Mercurial > hg
changeset 47238:6597255a4f94
revlogv2: track current index size in the docket
This help use to fix transaction safety on repos. See next changesets for details.
Differential Revision: https://phab.mercurial-scm.org/D10628
| author | Pierre-Yves David <pierre-yves.david@octobus.net> |
|---|---|
| date | Mon, 03 May 2021 12:34:52 +0200 |
| parents | 864f4ebe6a8d |
| children | 682f09857d69 |
| files | mercurial/configitems.py mercurial/localrepo.py mercurial/revlog.py mercurial/revlogutils/docket.py |
| diffstat | 4 files changed, 70 insertions(+), 12 deletions(-) [+] |
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--- a/mercurial/configitems.py Mon May 03 12:34:41 2021 +0200 +++ b/mercurial/configitems.py Mon May 03 12:34:52 2021 +0200 @@ -1157,6 +1157,7 @@ # - for censoring operation # - for stripping operation # - for rollback operation +# * proper streaming (race free) of the docket file # * store the data size in the docket to simplify sidedata rewrite. # * track garbage data to evemtually allow rewriting -existing- sidedata. # * Exchange-wise, we will also need to do something more efficient than
--- a/mercurial/localrepo.py Mon May 03 12:34:41 2021 +0200 +++ b/mercurial/localrepo.py Mon May 03 12:34:52 2021 +0200 @@ -739,6 +739,8 @@ if requirementsmod.REVLOGV2_REQUIREMENT in requirements: features.add(repository.REPO_FEATURE_SIDE_DATA) + # the revlogv2 docket introduced race condition that we need to fix + features.discard(repository.REPO_FEATURE_STREAM_CLONE) # The cache vfs is used to manage cache files. cachevfs = vfsmod.vfs(cachepath, cacheaudited=True)
--- a/mercurial/revlog.py Mon May 03 12:34:41 2021 +0200 +++ b/mercurial/revlog.py Mon May 03 12:34:52 2021 +0200 @@ -453,7 +453,7 @@ force_nodemap = opts.get(b'devel-force-nodemap', False) return new_header, mmapindexthreshold, force_nodemap - def _get_data(self, filepath, mmap_threshold): + def _get_data(self, filepath, mmap_threshold, size=None): """return a file content with or without mmap If the file is missing return the empty string""" @@ -462,10 +462,19 @@ if mmap_threshold is not None: file_size = self.opener.fstat(fp).st_size if file_size >= mmap_threshold: + if size is not None: + # avoid potentiel mmap crash + size = min(file_size, size) # TODO: should .close() to release resources without # relying on Python GC - return util.buffer(util.mmapread(fp)) - return fp.read() + if size is None: + return util.buffer(util.mmapread(fp)) + else: + return util.buffer(util.mmapread(fp, size)) + if size is None: + return fp.read() + else: + return fp.read(size) except IOError as inst: if inst.errno != errno.ENOENT: raise @@ -518,7 +527,17 @@ else: self._docket = docketutil.parse_docket(self, entry_data) self._indexfile = self._docket.index_filepath() - index_data = self._get_data(self._indexfile, mmapindexthreshold) + index_data = b'' + index_size = self._docket.index_end + if index_size > 0: + index_data = self._get_data( + self._indexfile, mmapindexthreshold, size=index_size + ) + if len(index_data) < index_size: + msg = _(b'too few index data for %s: got %d, expected %d') + msg %= (self.display_id, len(index_data), index_size) + raise error.RevlogError(msg) + self._inline = False # generaldelta implied by version 2 revlogs. self._generaldelta = True @@ -619,7 +638,10 @@ f = self.opener( self._indexfile, mode=b"r+", checkambig=self._checkambig ) - f.seek(0, os.SEEK_END) + if self._docket is None: + f.seek(0, os.SEEK_END) + else: + f.seek(self._docket.index_end, os.SEEK_SET) return f except IOError as inst: if inst.errno != errno.ENOENT: @@ -2022,6 +2044,8 @@ header = self.index.pack_header(header) e = header + e fp.write(e) + if self._docket is not None: + self._docket.index_end = fp.tell() # the temp file replace the real index when we exit the context # manager @@ -2440,7 +2464,10 @@ msg = b'adding revision outside `revlog._writing` context' raise error.ProgrammingError(msg) ifh, dfh = self._writinghandles - ifh.seek(0, os.SEEK_END) + if self._docket is None: + ifh.seek(0, os.SEEK_END) + else: + ifh.seek(self._docket.index_end, os.SEEK_SET) if dfh: dfh.seek(0, os.SEEK_END) @@ -2463,6 +2490,9 @@ if sidedata: ifh.write(sidedata) self._enforceinlinesize(transaction) + if self._docket is not None: + self._docket.index_end = self._writinghandles[0].tell() + nodemaputil.setup_persistent_nodemap(transaction, self) def addgroup( @@ -2632,6 +2662,11 @@ end += rev * self.index.entry_size transaction.add(self._indexfile, end) + if self._docket is not None: + # XXX we could, leverage the docket while stripping. However it is + # not powerfull enough at the time of this comment + self._docket.index_end = end + self._docket.write(transaction, stripping=True) # then reset internal state in memory to forget those revisions self._revisioncache = None
--- a/mercurial/revlogutils/docket.py Mon May 03 12:34:41 2021 +0200 +++ b/mercurial/revlogutils/docket.py Mon May 03 12:34:52 2021 +0200 @@ -28,36 +28,55 @@ # * 4 bytes: revlog version # | This is mandatory as docket must be compatible with the previous # | revlog index header. -S_HEADER = struct.Struct(constants.INDEX_HEADER.format) +# * 8 bytes: size of index data +S_HEADER = struct.Struct(constants.INDEX_HEADER.format + 'L') class RevlogDocket(object): """metadata associated with revlog""" - def __init__(self, revlog, version_header=None): + def __init__(self, revlog, version_header=None, index_end=0): self._version_header = version_header self._dirty = False self._radix = revlog.radix self._path = revlog._docket_file self._opener = revlog.opener + self._index_end = index_end def index_filepath(self): """file path to the current index file associated to this docket""" # very simplistic version at first return b"%s.idx" % self._radix - def write(self, transaction): + @property + def index_end(self): + return self._index_end + + @index_end.setter + def index_end(self, new_size): + if new_size != self._index_end: + self._index_end = new_size + self._dirty = True + + def write(self, transaction, stripping=False): """write the modification of disk if any This make the new content visible to all process""" if self._dirty: - transaction.addbackup(self._path, location=b'store') + if not stripping: + # XXX we could, leverage the docket while stripping. However it + # is not powerfull enough at the time of this comment + transaction.addbackup(self._path, location=b'store') with self._opener(self._path, mode=b'w', atomictemp=True) as f: f.write(self._serialize()) self._dirty = False def _serialize(self): - return S_HEADER.pack(self._version_header) + data = ( + self._version_header, + self._index_end, + ) + return S_HEADER.pack(*data) def default_docket(revlog, version_header): @@ -72,9 +91,10 @@ def parse_docket(revlog, data): """given some docket data return a docket object for the given revlog""" header = S_HEADER.unpack(data[: S_HEADER.size]) - (version_header,) = header + version_header, index_size = header docket = RevlogDocket( revlog, version_header=version_header, + index_end=index_size, ) return docket