): """build an opener that stores chunks in 'buf' instead of 'target'""" def _delay(name, mode=b'r', checkambig=False, **kwargs): if name != target: return opener(name, mode, **kwargs) assert not kwargs return appender(opener, name, mode, buf) return _delay @attr.s class _changelogrevision(object): # Extensions might modify _defaultextra, so let the constructor below pass # it in extra = attr.ib() manifest = attr.ib(default=nullid) user = attr.ib(default=b'') date = attr.ib(default=(0, 0)) files = attr.ib(default=attr.Factory(list)) filesadded = attr.ib(default=None) filesremoved = attr.ib(default=None) p1copies = attr.ib(default=None) p2copies = attr.ib(default=None) description = attr.ib(default=b'') class changelogrevision(object): """Holds results of a parsed changelog revision. Changelog revisions consist of multiple pieces of data, including the manifest node, user, and date. This object exposes a view into the parsed object. """ __slots__ = ( '_offsets', '_text', '_sidedata', '_cpsd', ) def __new__(cls, text, sidedata, cpsd): if not text: return _changelogrevision(extra=_defaultextra) self = super(changelogrevision, cls).__new__(cls) # We could return here and implement the following as an __init__. # But doing it here is equivalent and saves an extra function call. # format used: # nodeid\n : manifest node in ascii # user\n : user, no \n or \r allowed # time tz extra\n : date (time is int or float, timezone is int) # : extra is metadata, encoded and separated by '\0' # : older versions ignore it # files\n\n : files modified by the cset, no \n or \r allowed # (.*) : comment (free text, ideally utf-8) # # changelog v0 doesn't use extra nl1 = text.index(b'\n') nl2 = text.index(b'\n', nl1 + 1) nl3 = text.index(b'\n', nl2 + 1) # The list of files may be empty. Which means nl3 is the first of the # double newline that precedes the description. if text[nl3 + 1 : nl3 + 2] == b'\n': doublenl = nl3 else: doublenl = text.index(b'\n\n', nl3 + 1) self._offsets = (nl1, nl2, nl3, doublenl) self._text = text self._sidedata = sidedata self._cpsd = cpsd return self @property def manifest(self): return bin(self._text[0 : self._offsets[0]]) @property def user(self): off = self._offsets return encoding.tolocal(self._text[off[0] + 1 : off[1]]) @property def _rawdate(self): off = self._offsets dateextra = self._text[off[1] + 1 : off[2]] return dateextra.split(b' ', 2)[0:2] @property def _rawextra(self): off = self._offsets dateextra = self._text[off[1] + 1 : off[2]] fields = dateextra.split(b' ', 2) if len(fields) != 3: return None return fields[2] @property def date(self): raw = self._rawdate time = float(raw[0]) # Various tools did silly things with the timezone. try: timezone = int(raw[1]) except ValueError: timezone = 0 return time, timezone @property def extra(self): raw = self._rawextra if raw is None: return _defaultextra return decodeextra(raw) @property def files(self): off = self._offsets if off[2] == off[3]: return [] return self._text[off[2] + 1 : off[3]].split(b'\n') @property def filesadded(self): if self._cpsd: rawindices = self._sidedata.get(sidedatamod.SD_FILESADDED) if not rawindices: return [] else: rawindices = self.extra.get(b'filesadded') if rawindices is None: return None return metadata.decodefileindices(self.files, rawindices) @property def filesremoved(self): if self._cpsd: rawindices = self._sidedata.get(sidedatamod.SD_FILESREMOVED) if not rawindices: return [] else: rawindices = self.extra.get(b'filesremoved') if rawindices is None: return None return metadata.decodefileindices(self.files, rawindices) @property def p1copies(self): if self._cpsd: rawcopies = self._sidedata.get(sidedatamod.SD_P1COPIES) if not rawcopies: return {} else: rawcopies = self.extra.get(b'p1copies') if rawcopies is None: return None return metadata.decodecopies(self.files, rawcopies) @property def p2copies(self): if self._cpsd: