Prepares allocation for proper sync with mutator and bg threads.

runtime/vm/scavenger.cc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/scavenger.h"
 
 #include "vm/dart.h"
 #include "vm/dart_api_state.h"
 #include "vm/isolate.h"
 #include "vm/lockers.h"
@@ skipping 306 matching lines @@
                      intptr_t max_semi_capacity_in_words,
                      uword object_alignment)
     : heap_(heap),
       max_semi_capacity_in_words_(max_semi_capacity_in_words),
       object_alignment_(object_alignment),
       scavenging_(false),
       delayed_weak_properties_(NULL),
       gc_time_micros_(0),
       collections_(0),
       external_size_(0),
-      failed_to_promote_(false) {
+      failed_to_promote_(false),
+      space_lock_(new Mutex()) {
   // Verify assumptions about the first word in objects which the scavenger is
   // going to use for forwarding pointers.
   ASSERT(Object::tags_offset() == 0);
 
   // Set initial size resulting in a total of three different levels.
   const intptr_t initial_semi_capacity_in_words =
       max_semi_capacity_in_words /
       (FLAG_new_gen_growth_factor * FLAG_new_gen_growth_factor);
 
   const intptr_t kVmNameSize = 128;
@@ skipping 10 matching lines @@
 
   survivor_end_ = FirstObjectStart();
 
   UpdateMaxHeapCapacity();
   UpdateMaxHeapUsage();
 }
 
 Scavenger::~Scavenger() {
   ASSERT(!scavenging_);
   to_->Delete();
+  delete space_lock_;
 }
 
 intptr_t Scavenger::NewSizeInWords(intptr_t old_size_in_words) const {
   if (stats_history_.Size() == 0) {
     return old_size_in_words;
   }
   double garbage = stats_history_.Get(0).GarbageFraction();
   if (garbage < (FLAG_new_gen_garbage_threshold / 100.0)) {
     return Utils::Minimum(max_semi_capacity_in_words_,
                           old_size_in_words * FLAG_new_gen_growth_factor);
@@ skipping 337 matching lines @@
 #endif                                 // defined(DEBUG)
 
       WeakProperty::Clear(cur_weak);
 
       // Advance to next weak property in the queue.
       cur_weak = reinterpret_cast<RawWeakProperty*>(next_weak);
     }
   }
 }
 
+void Scavenger::MakeAllTLABsIterable(Isolate* isolate) const {
+  MonitorLocker ml(isolate->threads_lock(), false);
+  Thread* current = heap_->isolate()->thread_registry()->active_list();
+  while (current != NULL) {
+    if (current->HasActiveTLAB()) {
+      heap_->MakeTLABIterable(current);
+    }
+    current = current->next();
+  }
+  if (!isolate->IsMutatorThreadScheduled()) {
+    Thread* mutator_thread = isolate->mutator_thread();
+    heap_->MakeTLABIterable(mutator_thread);

[rmacnak, 2017/08/10 18:37:07]

An isolate might not have a mutator_thread yet.

[danunez, 2017/08/10 20:36:46]

Right. Adding a check for NULL mutator_thread.

+  }
+}
+
 void Scavenger::MakeNewSpaceIterable() const {
   ASSERT(heap_ != NULL);
-  Thread* mutator_thread = heap_->isolate()->mutator_thread();
-  if (mutator_thread != NULL && !scavenging_) {
-    if (mutator_thread->HasActiveTLAB()) {
-      ASSERT(mutator_thread->top() <= top_);
-      heap_->FillRemainingTLAB(mutator_thread);
-    }
+  if (!scavenging_) {
+    MakeAllTLABsIterable(heap_->isolate());
   }
 }
 
+void Scavenger::AbandonAllTLABs(Isolate* isolate) {
+  MonitorLocker ml(isolate->threads_lock(), false);
+  Thread* current = isolate->thread_registry()->active_list();
+  while (current != NULL) {
+    heap_->AbandonRemainingTLAB(current);
+    current = current->next();
+  }
+  if (!isolate->IsMutatorThreadScheduled()) {
+    Thread* mutator_thread = isolate->mutator_thread();

[rmacnak, 2017/08/10 18:37:06]

An isolate might not have a mutator_thread yet.

[danunez, 2017/08/10 20:36:46]

Done.

+    heap_->AbandonRemainingTLAB(mutator_thread);
+  }
+}
+
 void Scavenger::VisitObjectPointers(ObjectPointerVisitor* visitor) const {
   ASSERT(Thread::Current()->IsAtSafepoint() ||
          (Thread::Current()->task_kind() == Thread::kMarkerTask));
   MakeNewSpaceIterable();
   uword cur = FirstObjectStart();
   while (cur < top_) {
     RawObject* raw_obj = RawObject::FromAddr(cur);
     cur += raw_obj->VisitPointers(visitor);
   }
 }
@@ skipping 56 matching lines @@
   scavenging_ = true;
 
   failed_to_promote_ = false;
 
   PageSpace* page_space = heap_->old_space();
   NoSafepointScope no_safepoints;
 
   int64_t post_safe_point = OS::GetCurrentMonotonicMicros();
   heap_->RecordTime(kSafePoint, post_safe_point - pre_safe_point);
 
-  Thread* mutator_thread = isolate->mutator_thread();
-  if ((mutator_thread != NULL) && (mutator_thread->HasActiveTLAB())) {
-    heap_->AbandonRemainingTLAB(mutator_thread);
-  }
+  AbandonAllTLABs(isolate);
 
   // TODO(koda): Make verification more compatible with concurrent sweep.
   if (FLAG_verify_before_gc && !FLAG_concurrent_sweep) {
     OS::PrintErr("Verifying before Scavenge...");
     heap_->Verify(kForbidMarked);
     OS::PrintErr(" done.\n");
   }
 
   // Prepare for a scavenge.
   SpaceUsage usage_before = GetCurrentUsage();
@@ skipping 99 matching lines @@
   // Forces the next scavenge to promote all the objects in the new space.
   survivor_end_ = top_;
 
   Scavenge();
 
   // It is possible for objects to stay in the new space
   // if the VM cannot create more pages for these objects.
   ASSERT((UsedInWords() == 0) || failed_to_promote_);
 }
 
+int64_t Scavenger::FreeSpaceInWords(Isolate* isolate) const {
+  MonitorLocker ml(isolate->threads_lock(), false);
+  Thread* current = isolate->thread_registry()->active_list();

[rmacnak, 2017/08/10 18:37:07]

"active_list"  What about an unscheduled mutator thread?

[danunez, 2017/08/10 20:36:46]

Added a check for an unscheduled mutator thread.

+  int64_t free_space = 0;
+  while (current != NULL) {
+    if (current->HasActiveTLAB()) {
+      free_space += current->end() - current->top();
+    }
+    current = current->next();
+  }
+  return free_space >> kWordSizeLog2;
+}
+
 int64_t Scavenger::UsedInWords() const {
-  int64_t free_space_in_tlab = 0;
-  if (heap_->isolate()->IsMutatorThreadScheduled()) {
-    Thread* mutator_thread = heap_->isolate()->mutator_thread();
-    if (mutator_thread->HasActiveTLAB()) {
-      free_space_in_tlab =
-          (mutator_thread->end() - mutator_thread->top()) >> kWordSizeLog2;
-    }
-  }
+  int64_t free_space_in_tlab = FreeSpaceInWords(heap_->isolate());
   int64_t max_space_used = (top_ - FirstObjectStart()) >> kWordSizeLog2;
   return max_space_used - free_space_in_tlab;
 }
 
 }  // namespace dart