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1 // SPDX-License-Identifier: GPL-3.0-or-later
2
3 #ifndef NETDATA_LINKED_LISTS_H
4 #define NETDATA_LINKED_LISTS_H
5
6 // ---------------------------------------------------------------------------------------------
7 // double linked list management
8 // inspired by https://github.com/troydhanson/uthash/blob/master/src/utlist.h
9
10 #define DOUBLE_LINKED_LIST_PREPEND_ITEM_UNSAFE(head, item, prev, next) \
11 do { \
12 (item)->next = (head); \
13 \
14 if(likely(head)) { \
15 (item)->prev = (head)->prev; \
16 (head)->prev = (item); \
17 } \
18 else \
19 (item)->prev = (item); \
20 \
21 (head) = (item); \
22 } while (0)
23
24 #define DOUBLE_LINKED_LIST_APPEND_ITEM_UNSAFE(head, item, prev, next) \
25 do { \
26 \
27 (item)->next = NULL; \
28 \
29 if(likely(head)) { \
30 (item)->prev = (head)->prev; \
31 (head)->prev->next = (item); \
32 (head)->prev = (item); \
33 } \
34 else { \
35 (item)->prev = (item); \
36 (head) = (item); \
37 } \
38 \
39 } while (0)
40
41 #define DOUBLE_LINKED_LIST_REMOVE_ITEM_UNSAFE(head, item, prev, next) \
42 do { \
43 fatal_assert((head) != NULL); \
44 fatal_assert((item)->prev != NULL); \
45 \
46 if((item)->prev == (item)) \
47 /* it is the only item in the list */ \
48 (head) = NULL; \
49 \
50 else if((item) == (head)) { \
51 /* it is the first item */ \
52 fatal_assert((item)->next != NULL); \
53 (item)->next->prev = (item)->prev; \
54 (head) = (item)->next; \
55 } \
56 else { \
57 /* it is any other item */ \
58 (item)->prev->next = (item)->next; \
59 \
60 if ((item)->next) \
61 (item)->next->prev = (item)->prev; \
62 else \
63 (head)->prev = (item)->prev; \
64 } \
65 \
66 (item)->next = NULL; \
67 (item)->prev = NULL; \
68 } while (0)
69
70 #define DOUBLE_LINKED_LIST_INSERT_ITEM_BEFORE_UNSAFE(head, existing, item, prev, next) \
71 do { \
72 if (existing) { \
73 fatal_assert((head) != NULL); \
74 fatal_assert((item) != NULL); \
75 \
76 (item)->next = (existing); \
77 (item)->prev = (existing)->prev; \
78 (existing)->prev = (item); \
79 \
80 if ((head) == (existing)) \
81 (head) = (item); \
82 else \
83 (item)->prev->next = (item); \
84 \
85 } \
86 else \
87 DOUBLE_LINKED_LIST_APPEND_ITEM_UNSAFE(head, item, prev, next); \
88 \
89 } while (0)
90
91 #define DOUBLE_LINKED_LIST_INSERT_ITEM_AFTER_UNSAFE(head, existing, item, prev, next) \
92 do { \
93 if (existing) { \
94 fatal_assert((head) != NULL); \
95 fatal_assert((item) != NULL); \
96 \
97 (item)->next = (existing)->next; \
98 (item)->prev = (existing); \
99 (existing)->next = (item); \
100 \
101 if ((item)->next) \
102 (item)->next->prev = (item); \
103 else \
104 (head)->prev = (item); \
105 } \
106 else \
107 DOUBLE_LINKED_LIST_PREPEND_ITEM_UNSAFE(head, item, prev, next); \
108 \
109 } while (0)
110
111 #define DOUBLE_LINKED_LIST_APPEND_LIST_UNSAFE(head, head2, prev, next) \
112 do { \
113 if (head2) { \
114 if (head) { \
115 __typeof(head2) _head2_last_item = (head2)->prev; \
116 \
117 (head2)->prev = (head)->prev; \
118 (head)->prev->next = (head2); \
119 \
120 (head)->prev = _head2_last_item; \
121 } \
122 else \
123 (head) = (head2); \
124 } \
125 } while (0)
126
127 #define DOUBLE_LINKED_LIST_FOREACH_FORWARD(head, var, prev, next) \
128 for ((var) = (head); (var) ; (var) = (var)->next)
129
130 #define DOUBLE_LINKED_LIST_FOREACH_BACKWARD(head, var, prev, next) \
131 for ((var) = (head) ? (head)->prev : NULL ; (var) ; (var) = ((var) == (head)) ? NULL : (var)->prev)
132
133 #endif //NETDATA_LINKED_LISTS_H