Bug#53674: InnoDB: Error: unlock row could not find a 4 mode lock on the record

In semi-consistent read, only unlock freshly locked non-matching records.

lock_rec_lock_fast(): Return LOCK_REC_SUCCESS,
LOCK_REC_SUCCESS_CREATED, or LOCK_REC_FAIL instead of TRUE/FALSE.

enum db_err: Add DB_SUCCESS_LOCKED_REC for indicating a successful
operation where a record lock was created.

lock_sec_rec_read_check_and_lock(),
lock_clust_rec_read_check_and_lock(), lock_rec_enqueue_waiting(),
lock_rec_lock_slow(), lock_rec_lock(), row_ins_set_shared_rec_lock(),
row_ins_set_exclusive_rec_lock(), sel_set_rec_lock(),
row_sel_get_clust_rec_for_mysql(): Return DB_SUCCESS_LOCKED_REC if a
new record lock was created. Adjust callers.

row_unlock_for_mysql(): Correct the function documentation.

row_prebuilt_t::new_rec_locks: Correct the documentation.

3 files changed, 35 insertions, 33 deletions

diff --git a/storage/innodb_plugin/include/db0err.h b/storage/innodb_plugin/include/db0err.h
index 747e9b5364e..c841c2b4afe 100644
--- a/storage/innodb_plugin/include/db0err.h
+++ b/storage/innodb_plugin/include/db0err.h
@@ -28,6 +28,8 @@ Created 5/24/1996 Heikki Tuuri
 
 
 enum db_err {
+	DB_SUCCESS_LOCKED_REC = 9,	/*!< like DB_SUCCESS, but a new
+					explicit record lock was created */
 	DB_SUCCESS = 10,
 
 	/* The following are error codes */
diff --git a/storage/innodb_plugin/include/lock0lock.h b/storage/innodb_plugin/include/lock0lock.h
index 7d76cbe3c75..b3e1e5c4537 100644
--- a/storage/innodb_plugin/include/lock0lock.h
+++ b/storage/innodb_plugin/include/lock0lock.h
@@ -340,11 +340,12 @@ lock_sec_rec_modify_check_and_lock(
 	que_thr_t*	thr,	/*!< in: query thread */
 	mtr_t*		mtr);	/*!< in/out: mini-transaction */
 /*********************************************************************//**
-Like the counterpart for a clustered index below, but now we read a
+Like lock_clust_rec_read_check_and_lock(), but reads a
 secondary index record.
-@return	DB_SUCCESS, DB_LOCK_WAIT, DB_DEADLOCK, or DB_QUE_THR_SUSPENDED */
+@return	DB_SUCCESS, DB_SUCCESS_LOCKED_REC, DB_LOCK_WAIT, DB_DEADLOCK,
+or DB_QUE_THR_SUSPENDED */
 UNIV_INTERN
-ulint
+enum db_err
 lock_sec_rec_read_check_and_lock(
 /*=============================*/
 	ulint			flags,	/*!< in: if BTR_NO_LOCKING_FLAG
@@ -371,9 +372,10 @@ if the query thread should anyway be suspended for some reason; if not, then
 puts the transaction and the query thread to the lock wait state and inserts a
 waiting request for a record lock to the lock queue. Sets the requested mode
 lock on the record.
-@return	DB_SUCCESS, DB_LOCK_WAIT, DB_DEADLOCK, or DB_QUE_THR_SUSPENDED */
+@return	DB_SUCCESS, DB_SUCCESS_LOCKED_REC, DB_LOCK_WAIT, DB_DEADLOCK,
+or DB_QUE_THR_SUSPENDED */
 UNIV_INTERN
-ulint
+enum db_err
 lock_clust_rec_read_check_and_lock(
 /*===============================*/
 	ulint			flags,	/*!< in: if BTR_NO_LOCKING_FLAG
diff --git a/storage/innodb_plugin/include/row0mysql.h b/storage/innodb_plugin/include/row0mysql.h
index e90742abe7c..39ea240772c 100644
--- a/storage/innodb_plugin/include/row0mysql.h
+++ b/storage/innodb_plugin/include/row0mysql.h
@@ -264,27 +264,26 @@ row_update_for_mysql(
 	row_prebuilt_t*	prebuilt);	/*!< in: prebuilt struct in MySQL
 					handle */
 /*********************************************************************//**
-This can only be used when srv_locks_unsafe_for_binlog is TRUE or
-session is using a READ COMMITTED isolation level. Before
-calling this function we must use trx_reset_new_rec_lock_info() and
-trx_register_new_rec_lock() to store the information which new record locks
-really were set. This function removes a newly set lock under prebuilt->pcur,
-and also under prebuilt->clust_pcur. Currently, this is only used and tested
-in the case of an UPDATE or a DELETE statement, where the row lock is of the
-LOCK_X type.
-Thus, this implements a 'mini-rollback' that releases the latest record
-locks we set.
-@return	error code or DB_SUCCESS */
+This can only be used when srv_locks_unsafe_for_binlog is TRUE or this
+session is using a READ COMMITTED or READ UNCOMMITTED isolation level.
+Before calling this function row_search_for_mysql() must have
+initialized prebuilt->new_rec_locks to store the information which new
+record locks really were set. This function removes a newly set
+clustered index record lock under prebuilt->pcur or
+prebuilt->clust_pcur.  Thus, this implements a 'mini-rollback' that
+releases the latest clustered index record lock we set.
+@return error code or DB_SUCCESS */
 UNIV_INTERN
 int
 row_unlock_for_mysql(
 /*=================*/
-	row_prebuilt_t*	prebuilt,	/*!< in: prebuilt struct in MySQL
+	row_prebuilt_t*	prebuilt,	/*!< in/out: prebuilt struct in MySQL
 					handle */
-	ibool		has_latches_on_recs);/*!< TRUE if called so that we have
-					the latches on the records under pcur
-					and clust_pcur, and we do not need to
-					reposition the cursors. */
+	ibool		has_latches_on_recs);/*!< in: TRUE if called
+					so that we have the latches on
+					the records under pcur and
+					clust_pcur, and we do not need
+					to reposition the cursors. */
 /*********************************************************************//**
 Creates an query graph node of 'update' type to be used in the MySQL
 interface.
@@ -702,18 +701,17 @@ struct row_prebuilt_struct {
 	ulint		new_rec_locks;	/*!< normally 0; if
 					srv_locks_unsafe_for_binlog is
 					TRUE or session is using READ
-					COMMITTED isolation level, in a
-					cursor search, if we set a new
-					record lock on an index, this is
-					incremented; this is used in
-					releasing the locks under the
-					cursors if we are performing an
-					UPDATE and we determine after
-					retrieving the row that it does
-					not need to be locked; thus,
-					these can be used to implement a
-					'mini-rollback' that releases
-					the latest record locks */
+					COMMITTED or READ UNCOMMITTED
+					isolation level, set in
+					row_search_for_mysql() if we set a new
+					record lock on the secondary
+					or clustered index; this is
+					used in row_unlock_for_mysql()
+					when releasing the lock under
+					the cursor if we determine
+					after retrieving the row that
+					it does not need to be locked
+					('mini-rollback') */
 	ulint		mysql_prefix_len;/*!< byte offset of the end of
 					the last requested column */
 	ulint		mysql_row_len;	/*!< length in bytes of a row in the