[wasm-c-api] Roll bf31edf: Fix life times of host info

Host info used to be stored on the global reference underlying a Ref;
now it is stored in a JSWeakMap and hence tied to the lifetime of the
actual object on V8's heap.
Additionally, the internal metadata needed for C-API functions is now
stored on the SharedFunctionInfo and no longer overlaps with the host
info mechanism.

Bonus content:
Roll 6db391e: Remove a few more leftover uses of _enum types

Change-Id: Ibb1fa4b0dd5157fef15c030bac705a11aa3beaea
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1768368
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63400}

src/builtins/base.tq

@@ -1000,7 +1000,7 @@ extern class WasmJSFunctionData extends Struct {
 
 extern class WasmCapiFunctionData extends Struct {
   call_target: RawPtr;
-  embedder_data: RawPtr;
+  embedder_data: Foreign;  // Managed<wasm::FuncData>
   wrapper_code: Code;
   serialized_signature: ByteArray;  // PodArray<wasm::ValueType>
 }

src/compiler/wasm-compiler.cc

@@ -5952,9 +5952,9 @@ class WasmWrapperGraphBuilder : public WasmGraphBuilder {
     Node* sfi_data = LOAD_RAW(
         shared, SharedFunctionInfo::kFunctionDataOffset - kHeapObjectTag,
         MachineType::TypeCompressedTagged());
-    Node* host_data = LOAD_RAW(
+    Node* host_data_foreign = LOAD_RAW(
         sfi_data, WasmCapiFunctionData::kEmbedderDataOffset - kHeapObjectTag,
-        MachineType::Pointer());
+        MachineType::TypeCompressedTagged());
 
     BuildModifyThreadInWasmFlag(false);
     Node* isolate_root = BuildLoadIsolateRoot();
@@ -5968,11 +5968,12 @@ class WasmWrapperGraphBuilder : public WasmGraphBuilder {
     Node* function =
         graph()->NewNode(mcgraph()->common()->ExternalConstant(ref));
 
-    // Parameters: void* data, Address arguments.
+    // Parameters: Address host_data_foreign, Address arguments.
     MachineType host_sig_types[] = {
         MachineType::Pointer(), MachineType::Pointer(), MachineType::Pointer()};
     MachineSignature host_sig(1, 2, host_sig_types);
-    Node* return_value = BuildCCall(&host_sig, function, host_data, values);
+    Node* return_value =
+        BuildCCall(&host_sig, function, host_data_foreign, values);
 
     BuildModifyThreadInWasmFlag(true);
 

src/diagnostics/objects-printer.cc

@@ -2061,7 +2061,7 @@ void WasmCapiFunctionData::WasmCapiFunctionDataPrint(
     std::ostream& os) {  // NOLINT
   PrintHeader(os, "WasmCapiFunctionData");
   os << "\n - call_target: " << call_target();
-  os << "\n - embedder_data: " << embedder_data();
+  os << "\n - embedder_data: " << Brief(embedder_data());
   os << "\n - wrapper_code: " << Brief(wrapper_code());
   os << "\n - serialized_signature: " << Brief(serialized_signature());
   os << "\n";

src/wasm/c-api.cc

@@ -29,6 +29,8 @@
 #include "include/libplatform/libplatform.h"
 #include "src/api/api-inl.h"
 #include "src/compiler/wasm-compiler.h"
+#include "src/objects/js-collection-inl.h"
+#include "src/objects/managed.h"
 #include "src/objects/stack-frame-info-inl.h"
 #include "src/wasm/leb-helper.h"
 #include "src/wasm/module-instantiate.h"
@@ -270,6 +272,38 @@ StoreImpl::~StoreImpl() {
   delete create_params_.array_buffer_allocator;
 }
 
