Re: [cp-patches] [generics] RFC: instrumentation for defineClasses

[Nicolas Geoffray]

I'm committing this in since I had no objection.

2005-12-14  Nicolas Geoffray  <address@hidden>

   * java/lang/ClassLoader
   (defineClass(String,byte[],int,int,ProtectionDomain)):
   Calls VMClassLoader.defineClassWithTransformers instead
   of VMClassLoader.defineClass.
   * vm/reference/java/lang/VMClassLoader
   (defineClassWithTransformers): New method.
   (instrumenter): New Field.


Nicolas Geoffray wrote:

> Hi,
>
> I implemented the instrumentation of definition of classes in 
> classpath. With
> the previous implementation, the vm needed to call transformers, now the
> call is done in java.lang.ClassLoader.defineClass. This doesn't break
> the vm interface.
>
> The vm implementor needs to fill in VMClassLoader.instrumenter the
> java.lang.InstrumentationImpl object (or any other implementation, but 
> it should
> be noted that the VMClassLoader.redefineClassWithTransformers needs the
> instrumentation object to have a callTransformers method)
>
> The drawback of this implementation is that defineClass will allways 
> test if there
> is an InstrumentationImpl object that is defined. If a vm doesn't want 
> this test,
> it can still modify the VMClassLoader.redefineClassWithTransformers to 
> be the
> VMClassLoader.defineClass method.
>
> Nicolas
>
> 2005-12-09  Nicolas Geoffray  <address@hidden>
>
>     * java/lang/ClassLoader
>     (defineClass(String,byte[],int,int,ProtectionDomain)):
>     Calls VMClassLoader.defineClassWithTransformers instead
>     of VMClassLoader.defineClass.
>     * vm/reference/java/lang/VMClassLoader
>     (defineClassWithTransformers): New method.
>     (instrumenter): New Field.
>
> ------------------------------------------------------------------------
>
> Index: vm/reference/java/lang/VMClassLoader.java
> ===================================================================
> RCS file: 
> /cvsroot/classpath/classpath/vm/reference/java/lang/VMClassLoader.java,v
> retrieving revision 1.16.2.11
> diff -u -r1.16.2.11 VMClassLoader.java
> --- vm/reference/java/lang/VMClassLoader.java   2 Nov 2005 00:44:15 -0000       
> 1.16.2.11
> +++ vm/reference/java/lang/VMClassLoader.java   9 Dec 2005 10:59:27 -0000
> @@ -44,6 +44,8 @@
>
> import java.io.File;
> import java.io.IOException;
> +import java.lang.InstrumentationImpl;
> +import java.lang.instrument.Instrumentation;
> import java.net.MalformedURLException;
> import java.net.URL;
> import java.security.ProtectionDomain;
> @@ -346,4 +348,41 @@
>    * for this class.
>    */
>   static native Class findLoadedClass(ClassLoader cl, String name);
> +
> +  /**
> +   * The Instrumentation object created by the vm when agents are defined.
> +   */
> +  static final Instrumentation instrumenter = null;
> +
> +  /**
> +   * Call the transformers of the possible Instrumentation object
> +   *
> +   * @param loader the initiating loader
> +   * @param name the name of the class
> +   * @param data the data representing the classfile, in classfile format
> +   * @param offset the offset into the data where the classfile starts
> +   * @param len the length of the classfile data in the array
> +   * @param pd the protection domain
> +   * @return the new data representing the classfile
> +   */
> +  static final Class defineClassWithTransformers(ClassLoader loader,
> +      String name, byte[] data, int offset, int len, ProtectionDomain pd)
> +  {
> +    
> +    if (instrumenter != null)
> +      {
> +        byte[] modifiedData = new byte[len];
> +        System.arraycopy(data, offset, modifiedData, 0, len);
> +        modifiedData =
> +          ((InstrumentationImpl)instrumenter).callTransformers(loader, name,
> +            null, pd, modifiedData);
> +        
> +        return defineClass(loader, name, modifiedData, 0, modifiedData.length,
> +            pd);
> +      }
> +    else
> +      {
> +        return defineClass(loader, name, data, offset, len, pd);
> +      }
> +  }
> }
> Index: java/lang/ClassLoader.java
> ===================================================================
> RCS file: /cvsroot/classpath/classpath/java/lang/ClassLoader.java,v
> retrieving revision 1.31.2.14
> diff -u -r1.31.2.14 ClassLoader.java
> --- java/lang/ClassLoader.java  2 Nov 2005 00:43:33 -0000       1.31.2.14
> +++ java/lang/ClassLoader.java  9 Dec 2005 10:59:32 -0000
> @@ -467,7 +467,9 @@
>     checkInitialized();
>     if (domain == null)
>       domain = StaticData.defaultProtectionDomain;
> -    return VMClassLoader.defineClass(this, name, data, offset, len, domain);
> +    
> +    return VMClassLoader.defineClassWithTransformers(this, name, data, offset,
> +        len, domain);
>   }
>
>   /**
>  
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> Classpath-patches mailing list
> address@hidden
> http://lists.gnu.org/mailman/listinfo/classpath-patches
>  

