[d8] Use ValueSerializer for postMessage (instead of ad-hoc serializer)

src/d8.cc

 // Copyright 2012 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.
 
 #include <errno.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
 
 #include <algorithm>
@@ skipping 13 matching lines @@
 #include "include/libplatform/v8-tracing.h"
 #include "src/api.h"
 #include "src/base/cpu.h"
 #include "src/base/debug/stack_trace.h"
 #include "src/base/logging.h"
 #include "src/base/platform/platform.h"
 #include "src/base/platform/time.h"
 #include "src/base/sys-info.h"
 #include "src/basic-block-profiler.h"
 #include "src/interpreter/interpreter.h"
+#include "src/list-inl.h"
 #include "src/msan.h"
 #include "src/objects-inl.h"
 #include "src/snapshot/natives.h"
 #include "src/utils.h"
 #include "src/v8.h"
 
 #ifdef V8_INSPECTOR_ENABLED
 #include "include/v8-inspector.h"
 #endif  // V8_INSPECTOR_ENABLED
 
@@ skipping 167 matching lines @@
 
 v8::Platform* g_platform = NULL;
 
 static Local<Value> Throw(Isolate* isolate, const char* message) {
   return isolate->ThrowException(
       String::NewFromUtf8(isolate, message, NewStringType::kNormal)
           .ToLocalChecked());
 }
 
 
-bool FindInObjectList(Local<Object> object, const Shell::ObjectList& list) {
-  for (int i = 0; i < list.length(); ++i) {
-    if (list[i]->StrictEquals(object)) {
-      return true;
-    }
-  }
-  return false;
-}
-
-
 Worker* GetWorkerFromInternalField(Isolate* isolate, Local<Object> object) {
   if (object->InternalFieldCount() != 1) {
     Throw(isolate, "this is not a Worker");
     return NULL;
   }
 
   Worker* worker =
       static_cast<Worker*>(object->GetAlignedPointerFromInternalField(0));
   if (worker == NULL) {
     Throw(isolate, "Worker is defunct because main thread is terminating");
@@ skipping 162 matching lines @@
 base::OS::MemoryMappedFile* Shell::counters_file_ = NULL;
 CounterCollection Shell::local_counters_;
 CounterCollection* Shell::counters_ = &local_counters_;
 base::LazyMutex Shell::context_mutex_;
 const base::TimeTicks Shell::kInitialTicks =
     base::TimeTicks::HighResolutionNow();
 Global<Function> Shell::stringify_function_;
 base::LazyMutex Shell::workers_mutex_;
 bool Shell::allow_new_workers_ = true;
 i::List<Worker*> Shell::workers_;
-i::List<SharedArrayBuffer::Contents> Shell::externalized_shared_contents_;
+std::unordered_set<SharedArrayBuffer::Contents,
+                   Shell::SharedArrayBufferContentsHash,
+                   Shell::SharedArrayBufferContentsIsEqual>
+    Shell::externalized_shared_contents_;
 
 Global<Context> Shell::evaluation_context_;
 ArrayBuffer::Allocator* Shell::array_buffer_allocator;
 ShellOptions Shell::options;
 base::OnceType Shell::quit_once_ = V8_ONCE_INIT;
 
 bool CounterMap::Match(void* key1, void* key2) {
   const char* name1 = reinterpret_cast<const char*>(key1);
   const char* name2 = reinterpret_cast<const char*>(key2);
   return strcmp(name1, name2) == 0;
@@ skipping 719 matching lines @@
       return;
     }
     worker->StartExecuteInThread(*script);
   }
 }
 
 
 void Shell::WorkerPostMessage(const v8::FunctionCallbackInfo<v8::Value>& args) {
   Isolate* isolate = args.GetIsolate();
   HandleScope handle_scope(isolate);
-  Local<Context> context = isolate->GetCurrentContext();
 
   if (args.Length() < 1) {
     Throw(isolate, "Invalid argument");
     return;
   }
 
   Worker* worker = GetWorkerFromInternalField(isolate, args.Holder());
   if (!worker) {
     return;
   }
 
