[vm, api] Add Dart_UpdateExternalSize to the embedding API.

Allows an embedder (or native extension) to inform the VM when external memory is released before a weak handle is finalized.

Bug: https://github.com/dart-lang/sdk/issues/42078
Change-Id: Ifffd0c160e5305bc6e6752207a2315139f245e2f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/149245
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>

runtime/include/dart_api.h

@@ -489,6 +489,9 @@ Dart_NewWeakPersistentHandle(Dart_Handle object,
 DART_EXPORT void Dart_DeleteWeakPersistentHandle(
     Dart_WeakPersistentHandle object);
 
+DART_EXPORT void Dart_UpdateExternalSize(Dart_WeakPersistentHandle object,
+                                         intptr_t external_allocation_size);
+
 /*
  * ==========================
  * Initialization and Globals

runtime/vm/benchmark_test.cc

@@ -280,9 +280,8 @@ BENCHMARK(UseDartApi) {
       "  }\n"
       "}\n";
 
-  Dart_Handle lib = TestCase::LoadTestScript(
-      kScriptChars, reinterpret_cast<Dart_NativeEntryResolver>(bm_uda_lookup),
-      RESOLVED_USER_TEST_URI, false);
+  Dart_Handle lib = TestCase::LoadTestScript(kScriptChars, bm_uda_lookup,
+                                             RESOLVED_USER_TEST_URI, false);
   Dart_Handle result = Dart_FinalizeLoading(false);
   EXPECT_VALID(result);
 
@@ -381,9 +380,7 @@ BENCHMARK(KernelServiceCompileAll) {
   EXPECT_VALID(result);
   Dart_Handle service_lib = Dart_LookupLibrary(NewString("dart:vmservice_io"));
   ASSERT(!Dart_IsError(service_lib));
-  Dart_SetNativeResolver(
-      service_lib, reinterpret_cast<Dart_NativeEntryResolver>(NativeResolver),
-      NULL);
+  Dart_SetNativeResolver(service_lib, NativeResolver, NULL);
   result = Dart_FinalizeLoading(false);
   EXPECT_VALID(result);
 
@@ -491,9 +488,8 @@ BENCHMARK(FrameLookup) {
       "    return obj.method1(1);"
       "  }"
       "}";
-  Dart_Handle lib = TestCase::LoadTestScript(
-      kScriptChars,
-      reinterpret_cast<Dart_NativeEntryResolver>(StackFrameNativeResolver));
+  Dart_Handle lib =
+      TestCase::LoadTestScript(kScriptChars, StackFrameNativeResolver);
   Dart_Handle cls = Dart_GetClass(lib, NewString("StackFrameTest"));
   Dart_Handle result = Dart_Invoke(cls, NewString("testMain"), 0, NULL);
   EXPECT_VALID(result);

runtime/vm/dart_api_impl.cc

@@ -1000,6 +1000,18 @@ Dart_NewWeakPersistentHandle(Dart_Handle object,
                                    external_allocation_size, callback);
 }
 
+DART_EXPORT void Dart_UpdateExternalSize(Dart_WeakPersistentHandle object,
+                                         intptr_t external_size) {
+  IsolateGroup* isolate_group = IsolateGroup::Current();
+  CHECK_ISOLATE_GROUP(isolate_group);
+  NoSafepointScope no_safepoint_scope;
+  ApiState* state = isolate_group->api_state();
+  ASSERT(state != NULL);
+  ASSERT(state->IsActiveWeakPersistentHandle(object));
+  auto weak_ref = FinalizablePersistentHandle::Cast(object);
+  weak_ref->UpdateExternalSize(external_size, isolate_group);
+}
+
 DART_EXPORT void Dart_DeletePersistentHandle(Dart_PersistentHandle object) {
   IsolateGroup* isolate_group = IsolateGroup::Current();
   CHECK_ISOLATE_GROUP(isolate_group);
@@ -1023,7 +1035,7 @@ DART_EXPORT void Dart_DeleteWeakPersistentHandle(
   ASSERT(state != NULL);
   ASSERT(state->IsActiveWeakPersistentHandle(object));
   auto weak_ref = FinalizablePersistentHandle::Cast(object);
-  weak_ref->EnsureFreeExternal(isolate_group);
+  weak_ref->EnsureFreedExternal(isolate_group);
   state->FreeWeakPersistentHandle(weak_ref);
 }
 

runtime/vm/dart_api_impl_test.cc

@@ -3512,6 +3512,125 @@ TEST_CASE(DartAPI_WeakPersistentHandleExternalAllocationSizeOddReferents) {
   }
 }
 
