014931a858
While here clean up the RCS tags. Suggested by: lstewart MFC after: 2 weeks Sponsored by: Klara Inc, Netflix
514 lines
14 KiB
Groff
514 lines
14 KiB
Groff
.\" $OpenBSD: tree.3,v 1.7 2002/06/12 01:09:20 provos Exp $
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.\"
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.\" Copyright 2002 Niels Provos <provos@citi.umich.edu>
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.\" Copyright 2018-2019 Netflix, Inc.
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.\" All rights reserved.
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.\"
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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. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by Niels Provos.
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.\" 4. The name of the author may not be used to endorse or promote products
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.\" derived from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd October 14, 2019
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.Dt ARB 3
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.Os
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.Sh NAME
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.Nm ARB_PROTOTYPE ,
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.Nm ARB_PROTOTYPE_STATIC ,
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.Nm ARB_PROTOTYPE_INSERT ,
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.Nm ARB_PROTOTYPE_INSERT_COLOR ,
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.Nm ARB_PROTOTYPE_REMOVE ,
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.Nm ARB_PROTOTYPE_REMOVE_COLOR ,
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.Nm ARB_PROTOTYPE_FIND ,
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.Nm ARB_PROTOTYPE_NFIND ,
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.Nm ARB_PROTOTYPE_NEXT ,
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.Nm ARB_PROTOTYPE_PREV ,
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.Nm ARB_PROTOTYPE_MINMAX ,
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.Nm ARB_PROTOTYPE_REINSERT ,
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.Nm ARB_GENERATE ,
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.Nm ARB_GENERATE_STATIC ,
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.Nm ARB_GENERATE_INSERT ,
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.Nm ARB_GENERATE_INSERT_COLOR ,
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.Nm ARB_GENERATE_REMOVE ,
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.Nm ARB_GENERATE_REMOVE_COLOR ,
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.Nm ARB_GENERATE_FIND ,
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.Nm ARB_GENERATE_NFIND ,
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.Nm ARB_GENERATE_NEXT ,
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.Nm ARB_GENERATE_PREV ,
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.Nm ARB_GENERATE_MINMAX ,
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.Nm ARB_GENERATE_REINSERT ,
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.Nm ARB8_ENTRY ,
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.Nm ARB16_ENTRY ,
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.Nm ARB32_ENTRY ,
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.Nm ARB8_HEAD ,
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.Nm ARB16_HEAD ,
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.Nm ARB32_HEAD ,
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.Nm ARB_ALLOCSIZE ,
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.Nm ARB_INITIALIZER ,
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.Nm ARB_ROOT ,
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.Nm ARB_EMPTY ,
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.Nm ARB_FULL ,
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.Nm ARB_CURNODES ,
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.Nm ARB_MAXNODES ,
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.Nm ARB_NEXT ,
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.Nm ARB_PREV ,
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.Nm ARB_MIN ,
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.Nm ARB_MAX ,
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.Nm ARB_FIND ,
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.Nm ARB_NFIND ,
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.Nm ARB_LEFT ,
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.Nm ARB_LEFTIDX ,
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.Nm ARB_RIGHT ,
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.Nm ARB_RIGHTIDX ,
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.Nm ARB_PARENT ,
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.Nm ARB_PARENTIDX ,
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.Nm ARB_GETFREE ,
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.Nm ARB_FREEIDX ,
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.Nm ARB_FOREACH ,
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.Nm ARB_FOREACH_FROM ,
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.Nm ARB_FOREACH_SAFE ,
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.Nm ARB_FOREACH_REVERSE ,
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.Nm ARB_FOREACH_REVERSE_FROM ,
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.Nm ARB_FOREACH_REVERSE_SAFE ,
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.Nm ARB_INIT ,
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.Nm ARB_INSERT ,
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.Nm ARB_REMOVE ,
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.Nm ARB_REINSERT ,
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.Nm ARB_RESET_TREE
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.Nd "array-based red-black trees"
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.Sh SYNOPSIS
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.In sys/arb.h
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.Fn ARB_PROTOTYPE NAME TYPE FIELD CMP
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.Fn ARB_PROTOTYPE_STATIC NAME TYPE FIELD CMP
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.Fn ARB_PROTOTYPE_INSERT NAME TYPE ATTR
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.Fn ARB_PROTOTYPE_INSERT_COLOR NAME TYPE ATTR
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.Fn ARB_PROTOTYPE_REMOVE NAME TYPE ATTR
