notes: handle multiple worktrees

Before creating NOTES_MERGE_REF, check NOTES_MERGE_REF using
find_shared_symref and die if we find one.  This prevents simultaneous
merges to the same notes branch from different worktrees.

Signed-off-by: David Turner <dturner@twopensource.com>
Reviewed-by: Johan Herland <johan@herland.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/notes.c b/builtin/notes.c
index 68b6cd8..b97bcb0 100644 (file)
--- a/builtin/notes.c
+++ b/builtin/notes.c
@@ -19,6 +19,7 @@
 #include "string-list.h"
 #include "notes-merge.h"
 #include "notes-utils.h"
+#include "branch.h"
 
 static const char * const git_notes_usage[] = {
        N_("git notes [--ref <notes_ref>] [list [<object>]]"),
@@ -813,10 +814,15 @@ static int merge(int argc, const char **argv, const char *prefix)
                update_ref(msg.buf, default_notes_ref(), result_sha1, NULL,
                           0, UPDATE_REFS_DIE_ON_ERR);
        else { /* Merge has unresolved conflicts */
+               char *existing;
                /* Update .git/NOTES_MERGE_PARTIAL with partial merge result */
                update_ref(msg.buf, "NOTES_MERGE_PARTIAL", result_sha1, NULL,
                           0, UPDATE_REFS_DIE_ON_ERR);
                /* Store ref-to-be-updated into .git/NOTES_MERGE_REF */
+               existing = find_shared_symref("NOTES_MERGE_REF", default_notes_ref());
+               if (existing)
+                       die(_("A notes merge into %s is already in-progress at %s"),
+                           default_notes_ref(), existing);
                if (create_symref("NOTES_MERGE_REF", default_notes_ref(), NULL))
                        die("Failed to store link to current notes ref (%s)",
                            default_notes_ref());

diff --git a/t/t3320-notes-merge-worktrees.sh b/t/t3320-notes-merge-worktrees.sh
new file mode 100755 (executable)
index 0000000..1f71d58
--- /dev/null
+++ b/t/t3320-notes-merge-worktrees.sh
@@ -0,0 +1,72 @@
+#!/bin/sh
+#
+# Copyright (c) 2015 Twitter, Inc
+#
+
+test_description='Test merging of notes trees in multiple worktrees'
+
+. ./test-lib.sh
+
+test_expect_success 'setup commit' '
+       test_commit tantrum
+'
+
+commit_tantrum=$(git rev-parse tantrum^{commit})
+
+test_expect_success 'setup notes ref (x)' '
+       git config core.notesRef refs/notes/x &&
+       git notes add -m "x notes on tantrum" tantrum
+'
+
+test_expect_success 'setup local branch (y)' '
+       git update-ref refs/notes/y refs/notes/x &&
+       git config core.notesRef refs/notes/y &&
+       git notes remove tantrum
+'
+
+test_expect_success 'setup remote branch (z)' '
+       git update-ref refs/notes/z refs/notes/x &&
+       git config core.notesRef refs/notes/z &&
+       git notes add -f -m "conflicting notes on tantrum" tantrum
+'
+
+test_expect_success 'modify notes ref ourselves (x)' '
+       git config core.notesRef refs/notes/x &&
+       git notes add -f -m "more conflicting notes on tantrum" tantrum
+'
+
+test_expect_success 'create some new worktrees' '
+       git worktree add -b newbranch worktree master &&
+       git worktree add -b newbranch2 worktree2 master
+'
+
+test_expect_success 'merge z into y fails and sets NOTES_MERGE_REF' '
+       git config core.notesRef refs/notes/y &&
+       test_must_fail git notes merge z &&
+       echo "ref: refs/notes/y" >expect &&
+       test_cmp .git/NOTES_MERGE_REF expect
+'
+
+test_expect_success 'merge z into y while mid-merge in another workdir fails' '
+       (
+               cd worktree &&
+               git config core.notesRef refs/notes/y &&
+               test_must_fail git notes merge z 2>err &&
+               grep "A notes merge into refs/notes/y is already in-progress at" err
+       ) &&
+       test_path_is_missing .git/worktrees/worktree/NOTES_MERGE_REF
+'
+
+test_expect_success 'merge z into x while mid-merge on y succeeds' '
+       (
+               cd worktree2 &&
+               git config core.notesRef refs/notes/x &&
+               test_must_fail git notes merge z 2>&1 >out &&
+               grep "Automatic notes merge failed" out &&
+               grep -v "A notes merge into refs/notes/x is already in-progress in" out
+       ) &&
+       echo "ref: refs/notes/x" >expect &&
+       test_cmp .git/worktrees/worktree2/NOTES_MERGE_REF expect
+'
+
+test_done