view tests/test-repair-strip.t @ 17970:0b03454abae7

ancestor: faster algorithm for difference of ancestor sets

One of the major reasons rebase is slow in large repositories is
the computation of the detach set: the set of ancestors of the
changesets to rebase not in the destination parent. This is currently
done via a revset that does two walks all the way to the root of
the DAG. Instead of doing that, to find ancestors of a set <revs>
not in another set <common> we walk up the tree in reverse revision
number order, maintaining sets of nodes visited from <revs>, <common>
or both.

For the common case where the sets are close both topologically and
in revision number (relative to repository size), this has been
found to speed up rebase by around 15-20%. When the nodes are farther
apart and the DAG is highly branching, it is harder to say which
would win.

Here's how long computing the detach set takes in a linear repository
with over 400000 changesets, rebasing near tip:

Rebasing across 4 changesets
Revset method: 2.2s
New algorithm: 0.00015s

Rebasing across 250 changesets
Revset method: 2.2s
New algorithm: 0.00069s

Rebasing across 10000 changesets
Revset method: 2.4s
New algorithm: 0.019s

  $ "$TESTDIR/hghave" unix-permissions || exit 80

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "mq=">> $HGRCPATH

  $ teststrip() {
  >   hg -q up -C $1
  >   echo % before update $1, strip $2
  >   hg parents
  >   chmod -$3 $4
  >   hg strip $2 2>&1 | sed 's/\(bundle\).*/\1/' | sed 's/Permission denied.*\.hg\/store\/\(.*\)/Permission denied \.hg\/store\/\1/'
  >   echo % after update $1, strip $2
  >   chmod +$3 $4
  >   hg verify
  >   echo % journal contents
  >   if [ -f .hg/store/journal ]; then
  >       sed -e 's/\.i[^\n]*/\.i/' .hg/store/journal
  >   else
  >       echo "(no journal)"
  >   fi
  >   ls .hg/store/journal >/dev/null 2>&1 && hg recover
  >   ls .hg/strip-backup/* >/dev/null 2>&1 && hg unbundle -q .hg/strip-backup/*
  >   rm -rf .hg/strip-backup
  > }

  $ hg init test
  $ cd test
  $ echo a > a
  $ hg -q ci -m "a" -A
  $ echo b > b
  $ hg -q ci -m "b" -A
  $ echo b2 >> b
  $ hg -q ci -m "b2" -A
  $ echo c > c
  $ hg -q ci -m "c" -A
  $ teststrip 0 2 w .hg/store/data/b.i
  % before update 0, strip 2
  changeset:   0:cb9a9f314b8b
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     a
  
  saved backup bundle
  transaction abort!
  failed to truncate data/b.i
  rollback failed - please run hg recover
  strip failed, full bundle
  abort: Permission denied .hg/store/data/b.i
  % after update 0, strip 2
  abandoned transaction found - run hg recover
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
   b@?: rev 1 points to nonexistent changeset 2
   (expected 1)
   b@?: 736c29771fba not in manifests
  warning: orphan revlog 'data/c.i'
  2 files, 2 changesets, 3 total revisions
  2 warnings encountered!
  2 integrity errors encountered!
  % journal contents
  00changelog.i
  00manifest.i
  data/b.i
  data/c.i
  rolling back interrupted transaction
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  2 files, 2 changesets, 2 total revisions
  $ teststrip 0 2 r .hg/store/data/b.i
  % before update 0, strip 2
  changeset:   0:cb9a9f314b8b
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     a
  
  abort: Permission denied .hg/store/data/b.i
  % after update 0, strip 2
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  3 files, 4 changesets, 4 total revisions
  % journal contents
  (no journal)
  $ teststrip 0 2 w .hg/store/00manifest.i
  % before update 0, strip 2
  changeset:   0:cb9a9f314b8b
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     a
  
  saved backup bundle
  transaction abort!
  failed to truncate 00manifest.i
  rollback failed - please run hg recover
  strip failed, full bundle
  abort: Permission denied .hg/store/00manifest.i
  % after update 0, strip 2
  abandoned transaction found - run hg recover
  checking changesets
  checking manifests
   manifest@?: rev 2 points to nonexistent changeset 2
   manifest@?: 3362547cdf64 not in changesets
   manifest@?: rev 3 points to nonexistent changeset 3
   manifest@?: 265a85892ecb not in changesets
  crosschecking files in changesets and manifests
   c@3: in manifest but not in changeset
  checking files
   b@?: rev 1 points to nonexistent changeset 2
   (expected 1)
   c@?: rev 0 points to nonexistent changeset 3
  3 files, 2 changesets, 4 total revisions
  1 warnings encountered!
  7 integrity errors encountered!
  (first damaged changeset appears to be 3)
  % journal contents
  00changelog.i
  00manifest.i
  data/b.i
  data/c.i
  rolling back interrupted transaction
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  2 files, 2 changesets, 2 total revisions

  $ cd ..