LCOV - code coverage report
Current view: top level - src/include/lib - ilist.h (source / functions) Hit Total Coverage
Test: PostgreSQL 16devel Lines: 105 114 92.1 %
Date: 2022-12-05 12:10:47 Functions: 29 31 93.5 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * ilist.h
       4             :  *      integrated/inline doubly- and singly-linked lists
       5             :  *
       6             :  * These list types are useful when there are only a predetermined set of
       7             :  * lists that an object could be in.  List links are embedded directly into
       8             :  * the objects, and thus no extra memory management overhead is required.
       9             :  * (Of course, if only a small proportion of existing objects are in a list,
      10             :  * the link fields in the remainder would be wasted space.  But usually,
      11             :  * it saves space to not have separately-allocated list nodes.)
      12             :  *
      13             :  * The doubly-linked list comes in 2 forms.  dlist_head defines a head of a
      14             :  * doubly-linked list of dlist_nodes, whereas dclist_head defines the head of
      15             :  * a doubly-linked list of dlist_nodes with an additional 'count' field to
      16             :  * keep track of how many items are contained within the given list.  For
      17             :  * simplicity, dlist_head and dclist_head share the same node and iterator
      18             :  * types.  The functions to manipulate a dlist_head always have a name
      19             :  * starting with "dlist", whereas functions to manipulate a dclist_head have a
      20             :  * name starting with "dclist".  dclist_head comes with an additional function
      21             :  * (dclist_count) to return the number of entries in the list.  dclists are
      22             :  * able to store a maximum of PG_UINT32_MAX elements.  It is up to the caller
      23             :  * to ensure no more than this many items are added to a dclist.
      24             :  *
      25             :  * None of the functions here allocate any memory; they just manipulate
      26             :  * externally managed memory.  With the exception doubly-linked count lists
      27             :  * providing the ability to obtain the number of items in the list, the APIs
      28             :  * for singly and both doubly linked lists are identical as far as
      29             :  * capabilities of both allow.
      30             :  *
      31             :  * Each list has a list header, which exists even when the list is empty.
      32             :  * An empty singly-linked list has a NULL pointer in its header.
      33             :  *
      34             :  * For both doubly-linked list types, there are two valid ways to represent an
      35             :  * empty list.  The head's 'next' pointer can either be NULL or the head's
      36             :  * 'next' and 'prev' links can both point back to the list head (circular).
      37             :  * (If a dlist is modified and then all its elements are deleted, it will be
      38             :  * in the circular state.).  We prefer circular dlists because there are some
      39             :  * operations that can be done without branches (and thus faster) on lists
      40             :  * that use circular representation.  However, it is often convenient to
      41             :  * initialize list headers to zeroes rather than setting them up with an
      42             :  * explicit initialization function, so we also allow the NULL initalization.
      43             :  *
      44             :  * EXAMPLES
      45             :  *
      46             :  * Here's a simple example demonstrating how this can be used.  Let's assume
      47             :  * we want to store information about the tables contained in a database.
      48             :  *
      49             :  * #include "lib/ilist.h"
      50             :  *
      51             :  * // Define struct for the databases including a list header that will be
      52             :  * // used to access the nodes in the table list later on.
      53             :  * typedef struct my_database
      54             :  * {
      55             :  *      char       *datname;
      56             :  *      dlist_head  tables;
      57             :  *      // ...
      58             :  * } my_database;
      59             :  *
      60             :  * // Define struct for the tables.  Note the list_node element which stores
      61             :  * // prev/next list links.  The list_node element need not be first.
      62             :  * typedef struct my_table
      63             :  * {
      64             :  *      char       *tablename;
      65             :  *      dlist_node  list_node;
      66             :  *      perm_t      permissions;
      67             :  *      // ...
      68             :  * } my_table;
      69             :  *
      70             :  * // create a database
      71             :  * my_database *db = create_database();
      72             :  *
      73             :  * // and add a few tables to its table list
      74             :  * dlist_push_head(&db->tables, &create_table(db, "a")->list_node);
      75             :  * ...
      76             :  * dlist_push_head(&db->tables, &create_table(db, "b")->list_node);
      77             :  *
      78             :  *
      79             :  * To iterate over the table list, we allocate an iterator variable and use
      80             :  * a specialized looping construct.  Inside a dlist_foreach, the iterator's
      81             :  * 'cur' field can be used to access the current element.  iter.cur points to
      82             :  * a 'dlist_node', but most of the time what we want is the actual table
      83             :  * information; dlist_container() gives us that, like so:
      84             :  *
      85             :  * dlist_iter   iter;
      86             :  * dlist_foreach(iter, &db->tables)
      87             :  * {
      88             :  *      my_table   *tbl = dlist_container(my_table, list_node, iter.cur);
      89             :  *      printf("we have a table: %s in database %s\n",
      90             :  *             tbl->tablename, db->datname);
      91             :  * }
      92             :  *
      93             :  *
      94             :  * While a simple iteration is useful, we sometimes also want to manipulate
      95             :  * the list while iterating.  There is a different iterator element and looping
      96             :  * construct for that.  Suppose we want to delete tables that meet a certain
      97             :  * criterion:
      98             :  *
      99             :  * dlist_mutable_iter miter;
     100             :  * dlist_foreach_modify(miter, &db->tables)
     101             :  * {
     102             :  *      my_table   *tbl = dlist_container(my_table, list_node, miter.cur);
     103             :  *
     104             :  *      if (!tbl->to_be_deleted)
     105             :  *          continue;       // don't touch this one
     106             :  *
     107             :  *      // unlink the current table from the linked list
     108             :  *      dlist_delete(miter.cur);
     109             :  *      // as these lists never manage memory, we can still access the table
     110             :  *      // after it's been unlinked
     111             :  *      drop_table(db, tbl);
     112             :  * }
     113             :  *
     114             :  *
     115             :  * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
     116             :  * Portions Copyright (c) 1994, Regents of the University of California
     117             :  *
     118             :  * IDENTIFICATION
     119             :  *      src/include/lib/ilist.h
     120             :  *-------------------------------------------------------------------------
     121             :  */
     122             : #ifndef ILIST_H
     123             : #define ILIST_H
     124             : 
     125             : /*
     126             :  * Enable for extra debugging. This is rather expensive, so it's not enabled by
     127             :  * default even when USE_ASSERT_CHECKING.