+struct ManagedData {
+  ManagedData(void* info, void (*finalizer)(void*))
+      : info(info), finalizer(finalizer) {}
+
+  ~ManagedData() {
+    if (finalizer) (*finalizer)(info);
+  }
+
+  void* info;
+  void (*finalizer)(void*);
+};
+
+void StoreImpl::SetHostInfo(i::Handle<i::Object> object, void* info,
+                            void (*finalizer)(void*)) {
+  i::HandleScope scope(i_isolate());
+  // Ideally we would specify the total size kept alive by {info} here,
+  // but all we get from the embedder is a {void*}, so our best estimate
+  // is the size of the metadata.
+  size_t estimated_size = sizeof(ManagedData);
+  i::Handle<i::Object> wrapper = i::Managed<ManagedData>::FromRawPtr(
+      i_isolate(), estimated_size, new ManagedData(info, finalizer));
+  int32_t hash = object->GetOrCreateHash(i_isolate()).value();
+  i::JSWeakCollection::Set(host_info_map_, object, wrapper, hash);
+}
+
+void* StoreImpl::GetHostInfo(i::Handle<i::Object> key) {
+  i::Object raw =
+      i::EphemeronHashTable::cast(host_info_map_->table()).Lookup(key);
+  if (raw.IsTheHole(i_isolate())) return nullptr;
+  return i::Managed<ManagedData>::cast(raw).raw()->info;
+}
+
 template <>
 struct implement<Store> {
   using type = StoreImpl;
@@ -286,26 +320,29 @@ auto Store::make(Engine*) -> own<Store> {
   // Create isolate.
   store->create_params_.array_buffer_allocator =
       v8::ArrayBuffer::Allocator::NewDefaultAllocator();
-  auto isolate = v8::Isolate::New(store->create_params_);
+  v8::Isolate* isolate = v8::Isolate::New(store->create_params_);
   if (!isolate) return own<Store>();
+  store->isolate_ = isolate;
+  isolate->SetData(0, store.get());
+  // We intentionally do not call isolate->Enter() here, because that would
+  // prevent embedders from using stores with overlapping but non-nested
+  // lifetimes. The consequence is that Isolate::Current() is dysfunctional
+  // and hence must not be called by anything reachable via this file.
 
   {
     v8::HandleScope handle_scope(isolate);
 
     // Create context.
-    auto context = v8::Context::New(isolate);
+    v8::Local<v8::Context> context = v8::Context::New(isolate);
     if (context.IsEmpty()) return own<Store>();
-    v8::Context::Scope context_scope(context);
+    context->Enter();  // The Exit() call is in ~StoreImpl.
-
-    store->isolate_ = isolate;
     store->context_ = v8::Eternal<v8::Context>(isolate, context);
+
+    // Create weak map for Refs with host info.
+    i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+    store->host_info_map_ = i_isolate->global_handles()->Create(
+        *i_isolate->factory()->NewJSWeakMap());
   }
-  // We intentionally do not call isolate->Enter() here, because that would
-  // prevent embedders from using stores with overlapping but non-nested
-  // lifetimes. The consequence is that Isolate::Current() is dysfunctional
-  // and hence must not be called by anything reachable via this file.
-  store->context()->Enter();
-  isolate->SetData(0, store.get());
   // We want stack traces for traps.
   constexpr int kStackLimit = 10;
   isolate->SetCaptureStackTraceForUncaughtExceptions(true, kStackLimit,
@@ -712,15 +749,7 @@ class RefImpl {
     return make_own(seal<Ref>(self));
   }
 
-  void Reset() {
+  ~RefImpl() { i::GlobalHandles::Destroy(location()); }
-    i::GlobalHandles::Destroy(location());
-    if (host_data_) {
-      if (host_data_->finalizer) {
-        host_data_->finalizer(host_data_->info);
-      }
-      delete host_data_;
-    }
-  }
 
   own<Ref> copy() const { return make(store(), v8_object()); }
 
@@ -730,41 +759,20 @@ class RefImpl {
 
   i::Handle<JSType> v8_object() const { return i::Handle<JSType>::cast(val_); }
 
-  void* get_host_info() const {
+  void* get_host_info() const { return store()->GetHostInfo(v8_object()); }
-    if (host_data_ == nullptr) return nullptr;
-    return host_data_->info;
-  }
 
   void set_host_info(void* info, void (*finalizer)(void*)) {
-    host_data_ = new HostData(location(), info, finalizer);
+    store()->SetHostInfo(v8_object(), info, finalizer);
-    i::GlobalHandles::MakeWeak(host_data_->location, host_data_, &v8_finalizer,
-                               v8::WeakCallbackType::kParameter);
   }
 
  private:
-  struct HostData {
-    HostData(i::Address* location, void* info, void (*finalizer)(void*))
-        : location(location), info(info), finalizer(finalizer) {}
-    i::Address* location;
-    void* info;
-    void (*finalizer)(void*);
-  };
-
   RefImpl() {}
 
