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[PATCH v2 4/4] branch: record creation of renamed branch in HEAD's log

From
Kyle Meyer <kyle@kyleam.com>
Date
Feb 21, 2017, 01:10 UTC
Message-ID
<20170221011035.847-5-kyle@kyleam.com>
In-Reply-To
<20170221011035.847-1-kyle@kyleam.com>

Renaming the current branch adds an event to the current branch's log and to HEAD's log. However, the logged entries differ. The entry in the branch's log represents the entire renaming operation (the old and new hash are identical), whereas the entry in HEAD's log represents the deletion only (the new sha1 is null).

Extend replace_each_worktree_head_symref(), whose only caller is branch_rename(), to take a reflog message argument. This allows the creation of the new ref to be recorded in HEAD's log. As a result, the renaming event is represented by two entries (a deletion and a creation entry) in HEAD's log.

It's a bit unfortunate that the branch's log and HEAD's log now represent the renaming event in different ways. Given that the renaming operation is not atomic, the two-entry form is a more accurate representation of the operation and is more useful for debugging purposes if a failure occurs between the deletion and creation events. It would make sense to move the branch's log to the two-entry form, but this would involve changes to how the rename is carried out and to how the update flags and reflogs are processed for deletions, so it may not be worth the effort.

Based-on-patch-by: Jeff King <peff@peff.net>
Signed-off-by: Kyle Meyer <kyle@kyleam.com>
---
 branch.c             | 5 +++--
 branch.h             | 3 ++-
 builtin/branch.c     | 5 +++--
 refs.h               | 3 ++-
 refs/files-backend.c | 4 ++--
 t/t3200-branch.sh    | 5 +++--
 6 files changed, 15 insertions(+), 10 deletions(-)
diff --git a/branch.c b/branch.c
index b955d4f31..5c12036b0 100644
--- a/branch.c
+++ b/branch.c
@@ -345,7 +345,8 @@ void die_if_checked_out(const char *branch, int ignore_current_worktree)
 	    branch, wt->path);
 }
 
-int replace_each_worktree_head_symref(const char *oldref, const char *newref)
+int replace_each_worktree_head_symref(const char *oldref, const char *newref,
+				      const char *logmsg)
 {
 	int ret = 0;
 	struct worktree **worktrees = get_worktrees(0);
@@ -358,7 +359,7 @@ int replace_each_worktree_head_symref(const char *oldref, const char *newref)
 			continue;
 
 		if (set_worktree_head_symref(get_worktree_git_dir(worktrees[i]),
-					     newref)) {
+					     newref, logmsg)) {
 			ret = -1;
 			error(_("HEAD of working tree %s is not updated"),
 			      worktrees[i]->path);
diff --git a/branch.h b/branch.h
index 3103eb9ad..b07788558 100644
--- a/branch.h
+++ b/branch.h
@@ -71,6 +71,7 @@ extern void die_if_checked_out(const char *branch, int ignore_current_worktree);
  * This will be used when renaming a branch. Returns 0 if successful, non-zero
  * otherwise.
  */
-extern int replace_each_worktree_head_symref(const char *oldref, const char *newref);
+extern int replace_each_worktree_head_symref(const char *oldref, const char *newref,
+					     const char *logmsg);
 
 #endif
diff --git a/builtin/branch.c b/builtin/branch.c
index 8f8242e07..e1f97dcfc 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -579,14 +579,15 @@ static void rename_branch(const char *oldname, const char *newname, int force)
 
 	if (rename_ref(oldref.buf, newref.buf, logmsg.buf))
 		die(_("Branch rename failed"));
-	strbuf_release(&logmsg);
 
 	if (recovery)
 		warning(_("Renamed a misnamed branch '%s' away"), oldref.buf + 11);
 
-	if (replace_each_worktree_head_symref(oldref.buf, newref.buf))
+	if (replace_each_worktree_head_symref(oldref.buf, newref.buf, logmsg.buf))
 		die(_("Branch renamed to %s, but HEAD is not updated!"), newname);
 
+	strbuf_release(&logmsg);
+
 	strbuf_addf(&oldsection, "branch.%s", oldref.buf + 11);
 	strbuf_release(&oldref);
 	strbuf_addf(&newsection, "branch.%s", newref.buf + 11);
diff --git a/refs.h b/refs.h
index 5880886a7..e529f4c3a 100644
--- a/refs.h
+++ b/refs.h
@@ -334,7 +334,8 @@ int create_symref(const char *refname, const char *target, const char *logmsg);
  * $GIT_DIR points to.
  * Return 0 if successful, non-zero otherwise.
  * */
-int set_worktree_head_symref(const char *gitdir, const char *target);
+int set_worktree_head_symref(const char *gitdir, const char *target,
+			     const char *logmsg);
 
 enum action_on_err {
 	UPDATE_REFS_MSG_ON_ERR,
diff --git a/refs/files-backend.c b/refs/files-backend.c
index f6e7c192c..42b137bb1 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -3055,7 +3055,7 @@ static int files_create_symref(struct ref_store *ref_store,
 	return ret;
 }
 
