queue(3)

NAME

SLIST_EMPTY, SLIST_ENTRY, SLIST_FIRST, SLIST_FOREACH,

SLIST_FOREACH_SAFE

SLIST_HEAD, SLIST_HEAD_INITIALIZER, SLIST_INIT,

SLIST_INSERT_AFTER

SLIST_INSERT_HEAD, SLIST_NEXT, SLIST_REMOVE_HEAD,

SLIST_REMOVE

STAILQ_CONCAT, STAILQ_EMPTY, STAILQ_ENTRY, STAILQ_FIRST,

STAILQ_FOREACH

STAILQ_FOREACH_SAFE, STAILQ_HEAD, STAILQ_HEAD_INITIALIZER,

STAILQ_INIT

STAILQ_INSERT_AFTER, STAILQ_INSERT_HEAD, STAILQ_INSERT_TAIL,

STAILQ_LAST

STAILQ_NEXT, STAILQ_REMOVE_HEAD, STAILQ_REMOVE, LIST_EMPTY,

LIST_ENTRY

LIST_FIRST, LIST_FOREACH, LIST_FOREACH_SAFE, LIST_HEAD, LIST_HEAD_INITIALIZER, LIST_INIT, LIST_INSERT_AFTER,

LIST_INSERT_BEFORE

LIST_INSERT_HEAD, LIST_NEXT, LIST_REMOVE, TAILQ_CONCAT,

TAILQ_EMPTY

TAILQ_ENTRY, TAILQ_FIRST, TAILQ_FOREACH, TAILQ_FOREACH_SAFE, TAILQ_FOREACH_REVERSE, TAILQ_FOREACH_REVERSE_SAFE,

TAILQ_HEAD

TAILQ_HEAD_INITIALIZER, TAILQ_INIT, TAILQ_INSERT_AFTER, TAILQ_INSERT_BEFORE, TAILQ_INSERT_HEAD, TAILQ_INSERT_TAIL,

TAILQ_LAST

TAILQ_NEXT, TAILQ_PREV, TAILQ_REMOVE - implementations of
singly-linked lists, singly-linked tail queues, lists and tail queues

