lfs: fix the stall and corruption issue when concurrently uploading blobs
We've avoided the issue up to this point by gating worker usage with an
experimental config. See 10e62d5efa73, and the thread linked there for some of
the initial diagnosis, but essentially some data was being read from the blob
before an error occurred and `keepalive` retried, but didn't rewind the file
pointer. So the leading data was lost from the blob on the server, and the
connection stalled, trying to send more data than available.
In trying to recreate this, I was unable to do so uploading from Windows to
CentOS 7. But it reproduced every time going from CentOS 7 to another CentOS 7
over https.
I found recent fixes in the FaceBook repo to address this[1][2]. The commit
message for the first is:
The KeepAlive HTTP implementation is bugged in it's retry logic, it supports
reading from a file pointer, but doesn't support rewinding of the seek cursor
when it performs a retry. So it can happen that an upload fails for whatever
reason and will then 'hang' on the retry event.
The sequence of events that get triggered are:
- Upload file A, goes OK. Keep-Alive caches connection.
- Upload file B, fails due to (for example) failing Keep-Alive, but LFS file
pointer has been consumed for the upload and fd has been closed.
- Retry for file B starts, sets the Content-Length properly to the expected
file size, but since file pointer has been consumed no data will be uploaded,
causing the server to wait for the uploaded data until either client or
server reaches a timeout, making it seem as our mercurial process hangs.
This is just a stop-gap measure to prevent this behavior from blocking Mercurial
(LFS has retry logic). A proper solutions need to be build on top of this
stop-gap measure: for upload from file pointers, we should support fseek() on
the interface. Since we expect to consume the whole file always anyways, this
should be safe. This way we can seek back to the beginning on a retry.
I ported those two patches, and it works. But I see that `url._sendfile()` does
a rewind on `httpsendfile` objects[3], so maybe it's better to keep this all in
one place and avoid a second seek. We may still want the first FaceBook patch
as extra protection for this problem in general. The other two uses of
`httpsendfile` are in the wire protocol to upload bundles, and to upload
largefiles. Neither of these appear to use a worker, and I'm not sure why
workers seem to trigger this, or if this could have happened without a worker.
Since `httpsendfile` already has a `close()` method, that is dropped. That
class also explicitly says there's no `__len__` attribute, so that is removed
too. The override for `read()` is necessary to avoid the progressbar usage per
file.
[1] https://github.com/facebookexperimental/eden/commit/c350d6536d90c044c837abdd3675185644481469
[2] https://github.com/facebookexperimental/eden/commit/77f0d3fd0415e81b63e317e457af9c55c46103ee
[3] https://www.mercurial-scm.org/repo/hg/file/5.2.2/mercurial/url.py#l176
Differential Revision: https://phab.mercurial-scm.org/D7962
test stripping of filelogs where the linkrev doesn't always increase
$ echo '[extensions]' >> $HGRCPATH
$ echo 'strip =' >> $HGRCPATH
$ commit()
> {
> hg up -qC null
> count=1
> for i in "$@"; do
> for f in $i; do
> mkdir -p `dirname $f`
> echo $count > $f
> done
> count=`expr $count + 1`
> done
> hg commit -qAm "$*"
> }
2 1 0 2 0 1 2
$ mkdir files
$ cd files
$ hg init orig
$ cd orig
$ commit '201 210'
$ commit '102 120' '210'
$ commit '021'
$ commit '201' '021 120'
$ commit '012 021' '102 201' '120 210'
$ commit '102 120' '012 210' '021 201'
$ commit '201 210' '021 120' '012 102'
$ cd ..
$ hg clone -q -U -r 4 -r 5 -r 6 orig crossed
$ cd crossed
$ for i in 012 021 102 120 201 210; do
> echo $i
> hg debugindex $i
> echo
> done
012
rev linkrev nodeid p1 p2
0 0 b8e02f643373 000000000000 000000000000
1 1 5d9299349fc0 000000000000 000000000000
2 2 2661d26c6496 000000000000 000000000000
021
rev linkrev nodeid p1 p2
0 0 b8e02f643373 000000000000 000000000000
1 2 5d9299349fc0 000000000000 000000000000
2 1 2661d26c6496 000000000000 000000000000
102
rev linkrev nodeid p1 p2
0 1 b8e02f643373 000000000000 000000000000
1 0 5d9299349fc0 000000000000 000000000000
2 2 2661d26c6496 000000000000 000000000000
120
rev linkrev nodeid p1 p2
0 1 b8e02f643373 000000000000 000000000000
1 2 5d9299349fc0 000000000000 000000000000
2 0 2661d26c6496 000000000000 000000000000
201
rev linkrev nodeid p1 p2
0 2 b8e02f643373 000000000000 000000000000
1 0 5d9299349fc0 000000000000 000000000000
2 1 2661d26c6496 000000000000 000000000000
210
rev linkrev nodeid p1 p2
0 2 b8e02f643373 000000000000 000000000000
1 1 5d9299349fc0 000000000000 000000000000
2 0 2661d26c6496 000000000000 000000000000
$ cd ..
