Decode the Dart message into a Dart_CMessage structure before calling the native port callback

runtime/vm/snapshot.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_SNAPSHOT_H_
 #define VM_SNAPSHOT_H_
 
 #include "platform/assert.h"
 #include "vm/allocation.h"
 #include "vm/bitfield.h"
@@ skipping 403 matching lines @@
   enum Type {
     kTypeArguments = Dart_CObject::kNumberOfTypes,
     kDynamicType,
   };
 };
 
 
 // Reads a message snapshot into C structure.
 class CMessageReader : public BaseReader {
  public:
+  // Creates a message reader where the allocated Dart_CMessage
+  // structure and all the allocated Dart_CObject structures are
+  // allocated using the supplied allocation function.
   CMessageReader(const uint8_t* buffer, intptr_t length, ReAlloc alloc);
+  // Creates a message reader where the allocated Dart_CMessage
+  // structure and all the allocated Dart_CObject structures are
+  // allocated in the supplied zone. The supplied zone will also be
+  // used for temporary allocations for message decoding.
+  CMessageReader(const uint8_t* buffer, intptr_t length, Zone* zone);

[siva, 2012/02/04 01:55:43]

Ditto comment regarding this version of the constructor, do you really want
this,  can't we have an allocator that will do the same.

[Søren Gjesse, 2012/02/06 16:25:52]

See comment in native_message_handler.cc

   ~CMessageReader() { }
 
   Dart_CMessage* ReadMessage();
 
  private:
-  // Allocates a Dart_CObject object on the C heap.
+  // Allocate a piece of memory for the decoded message data.
+  uint8_t* Allocate(uint8_t* ptr, intptr_t old_size, intptr_t new_size);
+  // Allocates a Dart_CObject object.
   Dart_CObject* AllocateDartCObject();
-  // Allocates a Dart_CObject object with the specified type on the C heap.
+  // Allocates a Dart_CObject object with the specified type.
   Dart_CObject* AllocateDartCObject(Dart_CObject::Type type);
-  // Allocates a Dart_CObject object for the null object on the C heap.
+  // Allocates a Dart_CObject object for the null object.
   Dart_CObject* AllocateDartCObjectNull();
-  // Allocates a Dart_CObject object for a boolean object on the C heap.
+  // Allocates a Dart_CObject object for a boolean object.
   Dart_CObject* AllocateDartCObjectBool(bool value);
-  // Allocates a Dart_CObject object for for a 32-bit integer on the C heap.
+  // Allocates a Dart_CObject object for for a 32-bit integer.
   Dart_CObject* AllocateDartCObjectInt32(int32_t value);
-  // Allocates a Dart_CObject object for a double on the C heap.
+  // Allocates a Dart_CObject object for a double.
   Dart_CObject* AllocateDartCObjectDouble(double value);
-  // Allocates a Dart_CObject object for string data on the C heap.
+  // Allocates a Dart_CObject object for string data.
   Dart_CObject* AllocateDartCObjectString(intptr_t length);
-  // Allocates a C array of Dart_CObject objects on the C heap.
+  // Allocates a C array of Dart_CObject objects.
   Dart_CObject* AllocateDartCObjectArray(intptr_t length);
 
+  void Init();
+
   intptr_t LookupInternalClass(intptr_t class_header);
   Dart_CObject* ReadInlinedObject(intptr_t object_id);
   Dart_CObject* ReadObjectImpl(intptr_t header);
   Dart_CObject* ReadIndexedObject(intptr_t object_id);
   Dart_CObject* ReadObject();
 
   // Add object to backward references.
   void AddBackwardReference(intptr_t id, Dart_CObject* obj);
 
   Dart_CObject_Internal* AsInternal(Dart_CObject* object) {
     ASSERT(object->type >= Dart_CObject::kNumberOfTypes);
     return reinterpret_cast<Dart_CObject_Internal*>(object);
   }
 
+  // Allocation of the structures for the decoded message happens
+  // either in the supplied zone or using the supplied allocation
+  // function.
+  Zone* zone_;

[siva, 2012/02/04 01:55:43]

Ditto comment.

   ReAlloc alloc_;
   GrowableArray<Dart_CObject*> backward_references_;
 
   Dart_CObject type_arguments_marker;
   Dart_CObject dynamic_type_marker;
 };
 
 
 class BaseWriter {
  public:
@@ skipping 163 matching lines @@
 
  private:
   SnapshotWriter* writer_;
 
   DISALLOW_COPY_AND_ASSIGN(SnapshotWriterVisitor);
 };
 
 }  // namespace dart
 
 #endif  // VM_SNAPSHOT_H_