42     // Loops on this thread until it has exited the critical read section.
  43     while(true) {
  44       uintx cnt = Atomic::load_acquire(thread->get_rcu_counter());
  45       // This checks if the thread's counter is active. And if so is the counter
  46       // for a pre-existing reader (belongs to this grace period). A pre-existing
  47       // reader will have a lower counter than the global counter version for this
  48       // generation. If the counter is larger than the global counter version this
  49       //  is a new reader and we can continue.
  50       if (((cnt & COUNTER_ACTIVE) != 0) && (cnt - _gbl_cnt) > (max_uintx / 2)) {
  51         yield.wait();
  52       } else {
  53         break;
  54       }
  55     }
  56   }
  57 };
  58 
  59 void GlobalCounter::write_synchronize() {
  60   assert((*Thread::current()->get_rcu_counter() & COUNTER_ACTIVE) == 0x0, "must be outside a critcal section");
  61   // Atomic::add must provide fence since we have storeload dependency.
  62   uintx gbl_cnt = Atomic::add(COUNTER_INCREMENT, &_global_counter._counter);
  63 
  64   // Do all RCU threads.
  65   CounterThreadCheck ctc(gbl_cnt);
  66   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) {
  67     ctc.do_thread(thread);
  68   }
  69   for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
  70     ctc.do_thread(njti.current());
  71   }
  72 }

  42     // Loops on this thread until it has exited the critical read section.
  43     while(true) {
  44       uintx cnt = Atomic::load_acquire(thread->get_rcu_counter());
  45       // This checks if the thread's counter is active. And if so is the counter
  46       // for a pre-existing reader (belongs to this grace period). A pre-existing
  47       // reader will have a lower counter than the global counter version for this
  48       // generation. If the counter is larger than the global counter version this
  49       //  is a new reader and we can continue.
  50       if (((cnt & COUNTER_ACTIVE) != 0) && (cnt - _gbl_cnt) > (max_uintx / 2)) {
  51         yield.wait();
  52       } else {
  53         break;
  54       }
  55     }
  56   }
  57 };
  58 
  59 void GlobalCounter::write_synchronize() {
  60   assert((*Thread::current()->get_rcu_counter() & COUNTER_ACTIVE) == 0x0, "must be outside a critcal section");
  61   // Atomic::add must provide fence since we have storeload dependency.
  62   uintx gbl_cnt = Atomic::add(&_global_counter._counter, COUNTER_INCREMENT);
  63 
  64   // Do all RCU threads.
  65   CounterThreadCheck ctc(gbl_cnt);
  66   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) {
  67     ctc.do_thread(thread);
  68   }
  69   for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
  70     ctc.do_thread(njti.current());
  71   }
  72 }