1//===-- tsan_ilist.h --------------------------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file is a part of ThreadSanitizer (TSan), a race detector.
10//
11//===----------------------------------------------------------------------===//
12#ifndef TSAN_ILIST_H
13#define TSAN_ILIST_H
14
15#include "sanitizer_common/sanitizer_internal_defs.h"
16
17namespace __tsan {
18
19class INode {
20 public:
21  INode() = default;
22
23 private:
24  INode* next_ = nullptr;
25  INode* prev_ = nullptr;
26
27  template <typename Base, INode Base::*Node, typename Elem>
28  friend class IList;
29  INode(const INode&) = delete;
30  void operator=(const INode&) = delete;
31};
32
33// Intrusive doubly-linked list.
34//
35// The node class (MyNode) needs to include "INode foo" field,
36// then the list can be declared as IList<MyNode, &MyNode::foo>.
37// This design allows to link MyNode into multiple lists using
38// different INode fields.
39// The optional Elem template argument allows to specify node MDT
40// (most derived type) if it's different from MyNode.
41template <typename Base, INode Base::*Node, typename Elem = Base>
42class IList {
43 public:
44  IList();
45
46  void PushFront(Elem* e);
47  void PushBack(Elem* e);
48  void Remove(Elem* e);
49
50  Elem* PopFront();
51  Elem* PopBack();
52  Elem* Front();
53  Elem* Back();
54
55  // Prev links point towards front of the queue.
56  Elem* Prev(Elem* e);
57  // Next links point towards back of the queue.
58  Elem* Next(Elem* e);
59
60  uptr Size() const;
61  bool Empty() const;
62  bool Queued(Elem* e) const;
63
64 private:
65  INode node_;
66  uptr size_ = 0;
67
68  void Push(Elem* e, INode* after);
69  static INode* ToNode(Elem* e);
70  static Elem* ToElem(INode* n);
71
72  IList(const IList&) = delete;
73  void operator=(const IList&) = delete;
74};
75
76template <typename Base, INode Base::*Node, typename Elem>
77IList<Base, Node, Elem>::IList() {
78  node_.next_ = node_.prev_ = &node_;
79}
80
81template <typename Base, INode Base::*Node, typename Elem>
82void IList<Base, Node, Elem>::PushFront(Elem* e) {
83  Push(e, &node_);
84}
85
86template <typename Base, INode Base::*Node, typename Elem>
87void IList<Base, Node, Elem>::PushBack(Elem* e) {
88  Push(e, node_.prev_);
89}
90
91template <typename Base, INode Base::*Node, typename Elem>
92void IList<Base, Node, Elem>::Push(Elem* e, INode* after) {
93  INode* n = ToNode(e);
94  DCHECK_EQ(n->next_, nullptr);
95  DCHECK_EQ(n->prev_, nullptr);
96  INode* next = after->next_;
97  n->next_ = next;
98  n->prev_ = after;
99  next->prev_ = n;
100  after->next_ = n;
101  size_++;
102}
103
104template <typename Base, INode Base::*Node, typename Elem>
105void IList<Base, Node, Elem>::Remove(Elem* e) {
106  INode* n = ToNode(e);
107  INode* next = n->next_;
108  INode* prev = n->prev_;
109  DCHECK(next);
110  DCHECK(prev);
111  DCHECK(size_);
112  next->prev_ = prev;
113  prev->next_ = next;
114  n->prev_ = n->next_ = nullptr;
115  size_--;
116}
117
118template <typename Base, INode Base::*Node, typename Elem>
119Elem* IList<Base, Node, Elem>::PopFront() {
120  Elem* e = Front();
121  if (e)
122    Remove(e);
123  return e;
124}
125
126template <typename Base, INode Base::*Node, typename Elem>
127Elem* IList<Base, Node, Elem>::PopBack() {
128  Elem* e = Back();
129  if (e)
130    Remove(e);
131  return e;
132}
133
134template <typename Base, INode Base::*Node, typename Elem>
135Elem* IList<Base, Node, Elem>::Front() {
136  return size_ ? ToElem(node_.next_) : nullptr;
137}
138
139template <typename Base, INode Base::*Node, typename Elem>
140Elem* IList<Base, Node, Elem>::Back() {
141  return size_ ? ToElem(node_.prev_) : nullptr;
142}
143
144template <typename Base, INode Base::*Node, typename Elem>
145Elem* IList<Base, Node, Elem>::Prev(Elem* e) {
146  INode* n = ToNode(e);
147  DCHECK(n->prev_);
148  return n->prev_ != &node_ ? ToElem(n->prev_) : nullptr;
149}
150
151template <typename Base, INode Base::*Node, typename Elem>
152Elem* IList<Base, Node, Elem>::Next(Elem* e) {
153  INode* n = ToNode(e);
154  DCHECK(n->next_);
155  return n->next_ != &node_ ? ToElem(n->next_) : nullptr;
156}
157
158template <typename Base, INode Base::*Node, typename Elem>
159uptr IList<Base, Node, Elem>::Size() const {
160  return size_;
161}
162
163template <typename Base, INode Base::*Node, typename Elem>
164bool IList<Base, Node, Elem>::Empty() const {
165  return size_ == 0;
166}
167
168template <typename Base, INode Base::*Node, typename Elem>
169bool IList<Base, Node, Elem>::Queued(Elem* e) const {
170  INode* n = ToNode(e);
171  DCHECK_EQ(!n->next_, !n->prev_);
172  return n->next_;
173}
174
175template <typename Base, INode Base::*Node, typename Elem>
176INode* IList<Base, Node, Elem>::ToNode(Elem* e) {
177  return &(e->*Node);
178}
179
180template <typename Base, INode Base::*Node, typename Elem>
181Elem* IList<Base, Node, Elem>::ToElem(INode* n) {
182  return static_cast<Elem*>(reinterpret_cast<Base*>(
183      reinterpret_cast<uptr>(n) -
184      reinterpret_cast<uptr>(&(reinterpret_cast<Elem*>(0)->*Node))));
185}
186
187}  // namespace __tsan
188
189#endif
190