view tests/test-pull-pull-corruption.t @ 36738:613954a17a25

setdiscovery: back out changeset 5cfdf6137af8 (issue5809)

As explained in the bug report, this commit caused a performance
regression. The problem occurs when the local repo has very many
heads. Before 5cfdf6137af8, we used to get the remote's list of heads
and if these heads mostly overlapped with the local repo's heads, we
would mark these common heads as common, which would greatly reduce
the size of the set of undecided nodes.

Note that a similar problem existed before 5cfdf6137af8: If the local
repo had very many heads and the server just had a few (or many heads
from a disjoint set), we would do the same kind of slow discovery as
we would with 5cfdf6137af8 in the case where local and remote repos
share a large set of common nodes.

For now, we just back out 5cfdf6137af8. We should improve the
discovery in the "local has many heads, remote has few heads" case,
but let's do that after backing this out.

Differential Revision: https://phab.mercurial-scm.org/D2643

Corrupt an hg repo with two pulls.
create one repo with a long history

  $ hg init source1
  $ cd source1
  $ touch foo
  $ hg add foo
  $ for i in 1 2 3 4 5 6 7 8 9 10; do
  >     echo $i >> foo
  >     hg ci -m $i
  > done
  $ cd ..

create one repo with a shorter history

  $ hg clone -r 0 source1 source2
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets 495a0ec48aaf
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd source2
  $ echo a >> foo
  $ hg ci -m a
  $ cd ..

create a third repo to pull both other repos into it

  $ hg init corrupted
  $ cd corrupted

use a hook to make the second pull start while the first one is still running

  $ echo '[hooks]' >> .hg/hgrc
  $ echo 'prechangegroup = sleep 5' >> .hg/hgrc

start a pull...

  $ hg pull ../source1 > pull.out 2>&1 &

... and start another pull before the first one has finished

  $ sleep 1
  $ hg pull ../source2 2>/dev/null
  pulling from ../source2
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  new changesets ca3c05af513e
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ cat pull.out
  pulling from ../source1
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 10 changesets with 10 changes to 1 files
  new changesets 495a0ec48aaf:1e7b6c812ca8
  (run 'hg update' to get a working copy)

see the result

  $ wait
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 11 changesets, 11 total revisions

  $ cd ..