extensions: refuse to load extensions if minimum hg version not met
As the author of several 3rd party extensions, I frequently see bug
reports from users attempting to run my extension with an old version
of Mercurial that I no longer support in my extension. Oftentimes, the
extension will import just fine. But as soon as we run extsetup(),
reposetup(), or get into the guts of a wrapped function, we encounter
an exception and abort. Today, Mercurial will print a message about
extensions that don't have a "testedwith" declaring explicit
compatibility with the current version.
The existing mechanism is a good start. But it isn't as robust as I
would like. Specifically, Mercurial assumes compatibility by default.
This means extension authors must perform compatibility checking in
their extsetup() or we wait and see if we encounter an abort at
runtime. And, compatibility checking can involve a lot of code and
lots of error checking. It's a lot of effort for extension authors.
Oftentimes, extension authors know which versions of Mercurial there
extension works on and more importantly where it is broken.
This patch introduces a magic "minimumhgversion" attribute in
extensions. When found, the extension loading mechanism will compare
the declared version against the current Mercurial version. If the
extension explicitly states we require a newer Mercurial version, a
warning is printed and the extension isn't loaded beyond importing
the Python module. This causes a graceful failure while alerting
the user of the compatibility issue.
I would be receptive to the idea of making the failure more fatal.
However, care would need to be taken to not criple every hg command.
e.g. the user may use `hg config` to fix the hgrc and if we aborted
trying to run that, the user would effectively be locked out of `hg`!
A potential future improvement to this functionality would be to catch
ImportError for the extension/module and parse the source code for
"minimumhgversion = 'XXX'" and do similar checking. This way we could
give more information about why the extension failed to load.
prepare repo
$ hg init a
$ cd a
$ echo "some text" > FOO.txt
$ echo "another text" > bar.txt
$ echo "more text" > QUICK.txt
$ hg add
adding FOO.txt
adding QUICK.txt
adding bar.txt
$ hg ci -mtest1
verify
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
3 files, 1 changesets, 3 total revisions
verify with journal
$ touch .hg/store/journal
$ hg verify
abandoned transaction found - run hg recover
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
3 files, 1 changesets, 3 total revisions
$ rm .hg/store/journal
introduce some bugs in repo
$ cd .hg/store/data
$ mv _f_o_o.txt.i X_f_o_o.txt.i
$ mv bar.txt.i xbar.txt.i
$ rm _q_u_i_c_k.txt.i
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
warning: revlog 'data/FOO.txt.i' not in fncache!
0: empty or missing FOO.txt
FOO.txt@0: f62022d3d590 in manifests not found
warning: revlog 'data/QUICK.txt.i' not in fncache!
0: empty or missing QUICK.txt
QUICK.txt@0: 88b857db8eba in manifests not found
warning: revlog 'data/bar.txt.i' not in fncache!
0: empty or missing bar.txt
bar.txt@0: 256559129457 in manifests not found
3 files, 1 changesets, 0 total revisions
3 warnings encountered!
hint: run "hg debugrebuildfncache" to recover from corrupt fncache
6 integrity errors encountered!
(first damaged changeset appears to be 0)
[1]
$ cd ../../..
$ cd ..
test changelog without a manifest
$ hg init b
$ cd b
$ hg branch foo
marked working directory as branch foo
(branches are permanent and global, did you want a bookmark?)
$ hg ci -m branchfoo
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
0 files, 1 changesets, 0 total revisions
test revlog corruption
$ touch a
$ hg add a
$ hg ci -m a
$ echo 'corrupted' > b
$ dd if=.hg/store/data/a.i of=start bs=1 count=20 2>/dev/null
$ cat start b > .hg/store/data/a.i
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
a@1: broken revlog! (index data/a.i is corrupted)
warning: orphan revlog 'data/a.i'
1 files, 2 changesets, 0 total revisions
1 warnings encountered!
1 integrity errors encountered!
(first damaged changeset appears to be 1)
[1]
$ cd ..
test revlog format 0
$ revlog-formatv0.py
$ cd formatv0
$ hg verify
repository uses revlog format 0
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 1 changesets, 1 total revisions
$ cd ..