comparison mercurial/revlog.py @ 27070:7860366b46c9

revlog: improve documentation

There are a lot of functions and variables doing similar things.
Document the role and functionality of each to make it easier to
grok.

27069:4e554a7df1e9

        and can be used to implement COW semantics or the like.
        """
        self.indexfile = indexfile
        self.datafile = indexfile[:-2] + ".d"
        self.opener = opener
        self._cache = None
        self._basecache = None
        self._chunkcache = (0, '')
        self._chunkcachesize = 65536
        self._maxchainlen = None
        self._aggressivemergedeltas = False
        self.index = []
        self._pcache = {}
        self._nodecache = {nullid: nullrev}
        self._nodepos = None

        v = REVLOG_DEFAULT_VERSION
        opts = getattr(opener, 'options', None)

        """
        p1, p2 = self.parents(node)
        return hash(text, p1, p2) != node

    def _addchunk(self, offset, data):
        o, d = self._chunkcache
        # try to add to existing cache
        if o + len(d) == offset and len(d) + len(data) < _chunksize:
            self._chunkcache = o, d + data
        else:
            self._chunkcache = offset, data

    def _loadchunk(self, offset, length, df=None):
        """Load a chunk/segment from the revlog.

        Accepts absolute offset, length to read, and an optional existing
        file handle to read from.

        If an existing file handle is passed, it will be seeked and the
        original seek position will NOT be restored.
        """
        if df is not None:
            closehandle = False
        else:
            if self._inline:

        if offset != realoffset or reallength != length:
            return util.buffer(d, offset - realoffset, length)
        return d

    def _getchunk(self, offset, length, df=None):
        o, d = self._chunkcache
        l = len(d)

        # is it in the cache?
        cachestart = offset - o

            return util.buffer(d, cachestart, cacheend - cachestart)

        return self._loadchunk(offset, length, df=df)

    def _chunkraw(self, startrev, endrev, df=None):
        start = self.start(startrev)
        end = self.end(endrev)
        if self._inline:
            start += (startrev + 1) * self._io.size
            end += (endrev + 1) * self._io.size
        length = end - start
        return self._getchunk(start, length, df=df)

    def _chunk(self, rev, df=None):
        return decompress(self._chunkraw(rev, rev, df=df))

    def _chunks(self, revs, df=None):
        '''faster version of [self._chunk(rev) for rev in revs]

        Assumes that revs is in ascending order.'''
        if not revs:
            return []
        start = self.start
        length = self.length
        inline = self._inline

            ladd(decompress(buffer(data, chunkstart - offset, chunklength)))

        return l

    def _chunkclear(self):
        self._chunkcache = (0, '')

    def deltaparent(self, rev):
        """return deltaparent of the given revision"""
        base = self.index[rev][3]

27070:7860366b46c9

        and can be used to implement COW semantics or the like.
        """
        self.indexfile = indexfile
        self.datafile = indexfile[:-2] + ".d"
        self.opener = opener
        # 3-tuple of (node, rev, text) for a raw revision.
        self._cache = None
        # 2-tuple of (rev, baserev) defining the base revision the delta chain
        # begins at for a revision.
        self._basecache = None
        # 2-tuple of (offset, data) of raw data from the revlog at an offset.
        self._chunkcache = (0, '')
        # How much data to read and cache into the raw revlog data cache.
        self._chunkcachesize = 65536
        self._maxchainlen = None
        self._aggressivemergedeltas = False
        self.index = []
        # Mapping of partial identifiers to full nodes.
        self._pcache = {}
        # Mapping of revision integer to full node.
        self._nodecache = {nullid: nullrev}
        self._nodepos = None

        v = REVLOG_DEFAULT_VERSION
        opts = getattr(opener, 'options', None)

        """
        p1, p2 = self.parents(node)
        return hash(text, p1, p2) != node

    def _addchunk(self, offset, data):
        """Add a segment to the revlog cache.

        Accepts an absolute offset and the data that is at that location.
        """
        o, d = self._chunkcache
        # try to add to existing cache
        if o + len(d) == offset and len(d) + len(data) < _chunksize:
            self._chunkcache = o, d + data
        else:
            self._chunkcache = offset, data

    def _loadchunk(self, offset, length, df=None):
        """Load a segment of raw data from the revlog.

        Accepts an absolute offset, length to read, and an optional existing
        file handle to read from.

        If an existing file handle is passed, it will be seeked and the
        original seek position will NOT be restored.

        Returns a str or buffer of raw byte data.
        """
        if df is not None:
            closehandle = False
        else:
            if self._inline:

        if offset != realoffset or reallength != length:
            return util.buffer(d, offset - realoffset, length)
        return d

    def _getchunk(self, offset, length, df=None):
        """Obtain a segment of raw data from the revlog.

        Accepts an absolute offset, length of bytes to obtain, and an
        optional file handle to the already-opened revlog. If the file
        handle is used, it's original seek position will not be preserved.

        Requests for data may be returned from a cache.

        Returns a str or a buffer instance of raw byte data.
        """
        o, d = self._chunkcache
        l = len(d)

        # is it in the cache?
        cachestart = offset - o

            return util.buffer(d, cachestart, cacheend - cachestart)

        return self._loadchunk(offset, length, df=df)

    def _chunkraw(self, startrev, endrev, df=None):
        """Obtain a segment of raw data corresponding to a range of revisions.

        Accepts the start and end revisions and an optional already-open
        file handle to be used for reading. If the file handle is read, its
        seek position will not be preserved.

        Requests for data may be satisfied by a cache.

        Returns a str or a buffer instance of raw byte data. Callers will
        need to call ``self.start(rev)`` and ``self.length()`` to determine
        where each revision's data begins and ends.
        """
        start = self.start(startrev)
        end = self.end(endrev)
        if self._inline:
            start += (startrev + 1) * self._io.size
            end += (endrev + 1) * self._io.size
        length = end - start
        return self._getchunk(start, length, df=df)

    def _chunk(self, rev, df=None):
        """Obtain a single decompressed chunk for a revision.

        Accepts an integer revision and an optional already-open file handle
        to be used for reading. If used, the seek position of the file will not
        be preserved.

        Returns a str holding uncompressed data for the requested revision.
        """
        return decompress(self._chunkraw(rev, rev, df=df))

    def _chunks(self, revs, df=None):
        """Obtain decompressed chunks for the specified revisions.

        Accepts an iterable of numeric revisions that are assumed to be in
        ascending order. Also accepts an optional already-open file handle
        to be used for reading. If used, the seek position of the file will
        not be preserved.

        This function is similar to calling ``self._chunk()`` multiple times,
        but is faster.

        Returns a list with decompressed data for each requested revision.
        """
        if not revs:
            return []
        start = self.start
        length = self.length
        inline = self._inline

            ladd(decompress(buffer(data, chunkstart - offset, chunklength)))

        return l

    def _chunkclear(self):
        """Clear the raw chunk cache."""
        self._chunkcache = (0, '')

    def deltaparent(self, rev):
        """return deltaparent of the given revision"""
        base = self.index[rev][3]