[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
 
 #if !defined(_WIN32) && !defined(_WIN64)
 #include <unistd.h>  // NOLINT
 #else
 #include <windows.h>  // NOLINT
 #if defined(_MSC_VER)
 #include <crtdbg.h>  // NOLINT
 #endif               // defined(_MSC_VER)
 #endif               // !defined(_WIN32) && !defined(_WIN64)
 
 #ifndef DCHECK
 #define DCHECK(condition) assert(condition)
 #endif
 
 #ifndef CHECK
 #define CHECK(condition) assert(condition)
 #endif
 
+namespace std {
+
+template <>
+struct hash<v8::SharedArrayBuffer::Contents> {

[jbroman, 2017/01/24 18:53:43]

(I'm not a V8 owner, but...)

1. The Chromium/Google style guide recommends against specializing std::hash in
most cases.

2. It's particularly surprising to me to see std::hash and operator== declared
and defined here, as it risks ODR violations which are hard to track down. For
instance, another translation unit might define them differently (and it's
undefined how the difference is resolved). Additionally, a template might be
instantiated differently depending on whether these exist or not.

[binji, 2017/01/25 00:31:35]

Done.

+  size_t operator()(const v8::SharedArrayBuffer::Contents& contents) const {
+    return std::hash<void*>()(contents.Data()) ^
+           std::hash<size_t>()(contents.ByteLength());
+  }
+};
+
+}  // namespace std
+
 namespace v8 {
 
+bool operator==(const SharedArrayBuffer::Contents& a,
+                const SharedArrayBuffer::Contents& b) {
+  return a.Data() == b.Data() && a.ByteLength() == b.ByteLength();
+}
+
 namespace {
 
 const int MB = 1024 * 1024;
 const int kMaxWorkers = 50;
 
 #define USE_VM 1
 #define VM_THRESHOLD 65536
 // TODO(titzer): allocations should fail if >= 2gb because of
 // array buffers storing the lengths as a SMI internally.
 #define TWO_GB (2u * 1024u * 1024u * 1024u)
@@ skipping 138 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::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 732 matching lines @@
     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)) {
+  Local<Value> transfer =
+      args.Length() >= 2 ? args[1] : Local<Value>::Cast(Undefined(isolate));

[jbroman, 2017/01/24 18:53:43]

nit: is the Local<Value> cast necessary; I think it's implied.

[binji, 2017/01/25 00:31:36]

The two arms of the conditional have different types (Undefined returns
Value<Primitive>).

[jbroman, 2017/01/25 16:34:54]

OK, sorry.

Ordinarily the compiler would still add the conversion automatically, but
conversions in both directions are defined even though only one is legal
(neither SFINAEs away), so it gets confused. (A one-line change to the
definition of Local would fix this, but that discussion is well outside the
scope of this change.)

+  SerializationData* data;
+  if (Shell::SerializeValue(isolate, message, transfer).To(&data)) {
     worker->PostMessage(data);
-  } else {
-    delete 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();
   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, data).ToLocal(&value)) {

[jbroman, 2017/01/24 18:53:43]

nit: Just checking, if this fails (i.e. an exception is thrown from
DeserializeValue), you're okay with an exception being thrown from here?

[binji, 2017/01/25 00:31:35]

Yeah, it definitely will break the tests (or perhaps cause timeout), which is
all that really matters.

+      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 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) {
   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;
@@ skipping 119 matching lines @@
           if (onmessage->IsFunction()) {
             Local<Function> onmessage_fun = Local<Function>::Cast(onmessage);
             // Now wait for messages
             while (true) {
               in_semaphore_.Wait();
               SerializationData* data;
               if (!in_queue_.Dequeue(&data)) continue;
               if (data == NULL) {
                 break;
               }
-              int offset = 0;
-              Local<Value> data_value;
-              if (Shell::DeserializeValue(isolate, *data, &offset)
-                      .ToLocal(&data_value)) {
-                Local<Value> argv[] = {data_value};
+              Local<Value> value;
+              if (Shell::DeserializeValue(isolate, data).ToLocal(&value)) {

[jbroman, 2017/01/24 18:53:43]

If an exception is thrown from DeserializeValue, don't you want to catch it?
(Blink always catches and reports null instead, but up to you.) This is probably
less of an issue for in-process messaging than cross-process messaging, but it's
still possible (e.g. if array buffer allocation fails). I suspect you want to
catch it and pass it to Shell::ReportException, but up to you.