+#define EXAMPLE_RESOURCE_NATIVE_LIST(V)                                        \
+  V(ExampleResource_Allocate, 1)                                               \
+  V(ExampleResource_Use, 1)                                                    \
+  V(ExampleResource_Dispose, 1)
+
+EXAMPLE_RESOURCE_NATIVE_LIST(DECLARE_FUNCTION);
+
+static struct NativeEntries {
+  const char* name_;
+  Dart_NativeFunction function_;
+  int argument_count_;
+} ExampleResourceEntries[] = {EXAMPLE_RESOURCE_NATIVE_LIST(REGISTER_FUNCTION)};
+
+static Dart_NativeFunction ExampleResourceNativeResolver(
+    Dart_Handle name,
+    int argument_count,
+    bool* auto_setup_scope) {
+  const char* function_name = nullptr;
+  Dart_Handle result = Dart_StringToCString(name, &function_name);
+  ASSERT(!Dart_IsError(result));
+  ASSERT(function_name != nullptr);
+  ASSERT(auto_setup_scope != nullptr);
+  *auto_setup_scope = true;
+  int num_entries =
+      sizeof(ExampleResourceEntries) / sizeof(struct NativeEntries);
+  for (int i = 0; i < num_entries; i++) {
+    struct NativeEntries* entry = &(ExampleResourceEntries[i]);
+    if ((strcmp(function_name, entry->name_) == 0) &&
+        (entry->argument_count_ == argument_count)) {
+      return reinterpret_cast<Dart_NativeFunction>(entry->function_);
+    }
+  }
+  return nullptr;
+}
+
+struct ExampleResource {
+  Dart_WeakPersistentHandle self;
+  void* lots_of_memory;
+};
+
+void ExampleResourceFinalizer(void* isolate_peer,
+                              Dart_WeakPersistentHandle handle,
+                              void* peer) {
+  ExampleResource* resource = reinterpret_cast<ExampleResource*>(peer);
+  free(resource->lots_of_memory);
+  delete resource;
+}
+
+void FUNCTION_NAME(ExampleResource_Allocate)(Dart_NativeArguments native_args) {
+  Dart_Handle receiver = Dart_GetNativeArgument(native_args, 0);
+  intptr_t external_size = 10 * MB;
+  ExampleResource* resource = new ExampleResource();
+  resource->lots_of_memory = malloc(external_size);
+  resource->self = Dart_NewWeakPersistentHandle(
+      receiver, resource, external_size, ExampleResourceFinalizer);
+  EXPECT_VALID(Dart_SetNativeInstanceField(
+      receiver, 0, reinterpret_cast<intptr_t>(resource)));
+  // Some pretend resource initialization.
+  *reinterpret_cast<uint8_t*>(resource->lots_of_memory) = 123;
+}
+
+void FUNCTION_NAME(ExampleResource_Use)(Dart_NativeArguments native_args) {
+  Dart_Handle receiver = Dart_GetNativeArgument(native_args, 0);
+  intptr_t native_field = 0;
+  EXPECT_VALID(Dart_GetNativeInstanceField(receiver, 0, &native_field));
+  ExampleResource* resource = reinterpret_cast<ExampleResource*>(native_field);
+  if (resource->lots_of_memory == nullptr) {
+    Dart_ThrowException(Dart_NewStringFromCString(
+        "Attempt to use a disposed ExampleResource!"));
+    UNREACHABLE();
+  } else {
+    // Some pretend resource use.
+    EXPECT_EQ(123, *reinterpret_cast<uint8_t*>(resource->lots_of_memory));
+  }
+}
+
+void FUNCTION_NAME(ExampleResource_Dispose)(Dart_NativeArguments native_args) {
+  Dart_Handle receiver = Dart_GetNativeArgument(native_args, 0);
+  intptr_t native_field = 0;
+  EXPECT_VALID(Dart_GetNativeInstanceField(receiver, 0, &native_field));
+  ExampleResource* resource = reinterpret_cast<ExampleResource*>(native_field);
+  if (resource->lots_of_memory != nullptr) {
+    free(resource->lots_of_memory);
+    resource->lots_of_memory = nullptr;
+    Dart_UpdateExternalSize(resource->self, 0);
+  }
+}
+
+TEST_CASE(DartAPI_WeakPersistentHandleUpdateSize) {
+  const char* kScriptChars = R"(
+    import "dart:nativewrappers";
+    class ExampleResource extends NativeFieldWrapperClass1 {
+      ExampleResource() { _allocate(); }
+      void _allocate() native "ExampleResource_Allocate";
+      void use() native "ExampleResource_Use";
+      void dispose() native "ExampleResource_Dispose";
+    }
+    main() {
+      var res = new ExampleResource();
+      res.use();
+      res.dispose();
+      res.dispose();  // Idempotent
+      bool threw = false;
+      try {
+        res.use();
+      } catch (_) {
+        threw = true;
+      }
+      if (!threw) {
+        throw "Exception expected";
+      }
+    }
+  )";
+
+  Dart_Handle lib =
+      TestCase::LoadTestScript(kScriptChars, ExampleResourceNativeResolver);
+  EXPECT_VALID(Dart_Invoke(lib, NewString("main"), 0, NULL));
+}
+
 static Dart_WeakPersistentHandle weak1 = NULL;
 static Dart_WeakPersistentHandle weak2 = NULL;
 static Dart_WeakPersistentHandle weak3 = NULL;
@@ -5845,8 +5964,7 @@ TEST_CASE(DartAPI_ThrowException) {
   Dart_EnterScope();  // Start a Dart API scope for invoking API functions.
 