     128             :  */
     129             : /* #define ILIST_DEBUG */
     130             : 
     131             : /*
     132             :  * Node of a doubly linked list.
     133             :  *
     134             :  * Embed this in structs that need to be part of a doubly linked list.
     135             :  */
     136             : typedef struct dlist_node dlist_node;
     137             : struct dlist_node
     138             : {
     139             :     dlist_node *prev;
     140             :     dlist_node *next;
     141             : };
     142             : 
     143             : /*
     144             :  * Head of a doubly linked list.
     145             :  *
     146             :  * Non-empty lists are internally circularly linked.  Circular lists have the
     147             :  * advantage of not needing any branches in the most common list manipulations.
     148             :  * An empty list can also be represented as a pair of NULL pointers, making
     149             :  * initialization easier.
     150             :  */
     151             : typedef struct dlist_head
     152             : {
     153             :     /*
     154             :      * head.next either points to the first element of the list; to &head if
     155             :      * it's a circular empty list; or to NULL if empty and not circular.
     156             :      *
     157             :      * head.prev either points to the last element of the list; to &head if
     158             :      * it's a circular empty list; or to NULL if empty and not circular.
     159             :      */
     160             :     dlist_node  head;
     161             : } dlist_head;
     162             : 
     163             : 
     164             : /*
     165             :  * Doubly linked list iterator type for dlist_head and and dclist_head types.
     166             :  *
     167             :  * Used as state in dlist_foreach() and dlist_reverse_foreach() (and the
     168             :  * dclist variant thereof).
     169             :  *
     170             :  * To get the current element of the iteration use the 'cur' member.
     171             :  *
     172             :  * Iterations using this are *not* allowed to change the list while iterating!
     173             :  *
     174             :  * NB: We use an extra "end" field here to avoid multiple evaluations of
     175             :  * arguments in the dlist_foreach() and dclist_foreach() macros.
     176             :  */
     177             : typedef struct dlist_iter
     178             : {
     179             :     dlist_node *cur;            /* current element */
     180             :     dlist_node *end;            /* last node we'll iterate to */
     181             : } dlist_iter;
     182             : 
     183             : /*
     184             :  * Doubly linked list iterator for both dlist_head and dclist_head types.
     185             :  * This iterator type allows some modifications while iterating.
     186             :  *
     187             :  * Used as state in dlist_foreach_modify() and dclist_foreach_modify().
     188             :  *
     189             :  * To get the current element of the iteration use the 'cur' member.
     190             :  *
     191             :  * Iterations using this are only allowed to change the list at the current
     192             :  * point of iteration. It is fine to delete the current node, but it is *not*
     193             :  * fine to insert or delete adjacent nodes.
     194             :  *
     195             :  * NB: We need a separate type for mutable iterations so that we can store
     196             :  * the 'next' node of the current node in case it gets deleted or modified.
     197             :  */
     198             : typedef struct dlist_mutable_iter
     199             : {
     200             :     dlist_node *cur;            /* current element */
     201             :     dlist_node *next;           /* next node we'll iterate to */
     202             :     dlist_node *end;            /* last node we'll iterate to */
     203             : } dlist_mutable_iter;
     204             : 
     205             : /*
     206             :  * Head of a doubly linked list with a count of the number of items
     207             :  *
     208             :  * This internally makes use of a dlist to implement the actual list.  When
     209             :  * items are added or removed from the list the count is updated to reflect
     210             :  * the current number of items in the list.
     211             :  */
     212             : typedef struct dclist_head
     213             : {
     214             :     dlist_head  dlist;          /* the actual list header */
     215             :     uint32      count;          /* the number of items in the list */
     216             : } dclist_head;
     217             : 
     218             : /*
     219             :  * Node of a singly linked list.
     220             :  *
     221             :  * Embed this in structs that need to be part of a singly linked list.
     222             :  */
     223             : typedef struct slist_node slist_node;
     224             : struct slist_node
     225             : {
     226             :     slist_node *next;
     227             : };
     228             : 
     229             : /*
     230             :  * Head of a singly linked list.
     231             :  *
     232             :  * Singly linked lists are not circularly linked, in contrast to doubly linked
     233             :  * lists; we just set head.next to NULL if empty.  This doesn't incur any
     234             :  * additional branches in the usual manipulations.
     235             :  */
     236             : typedef struct slist_head
     237             : {
     238             :     slist_node  head;
     239             : } slist_head;
     240             : 
     241             : /*
     242             :  * Singly linked list iterator.
     243             :  *
     244             :  * Used as state in slist_foreach(). To get the current element of the
     245             :  * iteration use the 'cur' member.
