1 /*

     2  * Copyright (c) 2008, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

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

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 

    26 package sun.tracing;

    27 

    28 import java.lang.reflect.Method;

    29 import java.lang.reflect.Field;

    30 import com.sun.tracing.Probe;

    31 

    32 /**

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

    34  *

    35  * @since 1.7

    36  */

    37 public abstract class ProbeSkeleton implements Probe {

    38 

    39     protected Class<?>[] parameters;

    40 

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

    42         this.parameters = parameters;

    43     }

    44 

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

    46 

    47     /**

    48      * Triggers the probe with verified arguments.

    49      *

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

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

    52      * declared with.

    53      */

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

    55 

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

    57         if (o != null) {

    58             if ( !formal.isInstance(o) ) {

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

    60                     try {

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

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

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

    64                     } catch (Exception e) {

    65                         /* fall-through. */

    66                     }

    67                 }

    68                 return false;

    69             }

    70         }

    71         return true;

    72     }

    73 

    74     /**

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

    76      */

    77     public void trigger(Object ... args) {

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

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

    80         } else {

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

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

    83                     throw new IllegalArgumentException(

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

    85                 }

    86             }

    87             uncheckedTrigger(args);

    88         }

    89     }

    90 }