Mercurial > hg
view tests/test-patch-offset.t @ 27430:e240e914d226 stable
revlog: seek to end of file before writing (issue4943)
Revlogs were recently refactored to open file handles in "a+" and use a
persistent file handle for reading and writing. This drastically
reduced the number of file handles being opened.
Unfortunately, it appears that some versions of Solaris lose the file
offset when performing a write after the handle has been seeked.
The simplest workaround is to seek to EOF on files opened in a+ mode
before writing to them, which is what this patch does.
Ideally, this code would exist in the vfs layer. However, this would
require creating a proxy class for file objects in order to provide a
custom implementation of write(). This would add overhead. Since
revlogs are the only files we open in a+ mode, the one-off workaround
in revlog.py should be sufficient.
This patch appears to have little to no impact on performance on my
Linux machine.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Thu, 17 Dec 2015 17:16:02 -0800 |
parents | a387b0390082 |
children | 75be14993fda |
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$ cat > writepatterns.py <<EOF > import sys > > path = sys.argv[1] > patterns = sys.argv[2:] > > fp = file(path, 'wb') > for pattern in patterns: > count = int(pattern[0:-1]) > char = pattern[-1] + '\n' > fp.write(char*count) > fp.close() > EOF prepare repo $ hg init a $ cd a These initial lines of Xs were not in the original file used to generate the patch. So all the patch hunks need to be applied to a constant offset within this file. If the offset isn't tracked then the hunks can be applied to the wrong lines of this file. $ python ../writepatterns.py a 34X 10A 1B 10A 1C 10A 1B 10A 1D 10A 1B 10A 1E 10A 1B 10A $ hg commit -Am adda adding a This is a cleaner patch generated via diff In this case it reproduces the problem when the output of hg export does not import patch $ hg import -v -m 'b' -d '2 0' - <<EOF > --- a/a 2009-12-08 19:26:17.000000000 -0800 > +++ b/a 2009-12-08 19:26:17.000000000 -0800 > @@ -9,7 +9,7 @@ > A > A > B > -A > +a > A > A > A > @@ -53,7 +53,7 @@ > A > A > B > -A > +a > A > A > A > @@ -75,7 +75,7 @@ > A > A > B > -A > +a > A > A > A > EOF applying patch from stdin patching file a Hunk #1 succeeded at 43 (offset 34 lines). Hunk #2 succeeded at 87 (offset 34 lines). Hunk #3 succeeded at 109 (offset 34 lines). committing files: a committing manifest committing changelog created 189885cecb41 compare imported changes against reference file $ python ../writepatterns.py aref 34X 10A 1B 1a 9A 1C 10A 1B 10A 1D 10A 1B 1a 9A 1E 10A 1B 1a 9A $ diff aref a $ cd ..