From 0d2a6e4eba897e1a4f57aa987779aae183f3b7ce Mon Sep 17 00:00:00 2001
From: Ruben Dijkstra <rubendijkstra123@gmail.com>
Date: Tue, 19 Jul 2016 15:03:02 +0200
Subject: [PATCH] Extract class for Thread Safety checks

---
 .../core/CycleClassInitDependencyTest.java    | 14 ++++----
 .../querydsl/core/testutil/ThreadSafety.java  | 35 +++++++++++++++++++
 2 files changed, 41 insertions(+), 8 deletions(-)
 create mode 100644 querydsl-core/src/test/java/com/querydsl/core/testutil/ThreadSafety.java

diff --git a/querydsl-core/src/test/java/com/querydsl/core/CycleClassInitDependencyTest.java b/querydsl-core/src/test/java/com/querydsl/core/CycleClassInitDependencyTest.java
index 1ceb04c12..337e3200e 100644
--- a/querydsl-core/src/test/java/com/querydsl/core/CycleClassInitDependencyTest.java
+++ b/querydsl-core/src/test/java/com/querydsl/core/CycleClassInitDependencyTest.java
@@ -9,6 +9,8 @@ import org.junit.BeforeClass;
 import org.junit.Test;
 import org.reflections.util.ClasspathHelper;
 
+import com.querydsl.core.testutil.ThreadSafety;
+
 public class CycleClassInitDependencyTest {
 
     private static ClassLoader loader;
@@ -27,16 +29,12 @@ public class CycleClassInitDependencyTest {
     }
 
     @Test(timeout = 2000)
-    public void test() throws InterruptedException {
+    public void test() {
 
         // each thread wants to load one part of the dependency circle
-        Thread t1 = new Thread(new LoadClassRunnable("com.querydsl.core.types.dsl.NumberExpression"));
-        Thread t2 = new Thread(new LoadClassRunnable("com.querydsl.core.types.dsl.Expressions"));
-        t1.start();
-        t2.start();
-
-        t1.join();
-
+        ThreadSafety.check(
+                new LoadClassRunnable("com.querydsl.core.types.dsl.NumberExpression"),
+                new LoadClassRunnable("com.querydsl.core.types.dsl.Expressions"));
     }
 
     private static class LoadClassRunnable implements Runnable {
diff --git a/querydsl-core/src/test/java/com/querydsl/core/testutil/ThreadSafety.java b/querydsl-core/src/test/java/com/querydsl/core/testutil/ThreadSafety.java
new file mode 100644
index 000000000..2fda718b4
--- /dev/null
+++ b/querydsl-core/src/test/java/com/querydsl/core/testutil/ThreadSafety.java
@@ -0,0 +1,35 @@
+package com.querydsl.core.testutil;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.concurrent.*;
+
+import com.google.common.collect.Lists;
+import com.google.common.util.concurrent.Futures;
+import com.google.common.util.concurrent.MoreExecutors;
+
+public final class ThreadSafety {
+
+    private ThreadSafety() { }
+
+    public static void check(Runnable... runnables) {
+        Collection<Callable<Object>> callables = Lists.newArrayListWithCapacity(runnables.length);
+        ExecutorService executor = MoreExecutors.getExitingScheduledExecutorService(
+                new ScheduledThreadPoolExecutor(runnables.length));
+
+        for (Runnable runnable : runnables) {
+            callables.add(Executors.callable(runnable));
+        }
+        List<Future<Object>> result;
+        try {
+            result = executor.invokeAll(callables);
+        } catch (InterruptedException ex) {
+            throw new RuntimeException(ex);
+        }
+
+        for (Future<Object> each : result) {
+            // all need to complete successfully
+            Futures.getUnchecked(each);
+        }
+    }
+}