[Tarantool-patches] [PATCH 2/4] xrow: add ability to encode/decode ROLLBACK requests

[Serge Petrenko <sergepetrenko@tarantool.org>]

ROLLBACK request contains the same data as CONFIRM request.
The only difference is the request semantics. While a CONFIRM request
releases all the limbo entries up to the given lsn, the ROLLBACK request
rolls back all the entries with lsn greater than given one.

Part-of #4848
---
 src/box/iproto_constants.h |  9 +++++++++
 src/box/xrow.c             | 38 ++++++++++++++++++++++++++++++++++----
 src/box/xrow.h             | 23 +++++++++++++++++++++++
 3 files changed, 66 insertions(+), 4 deletions(-)

diff --git a/src/box/iproto_constants.h b/src/box/iproto_constants.h
index 1466b456f..45c8af236 100644
--- a/src/box/iproto_constants.h
+++ b/src/box/iproto_constants.h
@@ -221,6 +221,8 @@ enum iproto_type {
 
 	/** A confirmation message for synchronous transactions. */
 	IPROTO_CONFIRM = 40,
+	/** A rollback message for synchronous transactions. */
+	IPROTO_ROLLBACK = 41,
 
 	/** PING request */
 	IPROTO_PING = 64,
@@ -337,6 +339,13 @@ iproto_type_is_request(uint32_t type)
 	return type > IPROTO_OK && type <= IPROTO_TYPE_STAT_MAX;
 }
 
+/** CONFIRM/ROLLBACK entries for synchronous replication. */
+static inline bool
+iproto_type_is_synchro_request(uint32_t type)
+{
+	return type == IPROTO_CONFIRM || type == IPROTO_ROLLBACK;
+}
+
 /**
  * The request is "synchronous": no other requests
  * on this connection should be taken before this one
diff --git a/src/box/xrow.c b/src/box/xrow.c
index 896e001b7..7a79a18dd 100644
--- a/src/box/xrow.c
+++ b/src/box/xrow.c
@@ -879,7 +879,8 @@ xrow_encode_dml(const struct request *request, struct region *region,
 }
 
 int
-xrow_encode_confirm(struct xrow_header *row, uint32_t replica_id, int64_t lsn)
+xrow_encode_confirm_rollback(struct xrow_header *row, uint32_t replica_id,
+			     int64_t lsn)
 {
 	size_t len = mp_sizeof_map(2) + mp_sizeof_uint(IPROTO_REPLICA_ID) +
 		     mp_sizeof_uint(replica_id) + mp_sizeof_uint(IPROTO_LSN) +
@@ -903,13 +904,32 @@ xrow_encode_confirm(struct xrow_header *row, uint32_t replica_id, int64_t lsn)
 	row->body[0].iov_len = len;
 	row->bodycnt = 1;
 
-	row->type = IPROTO_CONFIRM;
-
 	return 0;
 }
 
 int
-xrow_decode_confirm(struct xrow_header *row, uint32_t *replica_id, int64_t *lsn)
+xrow_encode_confirm(struct xrow_header *row, uint32_t replica_id, int64_t lsn)
+{
+	int res = xrow_encode_confirm_rollback(row, replica_id, lsn);
+	if (res == 0) {
+		row->type = IPROTO_CONFIRM;
+	}
+	return res;
+}
+
+int
+xrow_encode_rollback(struct xrow_header *row, uint32_t replica_id, int64_t lsn)
+{
+	int res = xrow_encode_confirm_rollback(row, replica_id, lsn);
+	if (res == 0) {
+		row->type = IPROTO_ROLLBACK;
+	}
+	return res;
+}
+
+int
+xrow_decode_confirm_rollback(struct xrow_header *row, uint32_t *replica_id,
+			     int64_t *lsn)
 {
 	if (row->bodycnt == 0) {
 		diag_set(ClientError, ER_INVALID_MSGPACK, "request body");
@@ -956,6 +976,16 @@ xrow_decode_confirm(struct xrow_header *row, uint32_t *replica_id, int64_t *lsn)
 	return 0;
 }
 
+int xrow_decode_confirm(struct xrow_header *row, uint32_t *replica_id, int64_t *lsn)
+{
+	return xrow_decode_confirm_rollback(row, replica_id, lsn);
+}
+
+int xrow_decode_rollback(struct xrow_header *row, uint32_t *replica_id, int64_t *lsn)
+{
+	return xrow_decode_confirm_rollback(row, replica_id, lsn);
+}
+
 int
 xrow_to_iovec(const struct xrow_header *row, struct iovec *out)
 {
diff --git a/src/box/xrow.h b/src/box/xrow.h
index 027b6b14f..1def394e7 100644
--- a/src/box/xrow.h
+++ b/src/box/xrow.h
@@ -230,6 +230,29 @@ xrow_encode_confirm(struct xrow_header *row, uint32_t replica_id, int64_t lsn);
 int
 xrow_decode_confirm(struct xrow_header *row, uint32_t *replica_id, int64_t *lsn);
 
+/**
+ * Encode the ROLLBACK row body and set row type to
+ * IPROTO_ROLLBACK.
+ * @param row xrow header.
+ * @param replica_id master's instance id.
+ * @param lsn lsn to rollback to.
+ * @retval -1  on error.
+ * @retval 0 success.
+ */
+int
+xrow_encode_rollback(struct xrow_header *row, uint32_t replica_id, int64_t lsn);
+
+/**
+ * Decode the ROLLBACK row body.
+ * @param row xrow header.
+ * @param[out] replica_id master's instance id.
+ * @param[out] lsn lsn to rollback to.
+ * @retval -1 on error.
+ * @retval 0 success.
+ */
+int
+xrow_decode_rollback(struct xrow_header *row, uint32_t *replica_id, int64_t *lsn);
+
 /**
  * CALL/EVAL request.
  */
-- 
2.24.3 (Apple Git-128)