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.Fn ARB_PROTOTYPE_REMOVE_COLOR NAME TYPE ATTR
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.Fn ARB_PROTOTYPE_FIND NAME TYPE ATTR
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.Fn ARB_PROTOTYPE_NFIND NAME TYPE ATTR
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.Fn ARB_PROTOTYPE_NEXT NAME TYPE ATTR
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.Fn ARB_PROTOTYPE_PREV NAME TYPE ATTR
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.Fn ARB_PROTOTYPE_MINMAX NAME TYPE ATTR
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.Fn ARB_PROTOTYPE_REINSERT NAME TYPE ATTR
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.Fn ARB_GENERATE NAME TYPE FIELD CMP
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.Fn ARB_GENERATE_STATIC NAME TYPE FIELD CMP
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.Fn ARB_GENERATE_INSERT NAME TYPE FIELD CMP ATTR
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.Fn ARB_GENERATE_INSERT_COLOR NAME TYPE FIELD ATTR
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.Fn ARB_GENERATE_REMOVE NAME TYPE FIELD ATTR
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.Fn ARB_GENERATE_REMOVE_COLOR NAME TYPE FIELD ATTR
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.Fn ARB_GENERATE_FIND NAME TYPE FIELD CMP ATTR
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.Fn ARB_GENERATE_NFIND NAME TYPE FIELD CMP ATTR
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.Fn ARB_GENERATE_NEXT NAME TYPE FIELD ATTR
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.Fn ARB_GENERATE_PREV NAME TYPE FIELD ATTR
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.Fn ARB_GENERATE_MINMAX NAME TYPE FIELD ATTR
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.Fn ARB_GENERATE_REINSERT NAME TYPE FIELD CMP ATTR
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.Fn ARB<8|16|32>_ENTRY
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.Fn ARB<8|16|32>_HEAD HEADNAME TYPE
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.Ft "size_t"
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.Fn ARB_ALLOCSIZE "ARB_HEAD *head" "int<8|16|32>_t maxnodes" "struct TYPE *elm"
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.Fn ARB_INITIALIZER "ARB_HEAD *head" "int<8|16|32>_t maxnodes"
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.Ft "struct TYPE *"
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.Fn ARB_ROOT "ARB_HEAD *head"
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.Ft "bool"
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.Fn ARB_EMPTY "ARB_HEAD *head"
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.Ft "bool"
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.Fn ARB_FULL "ARB_HEAD *head"
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.Ft "int<8|16|32>_t"
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.Fn ARB_CURNODES "ARB_HEAD *head"
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.Ft "int<8|16|32>_t"
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.Fn ARB_MAXNODES "ARB_HEAD *head"
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.Ft "struct TYPE *"
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.Fn ARB_NEXT NAME "ARB_HEAD *head" "struct TYPE *elm"
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.Ft "struct TYPE *"
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.Fn ARB_PREV NAME "ARB_HEAD *head" "struct TYPE *elm"
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.Ft "struct TYPE *"
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.Fn ARB_MIN NAME "ARB_HEAD *head"
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.Ft "struct TYPE *"
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.Fn ARB_MAX NAME "ARB_HEAD *head"
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.Ft "struct TYPE *"
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.Fn ARB_FIND NAME "ARB_HEAD *head" "struct TYPE *elm"
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.Ft "struct TYPE *"
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.Fn ARB_NFIND NAME "ARB_HEAD *head" "struct TYPE *elm"
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.Ft "struct TYPE *"
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.Fn ARB_LEFT "struct TYPE *elm" "ARB_ENTRY NAME"
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.Ft "int<8|16|32>_t"
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.Fn ARB_LEFTIDX "struct TYPE *elm" "ARB_ENTRY NAME"
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.Ft "struct TYPE *"
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.Fn ARB_RIGHT "struct TYPE *elm" "ARB_ENTRY NAME"
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.Ft "int<8|16|32>_t"
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.Fn ARB_RIGHTIDX "struct TYPE *elm" "ARB_ENTRY NAME"
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.Ft "struct TYPE *"
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.Fn ARB_PARENT "struct TYPE *elm" "ARB_ENTRY NAME"
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.Ft "int<8|16|32>_t"
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.Fn ARB_PARENTIDX "struct TYPE *elm" "ARB_ENTRY NAME"
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.Ft "struct TYPE *"
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.Fn ARB_GETFREE "ARB_HEAD *head" "FIELD"
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.Ft "int<8|16|32>_t"
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.Fn ARB_FREEIDX "ARB_HEAD *head"
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.Fn ARB_FOREACH VARNAME NAME "ARB_HEAD *head"
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.Fn ARB_FOREACH_FROM "VARNAME" "NAME" "POS_VARNAME"
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.Fn ARB_FOREACH_SAFE "VARNAME" "NAME" "ARB_HEAD *head" "TEMP_VARNAME"
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.Fn ARB_FOREACH_REVERSE VARNAME NAME "ARB_HEAD *head"
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.Fn ARB_FOREACH_REVERSE_FROM "VARNAME" "NAME" "POS_VARNAME"
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.Fn ARB_FOREACH_REVERSE_SAFE "VARNAME" "NAME" "ARB_HEAD *head" "TEMP_VARNAME"
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.Ft void
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.Fn ARB_INIT "struct TYPE *elm" "FIELD" "ARB_HEAD *head" "int<8|16|32>_t maxnodes"
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.Ft "struct TYPE *"
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.Fn ARB_INSERT NAME "ARB_HEAD *head" "struct TYPE *elm"
