src: enable context snapshot after running per-context scripts

joyeecheung · targos · commit 228127fc67d9 · 2019-04-27T11:36:00.000+02:00
At build time, snapshot the context after running per-context scripts in the main instance, and in the final build, deserialize the context in the main instance. This provides a ~5% in the misc/startup benchmark when the instance is launched within a process that runs test/fixtures/semicolon.js. PR-URL: #27321 Refs: #17058 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Refael Ackermann <refack@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
diff --git a/src/node_main_instance.cc b/src/node_main_instance.cc
@@ -171,9 +171,13 @@ std::unique_ptr<Environment> NodeMainInstance::CreateMainEnvironment(
     isolate_->GetHeapProfiler()->StartTrackingHeapObjects(true);
   }
 
-  Local<Context> context = NewContext(isolate_);
+  Local<Context> context;
   if (deserialize_mode_) {
+    context =
+        Context::FromSnapshot(isolate_, kNodeContextIndex).ToLocalChecked();
     SetIsolateUpForNode(isolate_, IsolateSettingCategories::kErrorHandlers);
+  } else {
+    context = NewContext(isolate_);
   }
 
   CHECK(!context.IsEmpty());
diff --git a/src/node_main_instance.h b/src/node_main_instance.h
@@ -75,6 +75,8 @@ class NodeMainInstance {
   static const IndexArray* GetIsolateDataIndexes();
   static v8::StartupData* GetEmbeddedSnapshotBlob();
 
+  static const size_t kNodeContextIndex = 0;
+
  private:
   NodeMainInstance(const NodeMainInstance&) = delete;
   NodeMainInstance& operator=(const NodeMainInstance&) = delete;
diff --git a/tools/snapshot/snapshot_builder.cc b/tools/snapshot/snapshot_builder.cc
@@ -104,6 +104,9 @@ std::string SnapshotBuilder::Generate(
       HandleScope scope(isolate);
       creator.SetDefaultContext(Context::New(isolate));
       isolate_data_indexes = main_instance->isolate_data()->Serialize(&creator);
+
+      size_t index = creator.AddContext(NewContext(isolate));
+      CHECK_EQ(index, NodeMainInstance::kNodeContextIndex);
     }
 
     // Must be out of HandleScope

Original file line number	Diff line number	Diff line change
`@@ -171,9 +171,13 @@ std::unique_ptr<Environment> NodeMainInstance::CreateMainEnvironment(`
`171`	`171`	`isolate_->GetHeapProfiler()->StartTrackingHeapObjects(true);`
`172`	`172`	`}`
`173`	`173`
`174`		`- Local<Context> context = NewContext(isolate_);`
	`174`	`+ Local<Context> context;`
`175`	`175`	`if (deserialize_mode_) {`
	`176`	`+ context =`
	`177`	`+ Context::FromSnapshot(isolate_, kNodeContextIndex).ToLocalChecked();`
`176`	`178`	`SetIsolateUpForNode(isolate_, IsolateSettingCategories::kErrorHandlers);`
	`179`	`+ } else {`
	`180`	`+ context = NewContext(isolate_);`
`177`	`181`	`}`
`178`	`182`
`179`	`183`	`CHECK(!context.IsEmpty());`
Original file line number	Diff line number	Diff line change
`@@ -104,6 +104,9 @@ std::string SnapshotBuilder::Generate(`
`104`	`104`	`HandleScope scope(isolate);`
`105`	`105`	`creator.SetDefaultContext(Context::New(isolate));`
`106`	`106`	`isolate_data_indexes = main_instance->isolate_data()->Serialize(&creator);`
	`107`	`+`
	`108`	`+ size_t index = creator.AddContext(NewContext(isolate));`
	`109`	`+ CHECK_EQ(index, NodeMainInstance::kNodeContextIndex);`
`107`	`110`	`}`
`108`	`111`
`109`	`112`	`// Must be out of HandleScope`