MXS-1507: Add transaction replay statistics

Added a simple counter for the number of replayed transactions.

server/modules/routing/readwritesplit/readwritesplit.cc

@@ -370,6 +370,8 @@ void RWSplit::diagnostics(DCB *dcb)
                stats().n_slave, slave_pct);
     dcb_printf(dcb, "\tNumber of queries forwarded to all:     %" PRIu64 " (%.2f%%)\n",
                stats().n_all, all_pct);
+    dcb_printf(dcb, "\tNumber of replayed transactions:        %" PRIu64 "\n",
+               stats().n_trx_replay);
 
     if (*weightby)
     {
@@ -399,6 +401,7 @@ json_t* RWSplit::diagnostics_json() const
     json_object_set_new(rval, "route_master", json_integer(stats().n_master));
     json_object_set_new(rval, "route_slave", json_integer(stats().n_slave));
     json_object_set_new(rval, "route_all", json_integer(stats().n_all));
+    json_object_set_new(rval, "replayed_transactions", json_integer(stats().n_trx_replay));
 
     const char *weightby = serviceGetWeightingParameter(service());
 

server/modules/routing/readwritesplit/readwritesplit.hh

@@ -211,7 +211,8 @@ public:
         n_queries(0),
         n_master(0),
         n_slave(0),
-        n_all(0)
+        n_all(0),
+        n_trx_replay(0)
     {
     }
 
@@ -220,6 +221,7 @@ public:
     uint64_t n_master;          /**< Number of stmts sent to master */
     uint64_t n_slave;           /**< Number of stmts sent to slave */
     uint64_t n_all;             /**< Number of stmts sent to all */
+    uint64_t n_trx_replay;      /**< Number of replayed transactions */
 };
 
 class RWSplitSession;

server/modules/routing/readwritesplit/rwsplitsession.cc

@@ -380,6 +380,7 @@ void RWSplitSession::handle_trx_replay()
     {
         // No more statements to execute
         m_is_replay_active = false;
+        atomic_add_uint64(&m_router->stats().n_trx_replay, 1);
 
         // Check that the checksums match.
         SHA1Checksum chksum = m_trx.checksum();