   Local<Value> message = args[0];
-  ObjectList to_transfer;
-  if (args.Length() >= 2) {
-    if (!args[1]->IsArray()) {
-      Throw(isolate, "Transfer list must be an Array");
-      return;
-    }
-
-    Local<Array> transfer = Local<Array>::Cast(args[1]);
-    uint32_t length = transfer->Length();
-    for (uint32_t i = 0; i < length; ++i) {
-      Local<Value> element;
-      if (transfer->Get(context, i).ToLocal(&element)) {
-        if (!element->IsArrayBuffer() && !element->IsSharedArrayBuffer()) {
-          Throw(isolate,
-                "Transfer array elements must be an ArrayBuffer or "
-                "SharedArrayBuffer.");
-          break;
-        }
-
-        to_transfer.Add(Local<Object>::Cast(element));
-      }
-    }
-  }
-
-  ObjectList seen_objects;
-  SerializationData* data = new SerializationData;
-  if (SerializeValue(isolate, message, to_transfer, &seen_objects, data)) {
-    worker->PostMessage(data);
-  } else {
-    delete data;
+  Local<Value> transfer =
+      args.Length() >= 2 ? args[1] : Local<Value>::Cast(Undefined(isolate));
+  std::unique_ptr<SerializationData> data =
+      Shell::SerializeValue(isolate, message, transfer);
+  if (data) {
+    worker->PostMessage(std::move(data));
   }
 }
 
 
 void Shell::WorkerGetMessage(const v8::FunctionCallbackInfo<v8::Value>& args) {
   Isolate* isolate = args.GetIsolate();
   HandleScope handle_scope(isolate);
   Worker* worker = GetWorkerFromInternalField(isolate, args.Holder());
   if (!worker) {
     return;
   }
 
-  SerializationData* data = worker->GetMessage();
+  std::unique_ptr<SerializationData> data = worker->GetMessage();
   if (data) {
-    int offset = 0;
-    Local<Value> data_value;
-    if (Shell::DeserializeValue(isolate, *data, &offset).ToLocal(&data_value)) {
-      args.GetReturnValue().Set(data_value);
+    Local<Value> value;
+    if (Shell::DeserializeValue(isolate, std::move(data)).ToLocal(&value)) {
+      args.GetReturnValue().Set(value);
     }
-    delete data;
   }
 }
 
 
 void Shell::WorkerTerminate(const v8::FunctionCallbackInfo<v8::Value>& args) {
   Isolate* isolate = args.GetIsolate();
   HandleScope handle_scope(isolate);
   Worker* worker = GetWorkerFromInternalField(isolate, args.Holder());
   if (!worker) {
     return;
@@ skipping 915 matching lines @@
   if (thread_ == NULL) return;
   done_semaphore_.Wait();
 }
 
 
 void SourceGroup::JoinThread() {
   if (thread_ == NULL) return;
   thread_->Join();
 }
 
-
 SerializationData::~SerializationData() {
   // Any ArrayBuffer::Contents are owned by this SerializationData object if
-  // ownership hasn't been transferred out via ReadArrayBufferContents.
+  // ownership hasn't been transferred out.
   // SharedArrayBuffer::Contents may be used by multiple threads, so must be
   // cleaned up by the main thread in Shell::CleanupWorkers().
-  for (int i = 0; i < array_buffer_contents_.length(); ++i) {
-    ArrayBuffer::Contents& contents = array_buffer_contents_[i];
+  for (const auto& contents : array_buffer_contents_) {
     if (contents.Data()) {
       Shell::array_buffer_allocator->Free(contents.Data(),
                                           contents.ByteLength());
     }
   }
 }
 
-
-void SerializationData::WriteTag(SerializationTag tag) { data_.Add(tag); }
-
-
-void SerializationData::WriteMemory(const void* p, int length) {
-  if (length > 0) {
-    i::Vector<uint8_t> block = data_.AddBlock(0, length);
-    memcpy(&block[0], p, length);
-  }
+void SerializationData::ClearTransferredArrayBuffers() {
+  array_buffer_contents_.clear();
 }
 
-
-void SerializationData::WriteArrayBufferContents(
-    const ArrayBuffer::Contents& contents) {
-  array_buffer_contents_.Add(contents);
-  WriteTag(kSerializationTagTransferredArrayBuffer);
-  int index = array_buffer_contents_.length() - 1;
-  Write(index);
+void SerializationDataQueue::Enqueue(std::unique_ptr<SerializationData> data) {
+  base::LockGuard<base::Mutex> lock_guard(&mutex_);
+  data_.push_back(std::move(data));
 }
 
