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
      31 GNC        5194 : slist_delete(slist_head *head, const slist_node *node)
      32                 : {
      33 CBC        5194 :     slist_node *last = &head->head;
      34                 :     slist_node *cur;
      35            5194 :     bool        found PG_USED_FOR_ASSERTS_ONLY = false;
      36                 : 
      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                 :     }
      49            5194 :     Assert(found);
      50                 : 
      51                 :     slist_check(head);
      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 */