77   uint index;

    77   uint index;

    78   while (true) {

    78   while (true) {

    79     index = head_index(old_head);

    79     index = head_index(old_head);

    80     assert(index < _size, "invariant");

    80     assert(index < _size, "invariant");

    81     uintx new_head = make_head(_next[index], old_head);

    81     uintx new_head = make_head(_next[index], old_head);

    83     if (new_head == old_head) break;

    83     if (new_head == old_head) break;

    84     old_head = new_head;

    84     old_head = new_head;

    85   }

    85   }

    86   DEBUG_ONLY(_next[index] = Claimed;)

    86   DEBUG_ONLY(_next[index] = Claimed;)

    87   return _start + index;

    87   return _start + index;

    93   assert(_next[index] == Claimed, "precondition");

    93   assert(_next[index] == Claimed, "precondition");

    94   uintx old_head = Atomic::load(&_head);

    94   uintx old_head = Atomic::load(&_head);

    95   while (true) {

    95   while (true) {

    96     _next[index] = head_index(old_head);

    96     _next[index] = head_index(old_head);

    97     uintx new_head = make_head(index, old_head);

    97     uintx new_head = make_head(index, old_head);

    99     if (new_head == old_head) break;

    99     if (new_head == old_head) break;

   100     old_head = new_head;

   100     old_head = new_head;

   101   }

   101   }

   102   // Now that id has been released, permit another thread through the gate.

   102   // Now that id has been released, permit another thread through the gate.

   103   _sem.signal();

   103   _sem.signal();