-  static void v8_finalizer(const v8::WeakCallbackInfo<void>& info) {
-    HostData* data = reinterpret_cast<HostData*>(info.GetParameter());
-    i::GlobalHandles::Destroy(data->location);
-    if (data->finalizer) (*data->finalizer)(data->info);
-    delete data;
-  }
-
   i::Address* location() const {
     return reinterpret_cast<i::Address*>(val_.address());
   }
 
   i::Handle<i::JSReceiver> val_;
-  HostData* host_data_ = nullptr;
 };
 
 template <>
@@ -773,7 +781,6 @@ struct implement<Ref> {
 };
 
 Ref::~Ref() {
-  impl(this)->Reset();
   delete impl(this);
 }
 
@@ -1197,8 +1204,7 @@ struct FuncData {
     if (finalizer) (*finalizer)(env);
   }
 
-  static i::Address v8_callback(void* data, i::Address argv);
+  static i::Address v8_callback(i::Address host_data_foreign, i::Address argv);
-  static void finalize_func_data(void* data);
 };
 
 namespace {
@@ -1270,11 +1276,12 @@ auto make_func(Store* store_abs, FuncData* data) -> own<Func> {
   auto store = impl(store_abs);
   i::Isolate* isolate = store->i_isolate();
   i::HandleScope handle_scope(isolate);
+  i::Handle<i::Managed<FuncData>> embedder_data =
+      i::Managed<FuncData>::FromRawPtr(isolate, sizeof(FuncData), data);
   i::Handle<i::WasmCapiFunction> function = i::WasmCapiFunction::New(
-      isolate, reinterpret_cast<i::Address>(&FuncData::v8_callback), data,
+      isolate, reinterpret_cast<i::Address>(&FuncData::v8_callback),
-      SignatureHelper::Serialize(isolate, data->type.get()));
+      embedder_data, SignatureHelper::Serialize(isolate, data->type.get()));
   auto func = implement<Func>::type::make(store, function);
-  func->set_host_info(data, &FuncData::finalize_func_data);
   return func;
 }
 
@@ -1435,7 +1442,7 @@ void PopArgs(i::wasm::FunctionSig* sig, Val results[],
 
 own<Trap> CallWasmCapiFunction(i::WasmCapiFunctionData data, const Val args[],
                                Val results[]) {
-  FuncData* func_data = reinterpret_cast<FuncData*>(data.embedder_data());
+  FuncData* func_data = i::Managed<FuncData>::cast(data.embedder_data()).raw();
   if (func_data->kind == FuncData::kCallback) {
     return (func_data->callback)(args, results);
   }
@@ -1530,8 +1537,10 @@ auto Func::call(const Val args[], Val results[]) const -> own<Trap> {
   return nullptr;
 }
 
-i::Address FuncData::v8_callback(void* data, i::Address argv) {
+i::Address FuncData::v8_callback(i::Address host_data_foreign,
-  FuncData* self = reinterpret_cast<FuncData*>(data);
+                                 i::Address argv) {
+  FuncData* self =
+      i::Managed<FuncData>::cast(i::Object(host_data_foreign))->raw();
   StoreImpl* store = impl(self->store);
   i::Isolate* isolate = store->i_isolate();
   i::HandleScope scope(isolate);
@@ -1619,10 +1628,6 @@ i::Address FuncData::v8_callback(void* data, i::Address argv) {
   return i::kNullAddress;
 }
 
-void FuncData::finalize_func_data(void* data) {
-  delete reinterpret_cast<FuncData*>(data);
-}
-
 // Global Instances
 
 template <>
@@ -2251,7 +2256,7 @@ extern "C++" inline auto hide_mutability(wasm::Mutability mutability)
   return static_cast<wasm_mutability_t>(mutability);
 }
 
