8078021: SATB apply_closure_to_completed_buffer should have closure argument

Summary: Apply closure directly, eliminating registration.
Reviewed-by: stefank, tschatzl

src/share/vm/gc_implementation/g1/concurrentMark.cpp

@@ -4003,32 +4003,16 @@ void CMTask::drain_satb_buffers() {
 
   CMObjectClosure oc(this);
   SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
-  if (G1CollectedHeap::use_parallel_gc_threads()) {
-    satb_mq_set.set_par_closure(_worker_id, &oc);
-  } else {
-    satb_mq_set.set_closure(&oc);
-  }
 
   // This keeps claiming and applying the closure to completed buffers
   // until we run out of buffers or we need to abort.
-  if (G1CollectedHeap::use_parallel_gc_threads()) {
-    while (!has_aborted() &&
-           satb_mq_set.par_apply_closure_to_completed_buffer(_worker_id)) {
-      if (_cm->verbose_medium()) {
-        gclog_or_tty->print_cr("[%u] processed an SATB buffer", _worker_id);
-      }
-      statsOnly( ++_satb_buffers_processed );
-      regular_clock_call();
-    }
-  } else {
-    while (!has_aborted() &&
-           satb_mq_set.apply_closure_to_completed_buffer()) {
-      if (_cm->verbose_medium()) {
-        gclog_or_tty->print_cr("[%u] processed an SATB buffer", _worker_id);
-      }
-      statsOnly( ++_satb_buffers_processed );
-      regular_clock_call();
+  while (!has_aborted() &&
+         satb_mq_set.apply_closure_to_completed_buffer(&oc)) {
+    if (_cm->verbose_medium()) {
+      gclog_or_tty->print_cr("[%u] processed an SATB buffer", _worker_id);
     }
+    statsOnly( ++_satb_buffers_processed );
+    regular_clock_call();
   }
 
   _draining_satb_buffers = false;
@@ -4037,12 +4021,6 @@ void CMTask::drain_satb_buffers() {
          concurrent() ||
          satb_mq_set.completed_buffers_num() == 0, "invariant");
 
-  if (G1CollectedHeap::use_parallel_gc_threads()) {
-    satb_mq_set.set_par_closure(_worker_id, NULL);
-  } else {
-    satb_mq_set.set_closure(NULL);
-  }
-
   // again, this was a potentially expensive operation, decrease the
   // limits to get the regular clock call early
   decrease_limits();

src/share/vm/gc_implementation/g1/satbQueue.cpp

@@ -227,7 +227,7 @@ void ObjPtrQueue::print(const char* name,
 #endif // _MSC_VER
 
 SATBMarkQueueSet::SATBMarkQueueSet() :
-  PtrQueueSet(), _closure(NULL), _par_closures(NULL),
+  PtrQueueSet(),
   _shared_satb_queue(this, true /*perm*/) { }
 
 void SATBMarkQueueSet::initialize(Monitor* cbl_mon, Mutex* fl_lock,
@@ -235,9 +235,6 @@ void SATBMarkQueueSet::initialize(Monitor* cbl_mon, Mutex* fl_lock,
                                   Mutex* lock) {
   PtrQueueSet::initialize(cbl_mon, fl_lock, process_completed_threshold, -1);
   _shared_satb_queue.set_lock(lock);
-  if (ParallelGCThreads > 0) {
-    _par_closures = NEW_C_HEAP_ARRAY(ObjectClosure*, ParallelGCThreads, mtGC);
-  }
 }
 
 void SATBMarkQueueSet::handle_zero_index_for_thread(JavaThread* t) {
@@ -300,17 +297,7 @@ void SATBMarkQueueSet::filter_thread_buffers() {
   shared_satb_queue()->filter();
 }
 
-void SATBMarkQueueSet::set_closure(ObjectClosure* closure) {
-  _closure = closure;
-}
-
-void SATBMarkQueueSet::set_par_closure(int i, ObjectClosure* par_closure) {
-  assert(ParallelGCThreads > 0 && _par_closures != NULL, "Precondition");
-  _par_closures[i] = par_closure;
-}
-
-bool SATBMarkQueueSet::apply_closure_to_completed_buffer_work(bool par,
-                                                              uint worker) {
+bool SATBMarkQueueSet::apply_closure_to_completed_buffer(ObjectClosure* cl) {
   BufferNode* nd = NULL;
   {
     MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);
@@ -322,7 +309,6 @@ bool SATBMarkQueueSet::apply_closure_to_completed_buffer_work(bool par,
       if (_n_completed_buffers == 0) _process_completed = false;
     }
   }
-  ObjectClosure* cl = (par ? _par_closures[worker] : _closure);
   if (nd != NULL) {
     void **buf = BufferNode::make_buffer_from_node(nd);
     ObjPtrQueue::apply_closure_to_buffer(cl, buf, 0, _sz);

src/share/vm/gc_implementation/g1/satbQueue.hpp

@@ -75,16 +75,8 @@ public:
 };
 
 class SATBMarkQueueSet: public PtrQueueSet {
-  ObjectClosure* _closure;
-  ObjectClosure** _par_closures;  // One per ParGCThread.
-
   ObjPtrQueue _shared_satb_queue;
 
-  // Utility function to support sequential and parallel versions.  If
-  // "par" is true, then "worker" is the par thread id; if "false", worker
-  // is ignored.
-  bool apply_closure_to_completed_buffer_work(bool par, uint worker);
-
 #ifdef ASSERT
   void dump_active_states(bool expected_active);
   void verify_active_states(bool expected_active);
@@ -108,26 +100,10 @@ public:
   // Filter all the currently-active SATB buffers.
   void filter_thread_buffers();
 
-  // Register "blk" as "the closure" for all queues.  Only one such closure
-  // is allowed.  The "apply_closure_to_completed_buffer" method will apply
-  // this closure to a completed buffer, and "iterate_closure_all_threads"
-  // applies it to partially-filled buffers (the latter should only be done
-  // with the world stopped).
-  void set_closure(ObjectClosure* closure);
-  // Set the parallel closures: pointer is an array of pointers to
-  // closures, one for each parallel GC thread.
-  void set_par_closure(int i, ObjectClosure* closure);
-
   // If there exists some completed buffer, pop it, then apply the
-  // registered closure to all its elements, and return true.  If no
+  // closure to all its elements, and return true.  If no
   // completed buffers exist, return false.
-  bool apply_closure_to_completed_buffer() {
-    return apply_closure_to_completed_buffer_work(false, 0);
-  }
-  // Parallel version of the above.
-  bool par_apply_closure_to_completed_buffer(uint worker) {
-    return apply_closure_to_completed_buffer_work(true, worker);
-  }
+  bool apply_closure_to_completed_buffer(ObjectClosure* closure);
 
   // Apply the given closure on enqueued and currently-active buffers
   // respectively. Both methods are read-only, i.e., they do not