(split) LDP v3.24 -> v3.29 の定型的な変更内容を反映。

[linuxjm/LDP_man-pages.git] / draft / man3 / hash.3

.\" Copyright (c) 1990, 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.
.\"
.\"     @(#)hash.3      8.6 (Berkeley) 8/18/94
.\"
.\" Japanese Version Copyright (c) 1999 Shouichi Saito
.\"     all rights reserved.
.\" Translated Mon Jul 26 14:22:49 JST 1999
.\"     by Shouichi Saito <ss236rx@ymg.urban.ne.jp>
.\" Proofed Tue Aug 17 1999 by NAKANO Takeo <nakano@apm.seikei.ac.jp>
.\" Updated 2008-02-10, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>, LDP v2.77
.\"
.\"WORD:        access method           ¥¢¥¯¥»¥¹¥á¥½¥Ã¥É
.\"WORD:        bucket                  ¥Ð¥±¥Ã¥È
.\"
.TH HASH 3 1994-08-18 "" "Linux Programmer's Manual"
.UC 7
.SH ̾Á°
.\"O hash \- hash database access method
hash \- hash ¥Ç¡¼¥¿¥Ù¡¼¥¹¤Ø¤Î¥¢¥¯¥»¥¹¥á¥½¥Ã¥É
.SH ½ñ¼°
.nf
.ft B
#include <sys/types.h>
#include <db.h>
.ft R
.fi
.SH ÀâÌÀ
.\"O The routine
.\"O .BR dbopen (3)
.\"O is the library interface to database files.
.\"O One of the supported file formats is hash files.
¥ë¡¼¥Á¥ó
.BR dbopen (3)
¤Ï¥Ç¡¼¥¿¥Ù¡¼¥¹¥Õ¥¡¥¤¥ë¤ËÂФ¹¤ë¥é¥¤¥Ö¥é¥ê¥¤¥ó¥¿¡¼¥Õ¥§¡¼¥¹¤Ç¤¢¤ë¡£
¥µ¥Ý¡¼¥È¤µ¤ì¤Æ¤¤¤ë¥Õ¥¡¥¤¥ë¥Õ¥©¡¼¥Þ¥Ã¥È¤Î¤Ò¤È¤Ä¤Ë hash ¥Õ¥¡¥¤¥ë¤¬¤¢¤ë¡£
.\"O The general description of the database access methods is in
.\"O .BR dbopen (3),
.\"O this manual page describes only the hash specific information.
¥Ç¡¼¥¿¥Ù¡¼¥¹¤Ø¤Î¥¢¥¯¥»¥¹¥á¥½¥Ã¥É¤Ë´Ø¤¹¤ë°ìÈÌŪ¤Êµ­½Ò¤Ï
.BR dbopen (3)
¤Ë½ñ¤«¤ì¤Æ¤¤¤ë¡£
¤³¤Î¥Þ¥Ë¥å¥¢¥ë¥Ú¡¼¥¸¤Ç¤Ï hash ÆÃÍ­¤Î¾ðÊó¤Ë¤Ä¤¤¤Æ¤Î¤ßµ­½Ò¤¹¤ë¡£
.PP
.\"O The hash data structure is an extensible, dynamic hashing scheme.
hash ¥Ç¡¼¥¿¹½Â¤¤Ï¡¢³ÈÄ¥²Äǽ¤ÊưŪ¥Ï¥Ã¥·¥å¥¹¥­¡¼¥à¤Ç¤¢¤ë¡£
.PP
.\"O The access method specific data structure provided to
.\"O .BR dbopen (3)
.\"O is defined in the
.\"O .I <db.h>
.\"O include file as follows:
.BR dbopen (3)
¤ËÅϤµ¤ì¤ë hash ¥¢¥¯¥»¥¹¥á¥½¥Ã¥É¤ËÆÃÍ­¤Î¥Ç¡¼¥¿¹½Â¤ÂΤϡ¢
.I <db.h>
¥¤¥ó¥¯¥ë¡¼¥É¥Õ¥¡¥¤¥ë¤Ç°Ê²¼¤Î¤è¤¦¤ËÄêµÁ¤µ¤ì¤Æ¤¤¤ë¡£
.in +4n
.nf

typedef struct {
    unsigned int       bsize;
    unsigned int       ffactor;
    unsigned int       nelem;
    unsigned int       cachesize;
    uint32_t         (*hash)(const void *, size_t);
    int         lorder;
} HASHINFO;
.fi
.in
.PP
.\"O The elements of this structure are as follows:
¤³¤Î¹½Â¤ÂΤÎÍ×ÁǤò°Ê²¼¤Ë¼¨¤¹¡£
.TP 10
.I bsize
.\"O defines the hash table bucket size, and is, by default, 256 bytes.