-extern "C++" inline auto reveal_mutability(wasm_mutability_enum mutability)
+extern "C++" inline auto reveal_mutability(wasm_mutability_t mutability)
     -> wasm::Mutability {
   return static_cast<wasm::Mutability>(mutability);
 }
@@ -2278,7 +2283,7 @@ extern "C++" inline auto hide_externkind(wasm::ExternKind kind)
   return static_cast<wasm_externkind_t>(kind);
 }
 
-extern "C++" inline auto reveal_externkind(wasm_externkind_enum kind)
+extern "C++" inline auto reveal_externkind(wasm_externkind_t kind)
     -> wasm::ExternKind {
   return static_cast<wasm::ExternKind>(kind);
 }
@@ -2330,8 +2335,7 @@ WASM_DEFINE_TYPE(globaltype, wasm::GlobalType)
 wasm_globaltype_t* wasm_globaltype_new(wasm_valtype_t* content,
                                        wasm_mutability_t mutability) {
   return release_globaltype(wasm::GlobalType::make(
-      adopt_valtype(content),
+      adopt_valtype(content), reveal_mutability(mutability)));
-      reveal_mutability(static_cast<wasm_mutability_enum>(mutability))));
 }
 
 const wasm_valtype_t* wasm_globaltype_content(const wasm_globaltype_t* gt) {

src/wasm/c-api.h

@@ -7,8 +7,17 @@
 
 #include "include/v8.h"
 #include "src/common/globals.h"
+#include "src/handles/handles.h"
 #include "third_party/wasm-api/wasm.hh"
 
+namespace v8 {
+namespace internal {
+
+class JSWeakMap;
+
+}  // namespace internal
+}  // namespace v8
+
 namespace wasm {
 
 class StoreImpl {
@@ -27,6 +36,10 @@ class StoreImpl {
         reinterpret_cast<v8::Isolate*>(isolate)->GetData(0));
   }
 
+  void SetHostInfo(i::Handle<i::Object> object, void* info,
+                   void (*finalizer)(void*));
+  void* GetHostInfo(i::Handle<i::Object> key);
+
  private:
   friend own<Store> Store::make(Engine*);
 
@@ -35,6 +48,7 @@ class StoreImpl {
   v8::Isolate::CreateParams create_params_;
   v8::Isolate* isolate_ = nullptr;
   v8::Eternal<v8::Context> context_;
+  i::Handle<i::JSWeakMap> host_info_map_;
 };
 
 }  // namespace wasm

src/wasm/wasm-objects-inl.h

@@ -357,8 +357,7 @@ OBJECT_CONSTRUCTORS_IMPL(WasmCapiFunctionData, Struct)
 CAST_ACCESSOR(WasmCapiFunctionData)
 PRIMITIVE_ACCESSORS(WasmCapiFunctionData, call_target, Address,
                     kCallTargetOffset)
-PRIMITIVE_ACCESSORS(WasmCapiFunctionData, embedder_data, void*,
+ACCESSORS(WasmCapiFunctionData, embedder_data, Foreign, kEmbedderDataOffset)
-                    kEmbedderDataOffset)
 ACCESSORS(WasmCapiFunctionData, wrapper_code, Code, kWrapperCodeOffset)
 ACCESSORS(WasmCapiFunctionData, serialized_signature, PodArray<wasm::ValueType>,
           kSerializedSignatureOffset)

src/wasm/wasm-objects.cc

@@ -2162,13 +2162,13 @@ bool WasmCapiFunction::IsWasmCapiFunction(Object object) {
 }
 
 Handle<WasmCapiFunction> WasmCapiFunction::New(
-    Isolate* isolate, Address call_target, void* embedder_data,
+    Isolate* isolate, Address call_target, Handle<Foreign> embedder_data,
     Handle<PodArray<wasm::ValueType>> serialized_signature) {
   Handle<WasmCapiFunctionData> fun_data =
       Handle<WasmCapiFunctionData>::cast(isolate->factory()->NewStruct(
           WASM_CAPI_FUNCTION_DATA_TYPE, AllocationType::kOld));
   fun_data->set_call_target(call_target);
-  fun_data->set_embedder_data(embedder_data);
+  fun_data->set_embedder_data(*embedder_data);
   fun_data->set_serialized_signature(*serialized_signature);
   // TODO(jkummerow): Install a JavaScript wrapper. For now, calling
   // these functions directly is unsupported; they can only be called

src/wasm/wasm-objects.h

@@ -707,7 +707,7 @@ class WasmCapiFunction : public JSFunction {
   static bool IsWasmCapiFunction(Object object);
 
   static Handle<WasmCapiFunction> New(
-      Isolate* isolate, Address call_target, void* embedder_data,
+      Isolate* isolate, Address call_target, Handle<Foreign> embedder_data,
       Handle<PodArray<wasm::ValueType>> serialized_signature);
 
