Modifications to galera monitor to control whether selection of master is wanted.

.gitignore

@@ -34,3 +34,4 @@ depend.mk
 
 # Vi swap files
 .*.swp
+/build/

Documentation/Getting-Started/Configuration-Guide.md

@@ -440,6 +440,7 @@ backend_write_timeout=2
 # galeramon specific options
 disable_master_failback=0
 available_when_donor=0
+disable_master_role_setting=0
 ```
 
 #### `module`
@@ -510,6 +511,13 @@ This option if set to 1 will allow Galera monitor to keep a node in `Donor` stat
 
 As xtrabackup is a non-locking SST method, a node in `Donor` status can still be considered in sync. This option is not enabled by default and should be used as the administrator's discretion.
 
+#### `disable_master_role_setting`
+
+This option if set to 1 will stop the Galera monitor from setting the status of
+backend servers to master or slave.  It is applicable when the Galera router is
+being used to spread writes across multiple nodes, so that no server is to be
+nominated as the master.
+
 #### `backend_connect_timeout`
 
 This option, with default value of `3` sets the monitor connect timeout to backends.
@@ -1367,11 +1375,11 @@ Example:
 ```
 [Galera Listener]
 type=listener
-address=192.1681.3.33
+address=192.168.3.33
 port=4408
 socket=/servers/maxscale/galera.sock
 ```
 
-TCP/IP Traffic must be permitted to 192.1681.3.33 port 4408
+TCP/IP Traffic must be permitted to 192.168.3.33 port 4408
 
 For Unix socket, the socket file path (example: `/servers/maxscale/galera.sock`) must be writable by the Unix user MaxScale runs as.

server/core/config.c

@@ -43,6 +43,7 @@
  * 20/02/15	Markus Mäkelä		Added connection_timeout parameter for services
  * 05/03/15	Massimiliano	Pinto	Added notification_feedback support
  * 20/04/15	Guillaume Lefranc	Added available_when_donor parameter
+ * 22/04/15     Martin Brampton         Added disable_master_role_setting parameter
  *
  * @endverbatim
  */
@@ -1895,6 +1896,7 @@ static char *monitor_params[] =
 		"backend_read_timeout",
 		"backend_write_timeout",
 		"available_when_donor",
+                "disable_master_role_setting",
                 NULL
         };
 /**

server/modules/monitor/galera_mon.c

@@ -160,6 +160,7 @@ CONFIG_PARAMETER* params = (CONFIG_PARAMETER*)opt;
 		handle->interval = MONITOR_INTERVAL;
 		handle->disableMasterFailback = 0;
 		handle->availableWhenDonor = 0;
+                handle->disableMasterRoleSetting = 0;
 		handle->master = NULL;
 		handle->connect_timeout=DEFAULT_CONNECT_TIMEOUT;
 		handle->read_timeout=DEFAULT_READ_TIMEOUT;
@@ -172,8 +173,10 @@ CONFIG_PARAMETER* params = (CONFIG_PARAMETER*)opt;
 	{
 	    if(!strcmp(params->name,"disable_master_failback"))
 		handle->disableMasterFailback = config_truth_value(params->value);
-	    if(!strcmp(params->name,"available_when_donor"))
+	    else if(!strcmp(params->name,"available_when_donor"))
 		handle->availableWhenDonor = config_truth_value(params->value);
+	    else if(!strcmp(params->name,"disable_master_role_setting"))
+		handle->disableMasterRoleSetting = config_truth_value(params->value);
 	    params = params->next;
 	}
 
@@ -294,6 +297,7 @@ char		*sep;
 	dcb_printf(dcb,"\tSampling interval:\t%lu milliseconds\n", handle->interval);
 	dcb_printf(dcb,"\tMaster Failback:\t%s\n", (handle->disableMasterFailback == 1) ? "off" : "on");
 	dcb_printf(dcb,"\tAvailable when Donor:\t%s\n", (handle->availableWhenDonor == 1) ? "on" : "off");
+	dcb_printf(dcb,"\tMaster Role Setting Disabled:\t%s\n", (handle->disableMasterRoleSetting == 1) ? "on" : "off");
 	dcb_printf(dcb,"\tConnect Timeout:\t%i seconds\n", handle->connect_timeout);
 	dcb_printf(dcb,"\tRead Timeout:\t\t%i seconds\n", handle->read_timeout);
 	dcb_printf(dcb,"\tWrite Timeout:\t\t%i seconds\n", handle->write_timeout);