rawcopies = self._sidedata.get(sidedatamod.SD_P2COPIES) if not rawcopies: return {} else: rawcopies = self.extra.get(b'p2copies') if rawcopies is None: return None return metadata.decodecopies(self.files, rawcopies) @property def description(self): return encoding.tolocal(self._text[self._offsets[3] + 2 :]) class changelog(revlog.revlog): def __init__(self, opener, trypending=False): """Load a changelog revlog using an opener. If ``trypending`` is true, we attempt to load the index from a ``00changelog.i.a`` file instead of the default ``00changelog.i``. The ``00changelog.i.a`` file contains index (and possibly inline revision) data for a transaction that hasn't been finalized yet. It exists in a separate file to facilitate readers (such as hooks processes) accessing data before a transaction is finalized. """ if trypending and opener.exists(b'00changelog.i.a'): indexfile = b'00changelog.i.a' else: indexfile = b'00changelog.i' datafile = b'00changelog.d' revlog.revlog.__init__( self, opener, indexfile, datafile=datafile, checkambig=True, mmaplargeindex=True, persistentnodemap=opener.options.get(b'persistent-nodemap', False), ) if self._initempty and (self.version & 0xFFFF == revlog.REVLOGV1): # changelogs don't benefit from generaldelta. self.version &= ~revlog.FLAG_GENERALDELTA self._generaldelta = False # Delta chains for changelogs tend to be very small because entries # tend to be small and don't delta well with each. So disable delta # chains. self._storedeltachains = False self._realopener = opener self._delayed = False self._delaybuf = None self._divert = False self.filteredrevs = frozenset() self._copiesstorage = opener.options.get(b'copies-storage') def delayupdate(self, tr): """delay visibility of index updates to other readers""" if not self._delayed: if len(self) == 0: self._divert = True if self._realopener.exists(self.indexfile + b'.a'): self._realopener.unlink(self.indexfile + b'.a') self.opener = _divertopener(self._realopener, self.indexfile) else: self._delaybuf = [] self.opener = _delayopener( self._realopener, self.indexfile, self._delaybuf ) self._delayed = True tr.addpending(b'cl-%i' % id(self), self._writepending) tr.addfinalize(b'cl-%i' % id(self), self._finalize) def _finalize(self, tr): """finalize index updates""" self._delayed = False self.opener = self._realopener # move redirected index data back into place if self._divert: assert not self._delaybuf tmpname = self.indexfile + b".a" nfile = self.opener.open(tmpname) nfile.close() self.opener.rename(tmpname, self.indexfile, checkambig=True) elif self._delaybuf: fp = self.opener(self.indexfile, b'a', checkambig=True) fp.write(b"".join(self._delaybuf)) fp.close() self._delaybuf = None self._divert = False # split when we're done self._enforceinlinesize(tr) def _writepending(self, tr): """create a file containing the unfinalized state for pretxnchangegroup""" if self._delaybuf: # make a temporary copy of the index fp1 = self._realopener(self.indexfile) pendingfilename = self.indexfile + b".a" # register as a temp file to ensure cleanup on failure tr.registertmp(pendingfilename) # write existing data fp2 = self._realopener(pendingfilename, b"w") fp2.write(fp1.read()) # add pending data fp2.write(b"".join(self._delaybuf)) fp2.close() # switch modes so finalize can simply rename self._delaybuf = None self._divert = True self.opener = _divertopener(self._realopener, self.indexfile) if self._divert: return True return False def _enforceinlinesize(self, tr, fp=None): if not self._delayed: revlog.revlog._enforceinlinesize(self, tr, fp) def read(self, node): """Obtain data from a parsed changelog revision. Returns a 6-tuple of: - manifest node in binary - author/user as a localstr - date as a 2-tuple of (time, timezone) - list of files - commit message as a localstr - dict of extra metadata Unless you need to access all fields, consider calling ``changelogrevision`` instead, as it is faster for partial object access. """ d, s = self._revisiondata(node) c = changelogrevision( d, s, self._copiesstorage == b'changeset-sidedata' ) return (c.manifest, c.user, c.date, c.files, c.description, c.extra) def changelogrevision(self, nodeorrev): """Obtain a ``changelogrevision`` for a node or revision.""" text, sidedata = self._revisiondata(nodeorrev) return changelogrevision( text, sidedata, self._copiesstorage == b'changeset-sidedata' ) def readfiles(self, node): """ short version of read that only returns the files modified by the cset """ text = self.revision(node) if not text: return [] last = text.index(b"\n\n") l = text[:last].split(b'\n') return l[3:] def add( self, manifest, files, desc, transaction, p1, p2, user, date=None, extra=None, p1copies=None, p2copies=None, filesadded=None, filesremoved=None, ): # Convert to UTF-8 encoded bytestrings as the very first # thing: calling any method on a localstr object will turn it # into a str object and the cached UTF-8 string is thus lost. user, desc = encoding.fromlocal(user), encoding.fromlocal(desc) user = user.strip() # An empty username or a username with a "\n" will make the # revision text contain two "\n\n" sequences -> corrupt # repository since read cannot unpack the revision. if not user: raise error.StorageError(_(b"empty username")) if b"\n" in user: raise error.StorageError( _(b"username %r contains a newline") % pycompat.bytestr(user) ) desc = stripdesc(desc) if date: parseddate = b"%d %d" % dateutil.parsedate(date) else: parseddate = b"%d %d" % dateutil.makedate() if extra: branch = extra.get(b"branch") if branch in (b"default", b""): del extra[b"branch"] elif branch in (b".", b"null", b"tip"): raise error.StorageError( _(b'the name \'%s\' is reserved') % branch ) sortedfiles = sorted(files) sidedata = None if extra is not None: for name in ( b'p1copies', b'p2copies', b'filesadded', b'filesremoved', ): extra.pop(name, None) if p1copies is not None: p1copies = metadata.encodecopies(sortedfiles, p1copies) if p2copies is not None: p2copies = metadata.encodecopies(sortedfiles, p2copies) if filesadded is not None: filesadded = metadata.encodefileindices(sortedfiles, filesadded) if filesremoved is not None: filesremoved = metadata.encodefileindices(sortedfiles, filesremoved) if self._copiesstorage == b'extra': extrasentries = p1copies, p2copies, filesadded, filesremoved if extra is None and any(x is not None for x in extrasentries): extra = {} if p1copies is not None: extra[b'p1copies'] = p1copies if p2copies is not None: extra[b'p2copies'] = p2copies if filesadded is not None: extra[b'filesadded'] = filesadded if filesremoved is not None: extra[b'filesremoved'] = filesremoved elif self._copiesstorage == b'changeset-sidedata': sidedata = {} if p1copies: sidedata[sidedatamod.SD_P1COPIES] = p1copies if p2copies: sidedata[sidedatamod.SD_P2COPIES] = p2copies if filesadded: sidedata[sidedatamod.SD_FILESADDED] = filesadded if filesremoved: sidedata[sidedatamod.SD_FILESREMOVED] = filesremoved if not sidedata: sidedata = None if extra: extra = encodeextra(extra) parseddate = b"%s %s" % (parseddate, extra) l = [hex(manifest), user, parseddate] + sortedfiles + [b"", desc] text = b"\n".join(l) return self.addrevision( text, transaction, len(self), p1, p2, sidedata=sidedata ) def branchinfo(self, rev): """return the branch name and open/close state of a revision This function exists because creating a changectx object just to access this is costly.""" extra = self.read(rev)[5] return encoding.tolocal(extra.get(b"branch")), b'close' in extra def _nodeduplicatecallback(self, transaction, node): # keep track of revisions that got "re-added", eg: unbunde of know rev. # # We track them in a list to preserve their order from the source bundle duplicates = transaction.changes.setdefault(b'revduplicates', []) duplicates.append(self.rev(node))