chromium/v8/src/heap/page-metadata.h

// Copyright 2023 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_PAGE_METADATA_H_
#define V8_HEAP_PAGE_METADATA_H_

#include "src/heap/base-space.h"
#include "src/heap/free-list.h"
#include "src/heap/mutable-page-metadata.h"
#include "src/heap/spaces.h"

namespace v8 {
namespace internal {

class Heap;

// -----------------------------------------------------------------------------
// A page is a memory chunk of a size 256K. Large object pages may be larger.
//
// The only way to get a page pointer is by calling factory methods:
//   PageMetadata* p = PageMetadata::FromAddress(addr); or
//   PageMetadata* p = PageMetadata::FromAllocationAreaAddress(address);
class PageMetadata : public MutablePageMetadata { … };

// Validate our estimates on the header size.
static_assert …;
static_assert …;
static_assert …;

}  // namespace internal

namespace base {
// Define special hash function for page pointers, to be used with std data
// structures, e.g. std::unordered_set<PageMetadata*, base::hash<PageMetadata*>
template <>
struct hash<i::PageMetadata*> : hash<i::MemoryChunkMetadata*> { … };
template <>
struct hash<const i::PageMetadata*> : hash<const i::MemoryChunkMetadata*> { … };
}  // namespace base

}  // namespace v8

#endif  // V8_HEAP_PAGE_METADATA_H_