     246             :  *
     247             :  * It's allowed to modify the list while iterating, with the exception of
     248             :  * deleting the iterator's current node; deletion of that node requires
     249             :  * care if the iteration is to be continued afterward.  (Doing so and also
     250             :  * deleting or inserting adjacent list elements might misbehave; also, if
     251             :  * the user frees the current node's storage, continuing the iteration is
     252             :  * not safe.)
     253             :  *
     254             :  * NB: this wouldn't really need to be an extra struct, we could use an
     255             :  * slist_node * directly. We prefer a separate type for consistency.
     256             :  */
     257             : typedef struct slist_iter
     258             : {
     259             :     slist_node *cur;
     260             : } slist_iter;
     261             : 
     262             : /*
     263             :  * Singly linked list iterator allowing some modifications while iterating.
     264             :  *
     265             :  * Used as state in slist_foreach_modify(). To get the current element of the
     266             :  * iteration use the 'cur' member.
     267             :  *
     268             :  * The only list modification allowed while iterating is to remove the current
     269             :  * node via slist_delete_current() (*not* slist_delete()).  Insertion or
     270             :  * deletion of nodes adjacent to the current node would misbehave.
     271             :  */
     272             : typedef struct slist_mutable_iter
     273             : {
     274             :     slist_node *cur;            /* current element */
     275             :     slist_node *next;           /* next node we'll iterate to */
     276             :     slist_node *prev;           /* prev node, for deletions */
     277             : } slist_mutable_iter;
     278             : 
     279             : 
     280             : /* Static initializers */
     281             : #define DLIST_STATIC_INIT(name) {{&(name).head, &(name).head}}
     282             : #define DCLIST_STATIC_INIT(name) {{{&(name).dlist.head, &(name).dlist.head}}, 0}
     283             : #define SLIST_STATIC_INIT(name) {{NULL}}
     284             : 
     285             : 
     286             : /* Prototypes for functions too big to be inline */
     287             : 
     288             : /* Caution: this is O(n); consider using slist_delete_current() instead */
     289             : extern void slist_delete(slist_head *head, slist_node *node);
     290             : 
     291             : #ifdef ILIST_DEBUG
     292             : extern void dlist_member_check(dlist_head *head, dlist_node *node);
     293             : extern void dlist_check(dlist_head *head);
     294             : extern void slist_check(slist_head *head);
     295             : #else
     296             : /*
     297             :  * These seemingly useless casts to void are here to keep the compiler quiet
     298             :  * about the argument being unused in many functions in a non-debug compile,
     299             :  * in which functions the only point of passing the list head pointer is to be
     300             :  * able to run these checks.
     301             :  */
     302             : #define dlist_member_check(head, node) ((void) (head))
     303             : #define dlist_check(head)   ((void) (head))
     304             : #define slist_check(head)   ((void) (head))
     305             : #endif                          /* ILIST_DEBUG */
     306             : 
     307             : /* doubly linked list implementation */
     308             : 
     309             : /*
     310             :  * Initialize a doubly linked list.
     311             :  * Previous state will be thrown away without any cleanup.
     312             :  */
     313             : static inline void
     314     7140728 : dlist_init(dlist_head *head)
     315             : {
     316     7140728 :     head->head.next = head->head.prev = &head->head;
     317     7140728 : }
     318             : 
     319             : /*
     320             :  * Is the list empty?
     321             :  *
     322             :  * An empty list has either its first 'next' pointer set to NULL, or to itself.
     323             :  */
     324             : static inline bool
     325    15448258 : dlist_is_empty(dlist_head *head)
     326             : {
     327             :     dlist_check(head);
     328             : 
     329    15448258 :     return head->head.next == NULL || head->head.next == &(head->head);
     330             : }
     331             : 
     332             : /*
     333             :  * Insert a node at the beginning of the list.
     334             :  */
     335             : static inline void
     336    20500306 : dlist_push_head(dlist_head *head, dlist_node *node)
     337             : {
     338    20500306 :     if (head->head.next == NULL) /* convert NULL header to circular */
     339     4638566 :         dlist_init(head);
     340             : 
     341    20500306 :     node->next = head->head.next;
     342    20500306 :     node->prev = &head->head;
     343    20500306 :     node->next->prev = node;
     344    20500306 :     head->head.next = node;
     345             : 
     346             :     dlist_check(head);
     347    20500306 : }
     348             : 
     349             : /*
     350             :  * Insert a node at the end of the list.
     351             :  */
     352             : static inline void
     353     9009776 : dlist_push_tail(dlist_head *head, dlist_node *node)
     354             : {
     355     9009776 :     if (head->head.next == NULL) /* convert NULL header to circular */
     356        3378 :         dlist_init(head);
     357             : 
     358     9009776 :     node->next = &head->head;
     359     9009776 :     node->prev = head->head.prev;
     360     9009776 :     node->prev->next = node;
     361     9009776 :     head->head.prev = node;
     362             : 
     363             :     dlist_check(head);
     364     9009776 : }
     365             : 
     366             : /*
     367             :  * Insert a node after another *in the same list*
     368             :  */
     369             : static inline void
     370        1906 : dlist_insert_after(dlist_node *after, dlist_node *node)
     371             : {
     372        1906 :     node->prev = after;
     373        1906 :     node->next = after->next;
     374        1906 :     after->next = node;
     375        1906 :     node->next->prev = node;
     376        1906 : }
     377             : 
     378             : /*
     379             :  * Insert a node before another *in the same list*
     380             :  */
     381             : static inline void
     382           0 : dlist_insert_before(dlist_node *before, dlist_node *node)
     383             : {
     384           0 :     node->prev = before->prev;
     385           0 :     node->next = before;
     386           0 :     before->prev = node;
     387           0 :     node->prev->next = node;
     388           0 : }
     389             : 
     390             : /*
     391             :  * Delete 'node' from its list (it must be in one).