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.Ft "struct TYPE *"
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.Fn ARB_REMOVE NAME "ARB_HEAD *head" "struct TYPE *elm"
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.Ft "struct TYPE *"
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.Fn ARB_REINSERT NAME "ARB_HEAD *head" "struct TYPE *elm"
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.Ft void
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.Fn ARB_RESET_TREE "ARB_HEAD *head" NAME "int<8|16|32>_t maxnodes"
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.Sh DESCRIPTION
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These macros define data structures for and array-based red-black trees.
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They use a single, continuous chunk of memory, and are useful
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e.g., when the tree needs to be transferred between userspace and kernel.
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.Pp
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In the macro definitions,
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.Fa TYPE
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is the name tag of a user defined structure that must contain a field of type
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.Vt ARB_ENTRY ,
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named
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.Fa ENTRYNAME .
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The argument
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.Fa HEADNAME
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is the name tag of a user defined structure that must be declared
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using the
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.Fn ARB_HEAD
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macro.
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The argument
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.Fa NAME
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has to be a unique name prefix for every tree that is defined.
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.Pp
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The function prototypes are declared with
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.Fn ARB_PROTOTYPE ,
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or
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.Fn ARB_PROTOTYPE_STATIC .
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The function bodies are generated with
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.Fn ARB_GENERATE ,
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or
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.Fn ARB_GENERATE_STATIC .
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See the examples below for further explanation of how these macros are used.
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.Pp
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A red-black tree is a binary search tree with the node color as an
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extra attribute.
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It fulfills a set of conditions:
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.Bl -enum -offset indent
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.It
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Every search path from the root to a leaf consists of the same number of
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black nodes.
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.It
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Each red node (except for the root) has a black parent.
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.It
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Each leaf node is black.
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.El
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.Pp
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Every operation on a red-black tree is bounded as
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.Fn O "lg n" .
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The maximum height of a red-black tree is
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.Fn 2lg "n + 1" .
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.Pp
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.Fn ARB_*
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trees require entries to be allocated as an array, and uses array
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indices to link entries together.
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The maximum number of
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.Fn ARB_*
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tree entries is therefore constrained by the minimum of array size and choice of
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signed integer data type used to store array indices.
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Use
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.Fn ARB_ALLOCSIZE
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to compute the size of memory chunk to allocate.
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.Pp
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A red-black tree is headed by a structure defined by the
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.Fn ARB_HEAD
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macro.
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A
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structure is declared with either of the following:
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.Bd -ragged -offset indent
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.Fn ARB<8|16|32>_HEAD HEADNAME TYPE
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.Va head ;
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.Ed
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.Pp
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where
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.Fa HEADNAME
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is the name of the structure to be defined, and struct
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.Fa TYPE
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is the type of the elements to be inserted into the tree.
