Re: RFR(S): JDK-8030708: warnings from b119 for jdk/src/share/back: JNI exception pending

[David Holmes]

Hi Dmitry,

On 16/10/2014 8:08 PM, Dmitry Samersoff wrote:
David,
Changed. Thank you for review!

please, see:

http://cr.openjdk.java.net/~dsamersoff/JDK-8030708/webrev.02/

 102     if (weakRef == NULL || (*env)->ExceptionCheck(env)) {

Isn't the only time it will return NULL when an exception occurs? 
Conversely if an exception occurs then it must return NULL - so the 
exception check seems redundant.

But this also suggests you need similar logic at:

 182         weakRef = JNI_FUNC_PTR(env,NewWeakGlobalRef)(env, node->ref);

 456                 lref = JNI_FUNC_PTR(env,NewLocalRef)(env, node->ref);

Or more generally any JNI call from JVMTI should be wrapped in a way 
that checks for exceptions and clears them.

David

-Dmitry

On 2014-10-16 04:24, David Holmes wrote:
On 16/10/2014 12:33 AM, Dmitry Samersoff wrote:
David,

Sorry, copied wrong function!

I mean this call

weakRef = JNI_FUNC_PTR(env,NewWeakGlobalRef)(env, ref);

that can post  OutOfMemoryError

Okay, so shouldn't that be where the exception is cleared:

    /* Create weak reference to make sure we have a reference */
     weakRef = JNI_FUNC_PTR(env,NewWeakGlobalRef)(env, ref);
     if (weakRef == NULL) {
+       // < clear exception here >
         jvmtiDeallocate(node);
         return NULL;
     }

Thanks,
David
-----

commonRef_refToID() ->

createNode(JNIEnv *env, jobject ref) ->

weakRef = JNI_FUNC_PTR(env,NewWeakGlobalRef)(env, ref);

-Dmitry

On 2014-10-15 16:21, David Holmes wrote:
On 15/10/2014 8:39 PM, Dmitry Samersoff wrote:
On 2014-10-15 14:27, David Holmes wrote:
On 15/10/2014 8:08 PM, Dmitry Samersoff wrote:
Please review the fix:

http://cr.openjdk.java.net/~dsamersoff/JDK-8030708/webrev.01/

Added missed exception checks.

src/jdk.jdwp.agent/share/native/libjdwp/outStream.c

What is potentially posting the exception?

JvmtiEnv::GetTag(jobject object, jlong* tag_ptr) called from
commonRef_refToID()

You mean this call:

     error = JVMTI_FUNC_PTR(gdata->jvmti,GetTag)(gdata->jvmti, ref,
&tag);

x

in findNodeByRef which is called by commonRef_refToID?  JVM TI doesn't
post exceptions.

"JVM TI functions never throw exceptions; error conditions are
communicated via the function return value. Any existing exception state
is preserved across a call to a JVM TI function."

http://docs.oracle.com/javase/8/docs/platform/jvmti/jvmti.html

David

-Dmitry