DO NOT SUBMIT: switch to an on-heap stack for nested object serialization/deserialization

src/value-serializer.h

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_VALUE_SERIALIZER_H_
 #define V8_VALUE_SERIALIZER_H_
 
 #include <cstdint>
 #include <vector>
 
 #include "include/v8.h"
 #include "src/base/compiler-specific.h"
 #include "src/base/macros.h"
 #include "src/identity-map.h"
 #include "src/vector.h"
+#include "src/zone-containers.h"
 #include "src/zone.h"
 
 namespace v8 {
 namespace internal {
 
 class HeapNumber;
 class Isolate;
 class JSArrayBuffer;
 class JSArrayBufferView;
 class JSDate;
@@ skipping 18 matching lines @@
   explicit ValueSerializer(Isolate* isolate);
   ~ValueSerializer();
 
   /*
    * Writes out a header, which includes the format version.
    */
   void WriteHeader();
 
   /*
    * Serializes a V8 object into the buffer.
+   *
+   * Code internal to this class should use WriteObjectInternal instead, which
+   * will use the same states stack to avoid recursion on the call stack.
    */
   Maybe<bool> WriteObject(Handle<Object> object) WARN_UNUSED_RESULT;
 
   /*
    * Returns the stored data. This serializer should not be used once the buffer
    * is released. The contents are undefined if a previous write has failed.
    */
   std::vector<uint8_t> ReleaseBuffer() { return std::move(buffer_); }
 
   /*
@@ skipping 11 matching lines @@
   void WriteVarint(T value);
   template <typename T>
   void WriteZigZag(T value);
   void WriteDouble(double value);
   void WriteOneByteString(Vector<const uint8_t> chars);
   void WriteTwoByteString(Vector<const uc16> chars);
   void WriteRawBytes(const void* source, size_t length);
   uint8_t* ReserveRawBytes(size_t bytes);
 
   // Writing V8 objects of various kinds.
+  // These are expected to be used internally only. For objects which require
+  // recursive serialization, a state is pushed before returning.
+  // WriteObject will iterate on the states until the object is fully
+  // serialized.
+  Maybe<bool> WriteObjectInternal(Handle<Object> object) WARN_UNUSED_RESULT;
   void WriteOddball(Oddball* oddball);
   void WriteSmi(Smi* smi);
   void WriteHeapNumber(HeapNumber* number);
   void WriteString(Handle<String> string);
   Maybe<bool> WriteJSReceiver(Handle<JSReceiver> receiver) WARN_UNUSED_RESULT;
   Maybe<bool> WriteJSObject(Handle<JSObject> object) WARN_UNUSED_RESULT;
   Maybe<bool> WriteJSArray(Handle<JSArray> array) WARN_UNUSED_RESULT;
   void WriteJSDate(JSDate* date);
   Maybe<bool> WriteJSValue(Handle<JSValue> value) WARN_UNUSED_RESULT;
   void WriteJSRegExp(JSRegExp* regexp);
   Maybe<bool> WriteJSMap(Handle<JSMap> map) WARN_UNUSED_RESULT;
   Maybe<bool> WriteJSSet(Handle<JSSet> map) WARN_UNUSED_RESULT;
   Maybe<bool> WriteJSArrayBuffer(JSArrayBuffer* array_buffer);
   Maybe<bool> WriteJSArrayBufferView(JSArrayBufferView* array_buffer);
 
-  /*
-   * Reads the specified keys from the object and writes key-value pairs to the
-   * buffer. Returns the number of keys actually written, which may be smaller
-   * if some keys are not own properties when accessed.
-   */
-  Maybe<uint32_t> WriteJSObjectProperties(
-      Handle<JSObject> object, Handle<FixedArray> keys) WARN_UNUSED_RESULT;
-
   Isolate* const isolate_;
   std::vector<uint8_t> buffer_;
   Zone zone_;
 
   // To avoid extra lookups in the identity map, ID+1 is actually stored in the
   // map (checking if the used identity is zero is the fast way of checking if
   // the entry is new).
   IdentityMap<uint32_t> id_map_;
   uint32_t next_id_ = 0;
 
   // A similar map, for transferred array buffers.
   IdentityMap<uint32_t> array_buffer_transfer_map_;
 
