Merge branch '2.3' into develop

server/modules/routing/readwritesplit/rwsplit_route_stmt.cc

@@ -277,6 +277,11 @@ bool RWSplitSession::route_single_stmt(GWBUF* querybuf)
         }
         else if (TARGET_IS_MASTER(route_target))
         {
+            if (m_config.causal_reads)
+            {
+                gwbuf_set_type(querybuf, GWBUF_TYPE_TRACK_STATE);
+            }
+
             succp = handle_master_is_target(&target);
 
             if (!succp && should_migrate_trx(target))

server/modules/routing/readwritesplit/rwsplit_select_backends.cc

@@ -22,6 +22,7 @@
 #include <functional>
 #include <random>
 #include <iostream>
+#include <array>
 
 #include <maxbase/stopwatch.hh>
 #include <maxscale/router.hh>
@@ -193,6 +194,11 @@ BackendSelectFunction get_backend_select_function(select_criteria_t sc)
     return backend_cmp_current_load;
 }
 
+namespace
+{
+// Buffers for sorting the servers, thread_local to avoid repeated memory allocations
+thread_local std::array<PRWBackends, 3> priority_map;
+}
 
 /**
  * @brief Find the best slave candidate for routing reads.
@@ -208,7 +214,6 @@ PRWBackends::iterator find_best_backend(PRWBackends& backends,
                                         bool masters_accepts_reads)
 {
     // Group backends by priority. The set of highest priority backends will then compete.
-    std::map<int, PRWBackends> priority_map;
     int best_priority {INT_MAX};    // low numbers are high priority
 
     for (auto& psBackend : backends)
@@ -222,16 +227,16 @@ PRWBackends::iterator find_best_backend(PRWBackends& backends,
         {
             if (!is_busy)
             {
-                priority = 1;   // highest priority, idle servers
+                priority = 0;   // highest priority, idle servers
             }
             else
             {
-                priority = 13;      // lowest priority, busy servers
+                priority = 2;       // lowest priority, busy servers
             }
         }
         else
         {
-            priority = 2;   // idle masters with masters_accept_reads==false
+            priority = 1;   // idle masters with masters_accept_reads==false
         }
 
         priority_map[priority].push_back(psBackend);
@@ -239,8 +244,14 @@ PRWBackends::iterator find_best_backend(PRWBackends& backends,
     }
 
     auto best = select(priority_map[best_priority]);
+    auto rval = std::find(backends.begin(), backends.end(), *best);
 
-    return std::find(backends.begin(), backends.end(), *best);
+    for (auto& a : priority_map)
+    {
+        a.clear();
+    }
+
+    return rval;
 }
 
 /**

server/modules/routing/readwritesplit/rwsplitsession.cc

@@ -563,6 +563,17 @@ static bool server_is_shutting_down(GWBUF* writebuf)
     return err == ER_SERVER_SHUTDOWN || err == ER_NORMAL_SHUTDOWN || err == ER_SHUTDOWN_COMPLETE;
 }
 
+void RWSplitSession::close_stale_connections()
+{
+    for (auto& backend : m_backends)
+    {
+        if (backend->in_use() && !backend->can_connect())
+        {
+            backend->close();
+        }
+    }
+}
+
 void RWSplitSession::clientReply(GWBUF* writebuf, DCB* backend_dcb)
 {
     DCB* client_dcb = backend_dcb->session->client_dcb;
@@ -719,6 +730,15 @@ void RWSplitSession::clientReply(GWBUF* writebuf, DCB* backend_dcb)
         m_can_replay_trx = true;
     }
 
+    if (m_expected_responses == 0)
+    {
+        /**
+         * Close stale connections to servers in maintenance. Done here to avoid closing the connections
+         * before all responses have been received.
+         */
+        close_stale_connections();
+    }
+
     if (backend->in_use() && backend->has_session_commands())
     {
         // Backend is still in use and has more session commands to execute

server/modules/routing/readwritesplit/rwsplitsession.hh

@@ -144,6 +144,7 @@ private:
     void continue_large_session_write(GWBUF* querybuf, uint32_t type);
     bool route_single_stmt(GWBUF* querybuf);
     bool route_stored_query();
+    void close_stale_connections();
 
     mxs::RWBackend* get_hinted_backend(char* name);
     mxs::RWBackend* get_slave_backend(int max_rlag);

server/modules/routing/schemarouter/schemaroutersession.cc

@@ -1592,8 +1592,17 @@ bool SchemaRouterSession::send_tables(GWBUF* pPacket)
 
     if (database.empty())
     {
-        MXS_FREE(query);
-        return false;
+        // Was not a "show tables from x". If a current database is selected, use that as target.
+        if (!m_current_db.empty())
+        {
+            database = m_current_db;
+        }
+        else
+        {
+            // No current db, route the query to a server, likely getting "No database selected"
+            MXS_FREE(query);
+            return false;
+        }
     }
 
     ServerMap tablelist;