/*

 * Copyright (c) 2014, 2016, 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 jdk.vm.ci.services;

import java.lang.reflect.Method;

import java.util.Map;

/**

 * Provides utilities needed by JVMCI clients.

 */

public final class Services {

    // This class must be compilable and executable on JDK 8 since it's used in annotation

    // processors while building JDK 9 so use of API added in JDK 9 is made via reflection.

    private Services() {

    }

    @SuppressWarnings("unchecked")

    private static Map<String, String> initSavedProperties() throws InternalError {

        try {

            Class<?> vmClass = Class.forName("jdk.internal.misc.VM");

            Method m = vmClass.getMethod("getSavedProperties");

            return (Map<String, String>) m.invoke(null);

        } catch (Exception e) {

            throw new InternalError(e);

        }

    }

    static final Map<String, String> SAVED_PROPERTIES = initSavedProperties();

    static final boolean JVMCI_ENABLED = Boolean.parseBoolean(SAVED_PROPERTIES.get("jdk.internal.vm.ci.enabled"));

    /**

     * Checks that JVMCI is enabled in the VM and throws an error if it isn't.

     */

    static void checkJVMCIEnabled() {

        if (!JVMCI_ENABLED) {

            throw new Error("The EnableJVMCI VM option must be true (i.e., -XX:+EnableJVMCI) to use JVMCI");

        }

    }

    /**

     * Gets an unmodifiable copy of the system properties saved when {@link System} is initialized.

     */

    public static Map<String, String> getSavedProperties() {

        checkJVMCIEnabled();

        SecurityManager sm = System.getSecurityManager();

        if (sm != null) {

            sm.checkPermission(new JVMCIPermission());

        }

        return SAVED_PROPERTIES;

    }

    /**

     * Causes the JVMCI subsystem to be initialized if it isn't already initialized.

     */

    public static void initializeJVMCI() {

        checkJVMCIEnabled();

        try {

            Class.forName("jdk.vm.ci.runtime.JVMCI");

        } catch (ClassNotFoundException e) {

            throw new InternalError(e);

        }

    }

}