   Address GetHostCallTarget() const;
@@ -764,7 +764,7 @@ class WasmIndirectFunctionTable : public Struct {
 class WasmCapiFunctionData : public Struct {
  public:
   DECL_PRIMITIVE_ACCESSORS(call_target, Address)
-  DECL_PRIMITIVE_ACCESSORS(embedder_data, void*)
+  DECL_ACCESSORS(embedder_data, Foreign)
   DECL_ACCESSORS(wrapper_code, Code)
   DECL_ACCESSORS(serialized_signature, PodArray<wasm::ValueType>)
 
@@ -776,7 +776,7 @@ class WasmCapiFunctionData : public Struct {
   DEFINE_FIELD_OFFSET_CONSTANTS(HeapObject::kHeaderSize,
                                 TORQUE_GENERATED_WASM_CAPI_FUNCTION_DATA_FIELDS)
 
-  STATIC_ASSERT(kStartOfStrongFieldsOffset == kWrapperCodeOffset);
+  STATIC_ASSERT(kStartOfStrongFieldsOffset == kEmbedderDataOffset);
   using BodyDescriptor = FlexibleBodyDescriptor<kStartOfStrongFieldsOffset>;
 
   OBJECT_CONSTRUCTORS(WasmCapiFunctionData, Struct);

test/wasm-api-tests/finalize.cc

@@ -15,6 +15,8 @@ int g_functions_finalized = 0;
 int g_foreigns_finalized = 0;
 int g_modules_finalized = 0;
 
+const int kModuleMagic = 42;
+
 void FinalizeInstance(void* data) {
   int iteration = static_cast<int>(reinterpret_cast<intptr_t>(data));
   g_instances_finalized += iteration;
@@ -34,6 +36,31 @@ void FinalizeModule(void* data) {
   g_modules_finalized += static_cast<int>(reinterpret_cast<intptr_t>(data));
 }
 
+void RunInStore(Store* store, ZoneBuffer* wire_bytes, int iterations) {
+  size_t size = wire_bytes->end() - wire_bytes->begin();
+  vec<byte_t> binary = vec<byte_t>::make(
+      size, reinterpret_cast<byte_t*>(const_cast<byte*>(wire_bytes->begin())));
+  own<Module> module = Module::make(store, binary);
+  module->set_host_info(reinterpret_cast<void*>(kModuleMagic), &FinalizeModule);
+  for (int iteration = 0; iteration < iterations; iteration++) {
+    void* finalizer_data = reinterpret_cast<void*>(iteration);
+    own<Instance> instance = Instance::make(store, module.get(), nullptr);
+    EXPECT_NE(nullptr, instance.get());
+    instance->set_host_info(finalizer_data, &FinalizeInstance);
+
+    own<Func> func = instance->exports()[0]->func()->copy();
+    ASSERT_NE(func, nullptr);
+    func->set_host_info(finalizer_data, &FinalizeFunction);
+    Val args[] = {Val::i32(iteration)};
+    Val results[1];
+    func->call(args, results);
+    EXPECT_EQ(iteration, results[0].i32());
+
+    own<Foreign> foreign = Foreign::make(store);
+    foreign->set_host_info(finalizer_data, &FinalizeForeign);
+  }
+}
+
 }  // namespace
 