-
-void SerializationData::WriteSharedArrayBufferContents(
-    const SharedArrayBuffer::Contents& contents) {
-  shared_array_buffer_contents_.Add(contents);
-  WriteTag(kSerializationTagTransferredSharedArrayBuffer);
-  int index = shared_array_buffer_contents_.length() - 1;
-  Write(index);
-}
-
-
-SerializationTag SerializationData::ReadTag(int* offset) const {
-  return static_cast<SerializationTag>(Read<uint8_t>(offset));
-}
-
-
-void SerializationData::ReadMemory(void* p, int length, int* offset) const {
-  if (length > 0) {
-    memcpy(p, &data_[*offset], length);
-    (*offset) += length;
-  }
-}
-
-
-void SerializationData::ReadArrayBufferContents(ArrayBuffer::Contents* contents,
-                                                int* offset) const {
-  int index = Read<int>(offset);
-  DCHECK(index < array_buffer_contents_.length());
-  *contents = array_buffer_contents_[index];
-  // Ownership of this ArrayBuffer::Contents is passed to the caller. Neuter
-  // our copy so it won't be double-free'd when this SerializationData is
-  // destroyed.
-  array_buffer_contents_[index] = ArrayBuffer::Contents();
-}
-
-
-void SerializationData::ReadSharedArrayBufferContents(
-    SharedArrayBuffer::Contents* contents, int* offset) const {
-  int index = Read<int>(offset);
-  DCHECK(index < shared_array_buffer_contents_.length());
-  *contents = shared_array_buffer_contents_[index];
-}
-
-
-void SerializationDataQueue::Enqueue(SerializationData* data) {
+bool SerializationDataQueue::Dequeue(
+    std::unique_ptr<SerializationData>* out_data) {
+  out_data->reset();
   base::LockGuard<base::Mutex> lock_guard(&mutex_);
-  data_.Add(data);
-}
-
-
-bool SerializationDataQueue::Dequeue(SerializationData** data) {
-  base::LockGuard<base::Mutex> lock_guard(&mutex_);
-  *data = NULL;
-  if (data_.is_empty()) return false;
-  *data = data_.Remove(0);
+  if (data_.empty()) return false;
+  *out_data = std::move(data_[0]);
+  data_.erase(data_.begin());
   return true;
 }
 
 
 bool SerializationDataQueue::IsEmpty() {
   base::LockGuard<base::Mutex> lock_guard(&mutex_);
-  return data_.is_empty();
+  return data_.empty();
 }
 
 
 void SerializationDataQueue::Clear() {
   base::LockGuard<base::Mutex> lock_guard(&mutex_);
-  for (int i = 0; i < data_.length(); ++i) {
-    delete data_[i];
-  }
-  data_.Clear();
+  data_.clear();
 }
 
 
 Worker::Worker()
     : in_semaphore_(0),
       out_semaphore_(0),
       thread_(NULL),
       script_(NULL),
       running_(false) {}
 
 
 Worker::~Worker() {
   delete thread_;
   thread_ = NULL;
   delete[] script_;
   script_ = NULL;
   in_queue_.Clear();
   out_queue_.Clear();
 }
 
 
 void Worker::StartExecuteInThread(const char* script) {
   running_ = true;
   script_ = i::StrDup(script);
   thread_ = new WorkerThread(this);
   thread_->Start();
 }
 
-
-void Worker::PostMessage(SerializationData* data) {
-  in_queue_.Enqueue(data);
+void Worker::PostMessage(std::unique_ptr<SerializationData> data) {
+  in_queue_.Enqueue(std::move(data));
   in_semaphore_.Signal();
 }
 
-
-SerializationData* Worker::GetMessage() {
-  SerializationData* data = NULL;
-  while (!out_queue_.Dequeue(&data)) {
+std::unique_ptr<SerializationData> Worker::GetMessage() {
+  std::unique_ptr<SerializationData> result;
+  while (!out_queue_.Dequeue(&result)) {
     // If the worker is no longer running, and there are no messages in the
     // queue, don't expect any more messages from it.
     if (!base::NoBarrier_Load(&running_)) break;
     out_semaphore_.Wait();
   }
-  return data;
+  return result;
 }
 
 
 void Worker::Terminate() {
   base::NoBarrier_Store(&running_, false);
   // Post NULL to wake the Worker thread message loop, and tell it to stop
   // running.
   PostMessage(NULL);
 }
 