-int set_worktree_head_symref(const char *gitdir, const char *target)
+int set_worktree_head_symref(const char *gitdir, const char *target, const char *logmsg)
 {
 	static struct lock_file head_lock;
 	struct ref_lock *lock;
@@ -3083,7 +3083,7 @@ int set_worktree_head_symref(const char *gitdir, const char *target)
 	lock->lk = &head_lock;
 	lock->ref_name = xstrdup(head_rel);
 
-	ret = create_symref_locked(lock, head_rel, target, NULL);
+	ret = create_symref_locked(lock, head_rel, target, logmsg);
 
 	unlock_ref(lock); /* will free lock */
 	strbuf_release(&head_path);
diff --git a/t/t3200-branch.sh b/t/t3200-branch.sh
index 0dbc54003..d84837d08 100755
--- a/t/t3200-branch.sh
+++ b/t/t3200-branch.sh
@@ -139,9 +139,10 @@ test_expect_success 'git branch -M baz bam should succeed when baz is checked ou
 	test $(git rev-parse --abbrev-ref HEAD) = bam
 '
 
-test_expect_success 'git branch -M baz bam should add entry to .git/logs/HEAD' '
+test_expect_success 'git branch -M baz bam should add entries to .git/logs/HEAD' '
         msg="Branch: renamed refs/heads/baz to refs/heads/bam" &&
-	grep " 0\{40\}.*$msg$" .git/logs/HEAD
+	grep " 0\{40\}.*$msg$" .git/logs/HEAD &&
+	grep "^0\{40\}.*$msg$" .git/logs/HEAD
 '
 
 test_expect_success 'git branch -M baz bam should succeed when baz is checked out as linked working tree' '
-- 
2.11.1
Previous: Kyle MeyerNext: Kyle Meyer
Message 32 of 36 in “HEAD's reflog entry for a renamed branch”
  1. Kyle MeyerJan 16, 2017
  2. Jeff KingJan 26, 2017
  3. Junio C HamanoJan 26, 2017
  4. Jeff KingJan 26, 2017
  5. 0/3 delete_ref(): support reflog messagesKyle Meyer, Feb 17, 2017
  6. 1/3 delete_refs(): accept a reflog message argumentKyle Meyer, Feb 17, 2017
  7. Jeff KingFeb 17, 2017
  8. Junio C HamanoFeb 17, 2017
  9. Kyle MeyerFeb 17, 2017
  10. 2/3 update-ref: pass reflog message argument to delete_refsKyle Meyer, Feb 17, 2017
  11. Jeff KingFeb 17, 2017
  12. Junio C HamanoFeb 17, 2017
  13. Kyle MeyerFeb 17, 2017
  14. Jeff KingFeb 17, 2017
  15. 3/3 rename_ref: replace empty deletion message in HEAD's logKyle Meyer, Feb 17, 2017
  16. Jeff KingFeb 17, 2017
  17. Junio C HamanoFeb 17, 2017
  18. Jeff KingFeb 17, 2017
  19. Jeff KingFeb 17, 2017
  20. Junio C HamanoFeb 17, 2017
  21. Kyle MeyerFeb 17, 2017
  22. Kyle MeyerFeb 17, 2017
  23. Jeff KingFeb 17, 2017
  24. Junio C HamanoFeb 17, 2017
  25. Jeff KingFeb 17, 2017
  26. 0/4 delete_ref: support reflog messagesKyle Meyer, Feb 21, 2017
  27. 1/4 delete_ref: accept a reflog message argumentKyle Meyer, Feb 21, 2017
  28. Duy NguyenFeb 23, 2017
  29. Junio C HamanoFeb 23, 2017
  30. Kyle MeyerFeb 25, 2017
  31. 2/4 update-ref: pass reflog message to delete_ref()Kyle Meyer, Feb 21, 2017
  32. 4/4 branch: record creation of renamed branch in HEAD's logKyle Meyer, Feb 21, 2017
  33. 3/4 rename_ref: replace empty message in HEAD's logKyle Meyer, Feb 21, 2017
  34. Jeff KingFeb 21, 2017
  35. Junio C HamanoFeb 21, 2017
  36. Kyle MeyerFeb 21, 2017

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