Mercurial > hg > graal-compiler
view graal/com.oracle.graal.options/src/com/oracle/graal/options/StableOptionValue.java @ 21408:32ca2353accf
Truffle/Instrumentation: fix NPE hazard
author | Michael Van De Vanter <michael.van.de.vanter@oracle.com> |
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date | Sun, 17 May 2015 20:47:04 -0700 |
parents | af909f4b80a9 |
children | cecb4e39521c |
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/* * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package com.oracle.graal.options; /** * An option that always returns the same {@linkplain #getValue() value}. */ public class StableOptionValue<T> extends OptionValue<T> { /** * Creates a stable option value. */ public StableOptionValue(T value) { super(value); } /** * Used to assert the invariant for stability. Without using locks, this check is not safe * against races and so it's only an assertion. */ private boolean getValueCalled; /** * Creates an uninitialized stable option value for a subclass that initializes itself * {@link #initialValue() lazily}. */ public StableOptionValue() { } /** * Gets the value of this option. */ @Override public final T getValue() { T result = super.getValue(); assert initGetValueCalled(); return result; } private boolean initGetValueCalled() { getValueCalled = true; return true; } /** * {@inheritDoc} * <p> * This must only be called if {@link #getValue()} has never been called. */ @Override public final void setValue(Object v) { assert !getValueCalled; super.setValue(v); } }