[vm, gc] Require a safepoint for heap iteration.

runtime/vm/object_graph.cc

 // Copyright (c) 2014, 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/object_graph.h"
 
 #include "vm/dart.h"
 #include "vm/growable_array.h"
 #include "vm/isolate.h"
 #include "vm/object.h"
@@ skipping 187 matching lines @@
 
 ObjectGraph::ObjectGraph(Thread* thread) : StackResource(thread) {
   // The VM isolate has all its objects pre-marked, so iterating over it
   // would be a no-op.
   ASSERT(thread->isolate() != Dart::vm_isolate());
 }
 
 ObjectGraph::~ObjectGraph() {}
 
 void ObjectGraph::IterateObjects(ObjectGraph::Visitor* visitor) {
-  NoSafepointScope no_safepoint_scope_;
   Stack stack(isolate());
   isolate()->VisitObjectPointers(&stack, false);
   stack.TraverseGraph(visitor);
   Unmarker::UnmarkAll(isolate());
 }
 
 void ObjectGraph::IterateUserObjects(ObjectGraph::Visitor* visitor) {
-  NoSafepointScope no_safepoint_scope_;
   Stack stack(isolate());
   IterateUserFields(&stack);
   stack.include_vm_objects_ = false;
   stack.TraverseGraph(visitor);
   Unmarker::UnmarkAll(isolate());
 }
 
 void ObjectGraph::IterateObjectsFrom(const Object& root,
                                      ObjectGraph::Visitor* visitor) {
-  NoSafepointScope no_safepoint_scope_;
   Stack stack(isolate());
   RawObject* root_raw = root.raw();
   stack.VisitPointer(&root_raw);
   stack.TraverseGraph(visitor);
   Unmarker::UnmarkAll(isolate());
 }
 
 class InstanceAccumulator : public ObjectVisitor {
  public:
   InstanceAccumulator(ObjectGraph::Stack* stack, intptr_t class_id)
       : stack_(stack), class_id_(class_id) {}
 
   void VisitObject(RawObject* obj) {
     if (obj->GetClassId() == class_id_) {
       RawObject* rawobj = obj;
       stack_->VisitPointer(&rawobj);
     }
   }
 
  private:
   ObjectGraph::Stack* stack_;
   const intptr_t class_id_;
 
   DISALLOW_COPY_AND_ASSIGN(InstanceAccumulator);
 };
 
 void ObjectGraph::IterateObjectsFrom(intptr_t class_id,
                                      ObjectGraph::Visitor* visitor) {
-  NoSafepointScope no_safepoint_scope_;
+  HeapIterationScope iteration(thread());
   Stack stack(isolate());
 
   InstanceAccumulator accumulator(&stack, class_id);
-  isolate()->heap()->VisitObjectsNoImagePages(&accumulator);
+  iteration.IterateObjectsNoImagePages(&accumulator);
 
   stack.TraverseGraph(visitor);
   Unmarker::UnmarkAll(isolate());
 }
 
 class SizeVisitor : public ObjectGraph::Visitor {
  public:
   SizeVisitor() : size_(0) {}
   intptr_t size() const { return size_; }
   virtual bool ShouldSkip(RawObject* obj) const { return false; }
@@ skipping 24 matching lines @@
   explicit SizeExcludingClassVisitor(intptr_t skip) : skip_(skip) {}
   virtual bool ShouldSkip(RawObject* obj) const {
     return obj->GetClassId() == skip_;
   }
 
  private:
   const intptr_t skip_;
 };
 
 intptr_t ObjectGraph::SizeRetainedByInstance(const Object& obj) {
-  HeapIterationScope iteration_scope(true);
+  HeapIterationScope iteration_scope(Thread::Current(), true);
   SizeVisitor total;
   IterateObjects(&total);
   intptr_t size_total = total.size();
   SizeExcludingObjectVisitor excluding_obj(obj);
   IterateObjects(&excluding_obj);
   intptr_t size_excluding_obj = excluding_obj.size();
   return size_total - size_excluding_obj;
 }
 
 intptr_t ObjectGraph::SizeReachableByInstance(const Object& obj) {
-  HeapIterationScope iteration_scope(true);
+  HeapIterationScope iteration_scope(Thread::Current(), true);
   SizeVisitor total;
   IterateObjectsFrom(obj, &total);
   return total.size();
 }
 