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.Pp
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The
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.Fn ARB_HEAD
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variant includes a suffix denoting the signed integer data type size
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.Pq in bits
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used to store array indices.
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For example,
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.Fn ARB_HEAD8
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creates a red-black tree head strucutre with 8-bit signed array indices capable
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of indexing up to 128 entries.
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.Pp
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The
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.Fn ARB_ENTRY
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macro declares a structure that allows elements to be connected in the tree.
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Similarly to the
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.Fn ARB<8|16|32>_HEAD
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macro, the
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.Fn ARB_ENTRY
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variant includes a suffix denoting the signed integer data type size
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.Pq in bits
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used to store array indices.
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Entries should use the same number of bits as the tree head structure they will
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be linked into.
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.Pp
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In order to use the functions that manipulate the tree structure,
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their prototypes need to be declared with the
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.Fn ARB_PROTOTYPE
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or
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.Fn ARB_PROTOTYPE_STATIC
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macro,
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where
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.Fa NAME
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is a unique identifier for this particular tree.
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The
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.Fa TYPE
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argument is the type of the structure that is being managed
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by the tree.
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The
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.Fa FIELD
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argument is the name of the element defined by
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.Fn ARB_ENTRY .
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Individual prototypes can be declared with
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.Fn ARB_PROTOTYPE_INSERT ,
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.Fn ARB_PROTOTYPE_INSERT_COLOR ,
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.Fn ARB_PROTOTYPE_REMOVE ,
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.Fn ARB_PROTOTYPE_REMOVE_COLOR ,
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.Fn ARB_PROTOTYPE_FIND ,
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.Fn ARB_PROTOTYPE_NFIND ,
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.Fn ARB_PROTOTYPE_NEXT ,
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.Fn ARB_PROTOTYPE_PREV ,
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.Fn ARB_PROTOTYPE_MINMAX ,
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and
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.Fn ARB_PROTOTYPE_REINSERT
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in case not all functions are required.
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The individual prototype macros expect
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.Fa NAME ,
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.Fa TYPE ,
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and
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.Fa ATTR
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arguments.
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The
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.Fa ATTR
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argument must be empty for global functions or
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.Fa static
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for static functions.
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.Pp
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The function bodies are generated with the
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.Fn ARB_GENERATE
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or
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.Fn ARB_GENERATE_STATIC
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macro.
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These macros take the same arguments as the
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.Fn ARB_PROTOTYPE
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and
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.Fn ARB_PROTOTYPE_STATIC
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macros, but should be used only once.
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As an alternative individual function bodies are generated with the
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.Fn ARB_GENERATE_INSERT ,
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.Fn ARB_GENERATE_INSERT_COLOR ,
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.Fn ARB_GENERATE_REMOVE ,
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.Fn ARB_GENERATE_REMOVE_COLOR ,
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.Fn ARB_GENERATE_FIND ,
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.Fn ARB_GENERATE_NFIND ,
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.Fn ARB_GENERATE_NEXT ,
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.Fn ARB_GENERATE_PREV ,
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.Fn ARB_GENERATE_MINMAX ,
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and
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.Fn ARB_GENERATE_REINSERT
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macros.
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.Pp
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Finally,
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the
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.Fa CMP
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argument is the name of a function used to compare tree nodes
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with each other.
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The function takes two arguments of type
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.Vt "struct TYPE *" .
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If the first argument is smaller than the second, the function returns a
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value smaller than zero.
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If they are equal, the function returns zero.
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Otherwise, it should return a value greater than zero.
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The compare
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function defines the order of the tree elements.
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.Pp
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The
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.Fn ARB_INIT
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macro initializes the tree referenced by
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.Fa head ,
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with the array length of
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.Fa maxnodes .
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.Pp
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The red-black tree can also be initialized statically by using the
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.Fn ARB_INITIALIZER
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macro:
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.Bd -ragged -offset indent
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.Fn ARB<8|16|32>_HEAD HEADNAME TYPE
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.Va head
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=
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.Fn ARB_INITIALIZER &head maxnodes ;
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.Ed
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.Pp
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The
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.Fn ARB_INSERT
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macro inserts the new element
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.Fa elm
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into the tree.
