mercurial/node.py

narrow: add server logic to send cg while widening without ellipsis

Before this patch, if you try to widen a narrow clone without ellipsis enabled,
it will be broken and the exchange.pull() done by tracked command to widen the
clone will be no-op because no custom logic exists for this and server sees that
we have all csets and it says `no changes found`.

The widening with ellipsis send KILL for existing changegroups and send new
changegroups because of the change in ellipsis hash, but we can prevent that in
non-ellipsis cases.

This patch adds server side logic to send the changegroups for the changesets
which are on the client again with filelogs and manifests for the new includes.
This is a very starting implementation and we send changegroups and manifests
too while we can prevent them.

Following things can definitely be improved in the logic this patch adds:

  1) Send just the filelogs and treemanifests
  2) Send the filelogs only for the additions in the include

I tried 1) here but the code is coupled tightly and the way I was able to do
that was hacking into the changegroup generation code in a very dirty way, like
adding conditionals and preventing the yield.

This patch also adds a 'widen' kwarg to prevent other commands except widening
to go through that codepath.

The test changes demonstrate that the new implementation is correct and fixes
things.

Differential Revision: https://phab.mercurial-scm.org/D4383

# node.py - basic nodeid manipulation for mercurial
#
# Copyright 2005, 2006 Matt Mackall <[e-mail]>
#
# 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

import binascii

# This ugly style has a noticeable effect in manifest parsing
hex = binascii.hexlify
# Adapt to Python 3 API changes. If this ends up showing up in
# profiles, we can use this version only on Python 3, and forward
# binascii.unhexlify like we used to on Python 2.
def bin(s):
    try:
        return binascii.unhexlify(s)
    except binascii.Error as e:
        raise TypeError(e)

nullrev = -1
# In hex, this is '0000000000000000000000000000000000000000'
nullid = b"\0" * 20
nullhex = hex(nullid)

# Phony node value to stand-in for new files in some uses of
# manifests.
# In hex, this is '2121212121212121212121212121212121212121'
newnodeid = '!!!!!!!!!!!!!!!!!!!!'
# In hex, this is '3030303030303030303030303030306164646564'
addednodeid = '000000000000000added'
# In hex, this is '3030303030303030303030306d6f646966696564'
modifiednodeid = '000000000000modified'

wdirfilenodeids = {newnodeid, addednodeid, modifiednodeid}

# pseudo identifiers for working directory
# (they are experimental, so don't add too many dependencies on them)
wdirrev = 0x7fffffff
# In hex, this is 'ffffffffffffffffffffffffffffffffffffffff'
wdirid = b"\xff" * 20
wdirhex = hex(wdirid)

def short(node):
    return hex(node[:6])