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view tests/fixtures/branch_prop_edit.svndump @ 1233:0d0132cba155
editor: fix edge case with in memory file-store size limit
There are a few cases where we will set a single file into to the
editor's FileStore object more than once. Notably, for copied and
then modified files, we will set it at least twice. Three times if
editing fails (which it can for symlinks).
If we pass the in-memory storage limit in between the first (or second
if editing fails) time we set the file and the last time we set the
file, we will write the data to the in memory store the first time and
the file store the last time. We didn't remove it form the in-memory
store though, and we always prefer reading from the in-memory store.
This means we can sometimes end up with the wrong version of a file.
This is fairly unlikely to happen in normal use since you need to hit
the memory limit between two writes to the store for the same file.
We only write a file multiple times if a) the file (and not one of
it's parent directories) is copied and then modified or b) editing
fails. From what I can tell, it's only common for editing to fail for
symlinks, and they ten to be relatively small data that is unlikely to
push over the limit. Finally, the default limit is 100MB which I
would expect to be most often either well over (source code) or well
under (binaries or automated changes) the size of the changes files in
a single commit.
The easiest way to reproduce this is to set the in-memory cache size
to 0 and then commit a copied and modified symlink. The empty-string
version from the failed editing will be the one that persists. I
happened to stumble upon this while trying (and failing) to test a
bug-fix for a related bug with identical symptoms (empty simlink). I
have seen this in the wild, once, but couldn't reproduce it at the
time. The repo in question is quite large and quite active, so I am
quite confident in my estimation that this is a real, but very rare,
problem.
The test changes attached to this was mneant to test a related bug,
but turned out not to actually cover the bug in question. They did
trigger this bug though, and are worthwhile to test, so I kept them.
| author | David Schleimer <dschleimer@fb.com> |
|---|---|
| date | Mon, 07 Apr 2014 17:51:59 -0700 |
| parents | cf6fe8457570 |
| children |
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SVN-fs-dump-format-version: 2 UUID: ab14e60b-7e4b-473f-980a-26ace458a00f Revision-number: 0 Prop-content-length: 56 Content-length: 56 K 8 svn:date V 27 2008-12-12T00:18:13.309956Z PROPS-END Revision-number: 1 Prop-content-length: 114 Content-length: 114 K 7 svn:log V 14 branches trunk K 10 svn:author V 5 durin K 8 svn:date V 27 2008-12-12T00:18:14.083854Z PROPS-END Node-path: branches Node-kind: dir Node-action: add Prop-content-length: 10 Content-length: 10 PROPS-END Node-path: trunk Node-kind: dir Node-action: add Prop-content-length: 10 Content-length: 10 PROPS-END Revision-number: 2 Prop-content-length: 105 Content-length: 105 K 7 svn:log V 6 Files. K 10 svn:author V 5 durin K 8 svn:date V 27 2008-12-12T00:18:16.270290Z PROPS-END Node-path: trunk/alpha Node-kind: file Node-action: add Prop-content-length: 10 Text-content-length: 6 Text-content-md5: 9f9f90dbe3e5ee1218c86b8839db1995 Content-length: 16 PROPS-END alpha Node-path: trunk/beta Node-kind: file Node-action: add Prop-content-length: 10 Text-content-length: 5 Text-content-md5: f0cf2a92516045024a0c99147b28f05b Content-length: 15 PROPS-END beta Node-path: trunk/gamma Node-kind: file Node-action: add Prop-content-length: 10 Text-content-length: 6 Text-content-md5: 303febb9068384eca46b5b6516843b35 Content-length: 16 PROPS-END gamma Revision-number: 3 Prop-content-length: 113 Content-length: 113 K 7 svn:log V 13 make a branch K 10 svn:author V 5 durin K 8 svn:date V 27 2008-12-12T00:18:19.069446Z PROPS-END Node-path: branches/dev_branch Node-kind: dir Node-action: add Node-copyfrom-rev: 2 Node-copyfrom-path: trunk Revision-number: 4 Prop-content-length: 125 Content-length: 125 K 7 svn:log V 25 Add a file on the branch. K 10 svn:author V 5 durin K 8 svn:date V 27 2008-12-12T00:18:21.088611Z PROPS-END Node-path: branches/dev_branch/epsilon Node-kind: file Node-action: add Prop-content-length: 10 Text-content-length: 8 Text-content-md5: c40719840583e3f3e6744c02828d7cd9 Content-length: 18 PROPS-END epsilon Revision-number: 5 Prop-content-length: 124 Content-length: 124 K 7 svn:log V 24 Commit bogus propchange. K 10 svn:author V 5 durin K 8 svn:date V 27 2008-12-12T00:18:23.078263Z PROPS-END Node-path: branches/dev_branch Node-kind: dir Node-action: change Prop-content-length: 37 Content-length: 37 K 10 svn:ignore V 6 delta PROPS-END