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.\" Copyright (c) 1993
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.\" The Regents of the University of California. All rights reserved.
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2004-11-03 13:51:07 +00:00
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.\"
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2015-02-07 07:26:27 +00:00
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.\" %%%LICENSE_START(BSD_3_CLAUSE_UCB)
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2004-11-03 13:51:07 +00:00
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\" %%%LICENSE_END
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.\"
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.\" @(#)queue.3 8.2 (Berkeley) 1/24/94
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.\" $FreeBSD$
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.\"
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2015-02-07 07:14:26 +00:00
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.Dd February 7, 2015
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2015-02-07 06:39:47 +00:00
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.Dt QUEUE 3
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.Os
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.Sh NAME
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.Nd implementations of singly-linked lists, singly-linked tail queues,
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2020-08-24 06:50:23 +00:00
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lists, tail queues, and circular queues
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.Sh SYNOPSIS
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.Sh DESCRIPTION
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These macros define and operate on five types of data structures:
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singly-linked lists, singly-linked tail queues, lists, tail queues, and
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circular queues.
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All five structures support the following functionality:
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.Pp
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.Bl -enum -compact -offset indent
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.It
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Insertion of a new entry at the head of the list.
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.It
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Insertion of a new entry after any element in the list.
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.It
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O(1) removal of an entry from the head of the list.
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.It
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2004-11-03 13:51:07 +00:00
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Forward traversal through the list.
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queue.3: Comment out text for functions not in glibc (related: 6559169cac)
===========
DESCRIPTION
===========
I'm documenting ``CIRCLEQ_*`` macros in queue.3. While writing
this, I noticed that the documentation for some types of
queues/lists talked about swapping contents of two lists, but only
for some of them. I then found that those macros (``*_SWAP``)
don't exist in my system (Debian), but exist in BSD, and I also
found that a previous commit (6559169cac) commented out a lot of
the *_SWAP macros documentation, but not all, and the reason was
that they were not present on glibc.
I checked that I didn't have any of the *_SWAP macros on my glibc,
so I think this is probably that the commit simply forgot to
comment some of
them.
=======
TESTING
=======
I did ``sudo make`` and then visualized the man page with
``man 3 queue``, and the changes looked good.
I also noticed that the subsection ``Tail queue example`` contents
were wrong, as they contained calls to CIRCLEQ_* macros. I will
address that in a future patch, before I submit the patch
documenting CIRCLEQ_*.
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2020-08-04 09:40:41 +00:00
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.\" .It
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.\" Swapping the contents of two lists.
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.El
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.Pp
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Singly-linked lists are the simplest of the four data structures
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and support only the above functionality.
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Singly-linked lists are ideal for applications with large datasets
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and few or no removals,
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or for implementing a LIFO queue.
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Singly-linked lists add the following functionality:
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.Pp
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.Bl -enum -compact -offset indent
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.It
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O(n) removal of any entry in the list.
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.El
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.Pp
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Singly-linked tail queues add the following functionality:
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.Pp
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.Bl -enum -compact -offset indent
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.It
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Entries can be added at the end of a list.
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.It
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O(n) removal of any entry in the list.
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.It
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They may be concatenated.
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.El
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.Pp
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However:
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.Pp
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.Bl -enum -compact -offset indent
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.It
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All list insertions must specify the head of the list.
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.It
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Each head entry requires two pointers rather than one.
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.It
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Code size is about 15% greater and operations run about 20% slower
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2015-02-07 06:39:47 +00:00
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than singly-linked lists.
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.El
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.Pp
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Singly-linked tail queues are ideal for applications with large datasets and
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few or no removals,
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or for implementing a FIFO queue.
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.Pp
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All doubly linked types of data structures (lists and tail queues)
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additionally allow:
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.Pp
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.Bl -enum -compact -offset indent
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.It
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Insertion of a new entry before any element in the list.
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.It
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O(1) removal of any entry in the list.
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.El
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2017-08-25 18:54:52 +00:00
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.Pp
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However:
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.Pp
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.Bl -enum -compact -offset indent
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.It
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Each element requires two pointers rather than one.
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.It
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Code size and execution time of operations (except for removal) is about
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twice that of the singly-linked data-structures.
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.El
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.Pp
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Linked lists are the simplest of the doubly linked data structures.
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They add the following functionality over the above:
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.Pp
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2015-02-07 06:39:47 +00:00
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.Bl -enum -compact -offset indent
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.It
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They may be traversed backwards.
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.El
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.Pp
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2015-02-07 06:39:47 +00:00
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However:
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.Pp
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2015-02-07 06:39:47 +00:00
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.Bl -enum -compact -offset indent
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.It
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To traverse backwards, an entry to begin the traversal and the list in
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which it is contained must be specified.
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.El
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.Pp
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Tail queues add the following functionality:
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2020-08-24 15:06:59 +00:00
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.Pp
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2015-02-07 06:39:47 +00:00
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.Bl -enum -compact -offset indent
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.It
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2004-11-03 13:51:07 +00:00
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Entries can be added at the end of a list.
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2015-02-07 06:39:47 +00:00
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.It
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They may be traversed backwards, from tail to head.
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.It
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They may be concatenated.
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.El
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2017-08-25 18:54:52 +00:00
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.Pp
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2004-11-03 13:51:07 +00:00
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However:
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2017-08-25 18:54:52 +00:00
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.Pp
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2015-02-07 06:39:47 +00:00
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.Bl -enum -compact -offset indent
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.It
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2004-11-03 13:51:07 +00:00
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All list insertions and removals must specify the head of the list.
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2015-02-07 06:39:47 +00:00
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.It
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2004-11-03 13:51:07 +00:00
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Each head entry requires two pointers rather than one.
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2015-02-07 06:39:47 +00:00
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.It
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Code size is about 15% greater and operations run about 20% slower
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than singly-linked lists.
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.El
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2020-08-24 07:02:54 +00:00
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.Pp
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2020-08-24 06:50:23 +00:00
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Circular queues add the following functionality over the above:
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2020-08-24 07:02:54 +00:00
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.Pp
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2020-08-24 06:50:23 +00:00
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.Bl -enum -compact -offset indent
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.It
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The first and last entries are connected.
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.El
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.Pp
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However:
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.Pp
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.Bl -enum -compact -offset indent
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.It
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The termination condition for traversal is more complex.
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.It
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Code size is about 40% greater and operations run about 45% slower than lists.
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.El
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2020-10-10 19:02:27 +00:00
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.Sh EXAMPLES
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2015-02-07 07:11:04 +00:00
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.Sh CONFORMING TO
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2016-02-15 13:40:13 +00:00
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Not in POSIX.1, POSIX.1-2001 or POSIX.1-2008.
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2015-02-07 07:11:04 +00:00
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Present on the BSDs.
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.Nm queue
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functions first appeared in
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.Bx 4.4 .
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2017-04-24 19:14:58 +00:00
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.Sh SEE ALSO
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2020-10-23 14:57:37 +00:00
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.Xr circleq 3
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2017-04-24 19:14:58 +00:00
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.Xr insque 3
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2020-10-20 21:31:08 +00:00
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.Xr list 3
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2020-10-22 12:38:22 +00:00
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.Xr slist 3
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2020-10-24 22:30:21 +00:00
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.Xr stailq 3
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2020-10-25 09:36:52 +00:00
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.Xr tailq 3
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2015-04-18 08:55:56 +00:00
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.\" .Xr tree 3
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