NDB memcache: fix S scheduler to use version 2 of multiwait

Author: jdduncan

storage/ndb/memcache/src/schedulers/S_sched.cc

@@ -1,5 +1,5 @@
 /*
- Copyright (c) 2011, 2016, Oracle and/or its affiliates. All rights
+ Copyright (c) 2011, 2017, Oracle and/or its affiliates. All rights
  reserved.
  
  This program is free software; you can redistribute it and/or
@@ -824,9 +824,8 @@ void * S::Connection::run_ndb_poll_thread() {
   DEBUG_ENTER();
 
   NdbInstance *inst;
-  Ndb ** ready_list;
   int wait_timeout_millisec = 5000;
-  int min_ready;
+  int pct_ready;
   int in_flight = 0;
 
   while(1) {
@@ -841,24 +840,24 @@ void * S::Connection::run_ndb_poll_thread() {
       inst->next = 0;
       DEBUG_PRINT(" ** adding %d.%d to wait group ** ",
                   inst->wqitem->pipeline->id, inst->wqitem->id);
-      pollgroup->addNdb(inst->db);
-      n_added++;
-      in_flight++;
+      if(! pollgroup->push(inst->db)) {
+        n_added++;
+        in_flight++;
+      }
     }
 
     /* What's the minimum number of ready Ndb's to wake up for? */
-    int n = n_added / 4;
-    min_ready = n > 0 ? n : 1;
+    pct_ready = (n_added > 4) ? 25 : 1;
 
     /* Wait until something is ready to poll */
-    int nwaiting = pollgroup->wait(ready_list, wait_timeout_millisec, min_ready);
+    int nwaiting = pollgroup->wait(wait_timeout_millisec, pct_ready);
 
     /* Poll the ones that are ready */
     if(nwaiting > 0) {
       for(int i = 0; i < nwaiting ; i++) {
         in_flight--;
         assert(in_flight >= 0);
-        Ndb *db = ready_list[i];
+        Ndb *db = pollgroup->pop();
         inst = (NdbInstance *) db->getCustomData();
         DEBUG_PRINT("Polling %d.%d", inst->wqitem->pipeline->id, inst->wqitem->id);
         db->pollNdb(0, 1);
@@ -883,7 +882,6 @@ void * S::Connection::run_ndb_poll_thread() {
     }
   }
   return 0; /* not reached */
-  return 0; /* not reached */
 }