reference-summarizer.h

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// Copyright 2022 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.
 
#ifndef V8_HEAP_REFERENCE_SUMMARIZER_H_
#define V8_HEAP_REFERENCE_SUMMARIZER_H_
 
#include <unordered_set>
 
#include "src/objects/heap-object.h"
 
namespace v8 {
namespace internal {
 
class Heap;
 
class ReferenceSummary {
 public:
  ReferenceSummary() = default;
  ReferenceSummary(ReferenceSummary&& other) V8_NOEXCEPT
      : strong_references_(std::move(other.strong_references_)),
        weak_references_(std::move(other.weak_references_)) {}
 
  // Produces a set of objects referred to by the object. This function uses a
  // realistic marking visitor, so its results are likely to match real GC
  // behavior. Intended only for verification.
  static ReferenceSummary SummarizeReferencesFrom(Heap* heap,
                                                  Tagged<HeapObject> obj);
 
  using UnorderedHeapObjectSet =
      std::unordered_set<Tagged<HeapObject>, Object::Hasher,
                         Object::KeyEqualSafe>;
 
  // All objects which the chosen object has strong pointers to.
  UnorderedHeapObjectSet& strong_references() { return strong_references_; }
 
  // All objects which the chosen object has weak pointers to. The values in
  // ephemeron hash tables are also included here, even though they aren't
  // normal weak pointers.
  UnorderedHeapObjectSet& weak_references() { return weak_references_; }
 
  void Clear() {
    strong_references_.clear();
    weak_references_.clear();
  }
 
 private:
  UnorderedHeapObjectSet strong_references_;
  UnorderedHeapObjectSet weak_references_;
  DISALLOW_GARBAGE_COLLECTION(no_gc)
};
 
}  // namespace internal
}  // namespace v8
 
#endif  // V8_HEAP_REFERENCE_SUMMARIZER_H_