MXS-1418: Keep connections open if server is removed

The removal of a server from a service is intended to affect only new
sessions.

Added a test that checks that the connections are kept open even if the
server is removed from the service.

maxscale-system-test/CMakeLists.txt

@@ -484,6 +484,10 @@ add_test_executable(mxs1123.cpp mxs1123 mxs1123 LABELS maxscale REPL_BACKEND)
 # https://jira.mariadb.org/browse/MXS-1319
 add_test_executable(mxs1319.cpp mxs1319 replication LABELS MySQLAuth REPL_BACKEND)
 
+# MXS-1418: Removing a server from a service breaks the connection
+# https://jira.mariadb.org/browse/MXS-1418
+add_test_executable(mxs1418.cpp mxs1418 replication LABELS maxscale REPL_BACKEND)
+
 # 'namedserverfilter' test
 add_test_executable(namedserverfilter.cpp namedserverfilter namedserverfilter LABELS namedserverfilter LIGHT REPL_BACKEND)
 

maxscale-system-test/mxs1418.cpp

@@ -0,0 +1,73 @@
+/**
+ * @file Check that removing a server from a service doesn't break active connections
+ */
+
+#include "testconnections.h"
+
+static volatile bool running = true;
+
+void* thr(void* data)
+{
+    TestConnections* test = (TestConnections*)data;
+
+    while (running && test->global_result == 0)
+    {
+        test->set_timeout(60);
+        if (test->try_query(test->conn_rwsplit, "SELECT 1"))
+        {
+            test->tprintf("Failed to select via readwritesplit");
+        }
+        if (test->try_query(test->conn_master, "SELECT 1"))
+        {
+            test->tprintf("Failed to select via readconnroute master");
+        }
+        if (test->try_query(test->conn_slave, "SELECT 1"))
+        {
+            test->tprintf("Failed to select via readconnroute slave");
+        }
+    }
+
+    test->stop_timeout();
+
+    return NULL;
+}
+
+int main(int argc, char *argv[])
+{
+    TestConnections test(argc, argv);
+    test.connect_maxscale();
+
+    test.tprintf("Connect to MaxScale and continuously execute queries");
+    pthread_t thread;
+    pthread_create(&thread, NULL, thr, &test);
+    sleep(5);
+
+    test.tprintf("Remove all servers from all services");
+
+    for (int i = 3; i > -1; i--)
+    {
+        test.ssh_maxscale(true, "maxadmin remove server server%d \"RW Split Router\"", i);
+        test.ssh_maxscale(true, "maxadmin remove server server%d \"Read Connection Router Slave\"", i);
+        test.ssh_maxscale(true, "maxadmin remove server server%d \"Read Connection Router Master\"", i);
+    }
+
+    sleep(5);
+
+    test.tprintf("Stop queries and close the connections");
+    running = false;
+    pthread_join(thread, NULL);
+    test.close_maxscale_connections();
+
+    test.tprintf("Add all servers to all services");
+
+    for (int i = 3; i > -1; i--)
+    {
+        test.ssh_maxscale(true, "maxadmin add server server%d \"RW Split Router\"", i);
+        test.ssh_maxscale(true, "maxadmin add server server%d \"Read Connection Router Slave\"", i);
+        test.ssh_maxscale(true, "maxadmin add server server%d \"Read Connection Router Master\"", i);
+    }
+
+    test.check_maxscale_alive();
+
+    return test.global_result;
+}

server/modules/routing/readconnroute/readconnroute.c

@@ -522,10 +522,6 @@ static void log_closed_session(mysql_server_cmd_t mysql_command, bool is_closed,
     {
         sprintf(msg, "Server '%s' is down.", ref->server->unique_name);
     }
-    else if (!SERVER_REF_IS_ACTIVE(ref))
-    {
-        sprintf(msg, "Server '%s' was removed from the service.", ref->server->unique_name);
-    }
     else if (SERVER_IN_MAINT(ref->server))
     {
         sprintf(msg, "Server '%s' is in maintenance.", ref->server->unique_name);
@@ -579,7 +575,6 @@ routeQuery(MXS_ROUTER *instance, MXS_ROUTER_SESSION *router_session, GWBUF *queu
     }
 
     if (rses_is_closed || backend_dcb == NULL ||
-        !SERVER_REF_IS_ACTIVE(router_cli_ses->backend) ||
         !SERVER_IS_RUNNING(router_cli_ses->backend->server))
     {
         log_closed_session(mysql_command, rses_is_closed, router_cli_ses->backend);

server/modules/routing/readwritesplit/rwsplit_route_stmt.c

@@ -502,7 +502,6 @@ 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)))
@@ -537,7 +536,7 @@ 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]) || !SERVER_REF_IS_ACTIVE(b) ||
+            if (!BREF_IS_IN_USE(&backend_ref[i]) ||
                 (!SERVER_IS_MASTER(&server) && !SERVER_IS_SLAVE(&server)))
             {
                 continue;
@@ -627,7 +626,7 @@ bool rwsplit_get_dcb(DCB **p_dcb, ROUTER_CLIENT_SES *rses, backend_type_t btype,
      */
     if (btype == BE_MASTER)
     {
-        if (master_bref && SERVER_REF_IS_ACTIVE(master_bref->ref))
+        if (master_bref)
         {
             /** It is possible for the server status to change at any point in time
              * so copying it locally will make possible error messages