1 /*
2 * Copyright (c) 2016, 2020, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_JFR_UTILITIES_JFRDOUBLYLINKEDLIST_HPP
26 #define SHARE_JFR_UTILITIES_JFRDOUBLYLINKEDLIST_HPP
27
28 #include "memory/allocation.hpp"
29
30 template <typename T>
31 class JfrDoublyLinkedList {
32 private:
33 T* _head;
34 T* _tail;
35 size_t _count;
36
37 T** list_head() { return &_head; }
38 T** list_tail() { return &_tail; }
39
40 public:
41 typedef T Node;
42 JfrDoublyLinkedList() : _head(NULL), _tail(NULL), _count(0) {}
43 T* head() const { return _head; }
44 T* tail() const { return _tail; }
45 size_t count() const { return _count; }
46 T* clear(bool return_tail = false);
47 T* remove(T* const node);
48 void prepend(T* const node);
49 void append(T* const node);
50 void append_list(T* const head_node, T* const tail_node, size_t count);
51 bool in_list(const T* const target_node) const;
52 bool locate(const T* start_node, const T* const target_node) const;
53 };
54
55 template <typename T>
56 inline void JfrDoublyLinkedList<T>::prepend(T* const node) {
57 assert(node != NULL, "invariant");
58 node->set_prev(NULL);
59 assert(!in_list(node), "already in list error");
60 T** lh = list_head();
61 if (*lh != NULL) {
62 (*lh)->set_prev(node);
63 node->set_next(*lh);
64 } else {
65 T** lt = list_tail();
66 assert(*lt == NULL, "invariant");
67 *lt = node;
68 node->set_next(NULL);
69 assert(tail() == node, "invariant");
70 assert(node->next() == NULL, "invariant");
71 }
72 *lh = node;
73 ++_count;
74 assert(head() == node, "head error");
75 assert(in_list(node), "not in list error");
76 assert(node->prev() == NULL, "invariant");
77 }
78
79 template <typename T>
80 void JfrDoublyLinkedList<T>::append(T* const node) {
81 assert(node != NULL, "invariant");
82 node->set_next(NULL);
83 assert(!in_list(node), "already in list error");
84 T** lt = list_tail();
85 if (*lt != NULL) {
86 // already an existing tail
87 node->set_prev(*lt);
88 (*lt)->set_next(node);
89 } else {
90 // if no tail, also update head
91 assert(*lt == NULL, "invariant");
92 T** lh = list_head();
93 assert(*lh == NULL, "invariant");
94 node->set_prev(NULL);
95 *lh = node;
96 assert(head() == node, "invariant");
97 }
98 *lt = node;
99 ++_count;
100 assert(tail() == node, "invariant");
101 assert(in_list(node), "not in list error");
102 assert(node->next() == NULL, "invariant");
103 }
104
105 template <typename T>
106 T* JfrDoublyLinkedList<T>::remove(T* const node) {
107 assert(node != NULL, "invariant");
108 assert(in_list(node), "invariant");
109 T* const prev = (T*)node->prev();
110 T* const next = (T*)node->next();
111 if (prev == NULL) {
112 assert(head() == node, "head error");
113 if (next != NULL) {
114 next->set_prev(NULL);
115 } else {
116 assert(next == NULL, "invariant");
117 assert(tail() == node, "tail error");
118 T** lt = list_tail();
119 *lt = NULL;
120 assert(tail() == NULL, "invariant");
121 }
122 T** lh = list_head();
123 *lh = next;
124 assert(head() == next, "invariant");
125 } else {
126 assert(prev != NULL, "invariant");
127 if (next == NULL) {
128 assert(tail() == node, "tail error");
129 T** lt = list_tail();
130 *lt = prev;
131 assert(tail() == prev, "invariant");
132 } else {
133 next->set_prev(prev);
134 }
135 prev->set_next(next);
136 }
137 --_count;
138 assert(!in_list(node), "still in list error");
139 return node;
140 }
141
142 template <typename T>
143 T* JfrDoublyLinkedList<T>::clear(bool return_tail /* false */) {
144 T* const node = return_tail ? tail() : head();
145 T** l = list_head();
146 *l = NULL;
147 l = list_tail();
148 *l = NULL;
149 _count = 0;
150 assert(head() == NULL, "invariant");
151 assert(tail() == NULL, "invariant");
152 return node;
153 }
154
155 template <typename T>
156 bool JfrDoublyLinkedList<T>::locate(const T* node, const T* const target) const {
157 assert(target != NULL, "invariant");
158 while (node != NULL) {
159 if (node == target) {
160 return true;
161 }
162 node = (T*)node->next();
163 }
164 return false;
165 }
166
167 template <typename T>
168 bool JfrDoublyLinkedList<T>::in_list(const T* const target) const {
169 assert(target != NULL, "invariant");
170 return locate(head(), target);
171 }
172
173 template <typename T>
174 inline void validate_count_param(T* node, size_t count_param) {
175 assert(node != NULL, "invariant");
176 size_t count = 0;
177 while (node) {
178 ++count;
179 node = (T*)node->next();
180 }
181 assert(count_param == count, "invariant");
182 }
183
184 template <typename T>
185 void JfrDoublyLinkedList<T>::append_list(T* const head_node, T* const tail_node, size_t count) {
186 assert(head_node != NULL, "invariant");
187 assert(!in_list(head_node), "already in list error");
188 assert(tail_node != NULL, "invariant");
189 assert(!in_list(tail_node), "already in list error");
190 assert(tail_node->next() == NULL, "invariant");
191 // ensure passed in list nodes are connected
192 assert(locate(head_node, tail_node), "invariant");
193 T** lt = list_tail();
194 if (*lt != NULL) {
195 head_node->set_prev(*lt);
196 (*lt)->set_next(head_node);
197 } else {
198 // no head
199 assert(*lt == NULL, "invariant");
200 T** lh = list_head();
201 assert(*lh == NULL, "invariant");
202 head_node->set_prev(NULL);
203 *lh = head_node;
204 assert(head() == head_node, "invariant");
205 }
206 *lt = tail_node;
207 const T* node = head_node;
208 debug_only(validate_count_param(node, count);)
209 _count += count;
210 assert(tail() == tail_node, "invariant");
211 assert(in_list(tail_node), "not in list error");
212 assert(in_list(head_node), "not in list error");
213 }
214
215 #endif // SHARE_JFR_UTILITIES_JFRDOUBLYLINKEDLIST_HPP