From 2667f4968ac6ca9f1e81d652113f3ef067501750 Mon Sep 17 00:00:00 2001
From: Anna Henningsen <anna.henningsen@mongodb.com>
Date: Thu, 8 Dec 2022 14:42:56 +0100
Subject: [PATCH] src: mark generated `snapshot_data` as `const`

This renders the mutex protecting it unnecessary, since mutexes
only need to protect concurrent accesses to mutable data.
---
 src/node_snapshot_builder.h | 2 --
 src/node_snapshotable.cc    | 7 ++-----
 2 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/src/node_snapshot_builder.h b/src/node_snapshot_builder.h
index 2bea50a2540b2a..3367cd3d7a6c68 100644
--- a/src/node_snapshot_builder.h
+++ b/src/node_snapshot_builder.h
@@ -32,8 +32,6 @@ class NODE_EXTERN_PRIVATE SnapshotBuilder {
                                       v8::Isolate::CreateParams* params);
 
  private:
-  // Used to synchronize access to the snapshot data
-  static Mutex snapshot_data_mutex_;
   static const std::vector<intptr_t>& CollectExternalReferences();
 
   static std::unique_ptr<ExternalReferenceRegistry> registry_;
diff --git a/src/node_snapshotable.cc b/src/node_snapshotable.cc
index 2a4690b76f306e..145e9fa9c18c3c 100644
--- a/src/node_snapshotable.cc
+++ b/src/node_snapshotable.cc
@@ -978,7 +978,7 @@ static void WriteCodeCacheInitializer(std::ostream* ss, const std::string& id) {
   *ss << "    },\n";
 }
 
-void FormatBlob(std::ostream& ss, SnapshotData* data) {
+void FormatBlob(std::ostream& ss, const SnapshotData* data) {
   ss << R"(#include <cstddef>
 #include "env.h"
 #include "node_snapshot_builder.h"
@@ -1004,7 +1004,7 @@ static const int v8_snapshot_blob_size = )"
     WriteStaticCodeCacheData(&ss, item);
   }
 
-  ss << R"(SnapshotData snapshot_data {
+  ss << R"(const SnapshotData snapshot_data {
   // -- data_ownership begins --
   SnapshotData::DataOwnership::kNotOwned,
   // -- data_ownership ends --
@@ -1036,7 +1036,6 @@ static const int v8_snapshot_blob_size = )"
 };
 
 const SnapshotData* SnapshotBuilder::GetEmbeddedSnapshotData() {
-  Mutex::ScopedLock lock(snapshot_data_mutex_);
   return &snapshot_data;
 }
 }  // namespace node
@@ -1053,8 +1052,6 @@ static void ResetContextSettingsBeforeSnapshot(Local<Context> context) {
   context->AllowCodeGenerationFromStrings(true);
 }
 
-Mutex SnapshotBuilder::snapshot_data_mutex_;
-
 const std::vector<intptr_t>& SnapshotBuilder::CollectExternalReferences() {
   static auto registry = std::make_unique<ExternalReferenceRegistry>();
   return registry->external_references();