SYNOPSIS

#include <sys/queue.h>
SLIST_EMPTY(SLIST_HEAD *head);
SLIST_ENTRY(TYPE);
SLIST_FIRST(SLIST_HEAD *head);
SLIST_FOREACH(TYPE   *var,   SLIST_HEAD  *head,  SLIST_ENTRY
NAME);
SLIST_FOREACH_SAFE(TYPE *var, SLIST_HEAD *head,  SLIST_ENTRY
NAME,
        TYPE *temp_var);
SLIST_HEAD(HEADNAME, TYPE);
SLIST_HEAD_INITIALIZER(SLIST_HEAD head);
SLIST_INIT(SLIST_HEAD *head);
SLIST_INSERT_AFTER(TYPE  *listelm,  TYPE  *elm,  SLIST_ENTRY
NAME);
SLIST_INSERT_HEAD(SLIST_HEAD *head, TYPE  *elm,  SLIST_ENTRY
NAME);
SLIST_NEXT(TYPE *elm, SLIST_ENTRY NAME);
SLIST_REMOVE_HEAD(SLIST_HEAD *head, SLIST_ENTRY NAME);
SLIST_REMOVE(SLIST_HEAD  *head, TYPE *elm, TYPE, SLIST_ENTRY
NAME);
STAILQ_CONCAT(STAILQ_HEAD *head1, STAILQ_HEAD *head2);
STAILQ_EMPTY(STAILQ_HEAD *head);
STAILQ_ENTRY(TYPE);
STAILQ_FIRST(STAILQ_HEAD *head);
STAILQ_FOREACH(TYPE *var,  STAILQ_HEAD  *head,  STAILQ_ENTRY
NAME);
STAILQ_FOREACH_SAFE(TYPE     *var,     STAILQ_HEAD    *head,
STAILQ_ENTRY NAME,
        TYPE *temp_var);
STAILQ_HEAD(HEADNAME, TYPE);
STAILQ_HEAD_INITIALIZER(STAILQ_HEAD head);
STAILQ_INIT(STAILQ_HEAD *head);
STAILQ_INSERT_AFTER(STAILQ_HEAD *head, TYPE  *listelm,  TYPE
*elm,
        STAILQ_ENTRY NAME);
STAILQ_INSERT_HEAD(STAILQ_HEAD     *head,     TYPE     *elm,
STAILQ_ENTRY NAME);
STAILQ_INSERT_TAIL(STAILQ_HEAD     *head,     TYPE     *elm,
STAILQ_ENTRY NAME);
STAILQ_LAST(STAILQ_HEAD *head, TYPE, STAILQ_ENTRY NAME);
STAILQ_NEXT(TYPE *elm, STAILQ_ENTRY NAME);
STAILQ_REMOVE_HEAD(STAILQ_HEAD *head, STAILQ_ENTRY NAME);
STAILQ_REMOVE(STAILQ_HEAD    *head,    TYPE    *elm,   TYPE,
STAILQ_ENTRY NAME);
LIST_EMPTY(LIST_HEAD *head);
LIST_ENTRY(TYPE);
LIST_FIRST(LIST_HEAD *head);
LIST_FOREACH(TYPE *var, LIST_HEAD *head, LIST_ENTRY NAME);
LIST_FOREACH_SAFE(TYPE  *var,  LIST_HEAD  *head,  LIST_ENTRY
NAME,
        TYPE *temp_var);
LIST_HEAD(HEADNAME, TYPE);
LIST_HEAD_INITIALIZER(LIST_HEAD head);
LIST_INIT(LIST_HEAD *head);
LIST_INSERT_AFTER(TYPE   *listelm,   TYPE  *elm,  LIST_ENTRY
NAME);
LIST_INSERT_BEFORE(TYPE  *listelm,  TYPE  *elm,   LIST_ENTRY
NAME);
LIST_INSERT_HEAD(LIST_HEAD   *head,  TYPE  *elm,  LIST_ENTRY
NAME);
LIST_NEXT(TYPE *elm, LIST_ENTRY NAME);
LIST_REMOVE(TYPE *elm, LIST_ENTRY NAME);
TAILQ_CONCAT(TAILQ_HEAD    *head1,    TAILQ_HEAD     *head2,
TAILQ_ENTRY NAME);
TAILQ_EMPTY(TAILQ_HEAD *head);
TAILQ_ENTRY(TYPE);
TAILQ_FIRST(TAILQ_HEAD *head);
TAILQ_FOREACH(TYPE   *var,   TAILQ_HEAD  *head,  TAILQ_ENTRY
NAME);
TAILQ_FOREACH_SAFE(TYPE *var, TAILQ_HEAD *head,  TAILQ_ENTRY
NAME,
        TYPE *temp_var);
TAILQ_FOREACH_REVERSE(TYPE *var, TAILQ_HEAD *head, HEADNAME,
        TAILQ_ENTRY NAME);
TAILQ_FOREACH_REVERSE_SAFE(TYPE  *var,   TAILQ_HEAD   *head,
HEADNAME,
        TAILQ_ENTRY NAME, TYPE *temp_var);
TAILQ_HEAD(HEADNAME, TYPE);
TAILQ_HEAD_INITIALIZER(TAILQ_HEAD head);
TAILQ_INIT(TAILQ_HEAD *head);
TAILQ_INSERT_AFTER(TAILQ_HEAD  *head,  TYPE  *listelm,  TYPE
*elm,
        TAILQ_ENTRY NAME);
TAILQ_INSERT_BEFORE(TYPE *listelm,  TYPE  *elm,  TAILQ_ENTRY
NAME);
TAILQ_INSERT_HEAD(TAILQ_HEAD  *head,  TYPE *elm, TAILQ_ENTRY
NAME);
TAILQ_INSERT_TAIL(TAILQ_HEAD *head, TYPE  *elm,  TAILQ_ENTRY
NAME);
TAILQ_LAST(TAILQ_HEAD *head, HEADNAME);
TAILQ_NEXT(TYPE *elm, TAILQ_ENTRY NAME);
TAILQ_PREV(TYPE *elm, HEADNAME, TAILQ_ENTRY NAME);
TAILQ_REMOVE(TAILQ_HEAD *head, TYPE *elm, TAILQ_ENTRY NAME);

