Mercurial > hg
view tests/testlib/ext-sidedata.py @ 48507:58a3be48ddd2
simplemerge: stop merging file flags
As 384df4db6520 (merge: merge file flags together with file content,
2013-01-09) explains, we shouldn't do a 3-way merge of the
symlink. However, since 84614212ae39 (flags: actually merge flags in
simplemerge, 2020-05-16), we do that in
`simplemerge.simplemerge()`. What's more, the merging of the
executable flag there isn't actually necessary; it was made a no-op by
the very next commit, i.e. 4234c9af515d (flags: read flag from
dirstate/disk for workingcopyctx (issue5743), 2020-05-16).
I found the overall flag-merging code (not the bit in
`simplemerge.py`) very hard to follow, but I think I now finally
understand how it works. `mergestate.resolve()` calculates the merged
file flags and sets them on the local side of the merge (confusingly
by calling `_restore_backup()`). Then it calls
`filemerge.filemerge()`, which in turn calls
`simplemerge.simplemerge()` (if premerge is enabled). That means that
the flags on the local side `fcs.flags()` are already correct when the
flag-merging code in `simplemerge.simplemerge()` runs. Interestingly,
that code still works when the local side already has the merged
value, it just doesn't change the value. Here's a truth table to
explain why:
```
BLOMCAR
0000000
0011111
0101011
0111111
1000000
1010000
1100000
1111101
```
B: Base
L: Local
O: Other
M: Merged flags from `mergestate.resolve()`, i.e. what's called "local"
when we get to `simplemerge.simplemerge()`
C: `commonflags` in `simplemerge.simplemerge()`, i.e. `M & O`
A: `addedflags` in `simplemerge.simplemerge()`, i.e. `(M ^ O) - B`
R: Re-merged flags `simplemerge.simplemerge()`, i.e. `C | A`
As you can see, the re-merged flags are always unchanged compared to
the initial merged flags (R equals M).
Therefore, this patch effectively backs out 84614212ae39. (I might
later refactor this code to have the flags explicitly passed in.)
`simplemerge.simplemerge()` is also called from
`contrib/simplemerge.py`, but that code never passes any flags.
Differential Revision: https://phab.mercurial-scm.org/D11879
author | Martin von Zweigbergk <martinvonz@google.com> |
---|---|
date | Mon, 06 Dec 2021 23:17:43 -0800 |
parents | 9d9eb22b9b69 |
children | 6000f5b25c9b |
line wrap: on
line source
# ext-sidedata.py - small extension to test the sidedata logic # # Copyright 2019 Pierre-Yves David <pierre-yves.david@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.node import nullrev from mercurial import ( extensions, requirements, revlog, ) from mercurial.upgrade_utils import engine as upgrade_engine from mercurial.revlogutils import constants from mercurial.revlogutils import sidedata def wrapaddrevision( orig, self, text, transaction, link, p1, p2, *args, **kwargs ): if kwargs.get('sidedata') is None: kwargs['sidedata'] = {} sd = kwargs['sidedata'] ## let's store some arbitrary data just for testing # text length sd[sidedata.SD_TEST1] = struct.pack('>I', len(text)) # and sha2 hashes sha256 = hashlib.sha256(text).digest() sd[sidedata.SD_TEST2] = struct.pack('>32s', sha256) return orig(self, text, transaction, link, p1, p2, *args, **kwargs) def wrap_revisiondata(orig, self, nodeorrev, *args, **kwargs): text = orig(self, nodeorrev, *args, **kwargs) sd = self.sidedata(nodeorrev) if getattr(self, 'sidedatanocheck', False): return text if self.hassidedata: return text if nodeorrev != nullrev and nodeorrev != self.nullid: cat1 = sd.get(sidedata.SD_TEST1) if cat1 is not None and len(text) != struct.unpack('>I', cat1)[0]: raise RuntimeError('text size mismatch') expected = sd.get(sidedata.SD_TEST2) got = hashlib.sha256(text).digest() if expected is not None and got != expected: raise RuntimeError('sha256 mismatch') return text def wrapget_sidedata_helpers(orig, srcrepo, dstrepo): repo, computers, removers = orig(srcrepo, dstrepo) assert not computers and not removers # deal with composition later addedreqs = dstrepo.requirements - srcrepo.requirements if requirements.REVLOGV2_REQUIREMENT in addedreqs: def computer(repo, revlog, rev, old_sidedata): assert not old_sidedata # not supported yet update = {} revlog.sidedatanocheck = True try: text = revlog.revision(rev) finally: del revlog.sidedatanocheck ## let's store some arbitrary data just for testing # text length update[sidedata.SD_TEST1] = struct.pack('>I', len(text)) # and sha2 hashes sha256 = hashlib.sha256(text).digest() update[sidedata.SD_TEST2] = struct.pack('>32s', sha256) return update, (0, 0) srcrepo.register_sidedata_computer( constants.KIND_CHANGELOG, b"whatever", (sidedata.SD_TEST1, sidedata.SD_TEST2), computer, 0, ) dstrepo.register_wanted_sidedata(b"whatever") return sidedata.get_sidedata_helpers(srcrepo, dstrepo._wanted_sidedata) def extsetup(ui): extensions.wrapfunction(revlog.revlog, 'addrevision', wrapaddrevision) extensions.wrapfunction(revlog.revlog, '_revisiondata', wrap_revisiondata) extensions.wrapfunction( upgrade_engine, 'get_sidedata_helpers', wrapget_sidedata_helpers ) def reposetup(ui, repo): # We don't register sidedata computers because we don't care within these # tests repo.register_wanted_sidedata(sidedata.SD_TEST1) repo.register_wanted_sidedata(sidedata.SD_TEST2)