@@ -596,40 +600,47 @@ int			log_no_members = 1;
 		 * Decision depends on master_stickiness value set in configuration
 		 */
 
-		/* get the candidate master, followinf MIN(node_id) rule */
+		/* get the candidate master, following MIN(node_id) rule */
 		candidate_master = get_candidate_master(handle->databases);
 
 		/* Select the master, based on master_stickiness */
-		handle->master = set_cluster_master(handle->master, candidate_master, master_stickiness);
+                if (1 == handle->disableMasterRoleSetting) {
+                    handle->master = NULL;
+                }
+                else {
+                    handle->master = set_cluster_master(handle->master, candidate_master, master_stickiness);
+                }
 
 		ptr = handle->databases;
 
-		while (ptr && handle->master) {
+		while (ptr) {
 			if (!SERVER_IS_JOINED(ptr->server) || SERVER_IN_MAINT(ptr->server)) {
 				ptr = ptr->next;
 				continue;
 			}
 
-			if (ptr != handle->master) {
+                        if (handle->master) {
+                            if (ptr != handle->master) {
 				/* set the Slave role */
 				server_set_status(ptr->server, SERVER_SLAVE);
 				server_clear_status(ptr->server, SERVER_MASTER);
 
-				/* clear master stickyness */
+				/* clear master stickiness */
 				server_clear_status(ptr->server, SERVER_MASTER_STICKINESS);
-			} else {
+                            } else {
 				/* set the Master role */
 				server_set_status(handle->master->server, SERVER_MASTER);
 				server_clear_status(handle->master->server, SERVER_SLAVE);
 
 				if (candidate_master && handle->master->server->node_id != candidate_master->server->node_id) {
-					/* set master stickyness */
+					/* set master stickiness */
 					server_set_status(handle->master->server, SERVER_MASTER_STICKINESS);
 				} else {
-					/* clear master stickyness */
+					/* clear master stickiness */
 					server_clear_status(ptr->server, SERVER_MASTER_STICKINESS);
 				}			
-			}
+                            }
+                        }
 
 			is_cluster++;
 

server/modules/monitor/mysqlmon.h

@@ -35,7 +35,8 @@
  * 28/08/14	Massimiliano	Pinto	Addition of detectStaleMaster
  * 30/10/14	Massimiliano	Pinto	Addition of disableMasterFailback
  * 07/11/14	Massimiliano	Pinto	Addition of NetworkTimeout: connect, read, write
- * 20/05/15	Guillaume Lefranc	Addition of availableWhenDonor
+ * 20/04/15	Guillaume Lefranc	Addition of availableWhenDonor
+ * 22/04/15     Martin Brampton         Addition of disableMasterRoleSetting
  *
  * @endverbatim
  */
@@ -70,6 +71,7 @@ typedef struct {
 	int	detectStaleMaster;	/**< Monitor flag for MySQL replication Stale Master detection */
 	int	disableMasterFailback;	/**< Monitor flag for Galera Cluster Master failback */
 	int	availableWhenDonor;	/**< Monitor flag for Galera Cluster Donor availability */
+        int     disableMasterRoleSetting; /**< Monitor flag to disable setting master role */
 	MONITOR_SERVERS *master;	/**< Master server for MySQL Master/Slave replication */
 	MONITOR_SERVERS	*databases;     /**< Linked list of servers to monitor */
 	int	connect_timeout;	/**< Connect timeout in seconds for mysql_real_connect */

server/modules/routing/schemarouter/schemarouter.c

@@ -243,24 +243,23 @@ static int hashcmpfun(
 /**
  * Convert a length encoded string into a C string.
  * @param data Pointer to the first byte of the string
- * @param len Pointer to an integer where the length of the string will be stored. On errors this will be set to -1.
  * @return Pointer to the newly allocated string or NULL if the value is NULL or an error occurred
  */
-char* get_lenenc_str(void* data, int* len)
+char* get_lenenc_str(void* data)
 {
     unsigned char* ptr = (unsigned char*)data;
     char* rval;