DESCRIPTION

These macros define and operate on four types of data struc
tures: singlylinked lists, singly-linked tail queues, lists, and tail
queues. All four structures support the following functionality: 1. Insertion of a new entry at the head of the list. 2. Insertion of a new entry after any element in the
list. 3. O(1) removal of an entry from the head of the
list. 4. O(n) removal of any entry in the list. 5. Forward traversal through the list.
Singly-linked lists are the simplest of the four data struc
tures and support only the above functionality. Singly-linked lists are
ideal for applications with large datasets and few or no removals, or
for implementing a LIFO queue.
Singly-linked tail queues add the following functionality: 1. Entries can be added at the end of a list. 2. They may be concatenated.
However: 1. All list insertions must specify the head of the
list. 2. Each head entry requires two pointers rather than
one. 3. Code size is about 15% greater and operations run
about 20% slower than singly-linked lists.
Singly-linked tailqs are ideal for applications with large
datasets and few or no removals, or for implementing a FIFO queue.
All doubly linked types of data structures (lists and tail
queues) additionally allow: 1. Insertion of a new entry before any element in
the list. 2. O(1) removal of any entry in the list.
However: 1. Each elements requires two pointers rather than
one. 2. Code size and execution time of operations (ex
cept for removal) is about twice that of the singly-linked
data-structures.
Linked lists are the simplest of the doubly linked data
structures and support only the above functionality over singly-linked
lists.
Tail queues add the following functionality: 1. Entries can be added at the end of a list. 2. They may be traversed backwards, from tail to
head. 3. They may be concatenated.
However: 1. All list insertions and removals must specify the
head of the list.
2. Each head entry requires two pointers rather than
one. 3. Code size is about 15% greater and operations run
about 20% slower than singly-linked lists.
In the macro definitions, TYPE is the name of a user defined
structure, that must contain a field of type SLIST_ENTRY, STAILQ_ENTRY,
LIST_ENTRY, or TAILQ_ENTRY, named NAME. The argument HEADNAME is the
name of a user defined structure that must be declared using the macros
SLIST_HEAD, STAILQ_HEAD, LIST_HEAD, or TAILQ_HEAD. See the examples be
low for further explanation of how these macros are used.

SINGLY-LINKED LISTS

A singly-linked list is headed by a structure defined by the

SLIST_HEAD

macro. This structure contains a single pointer to the
first element on the list. The elements are singly linked for minimum space
and pointer manipulation overhead at the expense of O(n) removal for ar
bitrary elements. New elements can be added to the list after an ex
isting element
or at the head of the list. An SLIST_HEAD structure is de
clared as follows:: SLIST_HEAD(HEADNAME, TYPE) head;
where HEADNAME is the name of the structure to be defined,
and TYPE is the type of the elements to be linked into the list. A
pointer to the head of the list can later be declared as:: struct HEADNAME *headp;
(The names head and headp are user selectable.)
The macro SLIST_HEAD_INITIALIZER evaluates to an initializer
for the list head.
The macro SLIST_EMPTY evaluates to true if there are no ele
ments in the list.
The macro SLIST_ENTRY declares a structure that connects the
elements in the list.
The macro SLIST_FIRST returns the first element in the list
or NULL if the list is empty.
The macro SLIST_FOREACH traverses the list referenced by
head in the forward direction, assigning each element in turn to var.
The macro SLIST_FOREACH_SAFE traverses the list referenced
by head in the forward direction, assigning each element in turn to var.
However,
unlike SLIST_FOREACH() here it is permitted to both remove
var as well as free it from within the loop safely without interfering with
the traversal.
The macro SLIST_INIT initializes the list referenced by
head.
The macro SLIST_INSERT_HEAD inserts the new element elm at
the head of the list.
The macro SLIST_INSERT_AFTER inserts the new element elm af
ter the element listelm.
The macro SLIST_NEXT returns the next element in the list.
The macro SLIST_REMOVE_HEAD removes the element elm from the
head of the list. For optimum efficiency, elements being removed from
the head of the list should explicitly use this macro instead of the
generic
SLIST_REMOVE macro.
The macro SLIST_REMOVE removes the element elm from the
list.

