Mercurial > hg
view tests/test-sparse-revlog.t @ 42377:0546ead39a7e stable
manifest: avoid corruption by dropping removed files with pure (issue5801)
Previously, removed files would simply be marked by overwriting the first byte
with NUL and dropping their entry in `self.position`. But no effort was made to
ignore them when compacting the dictionary into text form. This allowed them to
slip into the manifest revision, since the code seems to be trying to minimize
the string operations by copying as large a chunk as possible. As part of this,
compact() walks the existing text based on entries in the `positions` list, and
consumed everything up to the next position entry. This typically resulted in
a ValueError complaining about unsorted manifest entries.
Sometimes it seems that files do get dropped in large repos- it seems to
correspond to there being a new entry that would take the same slot. A much
more trivial problem is that if the only changes were removals, `_compact()`
didn't even run because `__delitem__` doesn't add anything to `self.extradata`.
Now there's an explicit variable to flag this, both to allow `_compact()` to
run, and to avoid searching the manifest in cases where there are no removals.
In practice, this behavior was mostly obscured by the check in fastdelta() which
takes a different path that explicitly drops removed files if there are fewer
than 1000 changes. However, timeless has a repo where after rebasing tens of
commits, a totally different path[1] is taken that bypasses the change count
check and hits this problem.
[1] https://www.mercurial-scm.org/repo/hg/file/2338bdea4474/mercurial/manifest.py#l1511
author | Matt Harbison <matt_harbison@yahoo.com> |
---|---|
date | Thu, 23 May 2019 21:54:24 -0400 |
parents | 688fc33e105d |
children | 58a814d062ca |
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==================================== Test delta choice with sparse revlog ==================================== Sparse-revlog usually shows the most gain on Manifest. However, it is simpler to general an appropriate file, so we test with a single file instead. The goal is to observe intermediate snapshot being created. We need a large enough file. Part of the content needs to be replaced repeatedly while some of it changes rarely. $ bundlepath="$TESTDIR/artifacts/cache/big-file-churn.hg" $ expectedhash=`cat "$bundlepath".md5` #if slow $ if [ ! -f "$bundlepath" ]; then > "$TESTDIR"/artifacts/scripts/generate-churning-bundle.py > /dev/null > fi #else $ if [ ! -f "$bundlepath" ]; then > echo 'skipped: missing artifact, run "'"$TESTDIR"'/artifacts/scripts/generate-churning-bundle.py"' > exit 80 > fi #endif $ currenthash=`f -M "$bundlepath" | cut -d = -f 2` $ if [ "$currenthash" != "$expectedhash" ]; then > echo 'skipped: outdated artifact, md5 "'"$currenthash"'" expected "'"$expectedhash"'" run "'"$TESTDIR"'/artifacts/scripts/generate-churning-bundle.py"' > exit 80 > fi $ cat >> $HGRCPATH << EOF > [format] > sparse-revlog = yes > maxchainlen = 15 > [storage] > revlog.optimize-delta-parent-choice = yes > revlog.reuse-external-delta = no > EOF $ hg init sparse-repo $ cd sparse-repo $ hg unbundle $bundlepath adding changesets adding manifests adding file changes added 5001 changesets with 5001 changes to 1 files (+89 heads) new changesets 9706f5af64f4:d9032adc8114 (5001 drafts) (run 'hg heads' to see heads, 'hg merge' to merge) $ hg up 1 files updated, 0 files merged, 0 files removed, 0 files unresolved updated to "d9032adc8114: commit #5000" 89 other heads for branch "default" $ hg log --stat -r 0:3 changeset: 0:9706f5af64f4 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: initial commit SPARSE-REVLOG-TEST-FILE | 10500 ++++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 10500 insertions(+), 0 deletions(-) changeset: 1:724907deaa5e user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: commit #1 SPARSE-REVLOG-TEST-FILE | 1068 +++++++++++++++++++++++----------------------- 1 files changed, 534 insertions(+), 534 deletions(-) changeset: 2:62c41bce3e5d user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: commit #2 SPARSE-REVLOG-TEST-FILE | 1068 +++++++++++++++++++++++----------------------- 1 files changed, 534 insertions(+), 534 deletions(-) changeset: 3:348a9cbd6959 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: commit #3 SPARSE-REVLOG-TEST-FILE | 1068 +++++++++++++++++++++++----------------------- 1 files changed, 534 insertions(+), 534 deletions(-) $ f -s .hg/store/data/*.d .hg/store/data/_s_p_a_r_s_e-_r_e_v_l_o_g-_t_e_s_t-_f_i_l_e.d: size=63327412 $ hg debugrevlog * format : 1 flags : generaldelta revisions : 5001 merges : 625 (12.50%) normal : 4376 (87.50%) revisions : 5001 empty : 0 ( 0.00%) text : 0 (100.00%) delta : 0 (100.00%) snapshot : 383 ( 7.66%) lvl-0 : 3 ( 0.06%) lvl-1 : 20 ( 0.40%) lvl-2 : 68 ( 1.36%) lvl-3 : 112 ( 2.24%) lvl-4 : 180 ( 3.60%) deltas : 4618 (92.34%) revision size : 63327412 snapshot : 9886710 (15.61%) lvl-0 : 603104 ( 0.95%) lvl-1 : 1559991 ( 2.46%) lvl-2 : 2295592 ( 3.62%) lvl-3 : 2531199 ( 4.00%) lvl-4 : 2896824 ( 4.57%) deltas : 53440702 (84.39%) chunks : 5001 0x78 (x) : 5001 (100.00%) chunks size : 63327412 0x78 (x) : 63327412 (100.00%) avg chain length : 9 max chain length : 15 max chain reach : 28248745 compression ratio : 27 uncompressed data size (min/max/avg) : 346468 / 346472 / 346471 full revision size (min/max/avg) : 201008 / 201050 / 201034 inter-snapshot size (min/max/avg) : 11596 / 168150 / 24430 level-1 (min/max/avg) : 16653 / 168150 / 77999 level-2 (min/max/avg) : 12951 / 85595 / 33758 level-3 (min/max/avg) : 11608 / 43029 / 22599 level-4 (min/max/avg) : 11596 / 21632 / 16093 delta size (min/max/avg) : 10649 / 107163 / 11572 deltas against prev : 3910 (84.67%) where prev = p1 : 3910 (100.00%) where prev = p2 : 0 ( 0.00%) other : 0 ( 0.00%) deltas against p1 : 648 (14.03%) deltas against p2 : 60 ( 1.30%) deltas against other : 0 ( 0.00%)