Age Owner TLA Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * ilist.c
4 : * support for integrated/inline doubly- and singly- linked lists
5 : *
6 : * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
7 : * Portions Copyright (c) 1994, Regents of the University of California
8 : *
9 : *
10 : * IDENTIFICATION
11 : * src/backend/lib/ilist.c
12 : *
13 : * NOTES
14 : * This file only contains functions that are too big to be considered
15 : * for inlining. See ilist.h for most of the goodies.
16 : *
17 : *-------------------------------------------------------------------------
18 : */
19 : #include "postgres.h"
20 :
21 : #include "lib/ilist.h"
22 :
23 : /*
24 : * Delete 'node' from list.
25 : *
26 : * It is not allowed to delete a 'node' which is not in the list 'head'
27 : *
28 : * Caution: this is O(n); consider using slist_delete_current() instead.
29 : */
30 : void
87 peter 31 GNC 5194 : slist_delete(slist_head *head, const slist_node *node)
32 : {
3827 alvherre 33 CBC 5194 : slist_node *last = &head->head;
34 : slist_node *cur;
2118 tgl 35 5194 : bool found PG_USED_FOR_ASSERTS_ONLY = false;
36 :
3827 alvherre 37 19480 : while ((cur = last->next) != NULL)
38 : {
39 19480 : if (cur == node)
40 : {
41 5194 : last->next = cur->next;
42 : #ifdef USE_ASSERT_CHECKING
43 5194 : found = true;
44 : #endif
45 5194 : break;
46 : }
47 14286 : last = cur;
48 : }
3825 tgl 49 5194 : Assert(found);
50 :
51 : slist_check(head);
3827 alvherre 52 5194 : }
53 :
54 : #ifdef ILIST_DEBUG
55 : /*
56 : * dlist_member_check
57 : * Validate that 'node' is a member of 'head'
58 : */
59 : void
60 : dlist_member_check(const dlist_head *head, const dlist_node *node)
61 : {
62 : const dlist_node *cur;
63 :
64 : /* iteration open-coded to due to the use of const */
65 : for (cur = head->head.next; cur != &head->head; cur = cur->next)
66 : {
67 : if (cur == node)
68 : return;
69 : }
70 : elog(ERROR, "double linked list member check failure");
71 : }
72 :
73 : /*
74 : * Verify integrity of a doubly linked list
75 : */
76 : void
77 : dlist_check(const dlist_head *head)
78 : {
79 : dlist_node *cur;
80 :
81 : if (head == NULL)
82 : elog(ERROR, "doubly linked list head address is NULL");
83 :
84 : if (head->head.next == NULL && head->head.prev == NULL)
85 : return; /* OK, initialized as zeroes */
86 :
87 : /* iterate in forward direction */
88 : for (cur = head->head.next; cur != &head->head; cur = cur->next)
89 : {
90 : if (cur == NULL ||
91 : cur->next == NULL ||
92 : cur->prev == NULL ||
93 : cur->prev->next != cur ||
94 : cur->next->prev != cur)
95 : elog(ERROR, "doubly linked list is corrupted");
96 : }
97 :
98 : /* iterate in backward direction */
99 : for (cur = head->head.prev; cur != &head->head; cur = cur->prev)
100 : {
101 : if (cur == NULL ||
102 : cur->next == NULL ||
103 : cur->prev == NULL ||
104 : cur->prev->next != cur ||
105 : cur->next->prev != cur)
106 : elog(ERROR, "doubly linked list is corrupted");
107 : }
108 : }
109 :
110 : /*
111 : * Verify integrity of a singly linked list
112 : */
113 : void
114 : slist_check(const slist_head *head)
115 : {
116 : slist_node *cur;
117 :
118 : if (head == NULL)
119 : elog(ERROR, "singly linked list head address is NULL");
120 :
121 : /*
122 : * there isn't much we can test in a singly linked list except that it
123 : * actually ends sometime, i.e. hasn't introduced a cycle or similar
124 : */
125 : for (cur = head->head.next; cur != NULL; cur = cur->next)
126 : ;
127 : }
128 :
129 : #endif /* ILIST_DEBUG */
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