Merging Git notes

Merging Git notes branches has several differences from merging "normal"
branches. Although Git notes are initially stored as one flat tree the
tree may fanout when the number of notes becomes too large for efficient
access. In this case the first two hex digits of the note name will be
used as a subdirectory name and the rest 38 hex digits as the file name
under that directory. Similarly, when number of notes decreases a fanout
tree may collapse back into a flat tree. The Git notes merge algorithm
must take into account possibly different tree structures in different
note branches and must properly match them against each other.

Any conflict on a Git note is, by default, resolved by concatenating
the two conflicting versions of the note. A delete-edit conflict is, by
default, resolved by keeping the edit version.

The note merge logic is pluggable and the caller may provide custom
note merger that will perform different merging strategy.

Additionally, it is possible to have non-note entries inside a notes
tree. The merge algorithm must also take this fact into account and
will try to merge such non-note entries. However, in case of any merge
conflicts the merge operation will fail. Git notes merge algorithm is
currently not trying to do content merge of non-note entries.

Thanks to Shawn Pearce for patiently answering my questions related to
this topic, giving hints and providing code snippets.

Change-Id: I3b2335c76c766fd7ea25752e54087f9b19d69c88
Signed-off-by: Sasa Zivkov <sasa.zivkov@sap.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/org.eclipse.jgit/resources/org/eclipse/jgit/JGitText.properties b/org.eclipse.jgit/resources/org/eclipse/jgit/JGitText.properties
index 10d30cf023..c8f5920977 100644
--- a/org.eclipse.jgit/resources/org/eclipse/jgit/JGitText.properties
+++ b/org.eclipse.jgit/resources/org/eclipse/jgit/JGitText.properties
@@ -258,6 +258,8 @@ lockError=lock error: {0}
 lockOnNotClosed=Lock on {0} not closed.
 lockOnNotHeld=Lock on {0} not held.
 malformedpersonIdentString=Malformed PersonIdent string (no < was found): {0}
+mergeConflictOnNotes=Merge conflict on note {0}. base = {1}, ours = {2}, theirs = {2}
+mergeConflictOnNonNoteEntries=Merge conflict on non-note entries: base = {0}, ours = {1}, theirs = {2}
 mergeStrategyAlreadyExistsAsDefault=Merge strategy "{0}" already exists as a default strategy
 mergeStrategyDoesNotSupportHeads=merge strategy {0} does not support {1} heads to be merged into HEAD
 mergeUsingStrategyResultedInDescription=Merge of revisions {0} with base {1} using strategy {2} resulted in: {3}. {4}