Don't let stress write warmup data if n=0

patch by Eduard Tudenhoefner; reviewed by Stefania Alborghetti for CASSANDRA-13773

CHANGES.txt

@@ -1,4 +1,5 @@
 3.0.15
+ * Don't let stress write warmup data if n=0 (CASSANDRA-13773)
  * Gossip thread slows down when using batch commit log (CASSANDRA-12966)
  * Randomize batchlog endpoint selection with only 1 or 2 racks (CASSANDRA-12884)
  * Fix digest calculation for counter cells (CASSANDRA-13750)

tools/stress/src/org/apache/cassandra/stress/StressAction.java

@@ -54,6 +54,13 @@ public void run()
         // creating keyspace and column families
         settings.maybeCreateKeyspaces();
 
+        if (settings.command.count == 0)
+        {
+            output.println("N=0: SCHEMA CREATED, NOTHING ELSE DONE.");
+            settings.disconnect();
+            return;
+        }
+
         output.println("Sleeping 2s...");
         Uninterruptibles.sleepUninterruptibly(2, TimeUnit.SECONDS);
 
@@ -87,9 +94,7 @@ private void warmup(OpDistributionFactory operations)
     {
         PrintStream warmupOutput = new PrintStream(new OutputStream() { @Override public void write(int b) throws IOException { } } );
         // do 25% of iterations as warmup but no more than 50k (by default hotspot compiles methods after 10k invocations)
-        int iterations = (settings.command.count > 0
-                         ? Math.min(50000, (int)(settings.command.count * 0.25))
-                         : 50000) * settings.node.nodes.size();
+        int iterations = Math.min(50000, (int) (settings.command.count * 0.25)) * settings.node.nodes.size();
         int threads = 100;
 
         if (settings.rate.maxThreads > 0)