C++ (Cpp) JavaThread::can_call_java Examples

Example #1

File: javaCalls.cpp Project: lmsf/jdk9-dev

JavaCallWrapper::JavaCallWrapper(methodHandle callee_method, Handle receiver, JavaValue* result, TRAPS) {
  JavaThread* thread = (JavaThread *)THREAD;
  bool clear_pending_exception = true;

  guarantee(thread->is_Java_thread(), "crucial check - the VM thread cannot and must not escape to Java code");
  assert(!thread->owns_locks(), "must release all locks when leaving VM");
  guarantee(thread->can_call_java(), "cannot make java calls from the native compiler");
  _result   = result;

  // Allocate handle block for Java code. This must be done before we change thread_state to _thread_in_Java_or_stub,
  // since it can potentially block.
  JNIHandleBlock* new_handles = JNIHandleBlock::allocate_block(thread);

  // After this, we are official in JavaCode. This needs to be done before we change any of the thread local
  // info, since we cannot find oops before the new information is set up completely.
  ThreadStateTransition::transition(thread, _thread_in_vm, _thread_in_Java);

  // Make sure that we handle asynchronous stops and suspends _before_ we clear all thread state
  // in JavaCallWrapper::JavaCallWrapper(). This way, we can decide if we need to do any pd actions
  // to prepare for stop/suspend (flush register windows on sparcs, cache sp, or other state).
  if (thread->has_special_runtime_exit_condition()) {
    thread->handle_special_runtime_exit_condition();
    if (HAS_PENDING_EXCEPTION) {
      clear_pending_exception = false;
    }
  }


  // Make sure to set the oop's after the thread transition - since we can block there. No one is GC'ing
  // the JavaCallWrapper before the entry frame is on the stack.
  _callee_method = callee_method();
  _receiver = receiver();

#ifdef CHECK_UNHANDLED_OOPS
  THREAD->allow_unhandled_oop(&_receiver);
#endif // CHECK_UNHANDLED_OOPS

  _thread       = (JavaThread *)thread;
  _handles      = _thread->active_handles();    // save previous handle block & Java frame linkage

  // For the profiler, the last_Java_frame information in thread must always be in
  // legal state. We have no last Java frame if last_Java_sp == NULL so
  // the valid transition is to clear _last_Java_sp and then reset the rest of
  // the (platform specific) state.

  _anchor.copy(_thread->frame_anchor());
  _thread->frame_anchor()->clear();

  debug_only(_thread->inc_java_call_counter());
  _thread->set_active_handles(new_handles);     // install new handle block and reset Java frame linkage

  assert (_thread->thread_state() != _thread_in_native, "cannot set native pc to NULL");

  // clear any pending exception in thread (native calls start with no exception pending)
  if(clear_pending_exception) {
    _thread->clear_pending_exception();
  }

  if (_anchor.last_Java_sp() == NULL) {
    _thread->record_base_of_stack_pointer();
  }
}