Disconnect slave when pos is UNSAFE

Disconnect slave when pos is UNSAFE instead of sending an error that
stops the replication

server/modules/include/blr.h

@@ -180,6 +180,10 @@
 /* string len for master registration query  */
 #define BLRM_MASTER_REGITRATION_QUERY_LEN	255
 
+/* Read Binlog position states */
+#define SLAVE_POS_READ_OK			0x0
+#define SLAVE_POS_READ_ERR			0xff
+#define SLAVE_POS_READ_UNSAFE			0xfe
 /**
  * Some useful macros for examining the MySQL Response packets
  */

server/modules/routing/binlog/blr_file.c

@@ -419,7 +419,7 @@ struct	stat	statb;
 	memset(&hdbuf, '\0', BINLOG_EVENT_HDR_LEN);
 
 	/* set error indicator */
-	hdr->ok = 0xff;
+	hdr->ok = SLAVE_POS_READ_ERR;
 
 	if (!file)
 	{
@@ -428,6 +428,11 @@ struct	stat	statb;
 	}
 	if (fstat(file->fd, &statb) == 0)
 		filelen = statb.st_size;
+	else
+	{
+		snprintf(errmsg, BINLOG_ERROR_MSG_LEN, "Invalide size for binlog file '%s', pos %lu", file->binlogname, pos);
+		return NULL;
+	}
 
 	if (pos > filelen)
 	{
@@ -440,11 +445,12 @@ struct	stat	statb;
 	{
 		if (pos > router->binlog_position)
 		{
-			snprintf(errmsg, BINLOG_ERROR_MSG_LEN, "Requested position %lu is not available. Latest safe position %lu, end of binlog '%s' is %lu",
+			/* Unsafe position, slave will be disconnected by the calling routine */
-				pos, router->binlog_position, file->binlogname, router->current_pos);
+			snprintf(errmsg, BINLOG_ERROR_MSG_LEN, "Requested binlog position %lu. Position is unsafe so disconnecting. Latest safe position %lu, end of binlog file %lu", pos, router->binlog_position, router->current_pos);
+			hdr->ok = SLAVE_POS_READ_UNSAFE;
 		} else {
 			/* accessing last position is ok */
-			hdr->ok = 0x0;
+			hdr->ok = SLAVE_POS_READ_OK;
 		}
 
 		return NULL;
@@ -461,7 +467,7 @@ struct	stat	statb;
 				file->binlogname, pos)));
 
 			/* set ok indicator */
-			hdr->ok = 0x0;
+			hdr->ok = SLAVE_POS_READ_OK;
 
 			break;
 		case -1:
@@ -529,7 +535,7 @@ struct	stat	statb;
 					pos)));
 
 				/* set ok indicator */
-				hdr->ok = 0x0;
+				hdr->ok = SLAVE_POS_READ_OK;
 
 				break;
 			case -1:
@@ -615,7 +621,7 @@ struct	stat	statb;
 	}
 
 	/* set OK indicator */
-	hdr->ok = 0x0;
+	hdr->ok = SLAVE_POS_READ_OK;
 
 	return result;
 }

server/modules/routing/binlog/blr_slave.c

@@ -2048,9 +2048,10 @@ char read_errmsg[BINLOG_ERROR_MSG_LEN+1];
 	if (record == NULL) {
 		slave->stats.n_failed_read++;
 
-                if (hdr.ok == 0xff) {
+                if (hdr.ok == SLAVE_POS_READ_ERR) {
 			LOGIF(LE, (skygw_log_write(LOGFILE_ERROR,
-				"Slave %s:%i, server-id %d, binlog '%s', blr_read_binlog failure: %s",
+				"%s Slave %s:%i, server-id %d, binlog '%s', %s",
+				router->service->name,
 				slave->dcb->remote,
 				slave->port,
 				slave->serverid,
@@ -2063,12 +2064,37 @@ char read_errmsg[BINLOG_ERROR_MSG_LEN+1];
 
                         spinlock_release(&slave->catch_lock);
 
+			/*
+			 * Send an error that will stop slave replication
+			 */
                         blr_send_custom_error(slave->dcb, slave->seqno++, 0, read_errmsg, "HY000", 1236);
 
                         dcb_close(slave->dcb);
 
                         return 0;
                 }
+
+		if (hdr.ok == SLAVE_POS_READ_UNSAFE) {
+
+			ROUTER_OBJECT *router_obj= router->service->router;
+
+			LOGIF(LE, (skygw_log_write(LOGFILE_ERROR,
+				"%s: Slave %s:%i, server-id %d, binlog '%s', %s",
+				router->service->name,
+				slave->dcb->remote,
+				slave->port,
+				slave->serverid,
+				slave->binlogfile,
+				read_errmsg)));
+
+			/*
+			 * Close the slave session and socket
+			 * The slave will try to reconnect
+			 */
+			router_obj->closeSession(router->service->router_instance, slave);
+
+			return 0;
+		}
 	}
 	spinlock_acquire(&slave->catch_lock);
 	slave->cstate &= ~CS_BUSY;
@@ -2120,17 +2146,21 @@ char read_errmsg[BINLOG_ERROR_MSG_LEN+1];
 			if (slave->stats.n_caughtup == 1)
 			{
 				LOGIF(LM, (skygw_log_write(LOGFILE_MESSAGE,
-					"%s: Slave %s is up to date %s, %lu.",
+					"%s: Slave %s:%d, server-id %d is up to date '%s', position %lu.",
 					router->service->name,
 					slave->dcb->remote,
+					slave->port,
+					slave->serverid,
 					slave->binlogfile, (unsigned long)slave->binlog_pos)));
 			}
 			else if ((slave->stats.n_caughtup % 50) == 0)
 			{
 				LOGIF(LM, (skygw_log_write(LOGFILE_MESSAGE,
-					"%s: Slave %s is up to date %s, %lu.",
+					"%s: Slave %s:%d, server-id %d is up to date '%s', position %lu.",
 					router->service->name,
 					slave->dcb->remote,
+					slave->port,
+					slave->serverid,
 					slave->binlogfile, (unsigned long)slave->binlog_pos)));
 			}
 		}
@@ -2348,7 +2378,7 @@ char err_msg[BINLOG_ERROR_MSG_LEN+1];
 		return;
 	if ((record = blr_read_binlog(router, file, 4, &hdr, err_msg)) == NULL)
 	{
-		if (hdr.ok == 0xff) {
+		if (hdr.ok != SLAVE_POS_READ_OK) {
 			LOGIF(LE, (skygw_log_write(LOGFILE_ERROR,
 				"Slave %s:%i, server-id %d, binlog '%s', blr_read_binlog failure: %s",
 				slave->dcb->remote,