org.fusesource.lmdbjni.Unsafe Maven / Gradle / Ivy

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package org.fusesource.lmdbjni;

import java.lang.reflect.Field;
import java.security.AccessController;
import java.security.PrivilegedExceptionAction;

class Unsafe {
  /** unsafe may be null on android devices */
  public static sun.misc.Unsafe UNSAFE;
  public static int ADDRESS_SIZE;
  public static long ARRAY_BASE_OFFSET;

  static {
    if (!Util.isAndroid) {
      try {
        final PrivilegedExceptionAction action = new PrivilegedExceptionAction() {
          public sun.misc.Unsafe run() throws Exception {
            final Field field = sun.misc.Unsafe.class.getDeclaredField("theUnsafe");
            field.setAccessible(true);
            return (sun.misc.Unsafe) field.get(null);
          }
        };

        UNSAFE = AccessController.doPrivileged(action);
        ADDRESS_SIZE = UNSAFE.addressSize();
        ARRAY_BASE_OFFSET = UNSAFE.arrayBaseOffset(byte[].class);
      } catch (final Exception ex) {
        throw new RuntimeException(ex);
      }
    }
  }

  public static long getAddress(long address, int offset) {
    return Unsafe.UNSAFE.getAddress(address + Unsafe.ADDRESS_SIZE * offset);
  }

  public static long getLong(long address, int offset) {
    return Unsafe.UNSAFE.getLong(address + Unsafe.ADDRESS_SIZE * offset);
  }

  public static void putLong(long address, int offset, long value) {
    UNSAFE.putLong(null, address + Unsafe.ADDRESS_SIZE * offset, value);
  }

  public static void getBytes(long address, int index, byte[] key) {
    UNSAFE.copyMemory(null, address + index, key, ARRAY_BASE_OFFSET, key.length);
  }
}