[api] Prototype WeakRef implementation

src/heap/object-stats.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/heap/object-stats.h"
 
 #include "src/assembler-inl.h"
 #include "src/compilation-cache.h"
 #include "src/counters.h"
 #include "src/heap/heap-inl.h"
@@ skipping 411 matching lines @@
 void ObjectStatsCollector::RecordJSWeakCollectionDetails(
     JSWeakCollection* obj) {
   if (obj->table()->IsHashTable()) {
     ObjectHashTable* table = ObjectHashTable::cast(obj->table());
     int used = table->NumberOfElements() * ObjectHashTable::kEntrySize;
     size_t overhead = table->Size() - used;
     RecordFixedArrayHelper(obj, table, JS_WEAK_COLLECTION_SUB_TYPE, overhead);
   }
 }
 
+void ObjectStatsCollector::RecordJSWeakRefDetails(
+    JSWeakRef* obj) {
+  if (obj->executor() != nullptr) {
+    RecordJSFunctionDetails(obj->executor());
+  }
+  if (obj->holdings() != nullptr && obj->holdings()->IsObject()) {
+    // RecordObjectStats(obj->holdings());
+  }
+  WeakCell* cell = obj->target();
+  if (cell->cleared() != true && cell->value()->IsObject()) {
+    RecordJSObjectDetails(static_cast<JSObject*>(cell->value()));
+  }
+}
+
 void ObjectStatsCollector::RecordJSCollectionDetails(JSObject* obj) {
   // The JS versions use a different HashTable implementation that cannot use
   // the regular helper. Since overall impact is usually small just record
   // without overhead.
   if (obj->IsJSMap()) {
     RecordFixedArrayHelper(nullptr, FixedArray::cast(JSMap::cast(obj)->table()),
                            JS_COLLECTION_SUB_TYPE, 0);
   }
   if (obj->IsJSSet()) {
     RecordFixedArrayHelper(nullptr, FixedArray::cast(JSSet::cast(obj)->table()),
@@ skipping 138 matching lines @@
                           SLOW_TEMPLATE_INSTANTIATIONS_CACHE_SUB_TYPE);
     FixedArray* fast_cache = native_ctx->fast_template_instantiations_cache();
     stats_->RecordFixedArraySubTypeStats(
         fast_cache, FAST_TEMPLATE_INSTANTIATIONS_CACHE_SUB_TYPE,
         fast_cache->Size(), 0);
   }
 }
 
 }  // namespace internal
 }  // namespace v8