chromium/base/allocator/partition_allocator/src/partition_alloc/lightweight_quarantine.h

// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Lightweight Quarantine (LQ) provides a low-cost quarantine mechanism with
// following characteristics.
//
// - Built on PartitionAlloc: only supports allocations in a known root
// - As fast as PA: LQ just defers `Free()` handling and may benefit from thread
//   cache etc.
// - Thread-safe
// - No allocation time information: triggered on `Free()`
// - Don't use quarantined objects' payload - available for zapping
// - Don't allocate heap memory.
// - Flexible to support several applications
//
// `LightweightQuarantineRoot` represents one quarantine system
// (e.g. scheduler loop quarantine).
// `LightweightQuarantineBranch` provides a quarantine request interface.
// It belongs to a `LightweightQuarantineRoot` and there can be multiple
// instances (e.g. one per thread). By having one branch per thread, it requires
// no lock for faster quarantine.
// ┌────────────────────────────┐
// │PartitionRoot               │
// └┬──────────────────────────┬┘
// ┌▽────────────────────────┐┌▽────────────────────┐
// │LQRoot 1                 ││LQRoot 2             │
// └┬───────────┬───────────┬┘└──────────────┬──┬──┬┘
// ┌▽─────────┐┌▽─────────┐┌▽─────────┐      ▽  ▽  ▽
// │LQBranch 1││LQBranch 2││LQBranch 3│
// └──────────┘└──────────┘└──────────┘

#ifndef PARTITION_ALLOC_LIGHTWEIGHT_QUARANTINE_H_
#define PARTITION_ALLOC_LIGHTWEIGHT_QUARANTINE_H_

#include <array>
#include <atomic>
#include <cstdint>
#include <limits>
#include <memory>
#include <type_traits>
#include <vector>

#include "partition_alloc/internal_allocator_forward.h"
#include "partition_alloc/partition_alloc_base/component_export.h"
#include "partition_alloc/partition_alloc_base/rand_util.h"
#include "partition_alloc/partition_alloc_base/thread_annotations.h"
#include "partition_alloc/partition_alloc_forward.h"
#include "partition_alloc/partition_lock.h"
#include "partition_alloc/partition_stats.h"

namespace partition_alloc {

struct PartitionRoot;
struct LightweightQuarantineStats;

namespace internal {

struct LightweightQuarantineBranchConfig { … };

class LightweightQuarantineBranch;

class PA_COMPONENT_EXPORT(PARTITION_ALLOC) LightweightQuarantineRoot { … };

class PA_COMPONENT_EXPORT(PARTITION_ALLOC) LightweightQuarantineBranch { … };

}  // namespace internal

}  // namespace partition_alloc

#endif  // PARTITION_ALLOC_LIGHTWEIGHT_QUARANTINE_H_