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Differential D4572

localrepo: document and test bug around opening shared repos
ClosedPublic

Authored by indygreg on Sep 13 2018, 12:29 PM.

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rHG9de1a1c83cd7: localrepo: document and test bug around opening shared repos
Summary

As part of refactoring this code, I realized that we don't
validate the requirements of a shared repository. This commit
documents that next to the requirements validation code and adds a
test demonstrating the buggy behavior.

I'm not sure if I'll fix this. But it is definitely a bug that
users could encounter, as LFS, narrow, and potentially other
extensions dynamically add requirements on first use. One part
of this I'm not sure about is how to handle loading the .hg/hgrc
of the shared repo. We need to do that in order to load extensions.
But we don't want that repo's hgrc to overwrite the current repo's.

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rHG Mercurial
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Event Timeline

indygreg created this revision.Sep 13 2018, 12:29 PM
martinvonz added a subscriber: martinvonz.Sep 13 2018, 12:50 PM

FIWI, I don't think I would expect the .hg/hgrc of the source repo to be loaded. I don't think I'd be surprised if I configured an extension in the source repo and had to configure that in the share as well for it to work.

Closed by commit rHG9de1a1c83cd7: localrepo: document and test bug around opening shared repos (authored by indygreg). · Explain WhySep 18 2018, 6:00 PM
This revision was automatically updated to reflect the committed changes.

Revision Contents
Changeset List

PathPackages
Mmercurial/localrepo.py (13 lines)
Mtests/test-share.t (23 lines)

Diff 11170

mercurial/localrepo.py

supportedrequirements = gathersupportedrequirements(ui) supportedrequirements = gathersupportedrequirements(ui)
# We first validate the requirements are known. # We first validate the requirements are known.
ensurerequirementsrecognized(requirements, supportedrequirements) ensurerequirementsrecognized(requirements, supportedrequirements)
# Then we validate that the known set is reasonable to use together. # Then we validate that the known set is reasonable to use together.
ensurerequirementscompatible(ui, requirements) ensurerequirementscompatible(ui, requirements)
# TODO there are unhandled edge cases related to opening repositories with
# shared storage. If storage is shared, we should also test for requirements
# compatibility in the pointed-to repo. This entails loading the .hg/hgrc in
# that repo, as that repo may load extensions needed to open it. This is a
# bit complicated because we don't want the other hgrc to overwrite settings
# in this hgrc.
#
# This bug is somewhat mitigated by the fact that we copy the .hg/requires
# file when sharing repos. But if a requirement is added after the share is
# performed, thereby introducing a new requirement for the opener, we may
# will not see that and could encounter a run-time error interacting with
# that shared store since it has an unknown-to-us requirement.
# At this point, we know we should be capable of opening the repository. # At this point, we know we should be capable of opening the repository.
# Now get on with doing that. # Now get on with doing that.
return localrepository( return localrepository(
baseui=baseui, baseui=baseui,
ui=ui, ui=ui,
origroot=path, origroot=path,
wdirvfs=wdirvfs, wdirvfs=wdirvfs,

tests/test-share.t

[1] [1]
$ hg unshare $ hg unshare
abort: this is not a shared repo abort: this is not a shared repo
[255] [255]
$ cd ../.. $ cd ../..
$ rm -r thatdir $ rm -r thatdir
Demonstrate buggy behavior around requirements validation
See comment in localrepo.py:makelocalrepository() for more.
$ hg init sharenewrequires
$ hg share sharenewrequires shareoldrequires
updating working directory
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cat >> sharenewrequires/.hg/requires << EOF
> missing-requirement
> EOF
We cannot open the repo with the unknown requirement
$ hg -R sharenewrequires status
abort: repository requires features unknown to this Mercurial: missing-requirement!
(see https://mercurial-scm.org/wiki/MissingRequirement for more information)
[255]
BUG: we don't get the same error when opening the shared repo pointing to it
$ hg -R shareoldrequires status
Explicitly kill daemons to let the test exit on Windows Explicitly kill daemons to let the test exit on Windows
$ killdaemons.py $ killdaemons.py