481 lines
13 KiB
Groff
481 lines
13 KiB
Groff
.\" $NetBSD: queue.3,v 1.4 1995/07/03 00:25:36 mycroft Exp $
|
|
.\"
|
|
.\" Copyright (c) 1993 The Regents of the University of California.
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed by the University of
|
|
.\" California, Berkeley and its contributors.
|
|
.\" 4. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" @(#)queue.3 8.1 (Berkeley) 12/13/93
|
|
.\"
|
|
.Dd "December 13, 1993"
|
|
.Dt QUEUE 3
|
|
.Os BSD 4
|
|
.Sh NAME
|
|
.Nm LIST_ENTRY ,
|
|
.Nm LIST_HEAD ,
|
|
.Nm LIST_INIT ,
|
|
.Nm LIST_INSERT_AFTER ,
|
|
.Nm LIST_INSERT_BEFORE ,
|
|
.Nm LIST_INSERT_HEAD ,
|
|
.Nm LIST_REMOVE ,
|
|
.Nm TAILQ_ENTRY ,
|
|
.Nm TAILQ_HEAD ,
|
|
.Nm TAILQ_INIT ,
|
|
.Nm TAILQ_INSERT_AFTER ,
|
|
.Nm TAILQ_INSERT_BEFORE ,
|
|
.Nm TAILQ_INSERT_HEAD ,
|
|
.Nm TAILQ_INSERT_TAIL ,
|
|
.Nm TAILQ_REMOVE ,
|
|
.Nm CIRCLEQ_ENTRY ,
|
|
.Nm CIRCLEQ_HEAD ,
|
|
.Nm CIRCLEQ_INIT ,
|
|
.Nm CIRCLEQ_INSERT_AFTER ,
|
|
.Nm CIRCLEQ_INSERT_BEFORE ,
|
|
.Nm CIRCLEQ_INSERT_HEAD ,
|
|
.Nm CIRCLEQ_INSERT_TAIL ,
|
|
.Nm CIRCLEQ_REMOVE
|
|
.Nd implementations of lists, tail queues, and circular queues
|
|
.Sh SYNOPSIS
|
|
.Fd #include <sys/queue.h>
|
|
.sp
|
|
.Fn LIST_ENTRY "TYPE"
|
|
.Fn LIST_HEAD "HEADNAME" "TYPE"
|
|
.Fn LIST_INIT "LIST_HEAD *head"
|
|
.Fn LIST_INSERT_AFTER "TYPE *listelm" "TYPE *elm" "LIST_ENTRY NAME"
|
|
.Fn LIST_INSERT_BEFORE "TYPE *listelm" "TYPE *elm" "LIST_ENTRY NAME"
|
|
.Fn LIST_INSERT_HEAD "LIST_HEAD *head" "TYPE *elm" "LIST_ENTRY NAME"
|
|
.Fn LIST_REMOVE "TYPE *elm" "LIST_ENTRY NAME"
|
|
.sp
|
|
.Fn TAILQ_ENTRY "TYPE"
|
|
.Fn TAILQ_HEAD "HEADNAME" "TYPE"
|
|
.Fn TAILQ_INIT "TAILQ_HEAD *head"
|
|
.Fn TAILQ_INSERT_AFTER "TAILQ_HEAD *head" "TYPE *listelm" "TYPE *elm" "TAILQ_ENTRY NAME"
|
|
.Fn TAILQ_INSERT_BEFORE "TYPE *listelm" "TYPE *elm" "TAILQ_ENTRY NAME"
|
|
.Fn TAILQ_INSERT_HEAD "TAILQ_HEAD *head" "TYPE *elm" "TAILQ_ENTRY NAME"
|
|
.Fn TAILQ_INSERT_TAIL "TAILQ_HEAD *head" "TYPE *elm" "TAILQ_ENTRY NAME"
|
|
.Fn TAILQ_REMOVE "TAILQ_HEAD *head" "TYPE *elm" "TAILQ_ENTRY NAME"
|
|
.sp
|
|
.Fn CIRCLEQ_ENTRY "TYPE"
|
|
.Fn CIRCLEQ_HEAD "HEADNAME" "TYPE"
|
|
.Fn CIRCLEQ_INIT "CIRCLEQ_HEAD *head"
|
|
.Fn CIRCLEQ_INSERT_AFTER "CIRCLEQ_HEAD *head" "TYPE *listelm" "TYPE *elm" "CIRCLEQ_ENTRY NAME"
|
|
.Fn CIRCLEQ_INSERT_BEFORE "CIRCLEQ_HEAD *head" "TYPE *listelm" "TYPE *elm" "CIRCLEQ_ENTRY NAME"
|
|
.Fn CIRCLEQ_INSERT_HEAD "CIRCLEQ_HEAD *head" "TYPE *elm" "CIRCLEQ_ENTRY NAME"
|
|
.Fn CIRCLEQ_INSERT_TAIL "CIRCLEQ_HEAD *head" "TYPE *elm" "CIRCLEQ_ENTRY NAME"
|
|
.Fn CIRCLEQ_REMOVE "CIRCLEQ_HEAD *head" "TYPE *elm" "CIRCLEQ_ENTRY NAME"
|
|
.Sh DESCRIPTION
|
|
These macros define and operate on three types of data structures:
|
|
lists, tail queues, and circular queues.
