Hi all, This one is basically the technical post promised in my "Merge Policies" post. The proposal I make here is not an alternative to e.g. "Symmetric Merge" but rather a refined merge strategy that would also benefit the current merge.
Today, the merge algorithm will do the following for a merge from A -> B: * read / evaluate the merge info and change history to find the list of revisions to merge * fragment the list of revisions where they are non- contiguous; fragment = a revision range to merge * iteratively merge all fragments from A to B, optionally resolve conflicts after each fragment In end, we will always merge individual file or property changes but we plan the merge on tree-level. For many file nodes, this will unnecessary intermediate states where the merge got fragmented due to a change to some *other* file. This increases the probability of merge conflicts and their likelihood to show up again after each conflict resolution. Moreover, it masks cases where Symmetric Merge might select an optimized merge plan (see wiki for various examples). I propose to use the following two-phase merge workflow: (1) Planning phase - read / evaluate the merge info and change history to find the list of revisions to merge - break that down for each node changed on the source side - optionally handle renaming etc. - mark tree conflicts (not sure when to signal them to the user and when to resolve them; high-level fragmentation might become necessary) (2) Execution phase - merge changes on a per-node basis, i.e. all changes of that node get merged before the next node - fragmentation may still be necessary for *that file* - given the "merge plan" for a node, alternative merge strategies may be chosen That's all I currently have on merge and is not very very long-term ;) -- Stefan^2.
