Question

I’ve spent whole day on this problem and still have no idea how to solve it.

Here is the simplified code

JAVA

class javaclass{
private volatile boolean isTerminated;
  public void javamethod()
  {
  log.logInfo("java :"+isTerminated());
  }

  public int isTerminated()
  {
    return (isTerminated) ? 1 : 0;
  }

  public doJob()
  {
    executeNative();
  }

  private native int executeNative() throws Exception;
}

C++

bool cmethod()
{
cerr << "JNI " << wrapper::isTerminated() << "\n";
if(wrapper::isTerminated)
  return false;
jni->CallVoidMethod(self, apiJavamethod, xPoint); 
return true;
//apiJavamethod is jMethodId of javamethod
}

int wrapper::isTerminated()
{
  return jni->CallIntMethod(self, apiIsTerminated);
}

JNIEXPORT jint JNICALL NAMESPACE_javaclass_executeNative(JNIEnv* env, jobject self) {
  for(int i=0;i < _ITERATIONS;++i)
  {
    if(!cmethod())
      break;
  }

}

C++ cmethod is executed in some loop, which stops when C++ catches isTerminated().
In output i see:

….
….

in log:
java 0
java 1
java 1
java 1

in console:
JNI 0
JNI 0
JNI 0
JNI 1

So, JNI is somehow behind the real state of variable.
It produces an important bug in application (((

Maybe it’s some problem with java itself? (v.1.5, i forced to used it)

Any help is greatly appreciated.

Answer 1

I would suggest doing all the synchronization in one language or the other. It’s looking like “volatile” isn’t being respected across the boundary for some reason. Something like:

public doJob()
{
  while(!isTerminated)
    executeNative();
}