Reimplemented zone memory tracking to avoid race conditions that were causing crashes in the previo…

runtime/vm/zone.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 RUNTIME_VM_ZONE_H_
 #define RUNTIME_VM_ZONE_H_
 
 #include "platform/utils.h"
 #include "vm/allocation.h"
 #include "vm/handles.h"
@@ skipping 46 matching lines @@
   // TODO(zra): Remove these calls and replace them with calls to OS::SCreate
   // and OS::VSCreate.
   // These calls are deprecated. Do not add further calls to these functions.
   // instead use OS::SCreate and OS::VSCreate.
   // Make a zone-allocated string based on printf format and args.
   char* PrintToString(const char* format, ...) PRINTF_ATTRIBUTE(2, 3);
   char* VPrint(const char* format, va_list args);
 
   // Compute the total size of this zone. This includes wasted space that is
   // due to internal fragmentation in the segments.
-  intptr_t SizeInBytes() const;
+  uintptr_t SizeInBytes() const;
 
   // Computes the amount of space used in the zone.
-  intptr_t CapacityInBytes() const;
+  uintptr_t CapacityInBytes() const;
 
   // Structure for managing handles allocation.
   VMHandles* handles() { return &handles_; }
 
   void VisitObjectPointers(ObjectPointerVisitor* visitor);
 
   Zone* previous() const { return previous_; }
 
-#ifndef PRODUCT
-  void PrintJSON(JSONStream* stream) const;
-#endif
-
  private:
   Zone();
   ~Zone();  // Delete all memory associated with the zone.
 
   // All pointers returned from AllocateUnsafe() and New() have this alignment.
   static const intptr_t kAlignment = kDoubleSize;
 
   // Default initial chunk size.
   static const intptr_t kInitialChunkSize = 1 * KB;
 
@@ skipping 80 matching lines @@
 class StackZone : public StackResource {
  public:
   // Create an empty zone and set is at the current zone for the Thread.
   explicit StackZone(Thread* thread);
 
   // Delete all memory associated with the zone.
   ~StackZone();
 
   // Compute the total size of this zone. This includes wasted space that is
   // due to internal fragmentation in the segments.
-  intptr_t SizeInBytes() const { return zone_.SizeInBytes(); }
+  uintptr_t SizeInBytes() const { return zone_.SizeInBytes(); }
 
   // Computes the used space in the zone.
   intptr_t CapacityInBytes() const { return zone_.CapacityInBytes(); }
 
   Zone* GetZone() { return &zone_; }
 
  private:
   Zone zone_;
 
   template <typename T>
   friend class GrowableArray;
   template <typename T>
   friend class ZoneGrowableArray;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(StackZone);
 };
 
 inline uword Zone::AllocUnsafe(intptr_t size) {
   ASSERT(size >= 0);
-
   // Round up the requested size to fit the alignment.
   if (size > (kIntptrMax - kAlignment)) {
     FATAL1("Zone::Alloc: 'size' is too large: size=%" Pd "", size);
   }
   size = Utils::RoundUp(size, kAlignment);
 
   // Check if the requested size is available without expanding.
   uword result;
   intptr_t free_size = (limit_ - position_);
   if (free_size >= size) {
@@ skipping 31 matching lines @@
                                   intptr_t new_len) {
   CheckLength<ElementType>(new_len);
   const intptr_t kElementSize = sizeof(ElementType);
   uword old_end = reinterpret_cast<uword>(old_data) + (old_len * kElementSize);
   // Resize existing allocation if nothing was allocated in between...
   if (Utils::RoundUp(old_end, kAlignment) == position_) {
     uword new_end =
         reinterpret_cast<uword>(old_data) + (new_len * kElementSize);
     // ...and there is sufficient space.
     if (new_end <= limit_) {
+      ASSERT(new_len >= old_len);
       position_ = Utils::RoundUp(new_end, kAlignment);
       return old_data;
     }
   }
   if (new_len <= old_len) {
     return old_data;
   }
   ElementType* new_data = Alloc<ElementType>(new_len);
   if (old_data != 0) {
     memmove(reinterpret_cast<void*>(new_data),
             reinterpret_cast<void*>(old_data), old_len * kElementSize);
   }
   return new_data;
 }
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_ZONE_H_