[PATCH v9 21/44] refs.c: ref_transaction_commit should not free the transaction

[Ronnie Sahlberg <sahlberg@google.com>]

Change ref_transaction_commit so that it does not free the transaction.
Instead require that a caller will end a transaction by either calling
ref_transaction_rollback or ref_transaction_free.

By having the transaction object remaining valid after _commit returns allows
us to write much nicer code and still be able to call ref_transaction_rollback
safely. Instead of this horribleness
	t = ref_transaction_begin();
	if ((!t ||
	    ref_transaction_update(t, refname, sha1, oldval, flags,
				   !!oldval)) ||
	    (ref_transaction_commit(t, action, &err) && !(t = NULL))) {
		ref_transaction_rollback(t);

we can now just do the much nicer
	t = ref_transaction_begin();
	if (!t ||
	    ref_transaction_update(t, refname, sha1, oldval, flags,
				   !!oldval) ||
	    ref_transaction_commit(&t, action, &err)) {
		ref_transaction_rollback(t);
		... die/return ...

	ref_transaction_free(transaction);

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 branch.c             |  1 +
 builtin/commit.c     |  1 +
 builtin/replace.c    |  1 +
 builtin/tag.c        |  1 +
 builtin/update-ref.c |  1 +
 fast-import.c        |  4 ++--
 refs.c               | 14 ++++++--------
 refs.h               | 14 +++++++++-----
 sequencer.c          |  4 ++--
 9 files changed, 24 insertions(+), 17 deletions(-)

diff --git a/branch.c b/branch.c
index 8bf7588..f78a28b 100644
--- a/branch.c
+++ b/branch.c
@@ -304,6 +304,7 @@ void create_branch(const char *head,
 					   null_sha1, 0, !forcing, &err) ||
 		    ref_transaction_commit(transaction, msg, &err))
 			die("%s", err.buf);
+		ref_transaction_free(transaction);
 	}
 
 	if (real_ref && track)
diff --git a/builtin/commit.c b/builtin/commit.c
index c429216..6b888f2 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1726,6 +1726,7 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 		rollback_index_files();
 		die("%s", err.buf);
 	}
+	ref_transaction_free(transaction);
 
 	unlink(git_path("CHERRY_PICK_HEAD"));
 	unlink(git_path("REVERT_HEAD"));
diff --git a/builtin/replace.c b/builtin/replace.c
index e8932cd..af7f72d 100644
--- a/builtin/replace.c
+++ b/builtin/replace.c
@@ -164,6 +164,7 @@ static int replace_object_sha1(const char *object_ref,
 	    ref_transaction_commit(transaction, NULL, &err))
 		die("%s", err.buf);
 
+	ref_transaction_free(transaction);
 	return 0;
 }
 
diff --git a/builtin/tag.c b/builtin/tag.c
index b05f9a5..30b471c 100644
--- a/builtin/tag.c
+++ b/builtin/tag.c
@@ -708,6 +708,7 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 				   0, !is_null_sha1(prev), &err) ||
 	    ref_transaction_commit(transaction, NULL, &err))
 		die("%s", err.buf);
+	ref_transaction_free(transaction);
 	if (force && !is_null_sha1(prev) && hashcmp(prev, object))
 		printf(_("Updated tag '%s' (was %s)\n"), tag, find_unique_abbrev(prev, DEFAULT_ABBREV));
 
diff --git a/builtin/update-ref.c b/builtin/update-ref.c
index cdb71a8..4c2145e 100644
--- a/builtin/update-ref.c
+++ b/builtin/update-ref.c
@@ -373,6 +373,7 @@ int cmd_update_ref(int argc, const char **argv, const char *prefix)
 		update_refs_stdin();
 		if (ref_transaction_commit(transaction, msg, &err))
 			die("%s", err.buf);
+		ref_transaction_free(transaction);
 		return 0;
 	}
 
diff --git a/fast-import.c b/fast-import.c
index bac799c..6b186ce 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -1710,13 +1710,13 @@ static int update_branch(struct branch *b)
 	if (!transaction ||
 	    ref_transaction_update(transaction, b->name, b->sha1, old_sha1,
 				   0, 1, &err) ||
-	    (ref_transaction_commit(transaction, msg, &err) &&
-	     !(transaction = NULL))) {
+	    ref_transaction_commit(transaction, msg, &err)) {
 		ref_transaction_rollback(transaction);
 		error("%s", err.buf);
 		strbuf_release(&err);
 		return -1;
 	}
+	ref_transaction_free(transaction);
 	return 0;
 }
 
diff --git a/refs.c b/refs.c
index b4c7d04..016206b 100644
--- a/refs.c
+++ b/refs.c
@@ -3350,7 +3350,7 @@ struct ref_transaction *ref_transaction_begin(void)
 	return xcalloc(1, sizeof(struct ref_transaction));
 }
 
