Safer interface for heap iteration.

runtime/vm/heap.h

 // Copyright (c) 2012, 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.
 
 #ifndef VM_HEAP_H_
 #define VM_HEAP_H_
 
 #include "platform/assert.h"
 #include "vm/allocation.h"
 #include "vm/flags.h"
@@ skipping 87 matching lines @@
   // Move external size from new to old space. Does not by itself trigger GC.
   void PromoteExternal(intptr_t size);
 
   // Heap contains the specified address.
   bool Contains(uword addr) const;
   bool NewContains(uword addr) const;
   bool OldContains(uword addr) const;
   bool CodeContains(uword addr) const;
   bool StubCodeContains(uword addr) const;
 
-  // Visit all pointers. Caller must ensure concurrent sweeper is not running,
-  // and the visitor must not allocate (see issue 21620).
-  void VisitObjectPointers(ObjectPointerVisitor* visitor) const;
-
-  // Visit all objects, including FreeListElement "objects". Caller must ensure
-  // concurrent sweeper is not running, and the visitor must not allocate (see
-  // issue 21620).
-  void VisitObjects(ObjectVisitor* visitor) const;
+  void IterateObjects(ObjectVisitor* visitor) const;
+  void IterateOldObjects(ObjectVisitor* visitor) const;
+  void IterateObjectPointers(ObjectVisitor* visitor) const;
 
   // Find an object by visiting all pointers in the specified heap space,
   // the 'visitor' is used to determine if an object is found or not.
   // The 'visitor' function should be set up to return true if the
   // object is found, traversal through the heap space stops at that
   // point.
   // The 'visitor' function should return false if the object is not found,
   // traversal through the heap space continues.
-  // Returns null object if nothing is found. Must be called within a
-  // NoSafepointScope.
+  // Returns null object if nothing is found.
   RawInstructions* FindObjectInCodeSpace(FindObjectVisitor* visitor) const;
   RawObject* FindOldObject(FindObjectVisitor* visitor) const;
   RawObject* FindNewObject(FindObjectVisitor* visitor) const;
   RawObject* FindObject(FindObjectVisitor* visitor) const;
 
   void CollectGarbage(Space space);
   void CollectGarbage(Space space, ApiCallbacks api_callbacks, GCReason reason);
   void CollectAllGarbage();
 
   // Enables growth control on the page space heaps.  This should be
@@ skipping 141 matching lines @@
 
   Heap(Isolate* isolate,
        intptr_t max_new_gen_semi_words,  // Max capacity of new semi-space.
        intptr_t max_old_gen_words,
        intptr_t max_external_words);
 
   uword AllocateNew(intptr_t size);
   uword AllocateOld(intptr_t size, HeapPage::PageType type);
   uword AllocatePretenured(intptr_t size);
 
+  // Visit all pointers. Caller must ensure concurrent sweeper is not running,
+  // and the visitor must not allocate.
+  void VisitObjectPointers(ObjectPointerVisitor* visitor) const;
+
+  // Visit all objects, including FreeListElement "objects". Caller must ensure
+  // concurrent sweeper is not running, and the visitor must not allocate.
+  void VisitObjects(ObjectVisitor* visitor) const;
+
+  // Like Verify, but does not wait for concurrent sweeper, so caller must
+  // ensure thread-safety.
+  bool VerifyGC(MarkExpectation mark_expectation = kForbidMarked) const;
+
   // GC stats collection.
   void RecordBeforeGC(Space space, GCReason reason);
   void RecordAfterGC();
   void PrintStats();
   void UpdateClassHeapStatsBeforeGC(Heap::Space space);
   void UpdatePretenurePolicy();
 
   // If this heap is non-empty, updates start and end to the smallest range that
   // contains both the original [start, end) and the [lowest, highest) addresses
   // of this heap.
@@ skipping 14 matching lines @@
   // This heap is in read-only mode: No allocation is allowed.
   bool read_only_;
 
   // GC on the heap is in progress.
   bool gc_in_progress_;
 
   int pretenure_policy_;
 
   friend class ServiceEvent;
   friend class GCTestHelper;
+  friend class PageSpace;  // VerifyGC
   DISALLOW_COPY_AND_ASSIGN(Heap);
 };
 
 
 // Within a NoSafepointScope, the thread must not reach any safepoint. Used
 // around code that manipulates raw object pointers directly without handles.
 #if defined(DEBUG)
 class NoSafepointScope : public StackResource {
  public:
   NoSafepointScope();
   ~NoSafepointScope();
  private:
   DISALLOW_COPY_AND_ASSIGN(NoSafepointScope);
 };
 #else  // defined(DEBUG)
 class NoSafepointScope : public ValueObject {
  public:
   NoSafepointScope() {}
  private:
   DISALLOW_COPY_AND_ASSIGN(NoSafepointScope);
 };
 #endif  // defined(DEBUG)
 
 
+class HeapIterationScope : public StackResource {
+ public:
+  HeapIterationScope();
+  ~HeapIterationScope();
+ private:
+  NoSafepointScope no_safepoint_scope_;
+  PageSpace* old_space_;
+
+  DISALLOW_COPY_AND_ASSIGN(HeapIterationScope);
+};
+
+
 class NoHeapGrowthControlScope : public StackResource {
  public:
   NoHeapGrowthControlScope();
   ~NoHeapGrowthControlScope();
  private:
   bool current_growth_controller_state_;
   DISALLOW_COPY_AND_ASSIGN(NoHeapGrowthControlScope);
 };
 
 }  // namespace dart
 
 #endif  // VM_HEAP_H_