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.Pp
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The
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.Fn ARB_REMOVE
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macro removes the element
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.Fa elm
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from the tree pointed by
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.Fa head .
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.Pp
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The
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.Fn ARB_FIND
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and
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.Fn ARB_NFIND
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macros can be used to find a particular element in the tree.
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.Bd -literal -offset indent
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struct TYPE find, *res;
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find.key = 30;
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res = ARB_FIND(NAME, head, &find);
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.Ed
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.Pp
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The
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.Fn ARB_ROOT ,
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.Fn ARB_MIN ,
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.Fn ARB_MAX ,
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.Fn ARB_NEXT ,
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and
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.Fn ARB_PREV
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macros can be used to traverse the tree:
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.Pp
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.Dl "for (np = ARB_MIN(NAME, &head); np != NULL; np = ARB_NEXT(NAME, &head, np))"
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.Pp
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Or, for simplicity, one can use the
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.Fn ARB_FOREACH
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or
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.Fn ARB_FOREACH_REVERSE
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macro:
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.Bd -ragged -offset indent
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.Fn ARB_FOREACH np NAME head
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.Ed
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.Pp
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The macros
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.Fn ARB_FOREACH_SAFE
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and
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.Fn ARB_FOREACH_REVERSE_SAFE
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traverse the tree referenced by head
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in a forward or reverse direction respectively,
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assigning each element in turn to np.
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However, unlike their unsafe counterparts,
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they permit both the removal of np
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as well as freeing it from within the loop safely
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without interfering with the traversal.
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.Pp
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Both
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.Fn ARB_FOREACH_FROM
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and
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.Fn ARB_FOREACH_REVERSE_FROM
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may be used to continue an interrupted traversal
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in a forward or reverse direction respectively.
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The head pointer is not required.
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The pointer to the node from where to resume the traversal
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should be passed as their last argument,
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and will be overwritten to provide safe traversal.
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.Pp
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The
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.Fn ARB_EMPTY
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macro should be used to check whether a red-black tree is empty.
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.Pp
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Given that ARB trees have an intrinsic upper bound on the number of entries,
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some ARB-specific additional macros are defined.
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The
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.Fn ARB_FULL
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macro returns a boolean indicating whether the current number of tree entries
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equals the tree's maximum.
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The
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.Fn ARB_CURNODES
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and
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.Fn ARB_MAXNODES
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macros return the current and maximum number of entries respectively.
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The
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.Fn ARB_GETFREE
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macro returns a pointer to the next free entry in the array of entries, ready to
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be linked into the tree.
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The
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.Fn ARB_INSERT
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returns
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.Dv NULL
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if the element was inserted in the tree successfully, otherwise they
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return a pointer to the element with the colliding key.
|
|
.Pp
|
|
Accordingly,
|
|
.Fn ARB_REMOVE
|
|
returns the pointer to the removed element otherwise they return
|
|
.Dv NULL
|
|
to indicate an error.
|
|
.Pp
|
|
The
|
|
.Fn ARB_REINSERT
|
|
macro updates the position of the element
|
|
.Fa elm
|
|
in the tree.
|
|
This must be called if a member of a
|
|
.Nm tree
|
|
is modified in a way that affects comparison, such as by modifying
|
|
a node's key.
|
|
This is a lower overhead alternative to removing the element
|
|
and reinserting it again.
|
|
.Pp
|
|
The
|
|
.Fn ARB_RESET_TREE
|
|
macro discards the tree topology.
|
|
It does not modify embedded object values or the free list.
|
|
.Sh SEE ALSO
|
|
.Xr queue 3 ,
|
|
.Xr tree 3
|
|
.Sh HISTORY
|
|
The
|
|
.Nm ARB
|
|
macros first appeared in
|
|
.Fx 13.0 .
|
|
.Sh AUTHORS
|
|
The
|
|
.Nm ARB
|
|
macros were implemented by
|
|
.An Lawrence Stewart Aq Mt lstewart@FreeBSD.org ,
|
|
based on
|
|
.Xr tree 3
|
|
macros written by
|
|
.An Niels Provos .
|