[Bindings] Create and use V8 context snapshots

third_party/WebKit/Source/platform/bindings/V8PerIsolateData.cpp

Index: third_party/WebKit/Source/platform/bindings/V8PerIsolateData.cpp
diff --git a/third_party/WebKit/Source/platform/bindings/V8PerIsolateData.cpp b/third_party/WebKit/Source/platform/bindings/V8PerIsolateData.cpp
index 6ba47d5d3947f9fc8055d86f5092314861d21602..35dafe98777b6209dbcb9aa88b3f61ae774c6c0c 100644
--- a/third_party/WebKit/Source/platform/bindings/V8PerIsolateData.cpp
+++ b/third_party/WebKit/Source/platform/bindings/V8PerIsolateData.cpp
@@ -27,6 +27,7 @@
 
 #include <memory>
 
+#include "platform/RuntimeEnabledFeatures.h"
 #include "platform/ScriptForbiddenScope.h"
 #include "platform/WebTaskRunner.h"
 #include "platform/bindings/DOMDataStore.h"
@@ -52,18 +53,34 @@ static void MicrotasksCompletedCallback(v8::Isolate* isolate) {
   V8PerIsolateData::From(isolate)->RunEndOfScopeTasks();
 }
 
-V8PerIsolateData::V8PerIsolateData(WebTaskRunner* task_runner)
-    : isolate_holder_(
+V8PerIsolateData::V8PerIsolateData(
+    WebTaskRunner* task_runner,
+    intptr_t* table,
+    V8ContextSnapshotMode v8_context_snapshot_mode)
+    : v8_context_snapshot_mode_(v8_context_snapshot_mode),
+      isolate_holder_(
           task_runner ? task_runner->ToSingleThreadTaskRunner() : nullptr,
           gin::IsolateHolder::kSingleThread,
           IsMainThread() ? gin::IsolateHolder::kDisallowAtomicsWait
-                         : gin::IsolateHolder::kAllowAtomicsWait),
+                         : gin::IsolateHolder::kAllowAtomicsWait,
+          table,
+          v8_context_snapshot_mode_ == V8ContextSnapshotMode::kUseSnapshot
+              ? &startup_data_
+              : nullptr),
+      interface_template_map_for_v8_context_snapshot_(GetIsolate()),
       string_cache_(WTF::WrapUnique(new StringCache(GetIsolate()))),
       private_property_(V8PrivateProperty::Create()),
       constructor_mode_(ConstructorMode::kCreateNewObject),
       use_counter_disabled_(false),
       is_handling_recursion_level_error_(false),
       is_reporting_exception_(false) {
+  // If it fails to load the snapshot file, falls back to kDontUseSnapshot mode.
+  // TODO(peria): Remove this fallback routine.
+  if (v8_context_snapshot_mode_ == V8ContextSnapshotMode::kUseSnapshot &&
+      !startup_data_.data) {
+    v8_context_snapshot_mode_ = V8ContextSnapshotMode::kDontUseSnapshot;
+  }
+
   // FIXME: Remove once all v8::Isolate::GetCurrent() calls are gone.
   GetIsolate()->Enter();
   GetIsolate()->AddBeforeCallEnteredCallback(&BeforeCallEnteredCallback);
@@ -72,6 +89,24 @@ V8PerIsolateData::V8PerIsolateData(WebTaskRunner* task_runner)
     g_main_thread_per_isolate_data = this;
 }
 
+// This constructor is used for taking a V8 context snapshot. It must run on the
+// main thread.
+V8PerIsolateData::V8PerIsolateData(intptr_t* reference_table)
+    : v8_context_snapshot_mode_(V8ContextSnapshotMode::kTakeSnapshot),
+      isolate_holder_(reference_table, nullptr),
+      interface_template_map_for_v8_context_snapshot_(GetIsolate()),
+      string_cache_(WTF::WrapUnique(new StringCache(GetIsolate()))),
+      private_property_(V8PrivateProperty::Create()),
+      constructor_mode_(ConstructorMode::kCreateNewObject),
+      use_counter_disabled_(false),
+      is_handling_recursion_level_error_(false),
+      is_reporting_exception_(false) {
+  CHECK(IsMainThread());
+
+  // SnapshotCreator enters the isolate, so we don't call Isolate::Enter() here.
+  g_main_thread_per_isolate_data = this;
+}
+
 V8PerIsolateData::~V8PerIsolateData() {}
 
 v8::Isolate* V8PerIsolateData::MainThreadIsolate() {
@@ -79,8 +114,21 @@ v8::Isolate* V8PerIsolateData::MainThreadIsolate() {
   return g_main_thread_per_isolate_data->GetIsolate();
 }
 
-v8::Isolate* V8PerIsolateData::Initialize(WebTaskRunner* task_runner) {
-  V8PerIsolateData* data = new V8PerIsolateData(task_runner);
+v8::Isolate* V8PerIsolateData::Initialize(WebTaskRunner* task_runner,
+                                          intptr_t* reference_table,
+                                          V8ContextSnapshotMode context_mode) {
+  DCHECK(context_mode == V8ContextSnapshotMode::kDontUseSnapshot ||
+         reference_table);
+
+  V8PerIsolateData* data = nullptr;
+  if (context_mode == V8ContextSnapshotMode::kTakeSnapshot) {
+    CHECK(reference_table);
+    data = new V8PerIsolateData(reference_table);
+  } else {
+    data = new V8PerIsolateData(task_runner, reference_table, context_mode);
+  }
+  DCHECK(data);
+
   v8::Isolate* isolate = data->GetIsolate();
   isolate->SetData(gin::kEmbedderBlink, data);
   return isolate;
@@ -164,6 +212,11 @@ v8::Local<v8::FunctionTemplate> V8PerIsolateData::FindOrCreateOperationTemplate(
 v8::Local<v8::FunctionTemplate> V8PerIsolateData::FindInterfaceTemplate(
     const DOMWrapperWorld& world,
     const void* key) {
+  if (GetV8ContextSnapshotMode() == V8ContextSnapshotMode::kTakeSnapshot) {
+    const WrapperTypeInfo* type = reinterpret_cast<const WrapperTypeInfo*>(key);
+    return interface_template_map_for_v8_context_snapshot_.Get(type);
+  }
+
   auto& map = SelectInterfaceTemplateMap(world);
   auto result = map.find(key);
   if (result != map.end())
@@ -175,8 +228,19 @@ void V8PerIsolateData::SetInterfaceTemplate(
     const DOMWrapperWorld& world,
     const void* key,
     v8::Local<v8::FunctionTemplate> value) {
-  auto& map = SelectInterfaceTemplateMap(world);
-  map.insert(key, v8::Eternal<v8::FunctionTemplate>(GetIsolate(), value));
+  if (GetV8ContextSnapshotMode() == V8ContextSnapshotMode::kTakeSnapshot) {
+    auto& map = interface_template_map_for_v8_context_snapshot_;
+    const WrapperTypeInfo* type = reinterpret_cast<const WrapperTypeInfo*>(key);
+    map.Set(type, value);
+  } else {
+    auto& map = SelectInterfaceTemplateMap(world);
+    map.insert(key, v8::Eternal<v8::FunctionTemplate>(GetIsolate(), value));
+  }
+}
+
+void V8PerIsolateData::ClearPersistentsForV8ContextSnapshot() {
+  interface_template_map_for_v8_context_snapshot_.Clear();
+  private_property_.reset();
 }
 
 const v8::Eternal<v8::Name>* V8PerIsolateData::FindOrCreateEternalNameCache(