[PATCHv12 04/10] receive-pack.c: move transaction handling in a central place

[Stefan Beller <sbeller@google.com>]

This moves all code related to transactions into the
execute_commands_non_atomic function. This includes
beginning and committing the transaction as well as
dealing with the errors which may occur during the
begin and commit phase of a transaction.

No functional changes intended.

Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
---

Notes:
    v10, v11, v12:
     no changes
    
    v9:
     This was split up into the patch before and this one.
     This patch only deals with the transactions now.
    
    v8:
     move execute_commands_loop before execute_commands, so it compiles/links
     without warnings.
    
    v7:
     new in v7, this is part of the previous "[PATCH 4/7]
     receive-pack.c: receive-pack.c: use a single ref_transaction for atomic pushes"
    
    This covers the suggestion of patch 2 and 3 by Eric
    > patch 2: Factor out the main 'for' loop of execute_commands() into a
    > new function. This new function will eventually become
    > execute_commands_non_atomic(). At this point, execute_commands() is
    > pretty much in its final form with the exception of the upcoming 'if
    > (use_atomic)' conditional.
    > patch 3: Morph the function extracted in patch 2 into
    > execute_commands_non_atomic() by adding transaction handling inside
    > the 'for' loop (and applying the changes from the early part of the
    > patch which go along with that).

 builtin/receive-pack.c | 51 ++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 37 insertions(+), 14 deletions(-)

diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index 0ccfb3d..96e56a7 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -66,6 +66,7 @@ static const char *NONCE_SLOP = "SLOP";
 static const char *nonce_status;
 static long nonce_stamp_slop;
 static unsigned long nonce_stamp_slop_limit;
+static struct ref_transaction *transaction;
 
 static enum deny_action parse_deny_action(const char *var, const char *value)
 {
@@ -821,6 +822,7 @@ static const char *update(struct command *cmd, struct shallow_info *si)
 	}
 
 	if (is_null_sha1(new_sha1)) {
+		struct strbuf err = STRBUF_INIT;
 		if (!parse_object(old_sha1)) {
 			old_sha1 = NULL;
 			if (ref_exists(name)) {
@@ -830,35 +832,36 @@ static const char *update(struct command *cmd, struct shallow_info *si)
 				cmd->did_not_exist = 1;
 			}
 		}
-		if (delete_ref(namespaced_name, old_sha1, 0)) {
-			rp_error("failed to delete %s", name);
+		if (ref_transaction_delete(transaction,
+					   namespaced_name,
+					   old_sha1,
+					   0, old_sha1 != NULL,
+					   "push", &err)) {
+			rp_error("%s", err.buf);
+			strbuf_release(&err);
 			return "failed to delete";
 		}
+		strbuf_release(&err);
 		return NULL; /* good */
 	}
 	else {
 		struct strbuf err = STRBUF_INIT;
-		struct ref_transaction *transaction;
-
 		if (shallow_update && si->shallow_ref[cmd->index] &&
 		    update_shallow_ref(cmd, si))
 			return "shallow error";
 
-		transaction = ref_transaction_begin(&err);
-		if (!transaction ||
-		    ref_transaction_update(transaction, namespaced_name,
-					   new_sha1, old_sha1, 0, 1, "push",
-					   &err) ||
-		    ref_transaction_commit(transaction, &err)) {
-			ref_transaction_free(transaction);
-
+		if (ref_transaction_update(transaction,
+					   namespaced_name,
+					   new_sha1, old_sha1,
+					   0, 1, "push",
+					   &err)) {
 			rp_error("%s", err.buf);
 			strbuf_release(&err);
+
 			return "failed to update ref";
 		}
-
-		ref_transaction_free(transaction);
 		strbuf_release(&err);
+
 		return NULL; /* good */
 	}
 }
@@ -1068,12 +1071,32 @@ static void execute_commands_non_atomic(struct command *commands,
 					struct shallow_info *si)
 {
 	struct command *cmd;
+	struct strbuf err = STRBUF_INIT;
+
 	for (cmd = commands; cmd; cmd = cmd->next) {
 		if (!should_process_cmd(cmd))
 			continue;
 
+		transaction = ref_transaction_begin(&err);
+		if (!transaction) {
+			rp_error("%s", err.buf);
+			strbuf_reset(&err);
+			cmd->error_string = "transaction failed to start";
+			continue;
+		}
+
 		cmd->error_string = update(cmd, si);
+
+		if (!cmd->error_string
+		    && ref_transaction_commit(transaction, &err)) {
+			rp_error("%s", err.buf);
+			strbuf_reset(&err);
+			cmd->error_string = "failed to update ref";
+		}
+		ref_transaction_free(transaction);
 	}
+
+	strbuf_release(&err);
 }
 
 static void execute_commands(struct command *commands,
-- 
2.2.1.62.g3f15098