@@ skipping 43 matching lines @@
           // Get the message handler
           Local<Value> onmessage =
               global->Get(context, String::NewFromUtf8(isolate, "onmessage",
                                                        NewStringType::kNormal)
                                        .ToLocalChecked()).ToLocalChecked();
           if (onmessage->IsFunction()) {
             Local<Function> onmessage_fun = Local<Function>::Cast(onmessage);
             // Now wait for messages
             while (true) {
               in_semaphore_.Wait();
-              SerializationData* data;
+              std::unique_ptr<SerializationData> data;
               if (!in_queue_.Dequeue(&data)) continue;
-              if (data == NULL) {
+              if (!data) {
                 break;
               }
-              int offset = 0;
-              Local<Value> data_value;
-              if (Shell::DeserializeValue(isolate, *data, &offset)
-                      .ToLocal(&data_value)) {
-                Local<Value> argv[] = {data_value};
+              v8::TryCatch try_catch(isolate);
+              Local<Value> value;
+              if (Shell::DeserializeValue(isolate, std::move(data))
+                      .ToLocal(&value)) {
+                Local<Value> argv[] = {value};
                 (void)onmessage_fun->Call(context, global, 1, argv);
               }
-              delete data;
+              if (try_catch.HasCaught()) {
+                Shell::ReportException(isolate, &try_catch);
+              }
             }
           }
         }
       }
       DisposeModuleEmbedderData(context);
     }
     Shell::CollectGarbage(isolate);
   }
   isolate->Dispose();
 
   // Post NULL to wake the thread waiting on GetMessage() if there is one.
   out_queue_.Enqueue(NULL);
   out_semaphore_.Signal();
 }
 
 
 void Worker::PostMessageOut(const v8::FunctionCallbackInfo<v8::Value>& args) {
   Isolate* isolate = args.GetIsolate();
   HandleScope handle_scope(isolate);
 
   if (args.Length() < 1) {
     Throw(isolate, "Invalid argument");
     return;
   }
 
   Local<Value> message = args[0];
-
-  // TODO(binji): Allow transferring from worker to main thread?
-  Shell::ObjectList to_transfer;
-
-  Shell::ObjectList seen_objects;
-  SerializationData* data = new SerializationData;
-  if (Shell::SerializeValue(isolate, message, to_transfer, &seen_objects,
-                            data)) {
+  Local<Value> transfer = Undefined(isolate);
+  std::unique_ptr<SerializationData> data =
+      Shell::SerializeValue(isolate, message, transfer);
+  if (data) {
     DCHECK(args.Data()->IsExternal());
     Local<External> this_value = Local<External>::Cast(args.Data());
     Worker* worker = static_cast<Worker*>(this_value->Value());
-    worker->out_queue_.Enqueue(data);
+    worker->out_queue_.Enqueue(std::move(data));
     worker->out_semaphore_.Signal();
-  } else {
-    delete data;
   }
 }
 
 
 void SetFlagsFromString(const char* flags) {
   v8::V8::SetFlagsFromString(flags, static_cast<int>(strlen(flags)));
 }
 
 
 bool Shell::SetOptions(int argc, char* argv[]) {
@@ skipping 170 matching lines @@
 
 
 void Shell::EmptyMessageQueues(Isolate* isolate) {
   if (!i::FLAG_verify_predictable) {
     while (v8::platform::PumpMessageLoop(g_platform, isolate)) continue;
     v8::platform::RunIdleTasks(g_platform, isolate,
                                50.0 / base::Time::kMillisecondsPerSecond);
   }
 }
 