SINGLY-LINKED LIST EXAMPLE

SLIST_HEAD(slisthead, entry) head =: SLIST_HEAD_INITIALIZER(head);
struct slisthead *headp; /* Singly-linked
List head. */ struct entry { ... SLIST_ENTRY(entry) entries; /* Singly-linked
List. */ ...
} *n1, *n2, *n3, *np;
SLIST_INIT(&head); /* Initialize the
list. */
n1 = malloc(sizeof(struct entry)); /* Insert at the
head. */ SLIST_INSERT_HEAD(&head, n1, entries);
n2 = malloc(sizeof(struct entry)); /* Insert after. */ SLIST_INSERT_AFTER(n1, n2, entries);
SLIST_REMOVE(&head, n2, entry, entries);/* Deletion. */ free(n2);
n3 = SLIST_FIRST(&head); SLIST_REMOVE_HEAD(&head, entries); /* Deletion from the
head. */ free(n3);/* Forward traver
sal. */
SLIST_FOREACH(np, &head, entries) np-> ... /* Safe forward
traversal. */
SLIST_FOREACH_SAFE(np, &head, entries, np_temp) { np->do_stuff(); ... SLIST_REMOVE(&head, np, entry, entries); free(np);
}
while (!SLIST_EMPTY(&head)) { /* List Deletion. */ n1 = SLIST_FIRST(&head); SLIST_REMOVE_HEAD(&head, entries); free(n1);
}

SINGLY-LINKED TAIL QUEUES

A singly-linked tail queue is headed by a structure defined
by the
STAILQ_HEAD macro. This structure contains a pair of point
ers, one to the first element in the tail queue and the other to the
last element in the tail queue. The elements are singly linked for minimum
space and pointer manipulation overhead at the expense of O(n) removal
for arbitrary elements. New elements can be added to the tail queue
after an existing element, at the head of the tail queue, or at the
end of the
tail queue. A STAILQ_HEAD structure is declared as follows:: STAILQ_HEAD(HEADNAME, TYPE) head;
where HEADNAME is the name of the structure to be defined,
and TYPE is the type of the elements to be linked into the tail queue.
A pointer to the head of the tail queue can later be declared as:: struct HEADNAME *headp;
(The names head and headp are user selectable.)
The macro STAILQ_HEAD_INITIALIZER evaluates to an initializ
er for the tail queue head.
The macro STAILQ_CONCAT concatenates the tail queue headed
by head2 onto the end of the one headed by head1 removing all entries from
the former.
The macro STAILQ_EMPTY evaluates to true if there are no
items on the tail queue.
The macro STAILQ_ENTRY declares a structure that connects
the elements in the tail queue.
The macro STAILQ_FIRST returns the first item on the tail
queue or NULL if the tail queue is empty.
The macro STAILQ_FOREACH traverses the tail queue referenced
by head in the forward direction, assigning each element in turn to
var.
The macro STAILQ_FOREACH_SAFE traverses the tail queue ref
erenced by head in the forward direction, assigning each element in turn to
var. However, unlike STAILQ_FOREACH() here it is permitted to both
remove var as well as free it from within the loop safely without inter
fering with the traversal.
The macro STAILQ_INIT initializes the tail queue referenced
by head.
The macro STAILQ_INSERT_HEAD inserts the new element elm at
the head of the tail queue.
The macro STAILQ_INSERT_TAIL inserts the new element elm at
the end of the tail queue.
The macro STAILQ_INSERT_AFTER inserts the new element elm
after the element listelm.
The macro STAILQ_LAST returns the last item on the tail
queue. If the tail queue is empty the return value is undefined.
The macro STAILQ_NEXT returns the next item on the tail
queue, or NULL this item is the last.
The macro STAILQ_REMOVE_HEAD removes the element at the head
of the tail queue. For optimum efficiency, elements being removed from
the head of the tail queue should use this macro explicitly rather than
the generic
STAILQ_REMOVE macro.
The macro STAILQ_REMOVE removes the element elm from the
tail queue.

