hbase-common/src/main/java/org/apache/hadoop/hbase/util/UnsafeAvailChecker.java

   1 /**
   2  * Licensed to the Apache Software Foundation (ASF) under one
   3  * or more contributor license agreements.  See the NOTICE file
   4  * distributed with this work for additional information
   5  * regarding copyright ownership.  The ASF licenses this file
   6  * to you under the Apache License, Version 2.0 (the
   7  * "License"); you may not use this file except in compliance
   8  * with the License.  You may obtain a copy of the License at
   9  *
  10  *     http://www.apache.org/licenses/LICENSE-2.0
  11  *
  12  * Unless required by applicable law or agreed to in writing, software
  13  * distributed under the License is distributed on an "AS IS" BASIS,
  14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  15  * See the License for the specific language governing permissions and
  16  * limitations under the License.
  17  */
  18 package org.apache.hadoop.hbase.util;
  19
  20 import java.lang.reflect.Field;
  21 import java.lang.reflect.Method;
  22 import java.security.AccessController;
  23 import java.security.PrivilegedAction;
  24
  25 import org.apache.yetus.audience.InterfaceAudience;
  26 import org.slf4j.Logger;
  27 import org.slf4j.LoggerFactory;
  28
  29 @InterfaceAudience.Private
  30 public class UnsafeAvailChecker {
  31
  32   private static final String CLASS_NAME = "sun.misc.Unsafe";
  33   private static final Logger LOG = LoggerFactory.getLogger(UnsafeAvailChecker.class);
  34   private static boolean avail = false;
  35   private static boolean unaligned = false;
  36
  37   static {
  38     avail = AccessController.doPrivileged(new PrivilegedAction<Boolean>() {
  39       @Override
  40       public Boolean run() {
  41         try {
  42           Class<?> clazz = Class.forName(CLASS_NAME);
  43           Field f = clazz.getDeclaredField("theUnsafe");
  44           f.setAccessible(true);
  45           return f.get(null) != null;
  46         } catch (Throwable e) {
  47           LOG.warn("sun.misc.Unsafe is not available/accessible", e);
  48         }
  49         return false;
  50       }
  51     });
  52     // When Unsafe itself is not available/accessible consider unaligned as false.
  53     if (avail) {
  54       String arch = System.getProperty("os.arch");
  55       if ("ppc64".equals(arch) || "ppc64le".equals(arch) || "aarch64".equals(arch)) {
  56         // java.nio.Bits.unaligned() wrongly returns false on ppc (JDK-8165231),
  57         unaligned = true;
  58       } else {
  59         try {
  60           // Using java.nio.Bits#unaligned() to check for unaligned-access capability
  61           Class<?> clazz = Class.forName("java.nio.Bits");
  62           Method m = clazz.getDeclaredMethod("unaligned");
  63           m.setAccessible(true);
  64           unaligned = (Boolean) m.invoke(null);
  65         } catch (Exception e) {
  66           LOG.warn("java.nio.Bits#unaligned() check failed."
  67               + "Unsafe based read/write of primitive types won't be used", e);
  68         }
  69       }
  70     }
  71   }
  72
  73   /**
  74    * @return true when running JVM is having sun's Unsafe package available in it and it is
  75    *         accessible.
  76    */
  77   public static boolean isAvailable() {
  78     return avail;
  79   }
  80
  81   /**
  82    * @return true when running JVM is having sun's Unsafe package available in it and underlying
  83    *         system having unaligned-access capability.
  84    */
  85   public static boolean unaligned() {
  86     return unaligned;
  87   }
  88
  89   private UnsafeAvailChecker() {
  90     // private constructor to avoid instantiation
  91   }
  92 }