Added the backend delayq: this will assure incoming data are queued before mysql backend connection is complete

After connection data will be written to backend

include/dcb.h

@@ -132,6 +132,8 @@ typedef struct dcb {
 
 	SPINLOCK	writeqlock;	/**< Write Queue spinlock */
 	GWBUF		*writeq;	/**< Write Data Queue */
+	SPINLOCK	delayqlock;	/**< Delay Backend Write Queue spinlock */
+	GWBUF		*delayq;	/**< Delay Backend Write Data Queue */
 
 	DCBSTATS	stats;		/**< DCB related statistics */
 

modules/protocol/mysql_backend.c

@@ -704,3 +704,25 @@ int gw_mysql_connect(char *host, int port, char *dbname, char *user, uint8_t *pa
 
 }
 
+/**
+ * This routine writes the delayq via dcb_write
+ * The dcb->delayq contains data received from the client before
+ * mysql backend authentication succeded
+ *
+ * @param dcb The current backend DCB
+ * @return The dcb_write status
+ */
+static int backend_write_delayqueue(DCB *dcb)
+{
+        GWBUF *localq = NULL;
+
+        spinlock_acquire(&dcb->delayqlock);
+
+        localq = dcb->delayq;
+        dcb->delayq = NULL;
+
+        spinlock_release(&dcb->delayqlock);
+
+        return dcb_write(dcb, localq);
+}
+/////