 TEST_F(WasmCapiTest, InstanceFinalization) {
@@ -45,31 +72,114 @@ TEST_F(WasmCapiTest, InstanceFinalization) {
   g_functions_finalized = 0;
   g_foreigns_finalized = 0;
   g_modules_finalized = 0;
-  module()->set_host_info(reinterpret_cast<void*>(42), &FinalizeModule);
+  module()->set_host_info(reinterpret_cast<void*>(kModuleMagic),
+                          &FinalizeModule);
   static const int kIterations = 10;
-  for (int iteration = 0; iteration < kIterations; iteration++) {
+  RunInStore(store(), wire_bytes(), kIterations);
-    void* finalizer_data = reinterpret_cast<void*>(iteration);
+  {
-    own<Instance> instance = Instance::make(store(), module(), nullptr);
+    own<Store> store2 = Store::make(engine());
-    EXPECT_NE(nullptr, instance.get());
+    RunInStore(store2.get(), wire_bytes(), kIterations);
-    instance->set_host_info(finalizer_data, &FinalizeInstance);
-
-    own<Func> func = instance->exports()[0]->func()->copy();
-    ASSERT_NE(func, nullptr);
-    func->set_host_info(finalizer_data, &FinalizeFunction);
-
-    own<Foreign> foreign = Foreign::make(store());
-    foreign->set_host_info(finalizer_data, &FinalizeForeign);
   }
+  RunInStore(store(), wire_bytes(), kIterations);
   Shutdown();
   // Verify that (1) all finalizers were called, and (2) they passed the
   // correct host data: the loop above sets {i} as data, and the finalizer
-  // callbacks add them all up, so the expected value is
+  // callbacks add them all up, so the expected value after three rounds is
-  // sum([0, 1, ..., kIterations - 1]), which per Gauss's formula is:
+  // 3 * sum([0, 1, ..., kIterations - 1]), which per Gauss's formula is:
-  static const int kExpected = (kIterations * (kIterations - 1)) / 2;
+  static const int kExpected = 3 * ((kIterations * (kIterations - 1)) / 2);
   EXPECT_EQ(g_instances_finalized, kExpected);
+  // There are two functions per iteration.
   EXPECT_EQ(g_functions_finalized, kExpected);
   EXPECT_EQ(g_foreigns_finalized, kExpected);
-  EXPECT_EQ(g_modules_finalized, 42);
+  EXPECT_EQ(g_modules_finalized, 4 * kModuleMagic);
+}
+
+namespace {
+
+own<Trap> CapiFunction(void* env, const Val args[], Val results[]) {
+  int offset = static_cast<int>(reinterpret_cast<intptr_t>(env));
+  results[0] = Val::i32(offset + args[0].i32());
+  return nullptr;
+}
+
+int g_host_data_finalized = 0;
+int g_capi_function_finalized = 0;
+
+void FinalizeCapiFunction(void* data) {
+  int value = static_cast<int>(reinterpret_cast<intptr_t>(data));
+  g_capi_function_finalized += value;
+}
+
+void FinalizeHostData(void* data) {
+  g_host_data_finalized += static_cast<int>(reinterpret_cast<intptr_t>(data));
+}
+
+}  // namespace
+
+TEST_F(WasmCapiTest, CapiFunctionLifetimes) {
+  uint32_t func_index = builder()->AddImport(CStrVector("f"), wasm_i_i_sig());
+  builder()->ExportImportedFunction(CStrVector("f"), func_index);
+  Compile();
+  own<Instance> instance;
+  void* kHostData = reinterpret_cast<void*>(1234);
+  int base_summand = 1000;
+  {
+    // Test that the own<> pointers for Func and FuncType can go out of scope
+    // without affecting the ability of the Func to be called later.
+    own<FuncType> capi_func_type =
+        FuncType::make(ownvec<ValType>::make(ValType::make(::wasm::I32)),
+                       ownvec<ValType>::make(ValType::make(::wasm::I32)));
+    own<Func> capi_func =
+        Func::make(store(), capi_func_type.get(), &CapiFunction,
+                   reinterpret_cast<void*>(base_summand));
+    Extern* imports[] = {capi_func.get()};
+    instance = Instance::make(store(), module(), imports);
+    // TODO(jkummerow): It may or may not be desirable to be able to set
+    // host data even here and have it survive the import/export dance.
+    // We are awaiting resolution of the discussion at:
+    // https://github.com/WebAssembly/wasm-c-api/issues/100
+  }
+  {
+    ownvec<Extern> exports = instance->exports();
+    Func* exported_func = exports[0]->func();
+    constexpr int kArg = 123;
+    Val args[] = {Val::i32(kArg)};
+    Val results[1];
+    exported_func->call(args, results);
+    EXPECT_EQ(base_summand + kArg, results[0].i32());
+    // Host data should survive destruction of the own<> pointer.
+    exported_func->set_host_info(kHostData);
+  }
+  {
+    ownvec<Extern> exports = instance->exports();
+    Func* exported_func = exports[0]->func();
+    EXPECT_EQ(kHostData, exported_func->get_host_info());
+  }
+  // Test that a Func can have its own internal metadata, an {env}, and
+  // separate {host info}, without any of that interfering with each other.
+  g_host_data_finalized = 0;
+  g_capi_function_finalized = 0;
+  base_summand = 23;
+  constexpr int kFinalizerData = 345;
+  {
+    own<FuncType> capi_func_type =
+        FuncType::make(ownvec<ValType>::make(ValType::make(::wasm::I32)),
+                       ownvec<ValType>::make(ValType::make(::wasm::I32)));
+    own<Func> capi_func = Func::make(
+        store(), capi_func_type.get(), &CapiFunction,
+        reinterpret_cast<void*>(base_summand), &FinalizeCapiFunction);
+    capi_func->set_host_info(reinterpret_cast<void*>(kFinalizerData),
+                             &FinalizeHostData);
+    constexpr int kArg = 19;
+    Val args[] = {Val::i32(kArg)};
+    Val results[1];
+    capi_func->call(args, results);
+    EXPECT_EQ(base_summand + kArg, results[0].i32());
+  }
+  instance.reset();
+  Shutdown();
+  EXPECT_EQ(base_summand, g_capi_function_finalized);
+  EXPECT_EQ(kFinalizerData, g_host_data_finalized);
 }
 