Index: java/lang/ClassLoader.java
===================================================================
RCS file: /cvsroot/classpath/classpath/java/lang/ClassLoader.java,v
retrieving revision 1.31.2.14
diff -u -r1.31.2.14 ClassLoader.java
--- java/lang/ClassLoader.java  2 Nov 2005 00:43:33 -0000       1.31.2.14
+++ java/lang/ClassLoader.java  14 Dec 2005 09:21:31 -0000
@@ -467,7 +467,9 @@
     checkInitialized();
     if (domain == null)
       domain = StaticData.defaultProtectionDomain;
-    return VMClassLoader.defineClass(this, name, data, offset, len, domain);
+    
+    return VMClassLoader.defineClassWithTransformers(this, name, data, offset,
+        len, domain);
   }
 
   /**
Index: vm/reference/java/lang/VMClassLoader.java
===================================================================
RCS file: 
/cvsroot/classpath/classpath/vm/reference/java/lang/VMClassLoader.java,v
retrieving revision 1.16.2.11
diff -u -r1.16.2.11 VMClassLoader.java
--- vm/reference/java/lang/VMClassLoader.java   2 Nov 2005 00:44:15 -0000       
1.16.2.11
+++ vm/reference/java/lang/VMClassLoader.java   14 Dec 2005 09:21:35 -0000
@@ -44,6 +44,8 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.lang.InstrumentationImpl;
+import java.lang.instrument.Instrumentation;
 import java.net.MalformedURLException;
 import java.net.URL;
 import java.security.ProtectionDomain;
@@ -346,4 +348,45 @@
    * for this class.
    */
   static native Class findLoadedClass(ClassLoader cl, String name);
+
+  /**
+   * The Instrumentation object created by the vm when agents are defined.
+   */
+  static final Instrumentation instrumenter = null;
+
+  /**
+   * Call the transformers of the possible Instrumentation object. This
+   * implementation assumes the instrumenter is a
+   * <code>InstrumentationImpl</code> object. VM implementors would
+   * have to redefine this method if they provide their own implementation
+   * of the <code>Instrumentation</code> interface.
+   *
+   * @param loader the initiating loader
+   * @param name the name of the class
+   * @param data the data representing the classfile, in classfile format
+   * @param offset the offset into the data where the classfile starts
+   * @param len the length of the classfile data in the array
+   * @param pd the protection domain
+   * @return the new data representing the classfile
+   */
+  static final Class defineClassWithTransformers(ClassLoader loader,
+      String name, byte[] data, int offset, int len, ProtectionDomain pd)
+  {
+    
+    if (instrumenter != null)
+      {
+        byte[] modifiedData = new byte[len];
+        System.arraycopy(data, offset, modifiedData, 0, len);
+        modifiedData =
+          ((InstrumentationImpl)instrumenter).callTransformers(loader, name,
+            null, pd, modifiedData);
+        
+        return defineClass(loader, name, modifiedData, 0, modifiedData.length,
+            pd);
+      }
+    else
+      {
+        return defineClass(loader, name, data, offset, len, pd);
+      }
+  }
 }