Add missing file for HADOOP-6413.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@890588 13f79535-47bb-0310-9956-ffa450edef68

src/test/core/org/apache/hadoop/util/TestReflectionUtils.java

@@ -0,0 +1,120 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.util;
+
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.util.HashMap;
+
+import org.apache.hadoop.conf.Configuration;
+
+import static org.junit.Assert.*;
+import org.junit.Before;
+import org.junit.Test;
+
+public class TestReflectionUtils {
+
+  private static Class toConstruct[] = { String.class, TestReflectionUtils.class, HashMap.class };
+  private Throwable failure = null;
+
+  @Before
+  public void setUp() {
+    ReflectionUtils.clearCache();
+  }
+
+  @Test
+  public void testCache() throws Exception {
+    assertEquals(0, cacheSize());
+    doTestCache();
+    assertEquals(toConstruct.length, cacheSize());
+    ReflectionUtils.clearCache();
+    assertEquals(0, cacheSize());
+  }
+    
+    
+  @SuppressWarnings("unchecked")
+  private void doTestCache() {
+    for (int i=0; i<toConstruct.length; i++) {
+      Class cl = toConstruct[i];
+      Object x = ReflectionUtils.newInstance(cl, null);
+      Object y = ReflectionUtils.newInstance(cl, null);
+      assertEquals(cl, x.getClass());
+      assertEquals(cl, y.getClass());
+    }
+  }
+
+  @Test
+  public void testThreadSafe() throws Exception {
+    Thread[] th = new Thread[32];
+    for (int i=0; i<th.length; i++) {
+      th[i] = new Thread() {
+          public void run() {
+            try {
+              doTestCache();
+            } catch (Throwable t) {
+              failure = t;
+            }
+          }
+        };
+      th[i].start();
+    }
+    for (int i=0; i<th.length; i++) {
+      th[i].join();
+    }
+    if (failure != null) {
+      failure.printStackTrace();
+      fail(failure.getMessage());
+    }
+  }
+    
+  private int cacheSize() throws Exception {
+    return ReflectionUtils.getCacheSize();
+  }
+
+  @Test
+  public void testCantCreate() {
+    try {
+      ReflectionUtils.newInstance(NoDefaultCtor.class, null);
+      fail("invalid call should fail");
+    } catch (RuntimeException rte) {
+      assertEquals(NoSuchMethodException.class, rte.getCause().getClass());
+    }
+  }
+    
+  @SuppressWarnings("unchecked")
+  @Test
+  public void testCacheDoesntLeak() throws Exception {
+    int iterations=9999; // very fast, but a bit less reliable - bigger numbers force GC
+    for (int i=0; i<iterations; i++) {
+      URLClassLoader loader = new URLClassLoader(new URL[0], getClass().getClassLoader());
+      Class cl = Class.forName("org.apache.hadoop.util.TestReflectionUtils$LoadedInChild", false, loader);
+      Object o = ReflectionUtils.newInstance(cl, null);
+      assertEquals(cl, o.getClass());
+    }
+    System.gc();
+    assertTrue(cacheSize()+" too big", cacheSize()<iterations);
+  }
+    
+  private static class LoadedInChild {
+  }
+    
+  public static class NoDefaultCtor {
+    public NoDefaultCtor(int x) {}
+  }
+}