.\"O It may be preferable to increase the page size for disk-resident tables
.\"O and tables with large data items.
hash ¥Æ¡¼¥Ö¥ë¥Ð¥±¥Ã¥È (table bucket) ¤Î¥µ¥¤¥º¤òÄêµÁ¤¹¤ë¡£
¥Ç¥Õ¥©¥ë¥È¤Ï 256 ¥Ð¥¤¥È¤Ç¤¢¤ë¡£
¥Ç¥£¥¹¥¯¤ËÃÖ¤«¤ì¤ë¥Æ¡¼¥Ö¥ë¤ä¥Ç¡¼¥¿¥¢¥¤¥Æ¥à¤¬Â礭¤¤¥Æ¡¼¥Ö¥ë¤Ç¤Ï
¥Ú¡¼¥¸¥µ¥¤¥º¤òÂ礭¤¯¤¹¤ë¤Û¤¦¤¬Îɤ¤¤À¤í¤¦¡£
.TP
.I ffactor
.\"O indicates a desired density within the hash table.
.\"O It is an approximation of the number of keys allowed to accumulate in any
.\"O one bucket, determining when the hash table grows or shrinks.
.\"O The default value is 8.
¥æ¡¼¥¶¤¬Ë¾¤à hash ¥Æ¡¼¥Ö¥ëÃæ¤ÎÌ©Å٤Ǥ¢¤ë¡£
¤³¤ì¤Ï¤½¤ì¤¾¤ì¤Î¥Ð¥±¥Ã¥È¤Ë³ÊǼ¤Ç¤­¤ë¥­¡¼¤Î³µ¿ô¤Ç¤¢¤ê¡¢
hash ¥Æ¡¼¥Ö¥ë¤ò³ÈÂ硦½Ì¾®¤òºîÍѤ¹¤ë¡£
¥Ç¥Õ¥©¥ë¥È¤Ï 8 ¤Ç¤¢¤ë¡£
.TP
.I nelem
.\"O is an estimate of the final size of the hash table.
.\"O If not set or set too low, hash tables will expand gracefully as keys
.\"O are entered, although a slight performance degradation may be noticed.
.\"O The default value is 1.
hash ¥Æ¡¼¥Ö¥ë¤ÎºÇ½ª¥µ¥¤¥º¤òÂç¤Þ¤«¤Ë¸«ÀѤâ¤Ã¤¿ÃͤǤ¢¤ë¡£
¤³¤ÎÃͤ¬¥»¥Ã¥È¤µ¤ì¤Æ¤¤¤Ê¤«¤Ã¤¿¤ê¡¢¤¢¤Þ¤ê¤ËÄ㤯¥»¥Ã¥È¤µ¤ì¤Æ¤¤¤ë¤È¡¢
hash ¥Æ¡¼¥Ö¥ë¤Ï¥­¡¼¤¬Æþ¤Ã¤Æ¤¯¤ë¤Ë±þ¤¸¤Æ³ÈÄ¥¤µ¤ì¤ë¡£
¤·¤«¤·¾¯¤·¥Ñ¥Õ¥©¡¼¥Þ¥ó¥¹¤¬ (¤ª¤½¤é¤¯µ¤ÉÕ¤¯ÄøÅÙ¤Ë) Íî¤Á¤ë¡£
¥Ç¥Õ¥©¥ë¥ÈÃÍ¤Ï 1 ¤Ç¤¢¤ë¡£
.TP
.I cachesize
.\"O is the suggested maximum size, in bytes, of the memory cache.
.\"O This value is
.\"O .IR "only advisory" ,
.\"O and the access method will allocate more memory rather than fail.
¥á¥â¥ê¥­¥ã¥Ã¥·¥å¤ÎºÇÂçÃÍ (¥Ð¥¤¥Èñ°Ì) ¤Î»²¹ÍÃÍ¡£
¤³¤ÎÃͤÏ
.BR ¤¢¤¯¤Þ¤Ç»²¹Í¤Ç¤¢¤ê ¡¢
¥¢¥¯¥»¥¹¥á¥½¥Ã¥É¤Ï¤³¤ÎÃͤò±Û¤¨¤¿¥á¥â¥ê¤Î³ä¤êÅö¤Æ¤ËÀ®¸ù¤¹¤ë¤³¤È¤â¤¢¤ë¡£
.TP
.I hash
.\"O is a user-defined hash function.
