Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * proclist.h
4 : * operations on doubly-linked lists of pgprocnos
5 : *
6 : * The interface is similar to dlist from ilist.h, but uses pgprocno instead
7 : * of pointers. This allows proclist_head to be mapped at different addresses
8 : * in different backends.
9 : *
10 : * See proclist_types.h for the structs that these functions operate on. They
11 : * are separated to break a header dependency cycle with proc.h.
12 : *
13 : * Portions Copyright (c) 2016-2017, PostgreSQL Global Development Group
14 : *
15 : * IDENTIFICATION
16 : * src/include/storage/proclist.h
17 : *-------------------------------------------------------------------------
18 : */
19 : #ifndef PROCLIST_H
20 : #define PROCLIST_H
21 :
22 : #include "storage/proc.h"
23 : #include "storage/proclist_types.h"
24 :
25 : /*
26 : * Initialize a proclist.
27 : */
28 : static inline void
29 138996 : proclist_init(proclist_head *list)
30 : {
31 138996 : list->head = list->tail = INVALID_PGPROCNO;
32 138996 : }
33 :
34 : /*
35 : * Is the list empty?
36 : */
37 : static inline bool
38 4194 : proclist_is_empty(proclist_head *list)
39 : {
40 4194 : return list->head == INVALID_PGPROCNO;
41 : }
42 :
43 : /*
44 : * Get a pointer to a proclist_node inside a given PGPROC, given a procno and
45 : * an offset.
46 : */
47 : static inline proclist_node *
48 8330 : proclist_node_get(int procno, size_t node_offset)
49 : {
50 8330 : char *entry = (char *) GetPGProcByNumber(procno);
51 :
52 8330 : return (proclist_node *) (entry + node_offset);
53 : }
54 :
55 : /*
56 : * Insert a node at the beginning of a list.
57 : */
58 : static inline void
59 430 : proclist_push_head_offset(proclist_head *list, int procno, size_t node_offset)
60 : {
61 430 : proclist_node *node = proclist_node_get(procno, node_offset);
62 :
63 430 : if (list->head == INVALID_PGPROCNO)
64 : {
65 317 : Assert(list->tail == INVALID_PGPROCNO);
66 317 : node->next = node->prev = INVALID_PGPROCNO;
67 317 : list->head = list->tail = procno;
68 : }
69 : else
70 : {
71 113 : Assert(list->tail != INVALID_PGPROCNO);
72 113 : Assert(list->head != procno);
73 113 : Assert(list->tail != procno);
74 113 : node->next = list->head;
75 113 : proclist_node_get(node->next, node_offset)->prev = procno;
76 113 : node->prev = INVALID_PGPROCNO;
77 113 : list->head = procno;
78 : }
79 430 : }
80 :
81 : /*
82 : * Insert a node at the end of a list.
83 : */
84 : static inline void
85 2130 : proclist_push_tail_offset(proclist_head *list, int procno, size_t node_offset)
86 : {
87 2130 : proclist_node *node = proclist_node_get(procno, node_offset);
88 :
89 2130 : if (list->tail == INVALID_PGPROCNO)
90 : {
91 1919 : Assert(list->head == INVALID_PGPROCNO);
92 1919 : node->next = node->prev = INVALID_PGPROCNO;
93 1919 : list->head = list->tail = procno;
94 : }
95 : else
96 : {
97 211 : Assert(list->head != INVALID_PGPROCNO);
98 211 : Assert(list->head != procno);
99 211 : Assert(list->tail != procno);
100 211 : node->prev = list->tail;
101 211 : proclist_node_get(node->prev, node_offset)->next = procno;
102 211 : node->next = INVALID_PGPROCNO;
103 211 : list->tail = procno;
104 : }
105 2130 : }
106 :
107 : /*
108 : * Delete a node. The node must be in the list.
