base-space.h

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// Copyright 2020 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_BASE_SPACE_H_
#define V8_HEAP_BASE_SPACE_H_
 
#include <atomic>
 
#include "src/base/macros.h"
#include "src/common/globals.h"
#include "src/heap/heap-verifier.h"
#include "src/utils/allocation.h"
 
namespace v8 {
namespace internal {
 
class Heap;
 
// ----------------------------------------------------------------------------
// BaseSpace is the abstract superclass for all allocation spaces.
class V8_EXPORT_PRIVATE BaseSpace : public Malloced {
 public:
  BaseSpace(const BaseSpace&) = delete;
  BaseSpace& operator=(const BaseSpace&) = delete;
 
  Heap* heap() const {
    DCHECK_NOT_NULL(heap_);
    return heap_;
  }
 
  AllocationSpace identity() const { return id_; }
 
  // Return the total amount committed memory for this space, i.e., allocatable
  // memory and page headers.
  virtual size_t CommittedMemory() const { return committed_; }
 
  virtual size_t MaximumCommittedMemory() const { return max_committed_; }
 
  // Approximate amount of physical memory committed for this space.
  virtual size_t CommittedPhysicalMemory() const = 0;
 
  // Returns allocated size.
  virtual size_t Size() const = 0;
 
#ifdef VERIFY_HEAP
  virtual void Verify(Isolate* isolate,
                      SpaceVerificationVisitor* visitor) const = 0;
#endif  // VERIFY_HEAP
 
 protected:
  BaseSpace(Heap* heap, AllocationSpace id) : heap_(heap), id_(id) {}
 
  virtual ~BaseSpace() = default;
 
  void AccountCommitted(size_t bytes) {
    DCHECK_GE(committed_ + bytes, committed_);
    committed_ += bytes;
    if (committed_ > max_committed_) {
      max_committed_ = committed_;
    }
  }
 
  void AccountUncommitted(size_t bytes) {
    DCHECK_GE(committed_, committed_ - bytes);
    committed_ -= bytes;
  }
 
 protected:
  Heap* heap_;
  AllocationSpace id_;
 
  // Keeps track of committed memory in a space.
  std::atomic<size_t> committed_{0};
  size_t max_committed_ = 0;
};
 
}  // namespace internal
}  // namespace v8
 
#endif  // V8_HEAP_BASE_SPACE_H_