RFR (M) 8061651 - Interface to the Lookup Index Cache to improve URLClassPath search time (round 3)

[Ioi Lam]

On 10/27/14, 7:52 PM, Jiangli Zhou wrote:
> Hi Ioi,
>
> I have a question for following code in AppClassLoader.loadClass(). If 
> a class is 'known to not exist' for the AppClassLoader (not in the 
> AppClassLoader and parent classloaders' shared lookup cache), it seems 
> findLoadedClass() would only find classes that's dynamically loaded by 
> the parent loaders. The AppClassLoader would never try to load the 
> class. Is the AppClassLoader's lookup cache guaranteed to have all the 
> classes in it's path?
>
>  315             if (ucp.knownToNotExist(name)) {
>  316                 // The class of the given name is not found in 
> the parent
>  317                 // class loader as well as its local URLClassPath.
>  318                 // Check if this class has already been defined 
> dynamically;
>  319                 // if so, return the loaded class; otherwise, 
> skip the parent
>  320                 // delegation and findClass.
>  321                 synchronized (getClassLoadingLock(name)) {
>  322                     Class<?> c = findLoadedClass(name);
>  323                     if (c != null) {
>  324                         return c;
>  325                     }
>  326                 }
>  327                 throw new ClassNotFoundException(name);
>  328             }
The reason is to make the behavior consistent with 
java.lang.ClassLoader.loadClass():

     protected Class<?> loadClass(String name, boolean resolve)
         throws ClassNotFoundException
     {
         synchronized (getClassLoadingLock(name)) {
             // First, check if the class has already been loaded
             Class<?> c = findLoadedClass(name);
             ....

If <name> is not in any of the JAR files but was dynamically defined 
(using ClassLoader.defineClass, etc), then AppClassLoader.loadClass() 
should return the class without throwing ClassNotFoundException.

Thanks
- Ioi

> Thanks,
> Jiangli
>
> On 10/27/2014 3:32 PM, Ioi Lam wrote:
>> Hi David, I have update the latest webrev at:
>>
>> http://cr.openjdk.java.net/~iklam/8061651-lookup-index-open-v3/
>>
>> and fixed the "int cache[]" style you mentioned.
>>
>> This version also contains the JDK test case that Mandy requested:
>>
>> http://cr.openjdk.java.net/~iklam/8061651-lookup-index-open-v3/jdk/test/sun/misc/URLClassPath/EnableLookupCache.java.html 
>>
>>
>> Thanks
>> - Ioi
>>