SINGLY-LINKED TAIL QUEUE EXAMPLE

STAILQ_HEAD(stailhead, entry) head =: STAILQ_HEAD_INITIALIZER(head);
struct stailhead *headp; /* Singly-linked
tail queue head. */ struct entry { ... STAILQ_ENTRY(entry) entries; /* Tail queue. */ ...
} *n1, *n2, *n3, *np;
STAILQ_INIT(&head); /* Initialize the
queue. */
n1 = malloc(sizeof(struct entry)); /* Insert at the
head. */ STAILQ_INSERT_HEAD(&head, n1, entries);
n1 = malloc(sizeof(struct entry)); /* Insert at the
tail. */ STAILQ_INSERT_TAIL(&head, n1, entries);
n2 = malloc(sizeof(struct entry)); /* Insert after. */ STAILQ_INSERT_AFTER(&head, n1, n2, entries); /* Deletion. */
STAILQ_REMOVE(&head, n2, entry, entries); free(n2); /* Deletion from the
head. */
n3 = STAILQ_FIRST(&head); STAILQ_REMOVE_HEAD(&head, entries); free(n3);/* Forward traver
sal. */
STAILQ_FOREACH(np, &head, entries) np-> ... /* Safe forward
traversal. */
STAILQ_FOREACH_SAFE(np, &head, entries, np_temp) { np->do_stuff(); ... STAILQ_REMOVE(&head, np, entry, entries); free(np);
} /* TailQ Deletion.
*/
while (!STAILQ_EMPTY(&head)) { n1 = STAILQ_FIRST(&head); STAILQ_REMOVE_HEAD(&head, entries); free(n1);
} /* Faster TailQ
Deletion. */
n1 = STAILQ_FIRST(&head); while (n1 != NULL) { n2 = STAILQ_NEXT(n1, entries); free(n1); n1 = n2;
} STAILQ_INIT(&head);

LISTS

A list is headed by a structure defined by the LIST_HEAD
macro. This structure contains a single pointer to the first element on
the list. The elements are doubly linked so that an arbitrary element
can be removed without traversing the list. New elements can be
added to the list after an existing element, before an existing element,
or at the
head of the list. A LIST_HEAD structure is declared as fol
lows:: LIST_HEAD(HEADNAME, TYPE) head;
where HEADNAME is the name of the structure to be defined,
and TYPE is the type of the elements to be linked into the list. A
pointer to the head of the list can later be declared as:: struct HEADNAME *headp;
(The names head and headp are user selectable.)
The macro LIST_HEAD_INITIALIZER evaluates to an initializer
for the list head.
The macro LIST_EMPTY evaluates to true if there are no ele
ments in the list.
The macro LIST_ENTRY declares a structure that connects the
elements in the list.
The macro LIST_FIRST returns the first element in the list
or NULL if the list is empty.
The macro LIST_FOREACH traverses the list referenced by head
in the forward direction, assigning each element in turn to var.
The macro LIST_FOREACH_SAFE traverses the list referenced by
head in the forward direction, assigning each element in turn to var.
However,
unlike LIST_FOREACH() here it is permitted to both remove
var as well as free it from within the loop safely without interfering with
the traversal.
The macro LIST_INIT initializes the list referenced by head.
The macro LIST_INSERT_HEAD inserts the new element elm at
the head of the list.
The macro LIST_INSERT_AFTER inserts the new element elm af
ter the element listelm.
The macro LIST_INSERT_BEFORE inserts the new element elm be
fore the element listelm.
The macro LIST_NEXT returns the next element in the list, or
NULL if this is the last.
The macro LIST_REMOVE removes the element elm from the list.