|
|
All three structures support the following functionality:
|
|
.Bl -enum -compact -offset indent
|
|
.It
|
|
Insertion of a new entry at the head of the list.
|
|
.It
|
|
Insertion of a new entry before or after any element in the list.
|
|
.It
|
|
Removal of any entry in the list.
|
|
.It
|
|
Forward traversal through the list.
|
|
.El
|
|
.Pp
|
|
Lists are the simplest of the three data structures and support
|
|
only the above functionality.
|
|
.Pp
|
|
Tail queues add the following functionality:
|
|
.Bl -enum -compact -offset indent
|
|
.It
|
|
Entries can be added at the end of a list.
|
|
.El
|
|
However:
|
|
.Bl -enum -compact -offset indent
|
|
.It
|
|
All list insertions and removals, except insertion before another element, must
|
|
specify the head of the list.
|
|
.It
|
|
Each head entry requires two pointers rather than one.
|
|
.It
|
|
Code size is about 15% greater and operations run about 20% slower
|
|
than lists.
|
|
.El
|
|
.Pp
|
|
Circular queues add the following functionality:
|
|
.Bl -enum -compact -offset indent
|
|
.It
|
|
Entries can be added at the end of a list.
|
|
.It
|
|
They may be traversed backwards, from tail to head.
|
|
.El
|
|
However:
|
|
.Bl -enum -compact -offset indent
|
|
.It
|
|
All list insertions and removals must specify the head of the list.
|
|
.It
|
|
Each head entry requires two pointers rather than one.
|
|
.It
|
|
The termination condition for traversal is more complex.
|
|
.It
|
|
Code size is about 40% greater and operations run about 45% slower
|
|
than lists.
|
|
.El
|
|
.Pp
|
|
In the macro definitions,
|
|
.Fa TYPE
|
|
is the name of a user defined structure,
|
|
that must contain a field of type
|
|
.Li LIST_ENTRY ,
|
|
.Li TAILQ_ENTRY ,
|
|
or
|
|
.Li CIRCLEQ_ENTRY ,
|
|
named
|
|
.Fa NAME .
|
|
The argument
|
|
.Fa HEADNAME
|
|
is the name of a user defined structure that must be declared
|
|
using the macros
|
|
.Li LIST_HEAD ,
|
|
.Li TAILQ_HEAD ,
|
|
or
|
|
.Li CIRCLEQ_HEAD .
|
|
See the examples below for further explanation of how these
|
|
macros are used.
|
|
.Sh LISTS
|
|
A list is headed by a structure defined by the
|
|
.Nm 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
|
|
.Fa LIST_HEAD
|
|
structure is declared as follows:
|
|
.Bd -literal -offset indent
|
|
LIST_HEAD(HEADNAME, TYPE) head;
|
|
.Ed
|
|
.sp
|
|
where
|
|
.Fa HEADNAME
|
|
is the name of the structure to be defined, and
|
|
.Fa 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:
|
|
.Bd -literal -offset indent
|
|
struct HEADNAME *headp;
|
|
.Ed
|
|
.sp
|
|
(The names
|
|
.Li head
|
|
and
|
|
.Li headp
|
|
are user selectable.)
|
|
.Pp
|
|
The macro
|
|
.Nm LIST_ENTRY
|
|
declares a structure that connects the elements in
|
|
the list.
|
|
.Pp
|
|
The macro
|
|
.Nm LIST_INIT
|
|
initializes the list referenced by
|
|
.Fa head .
|
|
.Pp
|
|
The macro
|
|
.Nm LIST_INSERT_HEAD
|
|
inserts the new element
|
|
.Fa elm
|
|
at the head of the list.