     392             :  */
     393             : static inline void
     394    22195546 : dlist_delete(dlist_node *node)
     395             : {
     396    22195546 :     node->prev->next = node->next;
     397    22195546 :     node->next->prev = node->prev;
     398    22195546 : }
     399             : 
     400             : /*
     401             :  * Same as dlist_delete, but performs checks in ILIST_DEBUG builds to ensure
     402             :  * that 'node' belongs to 'head'.
     403             :  */
     404             : static inline void
     405      393754 : dlist_delete_from(dlist_head *head, dlist_node *node)
     406             : {
     407             :     dlist_member_check(head, node);
     408      393754 :     dlist_delete(node);
     409      393754 : }
     410             : 
     411             : /*
     412             :  * Remove and return the first node from a list (there must be one).
     413             :  */
     414             : static inline dlist_node *
     415         128 : dlist_pop_head_node(dlist_head *head)
     416             : {
     417             :     dlist_node *node;
     418             : 
     419             :     Assert(!dlist_is_empty(head));
     420         128 :     node = head->head.next;
     421         128 :     dlist_delete(node);
     422         128 :     return node;
     423             : }
     424             : 
     425             : /*
     426             :  * Move element from its current position in the list to the head position in
     427             :  * the same list.
     428             :  *
     429             :  * Undefined behaviour if 'node' is not already part of the list.
     430             :  */
     431             : static inline void
     432    93477364 : dlist_move_head(dlist_head *head, dlist_node *node)
     433             : {
     434             :     /* fast path if it's already at the head */
     435    93477364 :     if (head->head.next == node)
     436    89710770 :         return;
     437             : 
     438     3766594 :     dlist_delete(node);
     439     3766594 :     dlist_push_head(head, node);
     440             : 
     441             :     dlist_check(head);
     442             : }
     443             : 
     444             : /*
     445             :  * Move element from its current position in the list to the tail position in
     446             :  * the same list.
     447             :  *
     448             :  * Undefined behaviour if 'node' is not already part of the list.
     449             :  */
     450             : static inline void
     451      369006 : dlist_move_tail(dlist_head *head, dlist_node *node)
     452             : {
     453             :     /* fast path if it's already at the tail */
     454      369006 :     if (head->head.prev == node)
     455      198858 :         return;
     456             : 
     457      170148 :     dlist_delete(node);
     458      170148 :     dlist_push_tail(head, node);
     459             : 
     460             :     dlist_check(head);
     461             : }
     462             : 
     463             : /*
     464             :  * Check whether 'node' has a following node.
     465             :  * Caution: unreliable if 'node' is not in the list.
     466             :  */
     467             : static inline bool
     468     3706386 : dlist_has_next(dlist_head *head, dlist_node *node)
     469             : {
     470     3706386 :     return node->next != &head->head;
     471             : }
     472             : 
     473             : /*
     474             :  * Check whether 'node' has a preceding node.
     475             :  * Caution: unreliable if 'node' is not in the list.
     476             :  */
     477             : static inline bool
     478         260 : dlist_has_prev(dlist_head *head, dlist_node *node)
     479             : {
     480         260 :     return node->prev != &head->head;
     481             : }
     482             : 
     483             : /*
     484             :  * Return the next node in the list (there must be one).
     485             :  */
     486             : static inline dlist_node *
     487     3514034 : dlist_next_node(dlist_head *head, dlist_node *node)
     488             : {
     489             :     Assert(dlist_has_next(head, node));
     490     3514034 :     return node->next;
     491             : }
     492             : 
     493             : /*
     494             :  * Return previous node in the list (there must be one).
     495             :  */
     496             : static inline dlist_node *
     497         352 : dlist_prev_node(dlist_head *head, dlist_node *node)
     498             : {
     499             :     Assert(dlist_has_prev(head, node));
     500         352 :     return node->prev;
     501             : }
     502             : 
     503             : /* internal support function to get address of head element's struct */
     504             : static inline void *
     505     3333362 : dlist_head_element_off(dlist_head *head, size_t off)
     506             : {
     507             :     Assert(!dlist_is_empty(head));
     508     3333362 :     return (char *) head->head.next - off;
     509             : }
     510             : 
     511             : /*
     512             :  * Return the first node in the list (there must be one).
     513             :  */
     514             : static inline dlist_node *
     515       91706 : dlist_head_node(dlist_head *head)
     516             : {
     517       91706 :     return (dlist_node *) dlist_head_element_off(head, 0);
     518             : }
     519             : 
     520             : /* internal support function to get address of tail element's struct */
     521             : static inline void *
     522     1289364 : dlist_tail_element_off(dlist_head *head, size_t off)
     523             : {
     524             :     Assert(!dlist_is_empty(head));
     525     1289364 :     return (char *) head->head.prev - off;
     526             : }
     527             : 
     528             : /*
     529             :  * Return the last node in the list (there must be one).
     530             :  */
     531             : static inline dlist_node *
     532       49556 : dlist_tail_node(dlist_head *head)
     533             : {
     534       49556 :     return (dlist_node *) dlist_tail_element_off(head, 0);
     535             : }
     536             : 
     537             : /*
     538             :  * Return the containing struct of 'type' where 'membername' is the dlist_node
     539             :  * pointed at by 'ptr'.
     540             :  *
     541             :  * This is used to convert a dlist_node * back to its containing struct.