LIST EXAMPLE

LIST_HEAD(listhead, entry) head =: LIST_HEAD_INITIALIZER(head);
struct listhead *headp; /* List head. */ struct entry { ... LIST_ENTRY(entry) entries; /* List. */ ...
} *n1, *n2, *n3, *np, *np_temp;
LIST_INIT(&head); /* Initialize the
list. */
n1 = malloc(sizeof(struct entry)); /* Insert at the
head. */ LIST_INSERT_HEAD(&head, n1, entries);
n2 = malloc(sizeof(struct entry)); /* Insert after. */ LIST_INSERT_AFTER(n1, n2, entries);
n3 = malloc(sizeof(struct entry)); /* Insert before. */ LIST_INSERT_BEFORE(n2, n3, entries);
LIST_REMOVE(n2, entries); /* Deletion. */ free(n2);/* Forward traver
sal. */
LIST_FOREACH(np, &head, entries) np-> ...: /* Safe forward
traversal. */
LIST_FOREACH_SAFE(np, &head, entries, np_temp) { np->do_stuff(); ... LIST_REMOVE(np, entries); free(np);
}
while (!LIST_EMPTY(&head)) { /* List Deletion. */ n1 = LIST_FIRST(&head); LIST_REMOVE(n1, entries); free(n1);
}
n1 = LIST_FIRST(&head); /* Faster List Dele
tion. */ while (n1 != NULL) { n2 = LIST_NEXT(n1, entries); free(n1); n1 = n2;
} LIST_INIT(&head);

TAIL QUEUES

A tail queue is headed by a structure defined by the

TAILQ_HEAD

This structure contains a pair of pointers, one to the first
element in the tail queue and the other to the last element in the tail
queue. The elements are doubly linked so that an arbitrary element can
be removed without traversing the tail queue. New elements can be
added to the tail queue after an existing element, before an existing element,
at the head of the tail queue, or at the end of the tail queue. A
TAILQ_HEAD structure is declared as follows:: TAILQ_HEAD(HEADNAME, TYPE) head;
where HEADNAME is the name of the structure to be defined,
and TYPE is the type of the elements to be linked into the tail queue.
A pointer to the head of the tail queue can later be declared as:: struct HEADNAME *headp;
(The names head and headp are user selectable.)
The macro TAILQ_HEAD_INITIALIZER evaluates to an initializer
for the tail queue head.
The macro TAILQ_CONCAT concatenates the tail queue headed by
head2 onto the end of the one headed by head1 removing all entries from
the former.
The macro TAILQ_EMPTY evaluates to true if there are no
items on the tail queue.
The macro TAILQ_ENTRY declares a structure that connects the
elements in the tail queue.
The macro TAILQ_FIRST returns the first item on the tail
queue or NULL if the tail queue is empty.
The macro TAILQ_FOREACH traverses the tail queue referenced
by head in the forward direction, assigning each element in turn to
var. var is set to NULL if the loop completes normally, or if there were no
elements.
The macro TAILQ_FOREACH_REVERSE traverses the tail queue
referenced by head in the reverse direction, assigning each element in
turn to var.
The macros TAILQ_FOREACH_SAFE and TAILQ_FOREACH_REVERSE_SAFE
traverse the list referenced by head in the forward or reverse direction
respectively, assigning each element in turn to var. However, unlike
their unsafe
counterparts, TAILQ_FOREACH and TAILQ_FOREACH_REVERSE permit
to both remove var as well as free it from within the loop safely
without interfering with the traversal.
The macro TAILQ_INIT initializes the tail queue referenced
by head.
The macro TAILQ_INSERT_HEAD inserts the new element elm at
the head of the tail queue.
The macro TAILQ_INSERT_TAIL inserts the new element elm at
the end of the tail queue.
The macro TAILQ_INSERT_AFTER inserts the new element elm af
ter the element listelm.
The macro TAILQ_INSERT_BEFORE inserts the new element elm
before the element listelm.
The macro TAILQ_LAST returns the last item on the tail
queue. If the tail queue is empty the return value is undefined.
The macro TAILQ_NEXT returns the next item on the tail
queue, or NULL if this item is the last.
The macro TAILQ_PREV returns the previous item on the tail
queue, or NULL if this item is the first.
The macro TAILQ_REMOVE removes the element elm from the tail
queue.