-
-bool Shell::SerializeValue(Isolate* isolate, Local<Value> value,
-                           const ObjectList& to_transfer,
-                           ObjectList* seen_objects,
-                           SerializationData* out_data) {
-  DCHECK(out_data);
+class Serializer : public ValueSerializer::Delegate {
+ public:
+  explicit Serializer(Isolate* isolate)
+      : isolate_(isolate), serializer_(isolate, this) {}
+
+  Maybe<bool> WriteValue(Local<Context> context, Local<Value> value,
+                         Local<Value> transfer) {
+    bool ok;
+    DCHECK(!data_);
+    data_.reset(new SerializationData);
+    if (!PrepareTransfer(context, transfer).To(&ok)) {
+      return Nothing<bool>();
+    }
+    serializer_.WriteHeader();
+
+    if (!serializer_.WriteValue(context, value).To(&ok)) {
+      data_.reset();
+      return Nothing<bool>();
+    }
+
+    if (!FinalizeTransfer().To(&ok)) {
+      return Nothing<bool>();
+    }
+
+    std::pair<uint8_t*, size_t> pair = serializer_.Release();
+    data_->data_.reset(pair.first);
+    data_->size_ = pair.second;
+    return Just(true);
+  }
+
+  std::unique_ptr<SerializationData> Release() { return std::move(data_); }
+
+ protected:
+  // Implements ValueSerializer::Delegate.
+  void ThrowDataCloneError(Local<String> message) override {
+    isolate_->ThrowException(Exception::Error(message));
+  }
+
+  Maybe<uint32_t> GetSharedArrayBufferId(
+      Isolate* isolate, Local<SharedArrayBuffer> shared_array_buffer) override {
+    DCHECK(data_ != nullptr);
+    for (size_t index = 0; index < shared_array_buffers_.size(); ++index) {
+      if (shared_array_buffers_[index] == shared_array_buffer) {
+        return Just<uint32_t>(static_cast<uint32_t>(index));
+      }
+    }
+
+    size_t index = shared_array_buffers_.size();
+    shared_array_buffers_.emplace_back(isolate_, shared_array_buffer);
+    return Just<uint32_t>(static_cast<uint32_t>(index));
+  }
+
+  void* ReallocateBufferMemory(void* old_buffer, size_t size,
+                               size_t* actual_size) override {
+    void* result = realloc(old_buffer, size);
+    *actual_size = result ? size : 0;
+    return result;
+  }
+
+  void FreeBufferMemory(void* buffer) override { free(buffer); }
+
+ private:
+  Maybe<bool> PrepareTransfer(Local<Context> context, Local<Value> transfer) {
+    if (transfer->IsArray()) {
+      Local<Array> transfer_array = Local<Array>::Cast(transfer);
+      uint32_t length = transfer_array->Length();
+      for (uint32_t i = 0; i < length; ++i) {
+        Local<Value> element;
+        if (transfer_array->Get(context, i).ToLocal(&element)) {
+          if (!element->IsArrayBuffer()) {
+            Throw(isolate_, "Transfer array elements must be an ArrayBuffer");
+            break;
+          }
+
+          Local<ArrayBuffer> array_buffer = Local<ArrayBuffer>::Cast(element);
+          serializer_.TransferArrayBuffer(
+              static_cast<uint32_t>(array_buffers_.size()), array_buffer);
+          array_buffers_.emplace_back(isolate_, array_buffer);
+        } else {
+          return Nothing<bool>();
+        }
+      }
+      return Just(true);
+    } else if (transfer->IsUndefined()) {
+      return Just(true);
+    } else {
+      Throw(isolate_, "Transfer list must be an Array or undefined");
+      return Nothing<bool>();
+    }
+  }
+
+  Maybe<bool> FinalizeTransfer() {
+    for (const auto& global_array_buffer : array_buffers_) {
+      Local<ArrayBuffer> array_buffer =
+          Local<ArrayBuffer>::New(isolate_, global_array_buffer);
+      if (!array_buffer->IsNeuterable()) {
+        Throw(isolate_, "ArrayBuffer could not be transferred");
+        return Nothing<bool>();
+      }
+
+      if (!array_buffer->IsExternal()) {
+        array_buffer->Externalize();
+      }
+      ArrayBuffer::Contents contents = array_buffer->GetContents();
+      array_buffer->Neuter();