     542             :  */
     543             : #define dlist_container(type, membername, ptr)                              \
     544             :     (AssertVariableIsOfTypeMacro(ptr, dlist_node *),                        \
     545             :      AssertVariableIsOfTypeMacro(((type *) NULL)->membername, dlist_node),   \
     546             :      ((type *) ((char *) (ptr) - offsetof(type, membername))))
     547             : 
     548             : /*
     549             :  * Return the address of the first element in the list.
     550             :  *
     551             :  * The list must not be empty.
     552             :  */
     553             : #define dlist_head_element(type, membername, lhead)                         \
     554             :     (AssertVariableIsOfTypeMacro(((type *) NULL)->membername, dlist_node),   \
     555             :      (type *) dlist_head_element_off(lhead, offsetof(type, membername)))
     556             : 
     557             : /*
     558             :  * Return the address of the last element in the list.
     559             :  *
     560             :  * The list must not be empty.
     561             :  */
     562             : #define dlist_tail_element(type, membername, lhead)                         \
     563             :     (AssertVariableIsOfTypeMacro(((type *) NULL)->membername, dlist_node),   \
     564             :      ((type *) dlist_tail_element_off(lhead, offsetof(type, membername))))
     565             : 
     566             : /*
     567             :  * Iterate through the list pointed at by 'lhead' storing the state in 'iter'.
     568             :  *
     569             :  * Access the current element with iter.cur.
     570             :  *
     571             :  * It is *not* allowed to manipulate the list during iteration.
     572             :  */
     573             : #define dlist_foreach(iter, lhead)                                          \
     574             :     for (AssertVariableIsOfTypeMacro(iter, dlist_iter),                     \
     575             :          AssertVariableIsOfTypeMacro(lhead, dlist_head *),                  \
     576             :          (iter).end = &(lhead)->head,                                        \
     577             :          (iter).cur = (iter).end->next ? (iter).end->next : (iter).end;       \
     578             :          (iter).cur != (iter).end;                                          \
     579             :          (iter).cur = (iter).cur->next)
     580             : 
     581             : /*
     582             :  * Iterate through the list pointed at by 'lhead' storing the state in 'iter'.
     583             :  *
     584             :  * Access the current element with iter.cur.
     585             :  *
     586             :  * Iterations using this are only allowed to change the list at the current
     587             :  * point of iteration. It is fine to delete the current node, but it is *not*
     588             :  * fine to insert or delete adjacent nodes.
     589             :  */
     590             : #define dlist_foreach_modify(iter, lhead)                                   \
     591             :     for (AssertVariableIsOfTypeMacro(iter, dlist_mutable_iter),             \
     592             :          AssertVariableIsOfTypeMacro(lhead, dlist_head *),                  \
     593             :          (iter).end = &(lhead)->head,                                        \
     594             :          (iter).cur = (iter).end->next ? (iter).end->next : (iter).end,       \
     595             :          (iter).next = (iter).cur->next;                                 \
     596             :          (iter).cur != (iter).end;                                          \
     597             :          (iter).cur = (iter).next, (iter).next = (iter).cur->next)
     598             : 
     599             : /*
     600             :  * Iterate through the list in reverse order.
     601             :  *
     602             :  * It is *not* allowed to manipulate the list during iteration.
     603             :  */
     604             : #define dlist_reverse_foreach(iter, lhead)                                  \
     605             :     for (AssertVariableIsOfTypeMacro(iter, dlist_iter),                     \
     606             :          AssertVariableIsOfTypeMacro(lhead, dlist_head *),                  \
     607             :          (iter).end = &(lhead)->head,                                        \
     608             :          (iter).cur = (iter).end->prev ? (iter).end->prev : (iter).end;       \
     609             :          (iter).cur != (iter).end;                                          \
     610             :          (iter).cur = (iter).cur->prev)
     611             : 
     612             : /* doubly-linked count list implementation */
     613             : 
     614             : /*
     615             :  * dclist_init
     616             :  *      Initialize a doubly linked count list.
     617             :  *
     618             :  * Previous state will be thrown away without any cleanup.
     619             :  */
     620             : static inline void
     621     1469022 : dclist_init(dclist_head *head)
     622             : {
     623     1469022 :     dlist_init(&head->dlist);
     624     1469022 :     head->count = 0;
     625     1469022 : }
     626             : 
     627             : /*
     628             :  * dclist_is_empty
     629             :  *      Returns true if the list is empty, otherwise false.
     630             :  */
     631             : static inline bool
     632             : dclist_is_empty(dclist_head *head)
     633             : {
     634             :     Assert(dlist_is_empty(&head->dlist) == (head->count == 0));
     635             :     return (head->count == 0);
     636             : }
     637             : 
     638             : /*
     639             :  * dclist_push_head
     640             :  *      Insert a node at the beginning of the list.
     641             :  */
     642             : static inline void
     643         982 : dclist_push_head(dclist_head *head, dlist_node *node)
     644             : {
     645         982 :     if (head->dlist.head.next == NULL)   /* convert NULL header to circular */
     646           0 :         dclist_init(head);
     647             : 
     648         982 :     dlist_push_head(&head->dlist, node);
     649         982 :     head->count++;
     650             : 
     651             :     Assert(head->count > 0);  /* count overflow check */
     652         982 : }
     653             : 
     654             : /*
     655             :  * dclist_push_tail
     656             :  *      Insert a node at the end of the list.
