[Bindings] Create and use V8 context snapshots

gin/isolate_holder.cc

 // Copyright 2013 The Chromium 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 "gin/public/isolate_holder.h"
 
 #include <stddef.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ skipping 17 matching lines @@
 v8::ArrayBuffer::Allocator* g_array_buffer_allocator = nullptr;
 }  // namespace
 
 IsolateHolder::IsolateHolder(
     scoped_refptr<base::SingleThreadTaskRunner> task_runner)
     : IsolateHolder(std::move(task_runner), AccessMode::kSingleThread) {}
 
 IsolateHolder::IsolateHolder(
     scoped_refptr<base::SingleThreadTaskRunner> task_runner,
     AccessMode access_mode)
-    : IsolateHolder(std::move(task_runner), access_mode, kAllowAtomicsWait) {}
+    : IsolateHolder(std::move(task_runner),
+                    access_mode,
+                    kAllowAtomicsWait,
+                    nullptr,
+                    nullptr) {}
 
 IsolateHolder::IsolateHolder(
     scoped_refptr<base::SingleThreadTaskRunner> task_runner,
     AccessMode access_mode,
-    AllowAtomicsWaitMode atomics_wait_mode)
+    AllowAtomicsWaitMode atomics_wait_mode,
+    intptr_t* reference,
+    v8::StartupData* startup_data)
     : access_mode_(access_mode) {
   v8::ArrayBuffer::Allocator* allocator = g_array_buffer_allocator;
   CHECK(allocator) << "You need to invoke gin::IsolateHolder::Initialize first";
+
   v8::Isolate::CreateParams params;
   params.entry_hook = DebugImpl::GetFunctionEntryHook();
   params.code_event_handler = DebugImpl::GetJitCodeEventHandler();
   params.constraints.ConfigureDefaults(base::SysInfo::AmountOfPhysicalMemory(),
                                        base::SysInfo::AmountOfVirtualMemory());
   params.array_buffer_allocator = allocator;
   params.allow_atomics_wait = atomics_wait_mode == kAllowAtomicsWait;
+  params.external_references = reference;
+
+  if (startup_data) {
+    CHECK(reference);
+    V8Initializer::GetV8ContextData(&startup_data->data,
+                                    &startup_data->raw_size);
+    if (startup_data->data) {
+      params.snapshot_blob = startup_data;
+    }

[Yuki, 2017/05/30 14:35:56]

What happens if GetV8ContextData fails to load the snapshot blob?
Should we report an error if (!startup_data->data)?

[peria, 2017/06/01 08:33:32]

I can't agree to make it an error. Even if Chrome fails to load blob,
it can work with kDontUseSnapshot mode.

+  }
   isolate_ = v8::Isolate::New(params);
+
   isolate_data_.reset(
       new PerIsolateData(isolate_, allocator, access_mode, task_runner));
   isolate_memory_dump_provider_.reset(new V8IsolateMemoryDumpProvider(this));
 #if defined(OS_WIN)
   {
     void* code_range;
     size_t size;
     isolate_->GetCodeRange(&code_range, &size);
     Debug::CodeRangeCreatedCallback callback =
         DebugImpl::GetCodeRangeCreatedCallback();
     if (code_range && size && callback)
       callback(code_range, size);
   }
 #endif
 }
 
+IsolateHolder::IsolateHolder(v8::Isolate* isolate)
+    : isolate_(isolate), access_mode_(kSingleThread) {

[Yuki, 2017/05/30 14:35:56]

Could you avoid copy&pasting?  Can we have a helper function instead?

The former constructor above should call the helper function with the created
isolate.

[peria, 2017/06/01 08:33:32]

Done.
Will move to another CL.

+  v8::ArrayBuffer::Allocator* allocator = g_array_buffer_allocator;
+  CHECK(allocator) << "You need to invoke gin::IsolateHolder::Initialize first";
+  isolate_data_.reset(
+      new PerIsolateData(isolate_, allocator, access_mode_, nullptr));
+  isolate_memory_dump_provider_.reset(new V8IsolateMemoryDumpProvider(this));
+#if defined(OS_WIN)
+  {
+    void* code_range;
+    size_t size;
+    isolate_->GetCodeRange(&code_range, &size);
+    Debug::CodeRangeCreatedCallback callback =
+        DebugImpl::GetCodeRangeCreatedCallback();
+    if (code_range && size && callback)
+      callback(code_range, size);
+  }
+#endif
+}
+
 IsolateHolder::~IsolateHolder() {
   if (task_observer_.get())
     base::MessageLoop::current()->RemoveTaskObserver(task_observer_.get());
 #if defined(OS_WIN)
   {
     void* code_range;
     size_t size;
     isolate_->GetCodeRange(&code_range, &size);
     Debug::CodeRangeDeletedCallback callback =
         DebugImpl::GetCodeRangeDeletedCallback();
     if (code_range && callback)
       callback(code_range);
   }
 #endif
   isolate_memory_dump_provider_.reset();
   isolate_data_.reset();
   isolate_->Dispose();
-  isolate_ = NULL;
+  isolate_ = nullptr;
 }
 
 // static
 void IsolateHolder::Initialize(ScriptMode mode,
                                V8ExtrasMode v8_extras_mode,
                                v8::ArrayBuffer::Allocator* allocator) {
   CHECK(allocator);
   V8Initializer::Initialize(mode, v8_extras_mode);
   g_array_buffer_allocator = allocator;
 }
@@ skipping 10 matching lines @@
   task_observer_.reset();
 }
 
 void IsolateHolder::EnableIdleTasks(
     std::unique_ptr<V8IdleTaskRunner> idle_task_runner) {
   DCHECK(isolate_data_.get());
   isolate_data_->EnableIdleTasks(std::move(idle_task_runner));
 }
 
 }  // namespace gin