   // Load up a test script which extends the native wrapper class.
-  Dart_Handle lib = TestCase::LoadTestScript(
-      kScriptChars, reinterpret_cast<Dart_NativeEntryResolver>(native_lookup));
+  Dart_Handle lib = TestCase::LoadTestScript(kScriptChars, native_lookup);
 
   // Throwing an exception here should result in an error.
   result = Dart_ThrowException(NewString("This doesn't work"));
@@ -6032,9 +6150,7 @@ TEST_CASE(DartAPI_GetNativeArguments) {
       "                           obj2);"
       "}";
 
-  Dart_Handle lib = TestCase::LoadTestScript(
-      kScriptChars,
-      reinterpret_cast<Dart_NativeEntryResolver>(native_args_lookup));
+  Dart_Handle lib = TestCase::LoadTestScript(kScriptChars, native_args_lookup);
 
   const char* ascii_str = "string";
   intptr_t ascii_str_length = strlen(ascii_str);
@@ -6075,8 +6191,7 @@ TEST_CASE(DartAPI_GetNativeArgumentCount) {
       "  return obj.method1(77, 125);"
       "}";
 
-  Dart_Handle lib = TestCase::LoadTestScript(
-      kScriptChars, reinterpret_cast<Dart_NativeEntryResolver>(gnac_lookup));
+  Dart_Handle lib = TestCase::LoadTestScript(kScriptChars, gnac_lookup);
 
   Dart_Handle result = Dart_Invoke(lib, NewString("testMain"), 0, NULL);
   EXPECT_VALID(result);

runtime/vm/dart_api_state.h

@@ -219,29 +219,39 @@ class FinalizablePersistentHandle {
     if (SpaceForExternal() == Heap::kNew) {
       SetExternalNewSpaceBit();
     }
-    isolate_group->heap()->AllocateExternal(
-        raw()->GetClassIdMayBeSmi(), external_size(), SpaceForExternal());
+    isolate_group->heap()->AllocatedExternal(external_size(),
+                                             SpaceForExternal());
+  }
+  void UpdateExternalSize(intptr_t size, IsolateGroup* isolate_group) {
+    ASSERT(size >= 0);
+    intptr_t old_size = external_size();
+    set_external_size(size);
+    if (size > old_size) {
+      isolate_group->heap()->AllocatedExternal(size - old_size,
+                                               SpaceForExternal());
+    } else {
+      isolate_group->heap()->FreedExternal(old_size - size, SpaceForExternal());
+    }
   }
 
