We can use 32 bytes, but only 20 bytes will be used.
What’s the point then?
On 11/9/16, 5:22 PM, "Augie Fackler" <r...@durin42.com> wrote:
On Wed, Nov 02, 2016 at 07:06:44AM -0700, Stanislau Hlebik wrote:
> # HG changeset patch
> # User Stanislau Hlebik <st...@fb.com>
> # Date 1478016027 25200
> # Tue Nov 01 09:00:27 2016 -0700
> # Branch stable
> # Node ID f3da841e3d47ccbb0be3892b521607c09fdeab13
> # Parent a56a624a8a42b93ec980d2c284756a38719dffe6
> bookmarks: introduce binary encoding
>
> Bookmarks binary encoding will be used for `bookmarks` bundle2 part.
> The format is: <4 bytes - bookmark size, big-endian><bookmark>
> <1 byte - 0 if node is empty 1 otherwise><20 bytes node>
Enough other formats have 32 bytes of space for nodes (eg revlog) that
I suspect we should do 32 bytes here too. Thoughts?
> BookmarksEncodeError and BookmarksDecodeError maybe thrown if input is
> incorrect.
>
> diff --git a/mercurial/bookmarks.py b/mercurial/bookmarks.py
> --- a/mercurial/bookmarks.py
> +++ b/mercurial/bookmarks.py
> @@ -7,8 +7,10 @@
>
> from __future__ import absolute_import
>
> +import StringIO
> import errno
> import os
> +import struct
>
> from .i18n import _
> from .node import (
> @@ -23,6 +25,70 @@
> util,
> )
>
> +_NONEMPTYNODE = struct.pack('?', False)
> +_EMPTYNODE = struct.pack('?', True)
> +
> +def _unpackbookmarksize(stream):
> + """Returns 0 if stream is empty.
> + """
> +
> + expectedsize = struct.calcsize('>i')
> + encodedbookmarksize = stream.read(expectedsize)
> + if len(encodedbookmarksize) == 0:
> + return 0
> + if len(encodedbookmarksize) != expectedsize:
> + raise ValueError(
> + _('cannot decode bookmark size: '
> + 'expected size: %d, actual size: %d') %
> + (expectedsize, len(encodedbookmarksize)))
> + return struct.unpack('>i', encodedbookmarksize)[0]
> +
> +def encodebookmarks(bookmarks):
> + """Encodes bookmark to node mapping to the byte string.
> +
> + Format: <4 bytes - bookmark size><bookmark>
> + <1 byte - 0 if node is empty 1 otherwise><20 bytes node>
> + Node may be 20 byte binary string, 40 byte hex string or empty
> + """
> +
> + for bookmark, node in bookmarks.iteritems():
> + yield struct.pack('>i', (len(bookmark)))
> + yield encoding.fromlocal(bookmark)
> + if node:
> + if len(node) != 20 and len(node) != 40:
> + raise ValueError(_('node must be 20 or bytes long'))
> + if len(node) == 40:
> + node = bin(node)
> + yield _NONEMPTYNODE
> + yield node
> + else:
> + yield _EMPTYNODE
> +
> +def decodebookmarks(buf):
> + """Decodes buffer into bookmark to node mapping.
> +
> + Node is either 20 bytes or empty.
> + """
> +
> + stream = StringIO.StringIO(buf)
> + bookmarks = {}
> + bookmarksize = _unpackbookmarksize(stream)
> + while bookmarksize:
> + bookmark = stream.read(bookmarksize)
> + if len(bookmark) != bookmarksize:
> + raise ValueError(
> + _('cannot decode bookmark: expected size: %d, '
> + 'actual size: %d') % (bookmarksize, len(bookmark)))
> + bookmark = encoding.tolocal(bookmark)
> + packedemptynodeflag = stream.read(struct.calcsize('?'))
> + emptynode = struct.unpack('?', packedemptynodeflag)[0]
> + node = ''
> + if not emptynode:
> + node = stream.read(20)
> + bookmarks[bookmark] = node
> + bookmarksize = _unpackbookmarksize(stream)
> + return bookmarks
> +
> def _getbkfile(repo):
> """Hook so that extensions that mess with the store can hook bm
storage.
>
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