TAIL QUEUE EXAMPLE

TAILQ_HEAD(tailhead, entry) head =: TAILQ_HEAD_INITIALIZER(head);
struct tailhead *headp; /* Tail queue head.
*/ struct entry { ... TAILQ_ENTRY(entry) entries; /* Tail queue. */ ...
} *n1, *n2, *n3, *np;
TAILQ_INIT(&head); /* Initialize the
queue. */
n1 = malloc(sizeof(struct entry)); /* Insert at the
head. */ TAILQ_INSERT_HEAD(&head, n1, entries);
n1 = malloc(sizeof(struct entry)); /* Insert at the
tail. */ TAILQ_INSERT_TAIL(&head, n1, entries);
n2 = malloc(sizeof(struct entry)); /* Insert after. */ TAILQ_INSERT_AFTER(&head, n1, n2, entries);
n3 = malloc(sizeof(struct entry)); /* Insert before. */ TAILQ_INSERT_BEFORE(n2, n3, entries);
TAILQ_REMOVE(&head, n2, entries); /* Deletion. */ free(n2);/* Forward traver
sal. */
TAILQ_FOREACH(np, &head, entries) np-> ... /* Safe forward
traversal. */
TAILQ_FOREACH_SAFE(np, &head, entries, np_temp) { np->do_stuff(); ... TAILQ_REMOVE(&head, np, entries); free(np);
}/* Reverse traver
sal. */
TAILQ_FOREACH_REVERSE(np, &head, tailhead, entries) np-> ... /* TailQ Deletion.
*/
while (!TAILQ_EMPTY(&head)) { n1 = TAILQ_FIRST(&head); TAILQ_REMOVE(&head, n1, entries); free(n1);
} /* Faster TailQ
Deletion. */
n1 = TAILQ_FIRST(&head); while (n1 != NULL) { n2 = TAILQ_NEXT(n1, entries); free(n1); n1 = n2;
} TAILQ_INIT(&head);

HISTORY

The queue functions first appeared in 4.4BSD.
BSD January 24, 1994

docs.sk

comprehensive documentation repository

Most Viewed

queue(3)

NAME

SLIST_FOREACH_SAFE

SLIST_INSERT_AFTER

SLIST_REMOVE

STAILQ_FOREACH

STAILQ_INIT

STAILQ_LAST

LIST_ENTRY

LIST_INSERT_BEFORE

TAILQ_EMPTY

TAILQ_HEAD

TAILQ_LAST

SYNOPSIS

DESCRIPTION

SINGLY-LINKED LISTS

SLIST_HEAD

SINGLY-LINKED LIST EXAMPLE

SINGLY-LINKED TAIL QUEUES

SINGLY-LINKED TAIL QUEUE EXAMPLE

LISTS

LIST EXAMPLE

TAIL QUEUES

TAILQ_HEAD

TAIL QUEUE EXAMPLE

HISTORY