/*

 * Copyright 2008-2009 Sun Microsystems, Inc.  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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

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 */

package java.dyn;

import java.util.WeakHashMap;

import sun.reflect.Reflection;

import static sun.dyn.util.VerifyAccess.checkBootstrapPrivilege;

/**

 * Static methods which control the linkage of invokedynamic call sites.

 * @author John Rose, JSR 292 EG

 */

public class Linkage {

    private Linkage() {}  // do not instantiate

    /**

     * <em>PROVISIONAL API, WORK IN PROGRESS:</em>

     * Register a <em>bootstrap method</em> to use when linking a given caller class.

     * It must be a method handle of a type equivalent to {@link CallSite#CallSite}.

     * In other words, it must act as a factory method which accepts the arguments

     * to {@code CallSite}'s constructor (a class, a string, and a method type),

     * and returns a {@code CallSite} object (possibly of a subclass of {@code CallSite}).

     * <p>

     * The registration will fail with an {@code IllegalStateException} if any of the following conditions hold:

     * <ul>

     * <li>The caller of this method is in a different package than the {@code callerClass},

     *     and there is a security manager, and its {@code checkPermission} call throws

     *     when passed {@link LinkagePermission}("registerBootstrapMethod",callerClass).

     * <li>The given class already has a bootstrap method from a previous

     *     call to this method.

     * <li>The given class is already fully initialized.

     * <li>The given class is in the process of initialization, in another thread.

     * </ul>

     * Because of these rules, a class may install its own bootstrap method in

     * a static initializer.

     */

    public static

        Class callc = Reflection.getCallerClass(2);

        checkBootstrapPrivilege(callc, callerClass, "registerBootstrapMethod");

        synchronized (bootstrapMethods) {

            if (bootstrapMethods.containsKey(callerClass))

                throw new IllegalStateException("bootstrap method already declared in "+callerClass);

        }

    }

    static void checkBSM(MethodHandle mh) {

        if (mh == null)  throw new IllegalArgumentException("null bootstrap method");

        if (mh.type() == OLD_BOOTSTRAP_METHOD_TYPE) // FIXME: delete at EDR/PFD

            throw new WrongMethodTypeException("bootstrap method must be a CallSite factory");

        if (mh.type() != BOOTSTRAP_METHOD_TYPE)

            throw new WrongMethodTypeException(mh.toString());

    }

    /**

     * <em>PROVISIONAL API, WORK IN PROGRESS:</em>

     * Simplified version of registerBootstrapMethod for self-registration,

     * to be called from a static initializer.

     * Finds a static method of the required type in the

     * given class, and installs it on the caller.

     * @throws IllegalArgumentException if there is no such method

     */

    public static

    void registerBootstrapMethod(Class<?> runtime, String name) {

        Class callc = Reflection.getCallerClass(2);

        MethodHandle bootstrapMethod =

        // FIXME: exception processing wrong here

        checkBSM(bootstrapMethod);

        Linkage.registerBootstrapMethod(callc, bootstrapMethod);

    }

    /**

     * <em>PROVISIONAL API, WORK IN PROGRESS:</em>

     * Simplified version of registerBootstrapMethod for self-registration,

     * to be called from a static initializer.

     * Finds a static method of the required type in the

     * caller's class, and installs it on the caller.

     * @throws IllegalArgumentException if there is no such method

     */

    public static

    void registerBootstrapMethod(String name) {

        Class callc = Reflection.getCallerClass(2);

        MethodHandle bootstrapMethod =

        // FIXME: exception processing wrong here

        checkBSM(bootstrapMethod);

        Linkage.registerBootstrapMethod(callc, bootstrapMethod);

    }

    /**

     * <em>PROVISIONAL API, WORK IN PROGRESS:</em>

     * Report the bootstrap method registered for a given class.

     * Only callers privileged to set the bootstrap method may inquire

     * about it, because a bootstrap method is potentially a back-door entry

     * point into its class.

     */

    public static

    MethodHandle getBootstrapMethod(Class callerClass) {

        Class callc = Reflection.getCallerClass(2);

        checkBootstrapPrivilege(callc, callerClass, "registerBootstrapMethod");

        synchronized (bootstrapMethods) {

            return bootstrapMethods.get(callerClass);

        }

    }

    /**

     * <em>PROVISIONAL API, WORK IN PROGRESS:</em>

     * The type of any bootstrap method is a three-argument method

     * {@code (Class, String, MethodType)} returning a {@code CallSite}.

     */

    public static final MethodType BOOTSTRAP_METHOD_TYPE

    private static final MethodType OLD_BOOTSTRAP_METHOD_TYPE

    private static final WeakHashMap<Class, MethodHandle> bootstrapMethods =

            new WeakHashMap<Class, MethodHandle>();

    /**

     * <em>PROVISIONAL API, WORK IN PROGRESS:</em>

     * Invalidate all <code>invokedynamic</code> call sites everywhere.

     * <p>

     * When this method returns, every <code>invokedynamic</code> instruction

     * will invoke its bootstrap method on next call.

     * <p>

     * It is unspecified whether call sites already known to the Java

     * code will continue to be associated with <code>invokedynamic</code>

     * instructions.  If any call site is still so associated, its

     * {@link CallSite#getTarget()} method is guaranteed to return null

     * the invalidation operation completes.

     * <p>

     * Invalidation operations are likely to be slow.  Use them sparingly.

     */

    public static

    Object invalidateAll() {

        SecurityManager security = System.getSecurityManager();

        if (security != null) {

            security.checkPermission(new LinkagePermission("invalidateAll"));

        }

        throw new UnsupportedOperationException("NYI");

    }

    /**

     * <em>PROVISIONAL API, WORK IN PROGRESS:</em>

     * (These are exactly those sites which report the given class

     * via the {@link CallSite#callerClass()} method.)

     * <p>

     * When this method returns, every matching <code>invokedynamic</code>

     * instruction will invoke its bootstrap method on next call.

     * <p>

     * For additional semantics of call site invalidation,

     * see {@link #invalidateAll()}.

     */

    public static

    Object invalidateCallerClass(Class<?> callerClass) {

        SecurityManager security = System.getSecurityManager();

        if (security != null) {

            security.checkPermission(new LinkagePermission("invalidateAll", callerClass));

        }

        throw new UnsupportedOperationException("NYI");

    }

    private static Object doNotBootstrap(CallSite site, Object... arguments) {

        throw new UnsupportedOperationException("call site must not have null target: "+site);

    }

    private static final MethodHandle DO_NOT_BOOTSTRAP =

            MethodHandles.Lookup.IMPL_LOOKUP.findStatic(Linkage.class, "doNotBootstrap",

                OLD_BOOTSTRAP_METHOD_TYPE);

    // Up-call from the JVM.  Obsolete.  FIXME: Delete from VM then from here.

    static

    MethodHandle findBootstrapMethod(Class callerClass, Class searchBootstrapClass) {

        return DO_NOT_BOOTSTRAP;

    }

}