1 /*

     2  * Copyright 2007 Sun Microsystems, Inc. All rights reserved.

     3  * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.

     4  */

     5 

     6 package sun.tracing;

     7 

     8 import java.lang.reflect.Method;

     9 import java.lang.reflect.Field;

    10 import com.sun.tracing.Probe;

    11 

    12 /**

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

    14  *

    15  * @since 1.7

    16  */

    17 public abstract class ProbeSkeleton implements Probe {

    18 

    19     protected Class<?>[] parameters;

    20 

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

    22         this.parameters = parameters;

    23     }

    24 

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

    26 

    27     /**

    28      * Triggers the probe with verified arguments.

    29      *

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

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

    32      * declared with.

    33      */

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

    35 

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

    37         if (o != null) {

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

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

    40                     try {

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

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

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

    44                     } catch (Exception e) {

    45                         /* fall-through. */

    46                     }

    47                 }

    48                 return false;

    49             }

    50         }

    51         return true;

    52     }

    53 

    54     /**

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

    56      */

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

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

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

    60         } else {

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

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

    63                     throw new IllegalArgumentException(

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

    65                 }

    66             }

    67             uncheckedTrigger(args);

    68         }

    69     }

    70 }