   // Called when the referent becomes unreachable.
   void UpdateUnreachable(IsolateGroup* isolate_group) {
-    EnsureFreeExternal(isolate_group);
+    EnsureFreedExternal(isolate_group);
     Finalize(isolate_group, this);
   }
 
   // Called when the referent has moved, potentially between generations.
   void UpdateRelocated(IsolateGroup* isolate_group) {
     if (IsSetNewSpaceBit() && (SpaceForExternal() == Heap::kOld)) {
-      isolate_group->heap()->PromoteExternal(raw()->GetClassIdMayBeSmi(),
-                                             external_size());
+      isolate_group->heap()->PromotedExternal(external_size());
       ClearExternalNewSpaceBit();
     }
   }
 
   // Idempotent. Called when the handle is explicitly deleted or the
   // referent becomes unreachable.
-  void EnsureFreeExternal(IsolateGroup* isolate_group) {
-    isolate_group->heap()->FreeExternal(external_size(), SpaceForExternal());
+  void EnsureFreedExternal(IsolateGroup* isolate_group) {
+    isolate_group->heap()->FreedExternal(external_size(), SpaceForExternal());
     set_external_size(0);
   }
 

runtime/vm/exceptions_test.cc

@@ -114,8 +114,7 @@ TEST_CASE(UnhandledExceptions) {
       "  UnhandledExceptions.equals(2, Second.method1(1));\n"
       "  UnhandledExceptions.equals(3, Second.method3(1));\n"
       "}";
-  Dart_Handle lib = TestCase::LoadTestScript(
-      kScriptChars, reinterpret_cast<Dart_NativeEntryResolver>(native_lookup));
+  Dart_Handle lib = TestCase::LoadTestScript(kScriptChars, native_lookup);
   EXPECT_VALID(Dart_Invoke(lib, NewString("testMain"), 0, NULL));
 }
 

runtime/vm/heap/heap.cc

@@ -158,11 +158,11 @@ uword Heap::AllocateOld(intptr_t size, OldPage::PageType type) {
   return 0;
 }
 
-void Heap::AllocateExternal(intptr_t cid, intptr_t size, Space space) {
+void Heap::AllocatedExternal(intptr_t size, Space space) {
   ASSERT(Thread::Current()->no_safepoint_scope_depth() == 0);
   if (space == kNew) {
     Isolate::Current()->AssertCurrentThreadIsMutator();
-    new_space_.AllocateExternal(cid, size);
+    new_space_.AllocatedExternal(size);
     if (new_space_.ExternalInWords() <= (4 * new_space_.CapacityInWords())) {
       return;
     }
@@ -173,7 +173,7 @@ void Heap::AllocateExternal(intptr_t cid, intptr_t size, Space space) {
     // space GC check.
   } else {
     ASSERT(space == kOld);
-    old_space_.AllocateExternal(cid, size);
+    old_space_.AllocatedExternal(size);
   }
 
   if (old_space_.NeedsGarbageCollection()) {
@@ -183,18 +183,18 @@ void Heap::AllocateExternal(intptr_t cid, intptr_t size, Space space) {
   }
 }
 
-void Heap::FreeExternal(intptr_t size, Space space) {
+void Heap::FreedExternal(intptr_t size, Space space) {
   if (space == kNew) {
-    new_space_.FreeExternal(size);
+    new_space_.FreedExternal(size);
   } else {
     ASSERT(space == kOld);
-    old_space_.FreeExternal(size);
+    old_space_.FreedExternal(size);
   }
 }
 
-void Heap::PromoteExternal(intptr_t cid, intptr_t size) {
-  new_space_.FreeExternal(size);
-  old_space_.PromoteExternal(cid, size);
+void Heap::PromotedExternal(intptr_t size) {
+  new_space_.FreedExternal(size);
+  old_space_.AllocatedExternal(size);
 }
 
 bool Heap::Contains(uword addr) const {

runtime/vm/heap/heap.h

@@ -95,10 +95,10 @@ class Heap {
   }
 
   // Track external data.
-  void AllocateExternal(intptr_t cid, intptr_t size, Space space);
-  void FreeExternal(intptr_t size, Space space);
+  void AllocatedExternal(intptr_t size, Space space);
+  void FreedExternal(intptr_t size, Space space);
   // Move external size from new to old space. Does not by itself trigger GC.
-  void PromoteExternal(intptr_t cid, intptr_t size);
+  void PromotedExternal(intptr_t size);
 
