Mercurial > hg
view tests/test-empty-file.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 | f2719b387380 |
children |
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$ hg init a $ cd a $ touch empty1 $ hg add empty1 $ hg commit -m 'add empty1' $ touch empty2 $ hg add empty2 $ hg commit -m 'add empty2' $ hg up -C 0 0 files updated, 0 files merged, 1 files removed, 0 files unresolved $ touch empty3 $ hg add empty3 $ hg commit -m 'add empty3' created new head $ hg heads changeset: 2:a1cb177e0d44 tag: tip parent: 0:1e1d9c4e5b64 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: add empty3 changeset: 1:097d2b0e17f6 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: add empty2 $ hg merge 1 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) Before changeset 05257fd28591, we didn't notice the empty file that came from rev 1: $ hg status M empty2 $ hg commit -m merge $ hg manifest --debug tip b80de5d138758541c5f05265ad144ab9fa86d1db 644 empty1 b80de5d138758541c5f05265ad144ab9fa86d1db 644 empty2 b80de5d138758541c5f05265ad144ab9fa86d1db 644 empty3 $ cd ..