view tests/test-pull-pull-corruption.t @ 38486:4c0683655599

namespaces: let namespaces override singlenode() definition

Some namespaces have multiple nodes per name (meaning that their
namemap() returns multiple nodes). One such namespace is the "topics"
namespace (from the evolve repo). We also have our own internal
namespace at Google (for review units) that has multiple nodes per
name. These namespaces may not want to use the default "pick highest
revnum" resolution that we currently use when resolving a name to a
single node. As an example, they may decide that `hg co <name>` should
check out a commit that's last in some sense even if an earlier commit
had just been amended and thus had a higher revnum [1]. This patch
gives the namespace the option to continue to return multiple nodes
and to override how the best node is picked. Allowing namespaces to
override that may also be useful as an optimization (it may be cheaper
for the namespace to find just that node).

I have been arguing (in D3715) for using all the nodes returned from
namemap() when resolving the symbol to a revset, so e.g. `hg log -r
stable` would resolve to *all* nodes on stable, not just the one with
the highest revnum (except that I don't actually think we should
change it for the branch namespace because of BC). Most people seem
opposed to that. If we decide not to do it, I think we can deprecate
the namemap() function in favor of the new singlenode() (I find it
weird to have namespaces, like the branch namespace, where namemap()
isn't nodemap()'s inverse). I therefore think this patch makes sense
regardless of what we decide on that issue.


 [1] Actually, even the branch namespace would have wanted to override
     singlenode() if it had supported multiple nodes. That's because
     closes branch heads are mostly ignored, so "hg co default" will
     not check out the highest-revnum node if that's a closed head.

Differential Revision: https://phab.mercurial-scm.org/D3852

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 ..