   // Heap contains the specified address.
   bool Contains(uword addr) const;

runtime/vm/heap/pages.cc

@@ -569,21 +569,6 @@ void PageSpace::ReleaseLock(FreeList* freelist) {
   freelist->mutex()->Unlock();
 }
 
-void PageSpace::AllocateExternal(intptr_t cid, intptr_t size) {
-  intptr_t size_in_words = size >> kWordSizeLog2;
-  usage_.external_in_words += size_in_words;
-}
-
-void PageSpace::PromoteExternal(intptr_t cid, intptr_t size) {
-  intptr_t size_in_words = size >> kWordSizeLog2;
-  usage_.external_in_words += size_in_words;
-}
-
-void PageSpace::FreeExternal(intptr_t size) {
-  intptr_t size_in_words = size >> kWordSizeLog2;
-  usage_.external_in_words -= size_in_words;
-}
-
 class BasePageIterator : ValueObject {
  public:
   explicit BasePageIterator(const PageSpace* space) : space_(space) {}

runtime/vm/heap/pages.h

@@ -409,9 +409,16 @@ class PageSpace {
     allocated_black_in_words_.fetch_add(size >> kWordSizeLog2);
   }
 
-  void AllocateExternal(intptr_t cid, intptr_t size);
-  void PromoteExternal(intptr_t cid, intptr_t size);
-  void FreeExternal(intptr_t size);
+  void AllocatedExternal(intptr_t size) {
+    ASSERT(size >= 0);
+    intptr_t size_in_words = size >> kWordSizeLog2;
+    usage_.external_in_words += size_in_words;
+  }
+  void FreedExternal(intptr_t size) {
+    ASSERT(size >= 0);
+    intptr_t size_in_words = size >> kWordSizeLog2;
+    usage_.external_in_words -= size_in_words;
+  }
 
   // Bulk data allocation.
   FreeList* DataFreeList(intptr_t i = 0) {

runtime/vm/heap/scavenger.cc

@@ -1545,17 +1545,6 @@ void Scavenger::PrintToJSONObject(JSONObject* object) const {
 }
 #endif  // !PRODUCT
 
-void Scavenger::AllocateExternal(intptr_t cid, intptr_t size) {
-  ASSERT(size >= 0);
-  external_size_ += size;
-}
-
-void Scavenger::FreeExternal(intptr_t size) {
-  ASSERT(size >= 0);
-  external_size_ -= size;
-  ASSERT(external_size_ >= 0);
-}
-
 void Scavenger::Evacuate() {
   // We need a safepoint here to prevent allocation right before or right after
   // the scavenge.

runtime/vm/heap/scavenger.h

@@ -314,8 +314,16 @@ class Scavenger {
   void PrintToJSONObject(JSONObject* object) const;
 #endif  // !PRODUCT
 
-  void AllocateExternal(intptr_t cid, intptr_t size);
-  void FreeExternal(intptr_t size);
+  void AllocatedExternal(intptr_t size) {
+    ASSERT(size >= 0);
+    external_size_ += size;
+    ASSERT(external_size_ >= 0);
+  }
+  void FreedExternal(intptr_t size) {
+    ASSERT(size >= 0);
+    external_size_ -= size;
+    ASSERT(external_size_ >= 0);
+  }
 
   void MakeNewSpaceIterable();
   int64_t FreeSpaceInWords(Isolate* isolate) const;

runtime/vm/raw_object_snapshot.cc

@@ -1711,7 +1711,7 @@ void TransferableTypedDataLayout::WriteTo(SnapshotWriter* writer,
       [](void* data, Dart_WeakPersistentHandle handle, void* peer) {
         TransferableTypedDataPeer* tpeer =
             reinterpret_cast<TransferableTypedDataPeer*>(peer);
-        tpeer->handle()->EnsureFreeExternal(IsolateGroup::Current());
+        tpeer->handle()->EnsureFreedExternal(IsolateGroup::Current());
         tpeer->ClearData();
       });
 }