$ for i in 0 1 2; do
> hg clone -q -U --pull crossed $i
> echo "% Trying to strip revision $i"
> hg --cwd $i strip $i
> echo "% Verifying"
> hg --cwd $i verify
> echo
> done
% Trying to strip revision 0
saved backup bundle to $TESTTMP/files/0/.hg/strip-backup/cbb8c2f0a2e3-239800b9-backup.hg
% Verifying
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 2 changesets with 12 changes to 6 files
% Trying to strip revision 1
saved backup bundle to $TESTTMP/files/1/.hg/strip-backup/124ecc0cbec9-6104543f-backup.hg
% Verifying
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 2 changesets with 12 changes to 6 files
% Trying to strip revision 2
saved backup bundle to $TESTTMP/files/2/.hg/strip-backup/f6439b304a1a-c6505a5f-backup.hg
% Verifying
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 2 changesets with 12 changes to 6 files
$ cd ..
Do a similar test where the manifest revlog has unordered linkrevs
$ mkdir manifests
$ cd manifests
$ hg init orig
$ cd orig
$ commit 'file'
$ commit 'other'
$ commit '' 'other'
$ HGUSER=another-user; export HGUSER
$ commit 'file'
$ commit 'other' 'file'
$ cd ..
$ hg clone -q -U -r 1 -r 2 -r 3 -r 4 orig crossed
$ cd crossed
$ hg debugindex --manifest
rev linkrev nodeid p1 p2
0 2 6bbc6fee55c2 000000000000 000000000000
1 0 1c556153fe54 000000000000 000000000000
2 1 1f76dba919fd 000000000000 000000000000
3 3 bbee06ad59d5 000000000000 000000000000
$ cd ..
$ for i in 2 3; do
> hg clone -q -U --pull crossed $i
> echo "% Trying to strip revision $i"
> hg --cwd $i strip $i
> echo "% Verifying"
> hg --cwd $i verify
> echo
> done
% Trying to strip revision 2
saved backup bundle to $TESTTMP/manifests/2/.hg/strip-backup/f3015ad03c03-4d98bdc2-backup.hg
% Verifying
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 3 changesets with 3 changes to 2 files
% Trying to strip revision 3
saved backup bundle to $TESTTMP/manifests/3/.hg/strip-backup/9632aa303aa4-69192e3f-backup.hg
% Verifying
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 3 changesets with 3 changes to 2 files
$ cd ..
Now a similar test for a non-root manifest revlog
$ cat >> $HGRCPATH <<EOF
> [experimental]
> treemanifests = yes
> EOF
$ mkdir treemanifests
$ cd treemanifests
$
$ hg --config experimental.treemanifest=True init orig
$ cd orig
$ commit 'dir/file'
$ commit 'dir/other'
$ commit '' 'dir/other'
$ HGUSER=yet-another-user; export HGUSER
$ commit 'otherdir dir/file'
$ commit 'otherdir dir/other' 'otherdir dir/file'
$ cd ..
$ hg --config experimental.treemanifest=True clone -q -U -r 1 -r 2 -r 3 -r 4 orig crossed
$ cd crossed
$ hg debugindex --dir dir
rev linkrev nodeid p1 p2
0 2 6bbc6fee55c2 000000000000 000000000000
1 0 1c556153fe54 000000000000 000000000000
2 1 1f76dba919fd 000000000000 000000000000
3 3 bbee06ad59d5 000000000000 000000000000
$ cd ..
$ for i in 2 3; do
> hg --config experimental.treemanifest=True clone -q -U --pull crossed $i
> echo "% Trying to strip revision $i"
> hg --cwd $i strip $i
> echo "% Verifying"
> hg --cwd $i verify
> echo
> done
% Trying to strip revision 2
saved backup bundle to $TESTTMP/treemanifests/2/.hg/strip-backup/145f5c75f9ac-a105cfbe-backup.hg
% Verifying
checking changesets
checking manifests
checking directory manifests
crosschecking files in changesets and manifests
checking files
checked 3 changesets with 4 changes to 3 files
% Trying to strip revision 3
saved backup bundle to $TESTTMP/treemanifests/3/.hg/strip-backup/e4e3de5c3cb2-f4c70376-backup.hg
% Verifying
checking changesets
checking manifests
checking directory manifests
crosschecking files in changesets and manifests
checking files
checked 3 changesets with 4 changes to 3 files
$ cd ..