+      data_->array_buffer_contents_.push_back(contents);
+    }
+
+    for (const auto& global_shared_array_buffer : shared_array_buffers_) {
+      Local<SharedArrayBuffer> shared_array_buffer =
+          Local<SharedArrayBuffer>::New(isolate_, global_shared_array_buffer);
+      if (!shared_array_buffer->IsExternal()) {
+        shared_array_buffer->Externalize();
+      }
+      data_->shared_array_buffer_contents_.push_back(
+          shared_array_buffer->GetContents());
+    }
+
+    return Just(true);
+  }
+
+  Isolate* isolate_;
+  ValueSerializer serializer_;
+  std::unique_ptr<SerializationData> data_;
+  std::vector<Global<ArrayBuffer>> array_buffers_;
+  std::vector<Global<SharedArrayBuffer>> shared_array_buffers_;
+
+  DISALLOW_COPY_AND_ASSIGN(Serializer);
+};
+
+class Deserializer : public ValueDeserializer::Delegate {
+ public:
+  Deserializer(Isolate* isolate, std::unique_ptr<SerializationData> data)
+      : isolate_(isolate),
+        deserializer_(isolate, data->data(), data->size(), this),
+        data_(std::move(data)) {
+    deserializer_.SetSupportsLegacyWireFormat(true);
+  }
+
+  MaybeLocal<Value> ReadValue(Local<Context> context) {
+    bool read_header;
+    if (!deserializer_.ReadHeader(context).To(&read_header)) {
+      return MaybeLocal<Value>();
+    }
+
+    uint32_t index = 0;
+    for (const auto& contents : data_->array_buffer_contents()) {
+      Local<ArrayBuffer> array_buffer =
+          ArrayBuffer::New(isolate_, contents.Data(), contents.ByteLength());
+      deserializer_.TransferArrayBuffer(index++, array_buffer);
+    }
+
+    index = 0;
+    for (const auto& contents : data_->shared_array_buffer_contents()) {
+      Local<SharedArrayBuffer> shared_array_buffer = SharedArrayBuffer::New(
+          isolate_, contents.Data(), contents.ByteLength());
+      deserializer_.TransferSharedArrayBuffer(index++, shared_array_buffer);
+    }
+
+    MaybeLocal<Value> result = deserializer_.ReadValue(context);
+    if (!result.IsEmpty()) {
+      data_->ClearTransferredArrayBuffers();
+    }
+    return result;
+  }
+
+ private:
+  Isolate* isolate_;
+  ValueDeserializer deserializer_;
+  std::unique_ptr<SerializationData> data_;
+
+  DISALLOW_COPY_AND_ASSIGN(Deserializer);
+};
+
+std::unique_ptr<SerializationData> Shell::SerializeValue(
+    Isolate* isolate, Local<Value> value, Local<Value> transfer) {
+  bool ok;
   Local<Context> context = isolate->GetCurrentContext();
-
-  if (value->IsUndefined()) {
-    out_data->WriteTag(kSerializationTagUndefined);
-  } else if (value->IsNull()) {
-    out_data->WriteTag(kSerializationTagNull);
-  } else if (value->IsTrue()) {
-    out_data->WriteTag(kSerializationTagTrue);
-  } else if (value->IsFalse()) {
-    out_data->WriteTag(kSerializationTagFalse);
-  } else if (value->IsNumber()) {
-    Local<Number> num = Local<Number>::Cast(value);
-    double value = num->Value();
-    out_data->WriteTag(kSerializationTagNumber);
-    out_data->Write(value);
-  } else if (value->IsString()) {
-    v8::String::Utf8Value str(value);
-    out_data->WriteTag(kSerializationTagString);
-    out_data->Write(str.length());
-    out_data->WriteMemory(*str, str.length());
-  } else if (value->IsArray()) {
-    Local<Array> array = Local<Array>::Cast(value);
-    if (FindInObjectList(array, *seen_objects)) {
-      Throw(isolate, "Duplicated arrays not supported");
-      return false;
-    }
-    seen_objects->Add(array);
-    out_data->WriteTag(kSerializationTagArray);
-    uint32_t length = array->Length();
-    out_data->Write(length);
-    for (uint32_t i = 0; i < length; ++i) {
-      Local<Value> element_value;
-      if (array->Get(context, i).ToLocal(&element_value)) {
-        if (!SerializeValue(isolate, element_value, to_transfer, seen_objects,
-                            out_data))
-          return false;
-      } else {
-        Throw(isolate, "Failed to serialize array element.");