     657             :  */
     658             : static inline void
     659      395198 : dclist_push_tail(dclist_head *head, dlist_node *node)
     660             : {
     661      395198 :     if (head->dlist.head.next == NULL)   /* convert NULL header to circular */
     662         408 :         dclist_init(head);
     663             : 
     664      395198 :     dlist_push_tail(&head->dlist, node);
     665      395198 :     head->count++;
     666             : 
     667             :     Assert(head->count > 0);  /* count overflow check */
     668      395198 : }
     669             : 
     670             : /*
     671             :  * dclist_insert_after
     672             :  *      Insert a node after another *in the same list*
     673             :  *
     674             :  * Caution: 'after' must be a member of 'head'.
     675             :  */
     676             : static inline void
     677             : dclist_insert_after(dclist_head *head, dlist_node *after, dlist_node *node)
     678             : {
     679             :     dlist_member_check(&head->dlist, after);
     680             :     Assert(head->count > 0);  /* must be at least 1 already */
     681             : 
     682             :     dlist_insert_after(after, node);
     683             :     head->count++;
     684             : 
     685             :     Assert(head->count > 0);  /* count overflow check */
     686             : }
     687             : 
     688             : /*
     689             :  * dclist_insert_before
     690             :  *      Insert a node before another *in the same list*
     691             :  *
     692             :  * Caution: 'before' must be a member of 'head'.
     693             :  */
     694             : static inline void
     695             : dclist_insert_before(dclist_head *head, dlist_node *before, dlist_node *node)
     696             : {
     697             :     dlist_member_check(&head->dlist, before);
     698             :     Assert(head->count > 0);  /* must be at least 1 already */
     699             : 
     700             :     dlist_insert_before(before, node);
     701             :     head->count++;
     702             : 
     703             :     Assert(head->count > 0);  /* count overflow check */
     704             : }
     705             : 
     706             : /*
     707             :  * dclist_delete_from
     708             :  *      Deletes 'node' from 'head'.
     709             :  *
     710             :  * Caution: 'node' must be a member of 'head'.
     711             :  */
     712             : static inline void
     713      393754 : dclist_delete_from(dclist_head *head, dlist_node *node)
     714             : {
     715             :     Assert(head->count > 0);
     716             : 
     717      393754 :     dlist_delete_from(&head->dlist, node);
     718      393754 :     head->count--;
     719      393754 : }
     720             : 
     721             : /*
     722             :  * dclist_pop_head_node
     723             :  *      Remove and return the first node from a list (there must be one).
     724             :  */
     725             : static inline dlist_node *
     726             : dclist_pop_head_node(dclist_head *head)
     727             : {
     728             :     dlist_node *node;
     729             : 
     730             :     Assert(head->count > 0);
     731             : 
     732             :     node = dlist_pop_head_node(&head->dlist);
     733             :     head->count--;
     734             :     return node;
     735             : }
     736             : 
     737             : /*
     738             :  * dclist_move_head
     739             :  *      Move 'node' from its current position in the list to the head position
     740             :  *      in 'head'.
     741             :  *
     742             :  * Caution: 'node' must be a member of 'head'.
     743             :  */
     744             : static inline void
     745        5496 : dclist_move_head(dclist_head *head, dlist_node *node)
     746             : {
     747             :     dlist_member_check(&head->dlist, node);
     748             :     Assert(head->count > 0);
     749             : 
     750        5496 :     dlist_move_head(&head->dlist, node);
     751        5496 : }
     752             : 
     753             : /*
     754             :  * dclist_move_tail
     755             :  *      Move 'node' from its current position in the list to the tail position
     756             :  *      in 'head'.
     757             :  *
     758             :  * Caution: 'node' must be a member of 'head'.
     759             :  */
     760             : static inline void
     761             : dclist_move_tail(dclist_head *head, dlist_node *node)
     762             : {
     763             :     dlist_member_check(&head->dlist, node);
     764             :     Assert(head->count > 0);
     765             : 
     766             :     dlist_move_tail(&head->dlist, node);
     767             : }
     768             : 
     769             : /*
     770             :  * dclist_has_next
     771             :  *      Check whether 'node' has a following node.
     772             :  *
     773             :  * Caution: 'node' must be a member of 'head'.
     774             :  */
     775             : static inline bool
     776             : dclist_has_next(dclist_head *head, dlist_node *node)
     777             : {
     778             :     dlist_member_check(&head->dlist, node);
     779             :     Assert(head->count > 0);
     780             : 
     781             :     return dlist_has_next(&head->dlist, node);
     782             : }
     783             : 
     784             : /*
     785             :  * dclist_has_prev
     786             :  *      Check whether 'node' has a preceding node.
     787             :  *
     788             :  * Caution: 'node' must be a member of 'head'.
     789             :  */
     790             : static inline bool
     791             : dclist_has_prev(dclist_head *head, dlist_node *node)
     792             : {
     793             :     dlist_member_check(&head->dlist, node);
     794             :     Assert(head->count > 0);
     795             : 
     796             :     return dlist_has_prev(&head->dlist, node);
     797             : }
     798             : 
     799             : /*
     800             :  * dclist_next_node
     801             :  *      Return the next node in the list (there must be one).
     802             :  */
     803             : static inline dlist_node *
     804             : dclist_next_node(dclist_head *head, dlist_node *node)
     805             : {
     806             :     Assert(head->count > 0);
     807             : 
     808             :     return dlist_next_node(&head->dlist, node);
     809             : }
     810             : 
     811             : /*
     812             :  * dclist_prev_node
     813             :  *      Return the prev node in the list (there must be one).