 }  // namespace wasm

test/wasm-api-tests/wasm-api-test.h

@@ -115,6 +115,7 @@ class WasmCapiTest : public ::testing::Test {
   }
 
   void Shutdown() {
+    exports_.reset();
     instance_.reset();
     module_.reset();
     store_.reset();

third_party/wasm-api/README.v8

@@ -2,8 +2,8 @@ Name: Wasm C/C++ API
 Short Name: wasm-c-api
 URL: https://github.com/WebAssembly/wasm-c-api/
 Version: 0
-Revision: 5c742b048f7766a0c00be3a7af23fb71ba816026
+Revision: 6db391ee7121a0695602945d11001ea3e00b0afb
-Date: 2019-03-18
+Date: 2019-08-08
 License: Apache 2.0
 License File: LICENSE
 Security Critical: yes

third_party/wasm-api/example/finalize.c

@@ -9,23 +9,21 @@
 
 const int iterations = 100000;
 
+int live_count = 0;
+
 void finalize(void* data) {
   int i = (int)data;
   if (i % (iterations / 10) == 0) printf("Finalizing #%d...\n", i);
+  --live_count;
 }
 
-int main(int argc, const char* argv[]) {
+void run_in_store(wasm_store_t* store) {
-  // Initialize.
-  printf("Initializing...\n");
-  wasm_engine_t* engine = wasm_engine_new();
-  wasm_store_t* store = wasm_store_new(engine);
-
   // Load binary.
   printf("Loading binary...\n");
   FILE* file = fopen("finalize.wasm", "r");
   if (!file) {
     printf("> Error loading module!\n");
-    return 1;
+    exit(1);
   }
   fseek(file, 0L, SEEK_END);
   size_t file_size = ftell(file);
@@ -34,7 +32,7 @@ int main(int argc, const char* argv[]) {
   wasm_byte_vec_new_uninitialized(&binary, file_size);
   if (fread(binary.data, file_size, 1, file) != 1) {
     printf("> Error loading module!\n");
-    return 1;
+    exit(1);
   }
   fclose(file);
 