[binji, 2017/01/25 00:31:35]

Done.

+                Local<Value> argv[] = {value};
+                v8::TryCatch try_catch(isolate);
                 (void)onmessage_fun->Call(context, global, 1, argv);
+                if (try_catch.HasCaught()) {
+                  Shell::ReportException(isolate, &try_catch);
+                }
               }
-              delete data;
             }
           }
         }
       }
       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;
   }
 
+  SerializationData* data;

[jbroman, 2017/01/24 18:53:43]

Here and elsewhere: managing this memory by hand makes me uneasy. Have you
considered moving to unique_ptr so that you can be sure this isn't leaked?

[binji, 2017/01/25 00:31:35]

At the time when I originally wrote some of this, it seemed as though d8 wasn't
using std stuff, but now it seems more OK. Agreed it's nicer :)

   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);
+  if (Shell::SerializeValue(isolate, message, transfer).To(&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_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), data_(nullptr) {}
+
+  ~Serializer() { delete data_; }
+
+  Maybe<bool> WriteValue(Local<Context> context, Local<Value> value,
+                         Local<Value> transfer) {
+    bool ok;
+    DCHECK(data_ == nullptr);
+    data_ = new SerializationData;
+    if (!PrepareTransfer(context, transfer).To(&ok)) {
+      return Nothing<bool>();
+    }
+    serializer_.WriteHeader();
+
+    if (serializer_.WriteValue(context, value).To(&ok)) {
+      if (!FinalizeTransfer().To(&ok)) {
+        return Nothing<bool>();
+      }
+
+      std::pair<uint8_t*, size_t> pair = serializer_.Release();
+      data_->data_ = pair.first;
+      data_->size_ = pair.second;
+      return Just(true);
+    } else {
+      delete data_;
+      data_ = nullptr;
+    }
+    return Nothing<bool>();
+  }
+
+  SerializationData* Release() {
+    SerializationData* result = data_;
+    data_ = nullptr;
+    return result;
+  }
+
+ 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 {
+    *actual_size = size;
+    return realloc(old_buffer, size);
+  }
+
+  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)) {

[jbroman, 2017/01/24 18:53:43]

Not new, but this isn't very resilient against code doing strange things. If Get
throws, then there will be an exception on the isolate, but serialization will
still try to proceed. I don't know the use case of d8 to know how resilient you
need to be to bad script.

e.g. this array:
var transferList = [undefined];
Object.defineProperty(transferList, '0', function() { throw 'unexpected!'; });
worker.postMessage([], transferList);

[binji, 2017/01/25 00:31:35]

Good point, added a TryCatch.

+          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);
+        }
+      }
+      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_;
+  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, SerializationData* data)
+      : isolate_(isolate),
+        deserializer_(isolate, data->data(), data->size(), this),
+        data_(data) {
+    deserializer_.SetSupportsLegacyWireFormat(true);
+  }
+
+  ~Deserializer() { delete data_; }
+
+  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_;
+  SerializationData* data_;
+
+  DISALLOW_COPY_AND_ASSIGN(Deserializer);
+};
+
+Maybe<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)) {
+    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 Just(data);
+  }
+  return Nothing<SerializationData*>();
 }
 
-
 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);
+                                          SerializationData* data) {
+  Local<Value> value;
+  Local<Context> context = isolate->GetCurrentContext();
+  Deserializer deserializer(isolate, data);
+  if (deserializer.ReadValue(context).ToLocal(&value)) {
+    return MaybeLocal<Value>(value);
+  }
+  return MaybeLocal<Value>();
 }
 
 
 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