Mercurial > hg
view tests/test-pull-pull-corruption.t @ 20742:3681de20b0a7
parsers: fail fast if Python has wrong minor version (issue4110)
This change causes an informative ImportError to be raised when importing
the parsers extension module if the minor version of the currently-running
Python interpreter doesn't match that of the Python used when compiling
the extension module.
This change also exposes a parsers.versionerrortext constant in the
C implementation of the module. Its presence can be used to determine
whether this behavior is present in a version of the module. The value
of the constant is the leading text of the ImportError raised and is set
to "Python minor version mismatch".
Here is an example of what the new error looks like:
Traceback (most recent call last):
File "test.py", line 1, in <module>
import mercurial.parsers
ImportError: Python minor version mismatch: The Mercurial extension
modules were compiled with Python 2.7.6, but Mercurial is currently using
Python with sys.hexversion=33883888: Python 2.5.6
(r256:88840, Nov 18 2012, 05:37:10)
[GCC 4.2.1 Compatible Apple Clang 4.1 ((tags/Apple/clang-421.11.66))]
at: /opt/local/Library/Frameworks/Python.framework/Versions/2.5/Resources/
Python.app/Contents/MacOS/Python
The reason for raising an error in this scenario is that Python's C API
is known not to be compatible from minor version to minor version, even
if sys.api_version is the same. See for example this Python bug report
about incompatibilities between 2.5 and 2.6+:
http://bugs.python.org/issue8118
These incompatibilities can cause Mercurial to break in mysterious,
unforeseen ways. For example, when Mercurial compiled with Python 2.7 was
run with 2.5, the following crash occurred when running "hg status":
http://bz.selenic.com/show_bug.cgi?id=4110
After this crash was fixed, running with Python 2.5 no longer crashes, but
the following puzzling behavior still occurs:
$ hg status
...
File ".../mercurial/changelog.py", line 123, in __init__
revlog.revlog.__init__(self, opener, "00changelog.i")
File ".../mercurial/revlog.py", line 251, in __init__
d = self._io.parseindex(i, self._inline)
File ".../mercurial/revlog.py", line 158, in parseindex
index, cache = parsers.parse_index2(data, inline)
TypeError: data is not a string
which can be reproduced more simply with:
import mercurial.parsers as parsers
parsers.parse_index2("", True)
Both the crash and the TypeError occurred because the Python C API's
PyString_Check() returns the wrong value when the C header files from
Python 2.7 are run with Python 2.5. This is an example of an
incompatibility of the sort mentioned in the Python bug report above.
Failing fast with an informative error message results in a better user
experience in cases like the above. The information in the ImportError
also simplifies troubleshooting for those on Mercurial mailing lists, the
bug tracker, etc.
This patch only adds the version check to parsers.c, which is sufficient
to affect command-line commands like "hg status" and "hg summary".
An idea for a future improvement is to move the version-checking C code
to a more central location, and have it run when importing all
Mercurial extension modules and not just parsers.c.
author | Chris Jerdonek <chris.jerdonek@gmail.com> |
---|---|
date | Wed, 04 Dec 2013 20:38:27 -0800 |
parents | f2719b387380 |
children | eb586ed5d8ce |
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Corrupt an hg repo with two pulls. create one repo with a long history $ hg init source1 $ cd source1 $ touch foo $ hg add foo $ for i in 1 2 3 4 5 6 7 8 9 10; do > echo $i >> foo > hg ci -m $i > done $ cd .. create one repo with a shorter history $ hg clone -r 0 source1 source2 adding changesets adding manifests adding file changes added 1 changesets with 1 changes to 1 files updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ cd source2 $ echo a >> foo $ hg ci -m a $ cd .. create a third repo to pull both other repos into it $ hg init corrupted $ cd corrupted use a hook to make the second pull start while the first one is still running $ echo '[hooks]' >> .hg/hgrc $ echo 'prechangegroup = sleep 5' >> .hg/hgrc start a pull... $ hg pull ../source1 > pull.out 2>&1 & ... and start another pull before the first one has finished $ sleep 1 $ hg pull ../source2 2>/dev/null pulling from ../source2 searching for changes adding changesets adding manifests adding file changes added 1 changesets with 1 changes to 1 files (+1 heads) (run 'hg heads' to see heads, 'hg merge' to merge) $ cat pull.out pulling from ../source1 requesting all changes adding changesets adding manifests adding file changes added 10 changesets with 10 changes to 1 files (run 'hg update' to get a working copy) see the result $ wait $ hg verify checking changesets checking manifests crosschecking files in changesets and manifests checking files 1 files, 11 changesets, 11 total revisions $ cd ..