     814             :  */
     815             : static inline dlist_node *
     816             : dclist_prev_node(dclist_head *head, dlist_node *node)
     817             : {
     818             :     Assert(head->count > 0);
     819             : 
     820             :     return dlist_prev_node(&head->dlist, node);
     821             : }
     822             : 
     823             : /* internal support function to get address of head element's struct */
     824             : static inline void *
     825             : dclist_head_element_off(dclist_head *head, size_t off)
     826             : {
     827             :     Assert(!dclist_is_empty(head));
     828             : 
     829             :     return (char *) head->dlist.head.next - off;
     830             : }
     831             : 
     832             : /*
     833             :  * dclist_head_node
     834             :  *      Return the first node in the list (there must be one).
     835             :  */
     836             : static inline dlist_node *
     837             : dclist_head_node(dclist_head *head)
     838             : {
     839             :     Assert(head->count > 0);
     840             : 
     841             :     return (dlist_node *) dlist_head_element_off(&head->dlist, 0);
     842             : }
     843             : 
     844             : /* internal support function to get address of tail element's struct */
     845             : static inline void *
     846             : dclist_tail_element_off(dclist_head *head, size_t off)
     847             : {
     848             :     Assert(!dclist_is_empty(head));
     849             : 
     850             :     return (char *) head->dlist.head.prev - off;
     851             : }
     852             : 
     853             : /*
     854             :  * Return the last node in the list (there must be one).
     855             :  */
     856             : static inline dlist_node *
     857           0 : dclist_tail_node(dclist_head *head)
     858             : {
     859             :     Assert(head->count > 0);
     860             : 
     861           0 :     return (dlist_node *) dlist_tail_element_off(&head->dlist, 0);
     862             : }
     863             : 
     864             : /*
     865             :  * dclist_count
     866             :  *      Returns the stored number of entries in 'head'
     867             :  */
     868             : static inline uint32
     869     1140700 : dclist_count(dclist_head *head)
     870             : {
     871             :     Assert(dlist_is_empty(&head->dlist) == (head->count == 0));
     872             : 
     873     1140700 :     return head->count;
     874             : }
     875             : 
     876             : /*
     877             :  * Return the containing struct of 'type' where 'membername' is the dlist_node
     878             :  * pointed at by 'ptr'.
     879             :  *
     880             :  * This is used to convert a dlist_node * back to its containing struct.
     881             :  *
     882             :  * Note: This is effectively just the same as dlist_container, so reuse that.
     883             :  */
     884             : #define dclist_container(type, membername, ptr) \
     885             :         dlist_container(type, membername, ptr)
     886             : 
     887             :  /*
     888             :   * Return the address of the first element in the list.
     889             :   *
     890             :   * The list must not be empty.
     891             :   */
     892             : #define dclist_head_element(type, membername, lhead)                            \
     893             :     (AssertVariableIsOfTypeMacro(((type *) NULL)->membername, dlist_node),   \
     894             :      (type *) dclist_head_element_off(lhead, offsetof(type, membername)))
     895             : 
     896             :  /*
     897             :   * Return the address of the last element in the list.
     898             :   *
     899             :   * The list must not be empty.
     900             :   */
     901             : #define dclist_tail_element(type, membername, lhead)                            \
     902             :     (AssertVariableIsOfTypeMacro(((type *) NULL)->membername, dlist_node),   \
     903             :      ((type *) dclist_tail_element_off(lhead, offsetof(type, membername))))
     904             : 
     905             : 
     906             : /* Iterators for dclists */
     907             : #define dclist_foreach(iter, lhead) \
     908             :     dlist_foreach(iter, &((lhead)->dlist))
     909             : 
     910             : #define dclist_foreach_modify(iter, lhead) \
     911             :     dlist_foreach_modify(iter, &((lhead)->dlist))
     912             : 
     913             : #define dclist_reverse_foreach(iter, lhead) \
     914             :     dlist_reverse_foreach(iter, &((lhead)->dlist))
     915             : 
     916             : /* singly linked list implementation */
     917             : 
     918             : /*
     919             :  * Initialize a singly linked list.
     920             :  * Previous state will be thrown away without any cleanup.
     921             :  */
     922             : static inline void
     923      148974 : slist_init(slist_head *head)
     924             : {
     925      148974 :     head->head.next = NULL;
     926      148974 : }
     927             : 
     928             : /*
     929             :  * Is the list empty?
     930             :  */
     931             : static inline bool
     932       45368 : slist_is_empty(slist_head *head)
     933             : {
     934             :     slist_check(head);
     935             : 
     936       45368 :     return head->head.next == NULL;
     937             : }
     938             : 
     939             : /*
     940             :  * Insert a node at the beginning of the list.
     941             :  */
     942             : static inline void
     943     2091842 : slist_push_head(slist_head *head, slist_node *node)
     944             : {
     945     2091842 :     node->next = head->head.next;
     946     2091842 :     head->head.next = node;
     947             : 
     948             :     slist_check(head);
     949     2091842 : }
     950             : 
     951             : /*
     952             :  * Insert a node after another *in the same list*
     953             :  */
     954             : static inline void
     955             : slist_insert_after(slist_node *after, slist_node *node)
     956             : {
     957             :     node->next = after->next;
     958             :     after->next = node;
     959             : }
     960             : 
     961             : /*
     962             :  * Remove and return the first node from a list (there must be one).
     963             :  */
     964             : static inline slist_node *
     965       14170 : slist_pop_head_node(slist_head *head)
     966             : {
     967             :     slist_node *node;
     968             : 
     969             :     Assert(!slist_is_empty(head));
     970       14170 :     node = head->head.next;
     971       14170 :     head->head.next = node->next;
     972             :     slist_check(head);
     973       14170 :     return node;
     974             : }
     975             : 
     976             : /*
     977             :  * Check whether 'node' has a following node.