109 : */
110 : static inline void
111 2560 : proclist_delete_offset(proclist_head *list, int procno, size_t node_offset)
112 : {
113 2560 : proclist_node *node = proclist_node_get(procno, node_offset);
114 :
115 2560 : if (node->prev == INVALID_PGPROCNO)
116 2560 : list->head = node->next;
117 : else
118 0 : proclist_node_get(node->prev, node_offset)->next = node->next;
119 :
120 2560 : if (node->next == INVALID_PGPROCNO)
121 2236 : list->tail = node->prev;
122 : else
123 324 : proclist_node_get(node->next, node_offset)->prev = node->prev;
124 :
125 2560 : node->next = node->prev = INVALID_PGPROCNO;
126 2560 : }
127 :
128 : /*
129 : * Check if a node is currently in a list. It must be known that the node is
130 : * not in any _other_ proclist that uses the same proclist_node, so that the
131 : * only possibilities are that it is in this list or none.
132 : */
133 : static inline bool
134 0 : proclist_contains_offset(proclist_head *list, int procno,
135 : size_t node_offset)
136 : {
137 0 : proclist_node *node = proclist_node_get(procno, node_offset);
138 :
139 : /*
140 : * If this is not a member of a proclist, then the next and prev pointers
141 : * should be 0. Circular lists are not allowed so this condition is not
142 : * confusable with a real pgprocno 0.
143 : */
144 0 : if (node->prev == 0 && node->next == 0)
145 0 : return false;
146 :
147 : /* If there is a previous node, then this node must be in the list. */
148 0 : if (node->prev != INVALID_PGPROCNO)
149 0 : return true;
150 :
151 : /*
152 : * There is no previous node, so the only way this node can be in the list
153 : * is if it's the head node.
154 : */
155 0 : return list->head == procno;
156 : }
157 :
158 : /*
159 : * Remove and return the first node from a list (there must be one).
160 : */
161 : static inline PGPROC *
162 0 : proclist_pop_head_node_offset(proclist_head *list, size_t node_offset)
163 : {
164 : PGPROC *proc;
165 :
166 0 : Assert(!proclist_is_empty(list));
167 0 : proc = GetPGProcByNumber(list->head);
168 0 : proclist_delete_offset(list, list->head, node_offset);
169 0 : return proc;
170 : }
171 :
172 : /*
173 : * Helper macros to avoid repetition of offsetof(PGPROC, <member>).
174 : * 'link_member' is the name of a proclist_node member in PGPROC.
175 : */
176 : #define proclist_delete(list, procno, link_member) \
177 : proclist_delete_offset((list), (procno), offsetof(PGPROC, link_member))
178 : #define proclist_push_head(list, procno, link_member) \
179 : proclist_push_head_offset((list), (procno), offsetof(PGPROC, link_member))
180 : #define proclist_push_tail(list, procno, link_member) \
181 : proclist_push_tail_offset((list), (procno), offsetof(PGPROC, link_member))
182 : #define proclist_pop_head_node(list, link_member) \
183 : proclist_pop_head_node_offset((list), offsetof(PGPROC, link_member))
184 : #define proclist_contains(list, procno, link_member) \
185 : proclist_contains_offset((list), (procno), offsetof(PGPROC, link_member))
186 :
187 : /*
188 : * Iterate through the list pointed at by 'lhead', storing the current
189 : * position in 'iter'. 'link_member' is the name of a proclist_node member in
190 : * PGPROC. Access the current position with iter.cur.
191 : *
192 : * The only list modification allowed while iterating is deleting the current
193 : * node with proclist_delete(list, iter.cur, node_offset).
194 : */
195 : #define proclist_foreach_modify(iter, lhead, link_member) \
196 : for (AssertVariableIsOfTypeMacro(iter, proclist_mutable_iter), \
197 : AssertVariableIsOfTypeMacro(lhead, proclist_head *), \
198 : (iter).cur = (lhead)->head, \
199 : (iter).next = (iter).cur == INVALID_PGPROCNO ? INVALID_PGPROCNO : \
200 : proclist_node_get((iter).cur, \
201 : offsetof(PGPROC, link_member))->next; \
202 : (iter).cur != INVALID_PGPROCNO; \
203 : (iter).cur = (iter).next, \
204 : (iter).next = (iter).cur == INVALID_PGPROCNO ? INVALID_PGPROCNO : \
205 : proclist_node_get((iter).cur, \
206 : offsetof(PGPROC, link_member))->next)
207 :
208 : #endif
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