summaryrefslogtreecommitdiff
path: root/src/backend/lib/ilist.c
blob: 957a11812277b9991e6a0f6a82912e7c33532c6d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
/*-------------------------------------------------------------------------
 *
 * ilist.c
 *	  support for integrated/inline doubly- and singly- linked lists
 *
 * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  src/backend/lib/ilist.c
 *
 * NOTES
 *	  This file only contains functions that are too big to be considered
 *	  for inlining.  See ilist.h for most of the goodies.
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

/* See ilist.h */
#define ILIST_INCLUDE_DEFINITIONS

#include "lib/ilist.h"

/*
 * Delete 'node' from list.
 *
 * It is not allowed to delete a 'node' which is is not in the list 'head'
 *
 * Caution: this is O(n)
 */
void
slist_delete(slist_head *head, slist_node *node)
{
	slist_node *last = &head->head;
	slist_node *cur;
	bool found	PG_USED_FOR_ASSERTS_ONLY = false;

	while ((cur = last->next) != NULL)
	{
		if (cur == node)
		{
			last->next = cur->next;
#ifdef USE_ASSERT_CHECKING
			found = true;
#endif
			break;
		}
		last = cur;
	}
	Assert(found);

	slist_check(head);
}

#ifdef ILIST_DEBUG
/*
 * Verify integrity of a doubly linked list
 */
void
dlist_check(dlist_head *head)
{
	dlist_node *cur;

	if (head == NULL)
		elog(ERROR, "doubly linked list head address is NULL");

	if (head->head.next == NULL && head->head.prev == NULL)
		return;					/* OK, initialized as zeroes */

	/* iterate in forward direction */
	for (cur = head->head.next; cur != &head->head; cur = cur->next)
	{
		if (cur == NULL ||
			cur->next == NULL ||
			cur->prev == NULL ||
			cur->prev->next != cur ||
			cur->next->prev != cur)
			elog(ERROR, "doubly linked list is corrupted");
	}

	/* iterate in backward direction */
	for (cur = head->head.prev; cur != &head->head; cur = cur->prev)
	{
		if (cur == NULL ||
			cur->next == NULL ||
			cur->prev == NULL ||
			cur->prev->next != cur ||
			cur->next->prev != cur)
			elog(ERROR, "doubly linked list is corrupted");
	}
}

/*
 * Verify integrity of a singly linked list
 */
void
slist_check(slist_head *head)
{
	slist_node *cur;

	if (head == NULL)
		elog(ERROR, "singly linked list head address is NULL");

	/*
	 * there isn't much we can test in a singly linked list except that it
	 * actually ends sometime, i.e. hasn't introduced a cycle or similar
	 */
	for (cur = head->head.next; cur != NULL; cur = cur->next)
		;
}

#endif   /* ILIST_DEBUG */