Line data    Source code

       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * ilist.c
       4             :  *    support for integrated/inline doubly- and singly- linked lists
       5             :  *
       6             :  * Portions Copyright (c) 1996-2017, 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           0 : slist_delete(slist_head *head, slist_node *node)
      32             : {
      33           0 :     slist_node *last = &head->head;
      34             :     slist_node *cur;
      35           0 :     bool        found PG_USED_FOR_ASSERTS_ONLY = false;
      36             : 
      37           0 :     while ((cur = last->next) != NULL)
      38             :     {
      39           0 :         if (cur == node)
      40             :         {
      41           0 :             last->next = cur->next;
      42             : #ifdef USE_ASSERT_CHECKING
      43           0 :             found = true;
      44             : #endif
      45           0 :             break;
      46             :         }
      47           0 :         last = cur;
      48             :     }
      49           0 :     Assert(found);
      50             : 
      51             :     slist_check(head);
      52           0 : }
      53             : 
      54             : #ifdef ILIST_DEBUG
      55             : /*
      56             :  * Verify integrity of a doubly linked list
      57             :  */
      58             : void
      59             : dlist_check(dlist_head *head)
      60             : {
      61             :     dlist_node *cur;
      62             : 
      63             :     if (head == NULL)
      64             :         elog(ERROR, "doubly linked list head address is NULL");
      65             : 
      66             :     if (head->head.next == NULL && head->head.prev == NULL)
      67             :         return;                 /* OK, initialized as zeroes */
      68             : 
      69             :     /* iterate in forward direction */
      70             :     for (cur = head->head.next; cur != &head->head; cur = cur->next)
      71             :     {
      72             :         if (cur == NULL ||
      73             :             cur->next == NULL ||
      74             :             cur->prev == NULL ||
      75             :             cur->prev->next != cur ||
      76             :             cur->next->prev != cur)
      77             :             elog(ERROR, "doubly linked list is corrupted");
      78             :     }
      79             : 
      80             :     /* iterate in backward direction */
      81             :     for (cur = head->head.prev; cur != &head->head; cur = cur->prev)
      82             :     {
      83             :         if (cur == NULL ||
      84             :             cur->next == NULL ||
      85             :             cur->prev == NULL ||
      86             :             cur->prev->next != cur ||
      87             :             cur->next->prev != cur)
      88             :             elog(ERROR, "doubly linked list is corrupted");
      89             :     }
      90             : }
      91             : 
      92             : /*
      93             :  * Verify integrity of a singly linked list
      94             :  */
      95             : void
      96             : slist_check(slist_head *head)
      97             : {
      98             :     slist_node *cur;
      99             : 
     100             :     if (head == NULL)
     101             :         elog(ERROR, "singly linked list head address is NULL");
     102             : 
     103             :     /*
     104             :      * there isn't much we can test in a singly linked list except that it
     105             :      * actually ends sometime, i.e. hasn't introduced a cycle or similar
     106             :      */
     107             :     for (cur = head->head.next; cur != NULL; cur = cur->next)
     108             :         ;
     109             : }
     110             : 
     111             : #endif                          /* ILIST_DEBUG */