-        return false;
-      }
-    }
-  } else if (value->IsArrayBuffer()) {
-    Local<ArrayBuffer> array_buffer = Local<ArrayBuffer>::Cast(value);
-    if (FindInObjectList(array_buffer, *seen_objects)) {
-      Throw(isolate, "Duplicated array buffers not supported");
-      return false;
-    }
-    seen_objects->Add(array_buffer);
-    if (FindInObjectList(array_buffer, to_transfer)) {
-      // Transfer ArrayBuffer
-      if (!array_buffer->IsNeuterable()) {
-        Throw(isolate, "Attempting to transfer an un-neuterable ArrayBuffer");
-        return false;
-      }
-
-      ArrayBuffer::Contents contents = array_buffer->IsExternal()
-                                           ? array_buffer->GetContents()
-                                           : array_buffer->Externalize();
-      array_buffer->Neuter();
-      out_data->WriteArrayBufferContents(contents);
-    } else {
-      ArrayBuffer::Contents contents = array_buffer->GetContents();
-      // Clone ArrayBuffer
-      if (contents.ByteLength() > i::kMaxInt) {
-        Throw(isolate, "ArrayBuffer is too big to clone");
-        return false;
-      }
-
-      int32_t byte_length = static_cast<int32_t>(contents.ByteLength());
-      out_data->WriteTag(kSerializationTagArrayBuffer);
-      out_data->Write(byte_length);
-      out_data->WriteMemory(contents.Data(), byte_length);
-    }
-  } else if (value->IsSharedArrayBuffer()) {
-    Local<SharedArrayBuffer> sab = Local<SharedArrayBuffer>::Cast(value);
-    if (FindInObjectList(sab, *seen_objects)) {
-      Throw(isolate, "Duplicated shared array buffers not supported");
-      return false;
-    }
-    seen_objects->Add(sab);
-    if (!FindInObjectList(sab, to_transfer)) {
-      Throw(isolate, "SharedArrayBuffer must be transferred");
-      return false;
-    }
-
-    SharedArrayBuffer::Contents contents;
-    if (sab->IsExternal()) {
-      contents = sab->GetContents();
-    } else {
-      contents = sab->Externalize();
-      base::LockGuard<base::Mutex> lock_guard(workers_mutex_.Pointer());
-      externalized_shared_contents_.Add(contents);
-    }
-    out_data->WriteSharedArrayBufferContents(contents);
-  } else if (value->IsObject()) {
-    Local<Object> object = Local<Object>::Cast(value);
-    if (FindInObjectList(object, *seen_objects)) {
-      Throw(isolate, "Duplicated objects not supported");
-      return false;
-    }
-    seen_objects->Add(object);
-    Local<Array> property_names;
-    if (!object->GetOwnPropertyNames(context).ToLocal(&property_names)) {
-      Throw(isolate, "Unable to get property names");
-      return false;
-    }
-
-    uint32_t length = property_names->Length();
-    out_data->WriteTag(kSerializationTagObject);
-    out_data->Write(length);
-    for (uint32_t i = 0; i < length; ++i) {
-      Local<Value> name;
-      Local<Value> property_value;
-      if (property_names->Get(context, i).ToLocal(&name) &&
-          object->Get(context, name).ToLocal(&property_value)) {
-        if (!SerializeValue(isolate, name, to_transfer, seen_objects, out_data))
-          return false;
-        if (!SerializeValue(isolate, property_value, to_transfer, seen_objects,
-                            out_data))
-          return false;
-      } else {
-        Throw(isolate, "Failed to serialize property.");
-        return false;
-      }
-    }
-  } else {
-    Throw(isolate, "Don't know how to serialize object");
-    return false;
-  }
-
-  return true;
+  Serializer serializer(isolate);
+  if (serializer.WriteValue(context, value, transfer).To(&ok)) {
+    std::unique_ptr<SerializationData> data = serializer.Release();
+    base::LockGuard<base::Mutex> lock_guard(workers_mutex_.Pointer());
+    for (const auto& contents : data->shared_array_buffer_contents()) {
+      externalized_shared_contents_.insert(contents);
+    }
+    return data;
+  }
+  return std::unique_ptr<SerializationData>();

