/*

 * Copyright (c) 2008, 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.  Oracle designates this

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

 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package sun.tracing;

import java.lang.reflect.Method;

import java.lang.reflect.Field;

import com.sun.tracing.Probe;

/**

 * Provides common code for implementation of {@code Probe} classes.

 *

 * @since 1.7

 */

public abstract class ProbeSkeleton implements Probe {

    protected Class<?>[] parameters;

    protected ProbeSkeleton(Class<?>[] parameters) {

        this.parameters = parameters;

    }

    public abstract boolean isEnabled();  // framework-dependent

    /**

     * Triggers the probe with verified arguments.

     *

     * The caller of this method must have already determined that the

     * arity and types of the arguments match what the probe was

     * declared with.

     */

    public abstract void uncheckedTrigger(Object[] args); // framework-dependent

    private static boolean isAssignable(Object o, Class<?> formal) {

        if (o != null) {

            if ( !formal.isInstance(o) ) {

                if ( formal.isPrimitive() ) { // o might be a boxed primitive

                    try {

                        // Yuck.  There must be a better way of doing this

                        Field f = o.getClass().getField("TYPE");

                        return formal.isAssignableFrom((Class<?>)f.get(null));

                    } catch (Exception e) {

                        /* fall-through. */

                    }

                }

                return false;

            }

        }

        return true;

    }

    /**

     * Performs a type-check of the parameters before triggering the probe.

     */

    public void trigger(Object ... args) {

        if (args.length != parameters.length) {

            throw new IllegalArgumentException("Wrong number of arguments");

        } else {

            for (int i = 0; i < parameters.length; ++i) {

                if ( !isAssignable(args[i], parameters[i]) ) {

                    throw new IllegalArgumentException(

                            "Wrong type of argument at position " + i);

                }

            }

            uncheckedTrigger(args);

        }

    }

}