mutex stmt execution.

Signed-off-by: Jeff Ortel <[email protected]>

database/driver.go

@@ -147,9 +147,6 @@ func (c *Conn) BeginTx(ctx context.Context, opts driver.TxOptions) (tx driver.Tx
 
 // Prepare a statement.
 func (c *Conn) Prepare(query string) (stmt driver.Stmt, err error) {
-	if c.needsMutex(query) {
-		c.acquire()
-	}
 	stmt, err = c.wrapped.Prepare(query)
 	stmt = &Stmt{
 		conn:    c,
@@ -161,9 +158,6 @@ func (c *Conn) Prepare(query string) (stmt driver.Stmt, err error) {
 
 // PrepareContext prepares a statement with context.
 func (c *Conn) PrepareContext(ctx context.Context, query string) (stmt driver.Stmt, err error) {
-	if c.needsMutex(query) {
-		c.acquire()
-	}
 	if p, cast := c.wrapped.(driver.ConnPrepareContext); cast {
 		stmt, err = p.PrepareContext(ctx, query)
 	} else {
@@ -230,7 +224,6 @@ type Stmt struct {
 
 // Close the statement.
 func (s *Stmt) Close() (err error) {
-	defer s.conn.release()
 	err = s.wrapped.Close()
 	return
 }
@@ -243,12 +236,20 @@ func (s *Stmt) NumInput() (n int) {
 
 // Exec executes the statement.
 func (s *Stmt) Exec(args []driver.Value) (r driver.Result, err error) {
+	if s.needsMutex() {
+		s.conn.acquire()
+		defer s.conn.release()
+	}
 	r, err = s.wrapped.Exec(args)
 	return
 }
 
 // ExecContext executes the statement with context.
 func (s *Stmt) ExecContext(ctx context.Context, args []driver.NamedValue) (r driver.Result, err error) {
+	if s.needsMutex() {
+		s.conn.acquire()
+		defer s.conn.release()
+	}
 	if p, cast := s.wrapped.(driver.StmtExecContext); cast {
 		r, err = p.ExecContext(ctx, args)
 	} else {
@@ -259,12 +260,20 @@ func (s *Stmt) ExecContext(ctx context.Context, args []driver.NamedValue) (r dri
 
 // Query executes a query.
 func (s *Stmt) Query(args []driver.Value) (r driver.Rows, err error) {
+	if s.needsMutex() {
+		s.conn.acquire()
+		defer s.conn.release()
+	}
 	r, err = s.wrapped.Query(args)
 	return
 }
 
 // QueryContext executes a query.
 func (s *Stmt) QueryContext(ctx context.Context, args []driver.NamedValue) (r driver.Rows, err error) {
+	if s.needsMutex() {
+		s.conn.acquire()
+		defer s.conn.release()
+	}
 	if p, cast := s.wrapped.(driver.StmtQueryContext); cast {
 		r, err = p.QueryContext(ctx, args)
 	} else {
@@ -281,6 +290,12 @@ func (s *Stmt) values(named []driver.NamedValue) (out []driver.Value) {
 	return
 }
 
+// needsMutex returns true when the query should is a write operation.
+func (s *Stmt) needsMutex() (matched bool) {
+	matched = s.conn.needsMutex(s.query)
+	return
+}
+
 // Tx is a transaction.
 type Tx struct {
 	wrapped driver.Tx