[jbroman, 2017/01/26 21:53:03]

nit: Dunno about v8, but in Chromium/Blink I'd prefer "return nullptr" for
conciseness.

[binji, 2017/01/27 19:33:21]

Done.

 }
 
-
-MaybeLocal<Value> Shell::DeserializeValue(Isolate* isolate,
-                                          const SerializationData& data,
-                                          int* offset) {
-  DCHECK(offset);
-  EscapableHandleScope scope(isolate);
-  Local<Value> result;
-  SerializationTag tag = data.ReadTag(offset);
-
-  switch (tag) {
-    case kSerializationTagUndefined:
-      result = Undefined(isolate);
-      break;
-    case kSerializationTagNull:
-      result = Null(isolate);
-      break;
-    case kSerializationTagTrue:
-      result = True(isolate);
-      break;
-    case kSerializationTagFalse:
-      result = False(isolate);
-      break;
-    case kSerializationTagNumber:
-      result = Number::New(isolate, data.Read<double>(offset));
-      break;
-    case kSerializationTagString: {
-      int length = data.Read<int>(offset);
-      CHECK(length >= 0);
-      std::vector<char> buffer(length + 1);  // + 1 so it is never empty.
-      data.ReadMemory(&buffer[0], length, offset);
-      MaybeLocal<String> str =
-          String::NewFromUtf8(isolate, &buffer[0], NewStringType::kNormal,
-                              length).ToLocalChecked();
-      if (!str.IsEmpty()) result = str.ToLocalChecked();
-      break;
-    }
-    case kSerializationTagArray: {
-      uint32_t length = data.Read<uint32_t>(offset);
-      Local<Array> array = Array::New(isolate, length);
-      for (uint32_t i = 0; i < length; ++i) {
-        Local<Value> element_value;
-        CHECK(DeserializeValue(isolate, data, offset).ToLocal(&element_value));
-        array->Set(isolate->GetCurrentContext(), i, element_value).FromJust();
-      }
-      result = array;
-      break;
-    }
-    case kSerializationTagObject: {
-      int length = data.Read<int>(offset);
-      Local<Object> object = Object::New(isolate);
-      for (int i = 0; i < length; ++i) {
-        Local<Value> property_name;
-        CHECK(DeserializeValue(isolate, data, offset).ToLocal(&property_name));
-        Local<Value> property_value;
-        CHECK(DeserializeValue(isolate, data, offset).ToLocal(&property_value));
-        object->Set(isolate->GetCurrentContext(), property_name, property_value)
-            .FromJust();
-      }
-      result = object;
-      break;
-    }
-    case kSerializationTagArrayBuffer: {
-      int32_t byte_length = data.Read<int32_t>(offset);
-      Local<ArrayBuffer> array_buffer = ArrayBuffer::New(isolate, byte_length);
-      ArrayBuffer::Contents contents = array_buffer->GetContents();
-      DCHECK(static_cast<size_t>(byte_length) == contents.ByteLength());
-      data.ReadMemory(contents.Data(), byte_length, offset);
-      result = array_buffer;
-      break;
-    }
-    case kSerializationTagTransferredArrayBuffer: {
-      ArrayBuffer::Contents contents;
-      data.ReadArrayBufferContents(&contents, offset);
-      result = ArrayBuffer::New(isolate, contents.Data(), contents.ByteLength(),
-                                ArrayBufferCreationMode::kInternalized);
-      break;
-    }
-    case kSerializationTagTransferredSharedArrayBuffer: {
-      SharedArrayBuffer::Contents contents;
-      data.ReadSharedArrayBufferContents(&contents, offset);
-      result = SharedArrayBuffer::New(isolate, contents.Data(),
-                                      contents.ByteLength());
-      break;
-    }
-    default:
-      UNREACHABLE();
-  }
-
-  return scope.Escape(result);
+MaybeLocal<Value> Shell::DeserializeValue(
+    Isolate* isolate, std::unique_ptr<SerializationData> data) {
+  Local<Value> value;
+  Local<Context> context = isolate->GetCurrentContext();
+  Deserializer deserializer(isolate, std::move(data));
+  return deserializer.ReadValue(context);
 }
 
 
 void Shell::CleanupWorkers() {
   // Make a copy of workers_, because we don't want to call Worker::Terminate
   // while holding the workers_mutex_ lock. Otherwise, if a worker is about to
   // create a new Worker, it would deadlock.
   i::List<Worker*> workers_copy;
   {
     base::LockGuard<base::Mutex> lock_guard(workers_mutex_.Pointer());
     allow_new_workers_ = false;
     workers_copy.AddAll(workers_);
     workers_.Clear();
   }
 
   for (int i = 0; i < workers_copy.length(); ++i) {
     Worker* worker = workers_copy[i];
     worker->WaitForThread();
     delete worker;
   }
 
   // Now that all workers are terminated, we can re-enable Worker creation.
   base::LockGuard<base::Mutex> lock_guard(workers_mutex_.Pointer());
   allow_new_workers_ = true;
 
-  for (int i = 0; i < externalized_shared_contents_.length(); ++i) {
-    const SharedArrayBuffer::Contents& contents =
-        externalized_shared_contents_[i];
+  for (const auto& contents : externalized_shared_contents_) {
     Shell::array_buffer_allocator->Free(contents.Data(), contents.ByteLength());
   }
-  externalized_shared_contents_.Clear();
+  externalized_shared_contents_.clear();
 }
 
 
 static void DumpHeapConstants(i::Isolate* isolate) {
   i::Heap* heap = isolate->heap();
 
   // Dump the INSTANCE_TYPES table to the console.
   printf("# List of known V8 instance types.\n");
 #define DUMP_TYPE(T) printf("  %d: \"%s\",\n", i::T, #T);
   printf("INSTANCE_TYPES = {\n");
@@ skipping 207 matching lines @@
 }
 
 }  // namespace v8
 
 
 #ifndef GOOGLE3
 int main(int argc, char* argv[]) {
   return v8::Shell::Main(argc, argv);
 }
 #endif