-    long size, offset;
+    uintptr_t size;
+    long offset;
 
-    if(data == NULL || len == NULL)
+    if(data == NULL)
     {
-	*len = -1;
         return NULL;
     }
 
     if(*ptr < 251)
     {
-        size = *ptr;
+        size = (uintptr_t)*ptr;
         offset = 1;
     }
     else
@@ -268,7 +267,6 @@ char* get_lenenc_str(void* data, int* len)
         switch(*(ptr))
         {
         case 0xfb:
-            *len = 1;
             return NULL;
         case 0xfc:
             size = *(ptr + 1) + (*(ptr + 2) << 8);
@@ -280,8 +278,8 @@ char* get_lenenc_str(void* data, int* len)
             break;
         case 0xfe:
             size = *ptr + ((*(ptr + 2) << 8)) + (*(ptr + 3) << 16) +
-                    (*(ptr + 4) << 24) + (*(ptr + 5) << 32) + (*(ptr + 6) << 40) +
+                    (*(ptr + 4) << 24) + ((uintptr_t)*(ptr + 5) << 32) + ((uintptr_t)*(ptr + 6) << 40) +
-                    (*(ptr + 7) << 48) + (*(ptr + 8) << 56);
+                    ((uintptr_t)*(ptr + 7) << 48) + ((uintptr_t)*(ptr + 8) << 56);
             offset = 8;
             break;
         default:
@@ -297,7 +295,6 @@ char* get_lenenc_str(void* data, int* len)
         memset(rval + size,0,1);
 
     }
-    *len = size + offset;
     return rval;
 }
 
@@ -360,8 +357,7 @@ bool parse_showdb_response(ROUTER_CLIENT_SES* rses, backend_ref_t* bref, GWBUF**
        {
 	   int payloadlen = gw_mysql_get_byte3(ptr);
 	   int packetlen = payloadlen + 4;
-	   int len = 0;
+	   char* data = get_lenenc_str(ptr+4);
-	   char* data = get_lenenc_str(ptr+4,&len);
 
 	   if(data)
 	   {

server/modules/routing/schemarouter/shardrouter.c

@@ -262,25 +262,23 @@ hashcmpfun(
 /**
  * Convert a length encoded string into a C string.
  * @param data Pointer to the first byte of the string
- * @param len Pointer to an integer where the length of the string will be stored. On errors this will be set to -1.
  * @return Pointer to the newly allocated string or NULL if the value is NULL or an error occurred
  */
-char* get_lenenc_str(void* data, int* len)
+char* get_lenenc_str(void* data)
 {
     unsigned char* ptr = (unsigned char*)data;
     char* rval;
-    long size, offset;
+    uintptr_t size;
+    long offset;
 
-    if(data == NULL || len == NULL)
+    if(data == NULL)
     {
-	if(len)
-	    *len = -1;
         return NULL;
     }
 
     if(*ptr < 251)
     {
-        size = *ptr;
+        size = (uintptr_t)*ptr;
         offset = 1;
     }
     else
@@ -288,7 +286,6 @@ char* get_lenenc_str(void* data, int* len)
         switch(*(ptr))
         {
         case 0xfb:
-            *len = 1;
             return NULL;
         case 0xfc:
             size = *(ptr + 1) + (*(ptr + 2) << 8);
@@ -300,8 +297,8 @@ char* get_lenenc_str(void* data, int* len)
             break;
         case 0xfe:
             size = *ptr + ((*(ptr + 2) << 8)) + (*(ptr + 3) << 16) +
-                    (*(ptr + 4) << 24) + ((long)*(ptr + 5) << 32) + ((long)*(ptr + 6) << 40) +
+                    (*(ptr + 4) << 24) + ((uintptr_t)*(ptr + 5) << 32) + ((uintptr_t)*(ptr + 6) << 40) +
-                    ((long)*(ptr + 7) << 48) + ((long)*(ptr + 8) << 56);
+                    ((uintptr_t)*(ptr + 7) << 48) + ((uintptr_t)*(ptr + 8) << 56);
             offset = 8;
             break;
         default:
@@ -317,7 +314,6 @@ char* get_lenenc_str(void* data, int* len)
         memset(rval + size,0,1);
 
     }
-    *len = size + offset;
     return rval;
 }
 
@@ -360,8 +356,7 @@ parse_mapping_response(ROUTER_CLIENT_SES* rses, char* target, GWBUF* buf)
        {
 	   int payloadlen = gw_mysql_get_byte3(ptr);
 	   int packetlen = payloadlen + 4;
-	   int len = 0;
+	   char* data = get_lenenc_str(ptr+4);
-	   char* data = get_lenenc_str(ptr+4,&len);
 
 	   if(data)
 	   {