runtime/vm/dart_api_message.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_DART_API_MESSAGE_H_
#define VM_DART_API_MESSAGE_H_

#include "vm/dart_api_state.h"
#include "vm/snapshot.h"

namespace dart {

// Use this C structure for reading internal objects in the serialized
// data. These are objects that we need to process in order to
// generate the Dart_CObject graph but that we don't want to expose in
// that graph.
struct Dart_CObject_Internal : public Dart_CObject {
  enum Type {
    kTypeArguments = Dart_CObject::kNumberOfTypes,
    kDynamicType,
    kClass,
    kView,
    kUninitialized,
  };
  struct Dart_CObject_Internal* cls;
  union {
    struct {
      struct _Dart_CObject* library_url;
      struct _Dart_CObject* class_name;
    } as_class;
    struct {
      struct _Dart_CObject* buffer;
      int offset_in_bytes;
      int length;
    } as_view;
  } internal;
};


// Reads a message snapshot into a C structure.
class ApiMessageReader : public BaseReader {
 public:
  // The allocator passed is used to allocate memory for the C structure used
  // to represent the message snapshot. This allocator must keep track of the
  // memory allocated as there is no way to run through the resulting C
  // structure and free the individual pieces. Using a zone based allocator is
  // recommended.
  ApiMessageReader(const uint8_t* buffer, intptr_t length, ReAlloc alloc);
  ~ApiMessageReader() { }

  Dart_CObject* ReadMessage();

 private:
  class BackRefNode {
   public:
    BackRefNode(Dart_CObject* reference, DeserializeState state)
        : reference_(reference), state_(state) {}
    Dart_CObject* reference() const { return reference_; }
    void set_reference(Dart_CObject* reference) { reference_ = reference; }
    bool is_deserialized() const { return state_ == kIsDeserialized; }
    void set_state(DeserializeState value) { state_ = value; }

   private:
    Dart_CObject* reference_;
    DeserializeState state_;

    DISALLOW_COPY_AND_ASSIGN(BackRefNode);
  };

  // Allocates a Dart_CObject object.
  Dart_CObject* AllocateDartCObject();
  // Allocates a Dart_CObject object with the specified type.
  Dart_CObject* AllocateDartCObject(Dart_CObject::Type type);
  // Allocates a Dart_CObject object representing an unsupported
  // object in the API message.
  Dart_CObject* AllocateDartCObjectUnsupported();
  // Allocates a Dart_CObject object for the null object.
  Dart_CObject* AllocateDartCObjectNull();
  // 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.
  Dart_CObject* AllocateDartCObjectInt32(int32_t value);
  // Allocates a Dart_CObject object for for a 64-bit integer.
  Dart_CObject* AllocateDartCObjectInt64(int64_t value);
  // Allocates a Dart_CObject object for bigint data.
  Dart_CObject* AllocateDartCObjectBigint(intptr_t length);
  // Allocates a Dart_CObject object for a double.
  Dart_CObject* AllocateDartCObjectDouble(double value);
  // Allocates a Dart_CObject object for string data.
  Dart_CObject* AllocateDartCObjectString(intptr_t length);
  // Allocates a C Dart_CObject object for a typed data.
  Dart_CObject* AllocateDartCObjectTypedData(
      Dart_CObject::TypedDataType type, intptr_t length);
  // Allocates a C array of Dart_CObject objects.
  Dart_CObject* AllocateDartCObjectArray(intptr_t length);
  // Allocates a Dart_CObject_Internal object with the specified type.
  Dart_CObject_Internal* AllocateDartCObjectInternal(
      Dart_CObject_Internal::Type type);
  // Allocates a Dart_CObject_Internal object for a class object.
  Dart_CObject_Internal* AllocateDartCObjectClass();
  // Allocates a backwards reference node.
  BackRefNode* AllocateBackRefNode(Dart_CObject* ref, DeserializeState state);

  void Init();

  intptr_t LookupInternalClass(intptr_t class_header);
  Dart_CObject* ReadVMIsolateObject(intptr_t value);
  Dart_CObject* ReadInternalVMObject(intptr_t class_id, intptr_t object_id);
  Dart_CObject* ReadInlinedObject(intptr_t object_id);
  Dart_CObject* ReadObjectImpl();
  Dart_CObject* ReadIndexedObject(intptr_t object_id);
  Dart_CObject* ReadVMSymbol(intptr_t object_id);
  Dart_CObject* ReadObjectRef();
  Dart_CObject* ReadObject();

  // Add object to backward references.
  void AddBackRef(intptr_t id, Dart_CObject* obj, DeserializeState state);

  // Get an object from the backward references list.
  Dart_CObject* GetBackRef(intptr_t id);

  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.
  ReAlloc alloc_;
  ApiGrowableArray<BackRefNode*> backward_references_;
  Dart_CObject** vm_symbol_references_;

  Dart_CObject type_arguments_marker;
  Dart_CObject dynamic_type_marker;
};


class ApiMessageWriter : public BaseWriter {
 public:
  static const intptr_t kInitialSize = 512;
  ApiMessageWriter(uint8_t** buffer, ReAlloc alloc)
      : BaseWriter(buffer, alloc, kInitialSize),
        object_id_(0), forward_list_(NULL),
        forward_list_length_(0), forward_id_(0) {
    ASSERT(kDartCObjectTypeMask >= Dart_CObject::kNumberOfTypes - 1);
  }
  ~ApiMessageWriter() {
    ::free(forward_list_);
  }

  // Writes a message of integers.
  void WriteMessage(intptr_t field_count, intptr_t *data);

  // Writes a message with a single object.
  bool WriteCMessage(Dart_CObject* object);

 private:
  static const intptr_t kDartCObjectTypeBits = 4;
  static const intptr_t kDartCObjectTypeMask = (1 << kDartCObjectTypeBits) - 1;
  static const intptr_t kDartCObjectMarkMask = ~kDartCObjectTypeMask;
  static const intptr_t kDartCObjectMarkOffset = 1;

  void MarkCObject(Dart_CObject* object, intptr_t object_id);
  void UnmarkCObject(Dart_CObject* object);
  bool IsCObjectMarked(Dart_CObject* object);
  intptr_t GetMarkedCObjectMark(Dart_CObject* object);
  void UnmarkAllCObjects(Dart_CObject* object);
  void AddToForwardList(Dart_CObject* object);

  void WriteSmi(int64_t value);
  void WriteNullObject();
  void WriteMint(Dart_CObject* object, int64_t value);
  void WriteInt32(Dart_CObject* object);
  void WriteInt64(Dart_CObject* object);
  void WriteInlinedHeader(Dart_CObject* object);
  bool WriteCObject(Dart_CObject* object);
  bool WriteCObjectRef(Dart_CObject* object);
  bool WriteForwardedCObject(Dart_CObject* object);
  bool WriteCObjectInlined(Dart_CObject* object, Dart_CObject::Type type);

  intptr_t object_id_;
  Dart_CObject** forward_list_;
  intptr_t forward_list_length_;
  intptr_t forward_id_;

  DISALLOW_COPY_AND_ASSIGN(ApiMessageWriter);
};

}  // namespace dart

#endif  // VM_DART_API_MESSAGE_H_