+  // A stack of states.
+  struct State;
+  ZoneVector<State> states_;
+
   DISALLOW_COPY_AND_ASSIGN(ValueSerializer);
 };
 
 /*
  * Deserializes values from data written with ValueSerializer, or a compatible
  * implementation.
  */
 class ValueDeserializer {
  public:
   ValueDeserializer(Isolate* isolate, Vector<const uint8_t> data);
@@ skipping 38 matching lines @@
   Maybe<SerializationTag> PeekTag() const WARN_UNUSED_RESULT;
   void ConsumeTag(SerializationTag peeked_tag);
   Maybe<SerializationTag> ReadTag() WARN_UNUSED_RESULT;
   template <typename T>
   Maybe<T> ReadVarint() WARN_UNUSED_RESULT;
   template <typename T>
   Maybe<T> ReadZigZag() WARN_UNUSED_RESULT;
   Maybe<double> ReadDouble() WARN_UNUSED_RESULT;
   Maybe<Vector<const uint8_t>> ReadRawBytes(int size) WARN_UNUSED_RESULT;
 
-  // Like ReadObject, but skips logic for special cases in simulating the
-  // "stack machine".
+  // Reading V8 objects of specific kinds.
+  // These are expected to be used internally only. For objects which require
+  // recursive deserialization, a state is pushed before returning.
+  // ReadObject will iterate on the states until the object is fully
+  // serialized.
   MaybeHandle<Object> ReadObjectInternal() WARN_UNUSED_RESULT;
-
-  // Reading V8 objects of specific kinds.
-  // The tag is assumed to have already been read.
   MaybeHandle<String> ReadUtf8String() WARN_UNUSED_RESULT;
   MaybeHandle<String> ReadTwoByteString() WARN_UNUSED_RESULT;
   MaybeHandle<JSObject> ReadJSObject() WARN_UNUSED_RESULT;
   MaybeHandle<JSArray> ReadSparseJSArray() WARN_UNUSED_RESULT;
   MaybeHandle<JSArray> ReadDenseJSArray() WARN_UNUSED_RESULT;
   MaybeHandle<JSDate> ReadJSDate() WARN_UNUSED_RESULT;
   MaybeHandle<JSValue> ReadJSValue(SerializationTag tag) WARN_UNUSED_RESULT;
   MaybeHandle<JSRegExp> ReadJSRegExp() WARN_UNUSED_RESULT;
   MaybeHandle<JSMap> ReadJSMap() WARN_UNUSED_RESULT;
   MaybeHandle<JSSet> ReadJSSet() WARN_UNUSED_RESULT;
   MaybeHandle<JSArrayBuffer> ReadJSArrayBuffer() WARN_UNUSED_RESULT;
   MaybeHandle<JSArrayBuffer> ReadTransferredJSArrayBuffer(bool is_shared)
       WARN_UNUSED_RESULT;
   MaybeHandle<JSArrayBufferView> ReadJSArrayBufferView(
       Handle<JSArrayBuffer> buffer) WARN_UNUSED_RESULT;
 
-  /*
-   * Reads key-value pairs into the object until the specified end tag is
-   * encountered. If successful, returns the number of properties read.
-   */
-  Maybe<uint32_t> ReadJSObjectProperties(Handle<JSObject> object,
-                                         SerializationTag end_tag);
-
   // Manipulating the map from IDs to reified objects.
   bool HasObjectWithID(uint32_t id);
   MaybeHandle<JSReceiver> GetObjectWithID(uint32_t id);
   void AddObjectWithID(uint32_t id, Handle<JSReceiver> object);
 
   Isolate* const isolate_;
   const uint8_t* position_;
   const uint8_t* const end_;
   uint32_t version_ = 0;
   uint32_t next_id_ = 0;
 
   // Always global handles.
   Handle<SeededNumberDictionary> id_map_;
   MaybeHandle<SeededNumberDictionary> array_buffer_transfer_map_;
 
+  // A stack of states.
+  struct State;
+  std::vector<State> states_;
+
   DISALLOW_COPY_AND_ASSIGN(ValueDeserializer);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_VALUE_SERIALIZER_H_