// Copyright 2017 The Bazel Authors. All rights reserved. // // 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.google.devtools.build.lib.unsafe; import java.lang.reflect.Field; import java.security.AccessController; import java.security.PrivilegedActionException; import java.security.PrivilegedExceptionAction; import sun.misc.Unsafe; /** * An accessor for Unsafe. * *
Not for general consumption. Public only so that generated codecs in different packages can * access this. */ public class UnsafeProvider { private static final Unsafe UNSAFE = getUnsafe(); public static Unsafe getInstance() { return UNSAFE; } /** * Gets a reference to {@link sun.misc.Unsafe} throwing an {@link AssertionError} on failure. * *
Failure is highly unlikely, but possible if the underlying VM stores unsafe in an unexpected
* location.
*/
private static Unsafe getUnsafe() {
try {
// sun.misc.Unsafe is intentionally difficult to get a hold of - it gives us the power to
// do things like access raw memory and segfault the JVM.
return AccessController.doPrivileged(
new PrivilegedExceptionAction