|
|
.Pp
|
|
The macro
|
|
.Nm LIST_INSERT_AFTER
|
|
inserts the new element
|
|
.Fa elm
|
|
after the element
|
|
.Fa listelm .
|
|
.Pp
|
|
The macro
|
|
.Nm LIST_INSERT_BEFORE
|
|
inserts the new element
|
|
.Fa elm
|
|
before the element
|
|
.Fa listelm .
|
|
.Pp
|
|
The macro
|
|
.Nm LIST_REMOVE
|
|
removes the element
|
|
.Fa elm
|
|
from the list.
|
|
.Sh LIST EXAMPLE
|
|
.Bd -literal
|
|
LIST_HEAD(listhead, entry) head;
|
|
struct listhead *headp; /* List head. */
|
|
struct entry {
|
|
...
|
|
LIST_ENTRY(entry) entries; /* List. */
|
|
...
|
|
} *n1, *n2, *np;
|
|
|
|
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);
|
|
|
|
n2 = malloc(sizeof(struct entry)); /* Insert before. */
|
|
LIST_INSERT_BEFORE(n1, n2, entries);
|
|
/* Forward traversal. */
|
|
for (np = head.lh_first; np != NULL; np = np->entries.le_next)
|
|
np-> ...
|
|
|
|
while (head.lh_first != NULL) /* Delete. */
|
|
LIST_REMOVE(head.lh_first, entries);
|
|
.Ed
|
|
.Sh TAIL QUEUES
|
|
A tail queue is headed by a structure defined by the
|
|
.Nm TAILQ_HEAD
|
|
macro.
|
|
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 queue after an existing element,
|
|
before an existing element, at the head of the queue, or at the end
|
|
the queue.
|
|
A
|
|
.Fa TAILQ_HEAD
|
|
structure is declared as follows:
|
|
.Bd -literal -offset indent
|
|
TAILQ_HEAD(HEADNAME, TYPE) head;
|
|
.Ed
|
|
.sp
|
|
where
|
|
.Li HEADNAME
|
|
is the name of the structure to be defined, and
|
|
.Li 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:
|
|
.Bd -literal -offset indent
|
|
struct HEADNAME *headp;
|
|
.Ed
|
|
.sp
|
|
(The names
|
|
.Li head
|
|
and
|
|
.Li headp
|
|
are user selectable.)
|
|
.Pp
|
|
The macro
|
|
.Nm TAILQ_ENTRY
|
|
declares a structure that connects the elements in
|
|
the tail queue.
|
|
.Pp
|
|
The macro
|
|
.Nm TAILQ_INIT
|
|
initializes the tail queue referenced by
|
|
.Fa head .
|
|
.Pp
|
|
The macro
|
|
.Nm TAILQ_INSERT_HEAD
|
|
inserts the new element
|
|
.Fa elm
|
|
at the head of the tail queue.
|
|
.Pp
|
|
The macro
|
|
.Nm TAILQ_INSERT_TAIL
|
|
inserts the new element
|
|
.Fa elm
|
|
at the end of the tail queue.
|
|
.Pp
|
|
The macro
|
|
.Nm TAILQ_INSERT_AFTER
|
|
inserts the new element
|
|
.Fa elm
|
|
after the element
|
|
.Fa listelm .
|
|
.Pp
|
|
The macro
|
|
.Nm TAILQ_INSERT_BEFORE
|
|
inserts the new element
|
|
.Fa elm
|
|
before the element
|
|
.Fa listelm .
|
|
.Pp
|
|
The macro
|
|
.Nm TAILQ_REMOVE
|
|
removes the element
|
|
.Fa elm
|
|
from the tail queue.
|
|
.Sh TAIL QUEUE EXAMPLE
|
|
.Bd -literal
|
|
TAILQ_HEAD(tailhead, entry) head;
|
|
struct tailhead *headp; /* Tail queue head. */
|
|
struct entry {
|
|
...
|
|
TAILQ_ENTRY(entry) entries; /* Tail queue. */
|
|
...
|
|
} *n1, *n2, *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);
|
|
|
|
n2 = malloc(sizeof(struct entry)); /* Insert before. */
|
|
TAILQ_INSERT_BEFORE(n1, n2, entries);
|
|
/* Forward traversal. */
|
|
for (np = head.tqh_first; np != NULL; np = np->entries.tqe_next)
|
|
np-> ...
|
|
/* Delete. */
|
|
while (head.tqh_first != NULL)
|
|
TAILQ_REMOVE(&head, head.tqh_first, entries);
|
|
.Ed
|
|
.Sh CIRCULAR QUEUES
|
|
A circular queue is headed by a structure defined by the
|
|
.Nm CIRCLEQ_HEAD
|
|
macro.
