private static Object getUnsafe0() {
        Object unsafe;
        try {
            final Class<?> unsafeClass = Class.forName("sun.misc.Unsafe");
            final Field unsafeField = unsafeClass.getDeclaredField("theUnsafe");
            unsafeField.setAccessible(true);
            unsafe = unsafeField.get(null);
        } catch (final Throwable t) {
            if (LOG.isWarnEnabled()) {
                LOG.warn("sun.misc.Unsafe.theUnsafe: unavailable.", t);
            }
            unsafe = null;
        }
        return unsafe;
    }
Gets the field with the given name within the class, or
{@code null} if not found. If found, the field is made accessible.
jraft-core/src/main/java/com/alipay/sofa/jraft/util/internal/UnsafeUtil.java