Merge branch 'MXS-171' into develop

Documentation/routers/ReadWriteSplit.md

@@ -93,6 +93,13 @@ disable_sescmd_history=true
 disable_slave_recovery=true
 ```
 
+**`master_accept_reads`** allows the master server to be used for reads. This is a useful option to enable if you are using a small number of servers and wish to use the master for reads as well.
+
+```
+# Use the master for reads
+master_accept_reads=true
+```
+
 ## Limitations
 
 In Master-Slave replication cluster also read-only queries are routed to master too in the following situations:

server/modules/include/readwritesplit.h

@@ -252,6 +252,7 @@ typedef struct rwsplit_config_st {
         int               rw_max_sescmd_history_size;
         bool disable_sescmd_hist;
         bool disable_slave_recovery;
+        bool master_reads; /*< Use master for reads */
 } rwsplit_config_t;
      
 

server/modules/routing/readwritesplit/readwritesplit.c

@@ -1244,7 +1244,8 @@ static bool get_dcb(
 				SERVER_IS_SLAVE(b->backend_server) &&
 				(max_rlag == MAX_RLAG_UNDEFINED ||
 				(b->backend_server->rlag != MAX_RLAG_NOT_AVAILABLE &&
-				b->backend_server->rlag <= max_rlag)))
+				b->backend_server->rlag <= max_rlag)) &&
+				 !rses->rses_config.master_reads)
 			{
 				/** found slave */
 				candidate_bref = &backend_ref[i];
@@ -4589,6 +4590,10 @@ static void rwsplit_process_router_options(
 			{
 			    router->rwsplit_config.disable_slave_recovery = config_truth_value(value);
 			}
+			else if(strcmp(options[i],"master_accept_reads") == 0)
+			{
+			    router->rwsplit_config.master_reads = config_truth_value(value);
+			}
                 }
         } /*< for */
 }