 intptr_t ObjectGraph::SizeRetainedByClass(intptr_t class_id) {
-  HeapIterationScope iteration_scope(true);
+  HeapIterationScope iteration_scope(Thread::Current(), true);
   SizeVisitor total;
   IterateObjects(&total);
   intptr_t size_total = total.size();
   SizeExcludingClassVisitor excluding_class(class_id);
   IterateObjects(&excluding_class);
   intptr_t size_excluding_class = excluding_class.size();
   return size_total - size_excluding_class;
 }
 
 intptr_t ObjectGraph::SizeReachableByClass(intptr_t class_id) {
-  HeapIterationScope iteration_scope(true);
+  HeapIterationScope iteration_scope(Thread::Current(), true);
   SizeVisitor total;
   IterateObjectsFrom(class_id, &total);
   return total.size();
 }
 
 class RetainingPathVisitor : public ObjectGraph::Visitor {
  public:
   // We cannot use a GrowableObjectArray, since we must not trigger GC.
   RetainingPathVisitor(RawObject* obj, const Array& path)
       : thread_(Thread::Current()), obj_(obj), path_(path), length_(0) {
-    ASSERT(Thread::Current()->no_safepoint_scope_depth() != 0);
   }
 
   intptr_t length() const { return length_; }
 
   bool ShouldSkip(RawObject* obj) {
     // A retaining path through ICData is never the only retaining path,
     // and it is less informative than its alternatives.
     intptr_t cid = obj->GetClassId();
     switch (cid) {
       case kICDataCid:
@@ skipping 62 matching lines @@
 
  private:
   Thread* thread_;
   RawObject* obj_;
   const Array& path_;
   intptr_t length_;
   bool was_last_array_;
 };
 
 intptr_t ObjectGraph::RetainingPath(Object* obj, const Array& path) {
-  NoSafepointScope no_safepoint_scope_;
-  HeapIterationScope iteration_scope(true);
+  HeapIterationScope iteration_scope(Thread::Current(), true);
   // To break the trivial path, the handle 'obj' is temporarily cleared during
   // the search, but restored before returning.
   RawObject* raw = obj->raw();
   *obj = Object::null();
   RetainingPathVisitor visitor(raw, path);
   IterateUserObjects(&visitor);
   if (visitor.length() == 0) {
     IterateObjects(&visitor);
   }
   *obj = raw;
@@ skipping 58 matching lines @@
  private:
   RawObject* source_;
   RawObject* target_;
   const Array& references_;
   Object* scratch_;
   intptr_t length_;
 };
 
 intptr_t ObjectGraph::InboundReferences(Object* obj, const Array& references) {
   Object& scratch = Object::Handle();
-  NoSafepointScope no_safepoint_scope;
+  HeapIterationScope iteration(Thread::Current());
   InboundReferencesVisitor visitor(isolate(), obj->raw(), references, &scratch);
-  isolate()->heap()->IterateObjects(&visitor);
+  iteration.IterateObjects(&visitor);
   return visitor.length();
 }
 
 static void WritePtr(RawObject* raw, WriteStream* stream) {
   ASSERT(raw->IsHeapObject());
   ASSERT(raw->IsOldObject());
   uword addr = RawObject::ToAddr(raw);
   ASSERT(Utils::IsAligned(addr, kObjectAlignment));
   // Using units of kObjectAlignment makes the ids fit into Smis when parsed
   // in the Dart code of the Observatory.
@@ skipping 82 matching lines @@
 };
 
 intptr_t ObjectGraph::Serialize(WriteStream* stream,
                                 SnapshotRoots roots,
                                 bool collect_garbage) {
   if (collect_garbage) {
     isolate()->heap()->CollectAllGarbage();
   }
   // Current encoding assumes objects do not move, so promote everything to old.
   isolate()->heap()->new_space()->Evacuate();
-  HeapIterationScope iteration_scope(true);
+  HeapIterationScope iteration_scope(Thread::Current(), true);
 
   RawObject* kRootAddress = reinterpret_cast<RawObject*>(kHeapObjectTag);
   const intptr_t kRootCid = kIllegalCid;
   RawObject* kStackAddress =
       reinterpret_cast<RawObject*>(kObjectAlignment + kHeapObjectTag);
 
   stream->WriteUnsigned(kObjectAlignment);
   stream->WriteUnsigned(kStackCid);
 
   if (roots == kVM) {
@@ skipping 27 matching lines @@
   intptr_t object_count = visitor.count();
   if (roots == kVM) {
     object_count += 1;  // root
   } else {
     object_count += 2;  // root and stack
   }
   return object_count;
 }
 
 }  // namespace dart