001/*
002 * Copyright (c) 2012, 2015, Oracle and/or its affiliates. All rights reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation.
008 *
009 * This code is distributed in the hope that it will be useful, but WITHOUT
010 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
011 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
012 * version 2 for more details (a copy is included in the LICENSE file that
013 * accompanied this code).
014 *
015 * You should have received a copy of the GNU General Public License version
016 * 2 along with this work; if not, write to the Free Software Foundation,
017 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
018 *
019 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
020 * or visit www.oracle.com if you need additional information or have any
021 * questions.
022 */
023package com.oracle.graal.api.runtime;
024
025import java.util.*;
026
027import jdk.internal.jvmci.service.*;
028import sun.reflect.*;
029
030/**
031 * Access point for {@linkplain #getRuntime() retrieving} the single {@link GraalRuntime} instance.
032 */
033public class Graal {
034
035    private static final GraalRuntime runtime = initializeRuntime();
036
037    private static GraalRuntime initializeRuntime() {
038        GraalRuntimeAccess access = Services.loadSingle(GraalRuntimeAccess.class, false);
039        if (access != null) {
040            GraalRuntime rt = access.getRuntime();
041            assert rt != null;
042            return rt;
043        }
044        return new InvalidGraalRuntime();
045    }
046
047    /**
048     * Gets the singleton {@link GraalRuntime} instance available to the application.
049     */
050    public static GraalRuntime getRuntime() {
051        return runtime;
052    }
053
054    /**
055     * Gets a capability provided by the {@link GraalRuntime} instance available to the application.
056     *
057     * @throws UnsupportedOperationException if the capability is not available
058     */
059    @CallerSensitive
060    public static <T> T getRequiredCapability(Class<T> clazz) {
061        T t = getRuntime().getCapability(clazz);
062        if (t == null) {
063            String javaHome = System.getProperty("java.home");
064            String vmName = System.getProperty("java.vm.name");
065            Formatter errorMessage = new Formatter();
066            if (runtime.getClass() == InvalidGraalRuntime.class) {
067                errorMessage.format("The VM does not support the Graal API.%n");
068            } else {
069                errorMessage.format("The VM does not expose required Graal capability %s.%n", clazz.getName());
070            }
071            errorMessage.format("Currently used Java home directory is %s.%n", javaHome);
072            errorMessage.format("Currently used VM configuration is: %s", vmName);
073            throw new UnsupportedOperationException(errorMessage.toString());
074        }
075        return t;
076    }
077
078    private static final class InvalidGraalRuntime implements GraalRuntime {
079
080        @Override
081        public String getName() {
082            return "";
083        }
084
085        @Override
086        public <T> T getCapability(Class<T> clazz) {
087            return null;
088        }
089    }
090}