-static void ref_transaction_free(struct ref_transaction *transaction)
+void ref_transaction_free(struct ref_transaction *transaction)
 {
 	int i;
 
@@ -3451,10 +3451,10 @@ int update_ref(const char *action, const char *refname,
 	struct strbuf err = STRBUF_INIT;
 
 	t = ref_transaction_begin();
-	if ((!t ||
+	if (!t ||
 	    ref_transaction_update(t, refname, sha1, oldval, flags,
-				   !!oldval, &err)) ||
-	    (ref_transaction_commit(t, action, &err) && !(t = NULL))) {
+				   !!oldval, &err) ||
+	    ref_transaction_commit(t, action, &err)) {
 		const char *str = "update_ref failed for ref '%s': %s";
 
 		ref_transaction_rollback(t);
@@ -3468,6 +3468,7 @@ int update_ref(const char *action, const char *refname,
 		strbuf_release(&err);
 		return 1;
 	}
+	ref_transaction_free(t);
 	return 0;
 }
 
@@ -3502,10 +3503,8 @@ int ref_transaction_commit(struct ref_transaction *transaction,
 	int n = transaction->nr;
 	struct ref_update **updates = transaction->updates;
 
-	if (!n) {
-		ref_transaction_free(transaction);
+	if (!n)
 		return 0;
-	}
 
 	/* Allocate work space */
 	delnames = xmalloc(sizeof(*delnames) * n);
@@ -3572,7 +3571,6 @@ cleanup:
 		if (updates[i]->lock)
 			unlock_ref(updates[i]->lock);
 	free(delnames);
-	ref_transaction_free(transaction);
 	return ret;
 }
 
diff --git a/refs.h b/refs.h
index 2c2e694..608ca10 100644
--- a/refs.h
+++ b/refs.h
@@ -216,8 +216,8 @@ enum action_on_err {
 
 /*
  * Begin a reference transaction.  The reference transaction must
- * eventually be commited using ref_transaction_commit() or rolled
- * back using ref_transaction_rollback().
+ * eventually be freed by either calling ref_transaction_rollback()
+ * or ref_transaction_free().
  */
 struct ref_transaction *ref_transaction_begin(void);
 
@@ -285,13 +285,17 @@ int ref_transaction_delete(struct ref_transaction *transaction,
 /*
  * Commit all of the changes that have been queued in transaction, as
  * atomically as possible.  Return a nonzero value if there is a
- * problem.  The ref_transaction is freed by this function.
- * If err is non-NULL we will add an error string to it to explain why
- * the transaction failed. The string does not end in newline.
+ * problem. If err is non-NULL we will add an error string to it to explain
+ * why the transaction failed. The string does not end in newline.
  */
 int ref_transaction_commit(struct ref_transaction *transaction,
 			   const char *msg, struct strbuf *err);
 
+/*
+ * Free an existing transaction.
+ */
+void ref_transaction_free(struct ref_transaction *transaction);
+
 /** Lock a ref and then write its file */
 int update_ref(const char *action, const char *refname,
 		const unsigned char *sha1, const unsigned char *oldval,
diff --git a/sequencer.c b/sequencer.c
index e6b3bbc..f6f1536 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -286,14 +286,14 @@ static int fast_forward_to(const unsigned char *to, const unsigned char *from,
 	if (!transaction ||
 	    ref_transaction_update(transaction, "HEAD", to, from,
 				   0, !unborn, &err) ||
-	    (ref_transaction_commit(transaction, sb.buf, &err) &&
-	     !(transaction = NULL))) {
+	    ref_transaction_commit(transaction, sb.buf, &err)) {
 		ref_transaction_rollback(transaction);
 		error("%s", err.buf);
 		strbuf_release(&sb);
 		strbuf_release(&err);
 		return -1;
 	}
+	ref_transaction_free(transaction);
 
 	strbuf_release(&sb);
 	return 0;
-- 
2.0.0.rc3.477.gffe78a2