@@ -43,7 +41,7 @@ int main(int argc, const char* argv[]) {
   own wasm_module_t* module = wasm_module_new(store, &binary);
   if (!module) {
     printf("> Error compiling module!\n");
-    return 1;
+    exit(1);
   }
 
   wasm_byte_vec_delete(&binary);
@@ -56,18 +54,53 @@ int main(int argc, const char* argv[]) {
       wasm_instance_new(store, module, NULL, NULL);
     if (!instance) {
       printf("> Error instantiating module %d!\n", i);
-      return 1;
+      exit(1);
     }
     void* data = (void*)(intptr_t)i;
     wasm_instance_set_host_info_with_finalizer(instance, data, &finalize);
     wasm_instance_delete(instance);
+    ++live_count;
   }
 
   wasm_module_delete(module);
+}
+
+int main(int argc, const char* argv[]) {
+  // Initialize.
+  printf("Initializing...\n");
+  wasm_engine_t* engine = wasm_engine_new();
+
+  printf("Live count %d\n", live_count);
+  printf("Creating store 1...\n");
+  wasm_store_t* store1 = wasm_store_new(engine);
+
+  printf("Running in store 1...\n");
+  run_in_store(store1);
+  printf("Live count %d\n", live_count);
+
+  printf("Creating store 2...\n");
+  wasm_store_t* store2 = wasm_store_new(engine);
+
+  printf("Running in store 2...\n");
+  run_in_store(store2);
+  printf("Live count %d\n", live_count);
+
+  printf("Deleting store 2...\n");
+  wasm_store_delete(store2);
+  printf("Live count %d\n", live_count);
+
+  printf("Running in store 1...\n");
+  run_in_store(store1);
+  printf("Live count %d\n", live_count);
+
+  printf("Deleting store 1...\n");
+  wasm_store_delete(store1);
+  printf("Live count %d\n", live_count);
+
+  assert(live_count == 0);
 
   // Shut down.
   printf("Shutting down...\n");
-  wasm_store_delete(store);
   wasm_engine_delete(engine);
 
   // All done.

third_party/wasm-api/example/finalize.cc

@@ -9,20 +9,17 @@
 
 const int iterations = 100000;
 
+int live_count = 0;
+
 void finalize(void* data) {
   intptr_t i = reinterpret_cast<intptr_t>(data);
   if (i % (iterations / 10) == 0) {
     std::cout << "Finalizing #" << i << "..." << std::endl;
   }
+  --live_count;
 }
 
-void run() {
+void run_in_store(wasm::Store* store) {
-  // Initialize.
-  std::cout << "Initializing..." << std::endl;
-  auto engine = wasm::Engine::make();
-  auto store_ = wasm::Store::make(engine.get());
-  auto store = store_.get();
-
   // Load binary.
   std::cout << "Loading binary..." << std::endl;
   std::ifstream file("finalize.wasm");
@@ -55,6 +52,7 @@ void run() {
       exit(1);
     }
     instance->set_host_info(reinterpret_cast<void*>(i), &finalize);
+    ++live_count;
   }
 
   // Shut down.
@@ -62,8 +60,43 @@ void run() {
 }
 
 
+void run() {
+  // Initialize.
+  std::cout << "Initializing..." << std::endl;
+  auto engine = wasm::Engine::make();
+
+  std::cout << "Live count " << live_count << std::endl;
+  std::cout << "Creating store 1..." << std::endl;
+  auto store1 = wasm::Store::make(engine.get());
+
+  std::cout << "Running in store 1..." << std::endl;
+  run_in_store(store1.get());
+  std::cout << "Live count " << live_count << std::endl;
+
+  {
+    std::cout << "Creating store 2..." << std::endl;
+    auto store2 = wasm::Store::make(engine.get());
+
+    std::cout << "Running in store 2..." << std::endl;
+    run_in_store(store2.get());
+    std::cout << "Live count " << live_count << std::endl;
+
+    std::cout << "Deleting store 2..." << std::endl;
+    std::cout << "Live count " << live_count << std::endl;
+  }
+
+  std::cout << "Running in store 1..." << std::endl;
+  run_in_store(store1.get());
+  std::cout << "Live count " << live_count << std::endl;
+
+  std::cout << "Deleting store 1..." << std::endl;
+}
+
+
 int main(int argc, const char* argv[]) {
   run();
+  std::cout << "Live count " << live_count << std::endl;
+  assert(live_count == 0);
   std::cout << "Done." << std::endl;
   return 0;
 }