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view tests/fixtures/two_heads.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 | db32dee803a8 |
| children |
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SVN-fs-dump-format-version: 2 UUID: df2126f7-00ab-4d49-b42c-7e981dde0bcf Revision-number: 0 Prop-content-length: 56 Content-length: 56 K 8 svn:date V 27 2008-10-07T22:49:12.059692Z PROPS-END Revision-number: 1 Prop-content-length: 111 Content-length: 111 K 7 svn:log V 11 Empty dirs. K 10 svn:author V 5 durin K 8 svn:date V 27 2008-10-07T22:49:41.118037Z PROPS-END Node-path: branches Node-kind: dir Node-action: add Prop-content-length: 10 Content-length: 10 PROPS-END Node-path: tags 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: 108 Content-length: 108 K 7 svn:log V 9 Add alpha K 10 svn:author V 5 durin K 8 svn:date V 27 2008-10-07T23:23:02.991743Z PROPS-END Node-path: trunk/alpha Node-kind: file Node-action: add Prop-content-length: 10 Text-content-length: 12 Text-content-md5: 3c72ebf8bbd7fa88b1fdcee5398b5a17 Content-length: 22 PROPS-END file: alpha Revision-number: 3 Prop-content-length: 107 Content-length: 107 K 7 svn:log V 8 Add beta K 10 svn:author V 5 durin K 8 svn:date V 27 2008-10-07T23:28:22.651398Z PROPS-END Node-path: trunk/beta Node-kind: file Node-action: add Prop-content-length: 10 Text-content-length: 13 Text-content-md5: 981d1eb5fd0bbe05354c292105944863 Content-length: 23 PROPS-END Data of beta Revision-number: 4 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 2008-10-08T01:35:39.984789Z PROPS-END Node-path: branches/the_branch Node-kind: dir Node-action: add Node-copyfrom-rev: 3 Node-copyfrom-path: trunk Prop-content-length: 34 Content-length: 34 K 13 svn:mergeinfo V 0 PROPS-END Revision-number: 5 Prop-content-length: 123 Content-length: 123 K 7 svn:log V 23 add delta on the branch K 10 svn:author V 5 durin K 8 svn:date V 27 2008-10-08T01:39:05.520779Z PROPS-END Node-path: branches/the_branch/delta Node-kind: file Node-action: add Prop-content-length: 10 Text-content-length: 6 Text-content-md5: d2840cc81bc032bd1141b56687d0f93c Content-length: 16 PROPS-END delta Revision-number: 6 Prop-content-length: 119 Content-length: 119 K 7 svn:log V 19 Add gamma on trunk. K 10 svn:author V 5 durin K 8 svn:date V 27 2008-10-08T01:39:29.950892Z PROPS-END 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