From 65886dc38697a6d53d8f8d1feb039c81d37ee8d6 Mon Sep 17 00:00:00 2001
From: Markus Makela <markus.makela@mariadb.com>
Date: Mon, 7 Nov 2016 11:17:01 +0200
Subject: [PATCH] Check whether server references are active

Before a query is routed to a backend, the status of the server reference
is checked. This allows the servers that are removed from a service to be
ejected from the list of active servers for active sessions.
---
 .../readwritesplit/rwsplit_route_stmt.c       | 35 ++++++++++++-------
 .../readwritesplit/rwsplit_select_backends.c  |  7 ++--
 2 files changed, 28 insertions(+), 14 deletions(-)

diff --git a/server/modules/routing/readwritesplit/rwsplit_route_stmt.c b/server/modules/routing/readwritesplit/rwsplit_route_stmt.c
index 4ab38b8ed..298358b4f 100644
--- a/server/modules/routing/readwritesplit/rwsplit_route_stmt.c
+++ b/server/modules/routing/readwritesplit/rwsplit_route_stmt.c
@@ -543,6 +543,7 @@ bool rwsplit_get_dcb(DCB **p_dcb, ROUTER_CLIENT_SES *rses, backend_type_t btype,
              * server, or master.
              */
             if (BREF_IS_IN_USE((&backend_ref[i])) &&
+                SERVER_REF_IS_ACTIVE(b) &&
                 (strncasecmp(name, b->server->unique_name, PATH_MAX) == 0) &&
                 (SERVER_IS_SLAVE(&server) || SERVER_IS_RELAY_SERVER(&server) ||
                  SERVER_IS_MASTER(&server)))
@@ -577,7 +578,7 @@ bool rwsplit_get_dcb(DCB **p_dcb, ROUTER_CLIENT_SES *rses, backend_type_t btype,
              * Unused backend or backend which is not master nor
              * slave can't be used
              */
-            if (!BREF_IS_IN_USE(&backend_ref[i]) ||
+            if (!BREF_IS_IN_USE(&backend_ref[i]) || !SERVER_REF_IS_ACTIVE(b) ||
                 (!SERVER_IS_MASTER(&server) && !SERVER_IS_SLAVE(&server)))
             {
                 continue;
@@ -665,27 +666,37 @@ bool rwsplit_get_dcb(DCB **p_dcb, ROUTER_CLIENT_SES *rses, backend_type_t btype,
      */
     if (btype == BE_MASTER)
     {
-        if (master_bref)
+        if (master_bref && SERVER_REF_IS_ACTIVE(master_bref->ref))
         {
             /** It is possible for the server status to change at any point in time
              * so copying it locally will make possible error messages
              * easier to understand */
             SERVER server;
             server.status = master_bref->ref->server->status;
-            if (BREF_IS_IN_USE(master_bref) && SERVER_IS_MASTER(&server))
+
+            if (BREF_IS_IN_USE(master_bref))
             {
-                *p_dcb = master_bref->bref_dcb;
-                succp = true;
-                /** if bref is in use DCB should not be closed */
-                ss_dassert(master_bref->bref_dcb->state != DCB_STATE_ZOMBIE);
+                if (SERVER_IS_MASTER(&server))
+                {
+                    *p_dcb = master_bref->bref_dcb;
+                    succp = true;
+                    /** if bref is in use DCB should not be closed */
+                    ss_dassert(master_bref->bref_dcb->state != DCB_STATE_ZOMBIE);
+                }
+                else
+                {
+                    MXS_ERROR("Server '%s' should be master but "
+                              "is %s instead and can't be chosen as the master.",
+                              master_bref->ref->server->unique_name,
+                              STRSRVSTATUS(&server));
+                    succp = false;
+                }
             }
             else
             {
-                MXS_ERROR("Server at %s:%d should be master but "
-                          "is %s instead and can't be chosen to master.",
-                          master_bref->ref->server->name,
-                          master_bref->ref->server->port,
-                          STRSRVSTATUS(&server));
+                MXS_ERROR("Server '%s' is not in use and can't be "
+                          "chosen as the master.",
+                          master_bref->ref->server->unique_name);
                 succp = false;
             }
         }
diff --git a/server/modules/routing/readwritesplit/rwsplit_select_backends.c b/server/modules/routing/readwritesplit/rwsplit_select_backends.c
index fba1d7271..35875be65 100644
--- a/server/modules/routing/readwritesplit/rwsplit_select_backends.c
+++ b/server/modules/routing/readwritesplit/rwsplit_select_backends.c
@@ -106,7 +106,8 @@ bool select_connect_backend_servers(backend_ref_t **p_master_ref,
     SERVER_REF *master_host = get_root_master(backend_ref, router_nservers);
 
     if (router->rwsplit_config.rw_master_failure_mode == RW_FAIL_INSTANTLY &&
-        (master_host == NULL || SERVER_IS_DOWN(master_host->server)))
+        (master_host == NULL || !SERVER_REF_IS_ACTIVE(master_host) ||
+         SERVER_IS_DOWN(master_host->server)))
     {
         MXS_ERROR("Couldn't find suitable Master from %d candidates.", router_nservers);
         return false;
@@ -147,7 +148,9 @@ bool select_connect_backend_servers(backend_ref_t **p_master_ref,
     {
         SERVER *serv = backend_ref[i].ref->server;
 
-        if (!BREF_HAS_FAILED(&backend_ref[i]) && SERVER_IS_RUNNING(serv))
+        if (!BREF_HAS_FAILED(&backend_ref[i]) &&
+            SERVER_REF_IS_ACTIVE(backend_ref[i].ref) &&
+            SERVER_IS_RUNNING(serv))
         {
             /* check also for relay servers and don't take the master_host */
             if (slaves_found < max_nslaves &&