42 // Loops on this thread until it has exited the critical read section.
43 while(true) {
44 uintx cnt = OrderAccess::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 volatile uintx gbl_cnt = Atomic::add((uintx)COUNTER_INCREMENT, &_global_counter._counter);
63 // Do all RCU threads.
64 CounterThreadCheck ctc(gbl_cnt);
65 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) {
66 ctc.do_thread(thread);
67 }
68 ctc.do_thread(VMThread::vm_thread());
69 }
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42 // Loops on this thread until it has exited the critical read section.
43 while(true) {
44 uintx cnt = OrderAccess::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 volatile uintx gbl_cnt = Atomic::add((uintx)COUNTER_INCREMENT, &_global_counter._counter,
63 memory_order_conservative);
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 ctc.do_thread(VMThread::vm_thread());
70 }
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