src: make IsolateData store ArrayBufferAllocator

This enables us to identify whether we are using an
allocator that we know more about than what the generic
`ArrayBuffer::Allocator` API provides, in particular
whether it is `malloc()`-compatible.

PR-URL: nodejs/node#26207
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Joyee Cheung <[email protected]>

Author: addaleax

src/env-inl.h

@@ -47,8 +47,16 @@ inline uv_loop_t* IsolateData::event_loop() const {
   return event_loop_;
 }
 
-inline uint32_t* IsolateData::zero_fill_field() const {
-  return zero_fill_field_;
+inline bool IsolateData::uses_node_allocator() const {
+  return uses_node_allocator_;
+}
+
+inline v8::ArrayBuffer::Allocator* IsolateData::allocator() const {
+  return allocator_;
+}
+
+inline ArrayBufferAllocator* IsolateData::node_allocator() const {
+  return node_allocator_;
 }
 
 inline MultiIsolatePlatform* IsolateData::platform() const {

src/env.cc

@@ -36,11 +36,14 @@ void* Environment::kNodeContextTagPtr = const_cast<void*>(
 IsolateData::IsolateData(Isolate* isolate,
                          uv_loop_t* event_loop,
                          MultiIsolatePlatform* platform,
-                         uint32_t* zero_fill_field) :
-    isolate_(isolate),
-    event_loop_(event_loop),
-    zero_fill_field_(zero_fill_field),
-    platform_(platform) {
+                         ArrayBufferAllocator* node_allocator)
+    : isolate_(isolate),
+      event_loop_(event_loop),
+      allocator_(isolate->GetArrayBufferAllocator()),
+      node_allocator_(node_allocator),
+      uses_node_allocator_(allocator_ == node_allocator_),
+      platform_(platform) {
+  CHECK_NOT_NULL(allocator_);
   if (platform_ != nullptr)
     platform_->RegisterIsolate(isolate_, event_loop);
 

src/env.h

@@ -362,15 +362,19 @@ class Environment;
 
 class IsolateData {
  public:
-  IsolateData(v8::Isolate* isolate, uv_loop_t* event_loop,
+  IsolateData(v8::Isolate* isolate,
+              uv_loop_t* event_loop,
               MultiIsolatePlatform* platform = nullptr,
-              uint32_t* zero_fill_field = nullptr);
+              ArrayBufferAllocator* node_allocator = nullptr);
   ~IsolateData();
   inline uv_loop_t* event_loop() const;
-  inline uint32_t* zero_fill_field() const;
   inline MultiIsolatePlatform* platform() const;
   inline std::shared_ptr<PerIsolateOptions> options();
 
+  inline bool uses_node_allocator() const;
+  inline v8::ArrayBuffer::Allocator* allocator() const;
+  inline ArrayBufferAllocator* node_allocator() const;
+
 #define VP(PropertyName, StringValue) V(v8::Private, PropertyName)
 #define VY(PropertyName, StringValue) V(v8::Symbol, PropertyName)
 #define VS(PropertyName, StringValue) V(v8::String, PropertyName)
@@ -401,7 +405,9 @@ class IsolateData {
 
   v8::Isolate* const isolate_;
   uv_loop_t* const event_loop_;
-  uint32_t* const zero_fill_field_;
+  v8::ArrayBuffer::Allocator* const allocator_;
+  ArrayBufferAllocator* const node_allocator_;
+  const bool uses_node_allocator_;
   MultiIsolatePlatform* platform_;
   std::shared_ptr<PerIsolateOptions> options_;
 

src/node.cc

@@ -2832,7 +2832,7 @@ IsolateData* CreateIsolateData(
     uv_loop_t* loop,
     MultiIsolatePlatform* platform,
     ArrayBufferAllocator* allocator) {
-  return new IsolateData(isolate, loop, platform, allocator->zero_fill_field());
+  return new IsolateData(isolate, loop, platform, allocator);
 }