Remove reflection in ByteBufferUtils

src/main/java/com/metamx/common/ByteBufferUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011,2012 Metamarkets Group Inc.
+ * Copyright 2011-2016 Metamarkets Group Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,57 +16,25 @@
 
 package com.metamx.common;
 
-import com.google.common.base.Throwables;
+import sun.misc.Cleaner;
+import sun.nio.ch.DirectBuffer;
 
-import java.lang.reflect.InvocationTargetException;
-import java.lang.reflect.Method;
 import java.nio.ByteBuffer;
 import java.nio.MappedByteBuffer;
 
 /**
  */
 public class ByteBufferUtils
 {
-  private static final Method unmap;
-
-  private static final Method getCleaner;
-  private static final Method clean;
-
-
-  static {
-    try {
-      Method unmapMethod = Class.forName("sun.nio.ch.FileChannelImpl")
-                                .getDeclaredMethod("unmap", MappedByteBuffer.class);
-      unmapMethod.setAccessible(true);
-      unmap = unmapMethod;
-    }
-    catch (Exception e) {
-      throw new UOE(e, "Exception thrown while trying to find unmap method on MappedByteBuffer, "
-                       + "this method must exist in your VM in order for this to work");
-    }
-  }
-
-  static {
-    try {
-      getCleaner = Class.forName("java.nio.DirectByteBuffer").getDeclaredMethod("cleaner");
-      getCleaner.setAccessible(true);
-      clean = Class.forName("sun.misc.Cleaner").getDeclaredMethod("clean");
-      clean.setAccessible(true);
-    } catch(ClassNotFoundException | NoSuchMethodException e) {
-      throw new UOE("Exception thrown while trying to access ByteBuffer clean method.");
-    }
-  }
-
   /**
    * Releases memory held by the given direct ByteBuffer
    *
    * @param buffer buffer to free
    */
-  public static void free(ByteBuffer buffer) {
-    try {
-      clean.invoke(getCleaner.invoke(buffer));
-    } catch(IllegalAccessException | InvocationTargetException e) {
-      throw Throwables.propagate(e);
+  public static void free(ByteBuffer buffer)
+  {
+    if (buffer.isDirect()) {
+      clean((DirectBuffer) buffer);
     }
   }
 
@@ -78,11 +46,14 @@ public static void free(ByteBuffer buffer) {
    */
   public static void unmap(MappedByteBuffer buffer)
   {
-    try {
-      unmap.invoke(null, buffer);
-    }
-    catch (Exception e) {
-      throw Throwables.propagate(e);
+    free(buffer);
+  }
+
+  private static void clean(DirectBuffer buffer)
+  {
+    final Cleaner cleaner = buffer.cleaner();
+    if (cleaner != null) {
+      cleaner.clean();
     }
   }
 }

src/test/java/com/metamx/common/ByteBufferUtilsTest.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2016 Metamarkets Group Inc.
+ *
+ * Licensed 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 com.metamx.common;
+
+import com.google.common.io.Files;
+import junit.framework.Assert;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+import java.io.BufferedOutputStream;
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.OutputStream;
+import java.nio.ByteBuffer;
+import java.nio.MappedByteBuffer;
+import java.util.Arrays;
+
+public class ByteBufferUtilsTest
+{
+  @Rule
+  public TemporaryFolder temporaryFolder = new TemporaryFolder();
+
+  @Test
+  public void testUnmapDoesntCrashJVM() throws Exception
+  {
+    final File file = temporaryFolder.newFile("some_mmap_file");
+    try (final OutputStream os = new BufferedOutputStream(new FileOutputStream(file))) {
+      final byte[] data = new byte[4096];
+      Arrays.fill(data, (byte) 0x5A);
+      os.write(data);
+    }
+    final MappedByteBuffer mappedByteBuffer = Files.map(file);
+    Assert.assertEquals((byte) 0x5A, mappedByteBuffer.get(0));
+    ByteBufferUtils.unmap(mappedByteBuffer);
+    ByteBufferUtils.unmap(mappedByteBuffer);
+  }
+
+  @Test
+  public void testFreeDoesntCrashJVM() throws Exception
+  {
+    final ByteBuffer directBuffer = ByteBuffer.allocateDirect(4096);
+    ByteBufferUtils.free(directBuffer);
+    ByteBufferUtils.free(directBuffer);
+
+    final ByteBuffer heapBuffer = ByteBuffer.allocate(4096);
+    ByteBufferUtils.free(heapBuffer);
+  }
+}