sidedata-exchange: rewrite sidedata on-the-fly whenever possible
When a A exchanges with B, the difference of their supported sidedata categories
is made, and the responsibility is always with the client to generated it:
- If A pushes to B and B requires category `foo` that A does not have, A
will need to generate it when sending it to B.
- If A pulls from B and A needs category `foo`, it will generate `foo`
before the end of the transaction.
- Any category that is not required is removed. If peers are not compatible,
abort.
It is forbidden to rewrite sidedata for a rev that already has sidedata, since
that would introduce unreachable (garbage) data in the data file, something
we're not prepared for yet.
Differential Revision: https://phab.mercurial-scm.org/D10032
# coding: utf8
# ext-sidedata-3.py - small extension to test (differently still) the sidedata
# logic
#
# Simulates a client for a complex sidedata exchange.
#
# Copyright 2021 Raphaël Gomès <rgomes@octobus.net>
#
# 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 hashlib
import struct
from mercurial import (
extensions,
revlog,
)
from mercurial.revlogutils import sidedata as sidedatamod
def compute_sidedata_1(repo, revlog, rev, sidedata, text=None):
sidedata = sidedata.copy()
if text is None:
text = revlog.revision(rev)
sidedata[sidedatamod.SD_TEST1] = struct.pack('>I', len(text))
return sidedata
def compute_sidedata_2(repo, revlog, rev, sidedata, text=None):
sidedata = sidedata.copy()
if text is None:
text = revlog.revision(rev)
sha256 = hashlib.sha256(text).digest()
sidedata[sidedatamod.SD_TEST2] = struct.pack('>32s', sha256)
return sidedata
def compute_sidedata_3(repo, revlog, rev, sidedata, text=None):
sidedata = sidedata.copy()
if text is None:
text = revlog.revision(rev)
sha384 = hashlib.sha384(text).digest()
sidedata[sidedatamod.SD_TEST3] = struct.pack('>48s', sha384)
return sidedata
def wrapaddrevision(
orig, self, text, transaction, link, p1, p2, *args, **kwargs
):
if kwargs.get('sidedata') is None:
kwargs['sidedata'] = {}
sd = kwargs['sidedata']
sd = compute_sidedata_1(None, self, None, sd, text=text)
kwargs['sidedata'] = compute_sidedata_2(None, self, None, sd, text=text)
return orig(self, text, transaction, link, p1, p2, *args, **kwargs)
def extsetup(ui):
extensions.wrapfunction(revlog.revlog, 'addrevision', wrapaddrevision)
def reposetup(ui, repo):
# Sidedata keys happen to be the same as the categories, easier for testing.
for kind in (b'changelog', b'manifest', b'filelog'):
repo.register_sidedata_computer(
kind,
sidedatamod.SD_TEST1,
(sidedatamod.SD_TEST1,),
compute_sidedata_1,
)
repo.register_sidedata_computer(
kind,
sidedatamod.SD_TEST2,
(sidedatamod.SD_TEST2,),
compute_sidedata_2,
)
repo.register_sidedata_computer(
kind,
sidedatamod.SD_TEST3,
(sidedatamod.SD_TEST3,),
compute_sidedata_3,
)
repo.register_wanted_sidedata(sidedatamod.SD_TEST1)
repo.register_wanted_sidedata(sidedatamod.SD_TEST2)