- The blackhole queue
-
- Threads on this list behave like weak pointers during the normal
- phase of garbage collection: if the blackhole is reachable, then
- the thread is reachable too.
- -------------------------------------------------------------------------- */
-rtsBool
-traverseBlackholeQueue (void)
-{
- StgTSO *prev, *t, *tmp;
- rtsBool flag;
- nat type;
-
- flag = rtsFalse;
- prev = NULL;
-
- for (t = blackhole_queue; t != END_TSO_QUEUE; prev=t, t = t->_link) {
- // if the thread is not yet alive...
- if (! (tmp = (StgTSO *)isAlive((StgClosure*)t))) {
- // if the closure it is blocked on is either (a) a
- // reachable BLAKCHOLE or (b) not a BLACKHOLE, then we
- // make the thread alive.
- if (!isAlive(t->block_info.closure)) {
- type = get_itbl(t->block_info.closure)->type;
- if (type == BLACKHOLE || type == CAF_BLACKHOLE) {
- continue;
- }
- }
- evacuate((StgClosure **)&t);
- if (prev) {
- prev->_link = t;
- } else {
- blackhole_queue = t;
- }
- // no write barrier when on the blackhole queue,
- // because we traverse the whole queue on every GC.
- flag = rtsTrue;
- }
- }
- return flag;
-}
-
-/* -----------------------------------------------------------------------------