[Tarantool-patches] [PATCH 09/16] tx: introduce prepare sequence number

[Aleksandr Lyapunov <alyapunov@tarantool.org>]

---
 src/box/txn.c | 4 ++++
 src/box/txn.h | 5 +++++
 2 files changed, 9 insertions(+)

diff --git a/src/box/txn.c b/src/box/txn.c
index 0ba86cb..5964ca7 100644
--- a/src/box/txn.c
+++ b/src/box/txn.c
@@ -39,6 +39,8 @@
 
 struct tx_manager
 {
+	/** Last prepare-sequence-number that was assigned to preped TX. */
+	int64_t last_psn;
 };
 
 static struct tx_manager txm;
@@ -564,6 +566,8 @@ txn_journal_entry_new(struct txn *txn)
 static int
 txn_prepare(struct txn *txn)
 {
+	txn->psn = ++txm.last_psn;
+
 	if (txn_has_flag(txn, TXN_IS_ABORTED_BY_YIELD)) {
 		assert(!txn_has_flag(txn, TXN_CAN_YIELD));
 		diag_set(ClientError, ER_TRANSACTION_YIELD);
diff --git a/src/box/txn.h b/src/box/txn.h
index e2194b6..cd1665f 100644
--- a/src/box/txn.h
+++ b/src/box/txn.h
@@ -214,6 +214,11 @@ struct txn {
 	 * Valid IDs start from 1.
 	 */
 	int64_t id;
+	/**
+	 * A sequential ID that is assigned when the TX become prepared.
+	 * Transactions are committed on in that order.
+	 */
+	int64_t psn;
 	/** Status of the TX */
 	enum txn_status status;
 	/** List of statements in a transaction. */
-- 
2.7.4