Merge branch '3.0.x' into 3.1.x

Author: olim7t

changelog/README.md

@@ -109,6 +109,7 @@ Merged from 2.1 branch:
 - [bug] JAVA-1312: QueryBuilder modifies selected columns when manually selected.
 - [improvement] JAVA-1303: Add missing BoundStatement.setRoutingKey(ByteBuffer...)
 - [improvement] JAVA-262: Make internal executors customizable
+- [bug] JAVA-1320: prevent unnecessary task creation on empty pool
 
 
 ### 3.0.4

driver-core/src/main/java/com/datastax/driver/core/HostConnectionPool.java

@@ -200,11 +200,10 @@ ListenableFuture<Connection> borrowConnection(int maxQueueSize) {
                 int coreSize = options().getCoreConnectionsPerHost(hostDistance);
                 if (coreSize == 0) {
                     maybeSpawnNewConnection();
-                } else {
+                } else if (scheduledForCreation.compareAndSet(0, coreSize)) {
                     for (int i = 0; i < coreSize; i++) {
                         // We don't respect MAX_SIMULTANEOUS_CREATION here because it's  only to
                         // protect against creating connection in excess of core too quickly
-                        scheduledForCreation.incrementAndGet();
                         manager.blockingExecutor().submit(newConnectionTask);
                     }
                 }

driver-core/src/main/java/com/datastax/driver/core/ThreadingOptions.java

@@ -97,7 +97,7 @@ public ExecutorService createBlockingExecutor(String clusterName) {
                 2, 2,
                 DEFAULT_THREAD_KEEP_ALIVE_SECONDS, TimeUnit.SECONDS,
                 new LinkedBlockingQueue<Runnable>(),
-                createThreadFactory(clusterName, "worker"));
+                createThreadFactory(clusterName, "blocking-task-worker"));
         executor.allowCoreThreadTimeOut(true);
         return executor;
     }