     978             :  */
     979             : static inline bool
     980             : slist_has_next(slist_head *head, slist_node *node)
     981             : {
     982             :     slist_check(head);
     983             : 
     984             :     return node->next != NULL;
     985             : }
     986             : 
     987             : /*
     988             :  * Return the next node in the list (there must be one).
     989             :  */
     990             : static inline slist_node *
     991             : slist_next_node(slist_head *head, slist_node *node)
     992             : {
     993             :     Assert(slist_has_next(head, node));
     994             :     return node->next;
     995             : }
     996             : 
     997             : /* internal support function to get address of head element's struct */
     998             : static inline void *
     999             : slist_head_element_off(slist_head *head, size_t off)
    1000             : {
    1001             :     Assert(!slist_is_empty(head));
    1002             :     return (char *) head->head.next - off;
    1003             : }
    1004             : 
    1005             : /*
    1006             :  * Return the first node in the list (there must be one).
    1007             :  */
    1008             : static inline slist_node *
    1009             : slist_head_node(slist_head *head)
    1010             : {
    1011             :     return (slist_node *) slist_head_element_off(head, 0);
    1012             : }
    1013             : 
    1014             : /*
    1015             :  * Delete the list element the iterator currently points to.
    1016             :  *
    1017             :  * Caution: this modifies iter->cur, so don't use that again in the current
    1018             :  * loop iteration.
    1019             :  */
    1020             : static inline void
    1021      294230 : slist_delete_current(slist_mutable_iter *iter)
    1022             : {
    1023             :     /*
    1024             :      * Update previous element's forward link.  If the iteration is at the
    1025             :      * first list element, iter->prev will point to the list header's "head"
    1026             :      * field, so we don't need a special case for that.
    1027             :      */
    1028      294230 :     iter->prev->next = iter->next;
    1029             : 
    1030             :     /*
    1031             :      * Reset cur to prev, so that prev will continue to point to the prior
    1032             :      * valid list element after slist_foreach_modify() advances to the next.
    1033             :      */
    1034      294230 :     iter->cur = iter->prev;
    1035      294230 : }
    1036             : 
    1037             : /*
    1038             :  * Return the containing struct of 'type' where 'membername' is the slist_node
    1039             :  * pointed at by 'ptr'.
    1040             :  *
    1041             :  * This is used to convert a slist_node * back to its containing struct.
    1042             :  */
    1043             : #define slist_container(type, membername, ptr)                              \
    1044             :     (AssertVariableIsOfTypeMacro(ptr, slist_node *),                        \
    1045             :      AssertVariableIsOfTypeMacro(((type *) NULL)->membername, slist_node),   \
    1046             :      ((type *) ((char *) (ptr) - offsetof(type, membername))))
    1047             : 
    1048             : /*
    1049             :  * Return the address of the first element in the list.
    1050             :  *
    1051             :  * The list must not be empty.
    1052             :  */
    1053             : #define slist_head_element(type, membername, lhead)                         \
    1054             :     (AssertVariableIsOfTypeMacro(((type *) NULL)->membername, slist_node),   \
    1055             :      (type *) slist_head_element_off(lhead, offsetof(type, membername)))
    1056             : 
    1057             : /*
    1058             :  * Iterate through the list pointed at by 'lhead' storing the state in 'iter'.
    1059             :  *
    1060             :  * Access the current element with iter.cur.
    1061             :  *
    1062             :  * It's allowed to modify the list while iterating, with the exception of
    1063             :  * deleting the iterator's current node; deletion of that node requires
    1064             :  * care if the iteration is to be continued afterward.  (Doing so and also
    1065             :  * deleting or inserting adjacent list elements might misbehave; also, if
    1066             :  * the user frees the current node's storage, continuing the iteration is
    1067             :  * not safe.)
    1068             :  */
    1069             : #define slist_foreach(iter, lhead)                                          \
    1070             :     for (AssertVariableIsOfTypeMacro(iter, slist_iter),                     \
    1071             :          AssertVariableIsOfTypeMacro(lhead, slist_head *),                  \
    1072             :          (iter).cur = (lhead)->head.next;                                    \
    1073             :          (iter).cur != NULL;                                                \
    1074             :          (iter).cur = (iter).cur->next)
    1075             : 
    1076             : /*
    1077             :  * Iterate through the list pointed at by 'lhead' storing the state in 'iter'.
    1078             :  *
    1079             :  * Access the current element with iter.cur.
    1080             :  *
    1081             :  * The only list modification allowed while iterating is to remove the current
    1082             :  * node via slist_delete_current() (*not* slist_delete()).  Insertion or
    1083             :  * deletion of nodes adjacent to the current node would misbehave.
    1084             :  */
    1085             : #define slist_foreach_modify(iter, lhead)                                   \
    1086             :     for (AssertVariableIsOfTypeMacro(iter, slist_mutable_iter),             \
    1087             :          AssertVariableIsOfTypeMacro(lhead, slist_head *),                  \
    1088             :          (iter).prev = &(lhead)->head,                                       \
    1089             :          (iter).cur = (iter).prev->next,                                 \
    1090             :          (iter).next = (iter).cur ? (iter).cur->next : NULL;             \
    1091             :          (iter).cur != NULL;                                                \
    1092             :          (iter).prev = (iter).cur,                                          \
    1093             :          (iter).cur = (iter).next,                                          \
    1094             :          (iter).next = (iter).next ? (iter).next->next : NULL)
    1095             : 
    1096             : #endif                          /* ILIST_H */

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