* Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved.

import jdk.vm.ci.common.NativeImageReinitialize;

import jdk.vm.ci.services.Services;

    /**

     * Singleton instance lazily initialized via double-checked locking.

     */

    @NativeImageReinitialize private static volatile JVMCIRuntime runtime;

    @NativeImageReinitialize private static boolean initializing;

    private static native JVMCIRuntime initializeRuntime();

        JVMCIRuntime result = runtime;

        if (result == null) {

            synchronized (JVMCI.class) {

                result = runtime;

                if (result == null) {

                    if (initializing) {

                        // In recursive call from HotSpotJVMCIRuntime.runtime

                        // so no need to re-enter initializeRuntime below. This

                        // path is only entered if JVMCI initialization starts

                        // with JVMCI.getRuntime().

                        return null;

                    }

                    initializing = true;

                    try {

                        runtime = result = initializeRuntime();

                    } catch (UnsatisfiedLinkError e) {

                        String javaHome = Services.getSavedProperty("java.home");

                        String vmName = Services.getSavedProperty("java.vm.name");

                        Formatter errorMessage = new Formatter();

                        errorMessage.format("The VM does not support the JVMCI API.%n");

                        errorMessage.format("Currently used Java home directory is %s.%n", javaHome);

                        errorMessage.format("Currently used VM configuration is: %s", vmName);

                        throw new UnsupportedOperationException(errorMessage.toString());

                    }

                }

            }

        return result;