obsolete: explicitly track folds inside the markers
We now record information to be able to recognize "fold" event from
obsolescence markers. To do so, we track the following pieces of information:
a) a fold ID. Unique to that fold (per successor),
b) the number of predecessors,
c) the index of the predecessor in that fold.
We will now be able to create an algorithm able to find "predecessorssets".
We now store this data in the generic "metadata" field of the markers.
Updating the format to have a more compact storage for this would be useful.
This way of tracking a fold through multiple markers could be applied to split
too. This would have two advantages:
1) We get a simpler format, since number of successors is limited to [0-1].
2) We can better deal with situations where only some of the split successors
are pushed to a remote repository.
We should look into the relevance of such a change before updating the on-disk
format.
note: unlike splits, folds do not have to deal with cases where only some of
the markers have been synchronized. As they all share the same successor
changesets, they are all relevant to the same nodes.
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
checked 11 changesets with 11 changes to 1 files
$ cd ..