|
|
This structure contains a pair of pointers,
|
|
one to the first element in the circular queue and the other to the
|
|
last element in the circular queue.
|
|
The elements are doubly linked so that an arbitrary element can be
|
|
removed without traversing the queue.
|
|
New elements can be added to the queue after an existing element,
|
|
before an existing element, at the head of the queue, or at the end
|
|
of the queue.
|
|
A
|
|
.Fa CIRCLEQ_HEAD
|
|
structure is declared as follows:
|
|
.Bd -literal -offset indent
|
|
CIRCLEQ_HEAD(HEADNAME, TYPE) head;
|
|
.Ed
|
|
.sp
|
|
where
|
|
.Li HEADNAME
|
|
is the name of the structure to be defined, and
|
|
.Li TYPE
|
|
is the type of the elements to be linked into the circular queue.
|
|
A pointer to the head of the circular queue can later be declared as:
|
|
.Bd -literal -offset indent
|
|
struct HEADNAME *headp;
|
|
.Ed
|
|
.sp
|
|
(The names
|
|
.Li head
|
|
and
|
|
.Li headp
|
|
are user selectable.)
|
|
.Pp
|
|
The macro
|
|
.Nm CIRCLEQ_ENTRY
|
|
declares a structure that connects the elements in
|
|
the circular queue.
|
|
.Pp
|
|
The macro
|
|
.Nm CIRCLEQ_INIT
|
|
initializes the circular queue referenced by
|
|
.Fa head .
|
|
.Pp
|
|
The macro
|
|
.Nm CIRCLEQ_INSERT_HEAD
|
|
inserts the new element
|
|
.Fa elm
|
|
at the head of the circular queue.
|
|
.Pp
|
|
The macro
|
|
.Nm CIRCLEQ_INSERT_TAIL
|
|
inserts the new element
|
|
.Fa elm
|
|
at the end of the circular queue.
|
|
.Pp
|
|
The macro
|
|
.Nm CIRCLEQ_INSERT_AFTER
|
|
inserts the new element
|
|
.Fa elm
|
|
after the element
|
|
.Fa listelm .
|
|
.Pp
|
|
The macro
|
|
.Nm CIRCLEQ_INSERT_BEFORE
|
|
inserts the new element
|
|
.Fa elm
|
|
before the element
|
|
.Fa listelm .
|
|
.Pp
|
|
The macro
|
|
.Nm CIRCLEQ_REMOVE
|
|
removes the element
|
|
.Fa elm
|
|
from the circular queue.
|
|
.Sh CIRCULAR QUEUE EXAMPLE
|
|
.Bd -literal
|
|
CIRCLEQ_HEAD(circleq, entry) head;
|
|
struct circleq *headp; /* Circular queue head. */
|
|
struct entry {
|
|
...
|
|
CIRCLEQ_ENTRY entries; /* Circular queue. */
|
|
...
|
|
} *n1, *n2, *np;
|
|
|
|
CIRCLEQ_INIT(&head); /* Initialize the circular queue. */
|
|
|
|
n1 = malloc(sizeof(struct entry)); /* Insert at the head. */
|
|
CIRCLEQ_INSERT_HEAD(&head, n1, entries);
|
|
|
|
n1 = malloc(sizeof(struct entry)); /* Insert at the tail. */
|
|
CIRCLEQ_INSERT_TAIL(&head, n1, entries);
|
|
|
|
n2 = malloc(sizeof(struct entry)); /* Insert after. */
|
|
CIRCLEQ_INSERT_AFTER(&head, n1, n2, entries);
|
|
|
|
n2 = malloc(sizeof(struct entry)); /* Insert before. */
|
|
CIRCLEQ_INSERT_BEFORE(&head, n1, n2, entries);
|
|
/* Forward traversal. */
|
|
for (np = head.cqh_first; np != (void *)&head; np = np->entries.cqe_next)
|
|
np-> ...
|
|
/* Reverse traversal. */
|
|
for (np = head.cqh_last; np != (void *)&head; np = np->entries.cqe_prev)
|
|
np-> ...
|
|
/* Delete. */
|
|
while (head.cqh_first != (void *)&head)
|
|
CIRCLEQ_REMOVE(&head, head.cqh_first, entries);
|
|
.Ed
|
|
.Sh HISTORY
|
|
The
|
|
.Nm queue
|
|
functions first appeared in 4.4BSD.
|