[jboss-as7-dev] Component upgrade of Javassist for AS7-5127...

[Kabir Khan]

On 6 Jul 2012, at 13:57, Scott Marlow wrote:

> We aren't using the latest Javassist on AS7 master.  Any arguments 
> against switching to the latest/shiniest 3.1.7.0-GA javassist?  That has 
> a fix for AS7-5127.
> 
> Currently, the following AS7 modules have dependencies on Javassist:
> 
> org.jboss.ws.native.jbossws-native-core
> org.jboss.weld.core
> org.jboss.as.weld
> org.scannotation.scannotation
> org.hibernate (envers also)
> 
> Also, could someone (familiar with javassist) take a look at the code 
> change that AS7-5127 wants brought into AS7?  In the updated method, 
> parameter "java.lang.reflect.Method[] methods" is read outside of the 
> synchronized lock.
I believe the check on line 53 needs to happen in a synchronized block as well to make sure it gets the latest, so rather than
	if (methods[index] == null) {
 	    Method m1 = thisMethod == null ? null
 	         : findMethod(self, thisMethod, desc);
 	   Method m0 = findSuperMethod(self, superMethod, desc);
 	   synchronized (methods) {
               if (methods[index] == null) {
                 methods[index + 1] = m1;
 	         methods[index] = m0;
 	      }
          }
      }

Something along the lines of this would be more correct
   
   Method existing = null;
   synchronized (methods) {
       Method existing = methods[index];
   }
   if (existing == null) {
 	    Method m1 = thisMethod == null ? null
 	         : findMethod(self, thisMethod, desc);
 	   Method m0 = findSuperMethod(self, superMethod, desc);
 	   synchronized (methods) {
               if (methods[index] == null) {
                 methods[index + 1] = m1;
 	         methods[index] = m0;
 	      }
          }
      }



> 
> code change is here 
> https://source.jboss.org/browse/Javassist/trunk/src/main/javassist/util/proxy/RuntimeSupport.java?u=-1&r1=591&r2=637 
> 
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