.\"O Since no hash function performs equally well on all possible data, the
.\"O user may find that the built-in hash function does poorly on a particular
.\"O data set.
¤Ï¥æ¡¼¥¶¡¼ÄêµÁ¤Î hash ´Ø¿ô¤Ç¤¢¤ë¡£
Á´¤Æ¤Î¥Ç¡¼¥¿¤ËÂФ·¤Æ¤¦¤Þ¤¯ºîÍѤ¹¤ë hash ´Ø¿ô¤È¸À¤¦¤Î¤Ï¤Ê¤¤¤«¤é¡¢
ÆÃÄê¤Î¥Ç¡¼¥¿¥»¥Ã¥È¤ËÂФ·¤Æ¤ÏÁȤ߹þ¤ß¤Î hash ´Ø¿ô¤Ç¤Ï
¥Ñ¥Õ¥©¡¼¥Þ¥ó¥¹¤¬Ä㤤¤³¤È¤â¤¢¤ë¤«¤â¤·¤ì¤Ê¤¤¡£
.\"O A user-specified hash functions must take two arguments (a pointer to a byte
.\"O string and a length) and return a 32-bit quantity to be used as the hash
.\"O value.
¥æ¡¼¥¶¡¼ÄêµÁ¤Î hash ´Ø¿ô¤ÏÆó¤Ä¤Î°ú¿ô¤ò¤È¤é¤Ê¤¯¤Æ¤Ï¤Ê¤é¤Ê¤¤ (¥Ð¥¤¥Èʸ»ú
Îó¤Ø¤Î¥Ý¥¤¥ó¥¿¤È¡¢Ä¹¤µ)¡£
¤½¤·¤Æ hash ÃͤȤ·¤Æ»È¤ï¤ì¤ë 32¥Ó¥Ã¥È¤ÎÃͤòÊÖ¤µ¤Ê¤¯¤Æ¤Ï¤Ê¤é¤Ê¤¤¡£
.TP
.I lorder
.\"O is the byte order for integers in the stored database metadata.
.\"O The number should represent the order as an integer; for example,
.\"O big endian order would be the number 4,321.
¥Ç¡¼¥¿¥Ù¡¼¥¹¤Ë³ÊǼ¤µ¤ì¤Æ¤¤¤ë¥á¥¿¥Ç¡¼¥¿¤ÎÀ°¿ôÃͤΥХ¤¥È¥ª¡¼¥À¡¼¡£
¤³¤Î¿ô»ú¤Ï¡¢½ç½ø¤òÀ°¿ô¤Çɽ¤·¤¿¤â¤Î¤Ç¤¢¤ë¡£
Î㤨¤Ð¥Ó¥Ã¥°¥¨¥ó¥Ç¥£¥¢¥ó¤Ê¤é¡¢¤³¤Î¿ôÃÍ¤Ï 4,321 ¤È¤Ê¤ë¡£
.\"O If
.I lorder
.\"O is 0 (no order is specified) the current host order is used.
.\"O If the file already exists, the specified value is ignored and the
.\"O value specified when the tree was created is used.
¤¬ 0 (»ØÄꤵ¤ì¤Æ¤¤¤Ê¤¤)¾ì¹ç¡¢¸½ºß¤Î¥Û¥¹¥È
¤Ç»È¤ï¤ì¤Æ¤¤¤ëʤӽ礬»È¤ï¤ì¤ë¡£
¥Õ¥¡¥¤¥ë¤¬´û¤Ë¸ºß¤¹¤ë¾ì¹ç¡¢»ØÄꤷ¤¿ÃͤÏ̵»ë¤µ¤ì¥Ä¥ê¡¼¤¬ºî¤é¤ì
¤¿»þ¤Ë»ØÄꤵ¤ì¤Æ¤¤¤¿Ãͤ¬»È¤ï¤ì¤ë¡£
.PP
.\"O If the file already exists (and the
.\"O .B O_TRUNC
.\"O flag is not specified), the
.\"O values specified for
.\"O .IR bsize ,
.\"O .IR ffactor ,
.\"O .IR lorder ,
.\"O and
.\"O .I nelem
.\"O are
.\"O ignored and the values specified when the tree was created are used.
.\"NAKANO the tree ¢ª the hash, ¤Ç¤·¤ç¤¦.
¥Õ¥¡¥¤¥ë¤¬´û¤Ë¸ºß¤·¤Æ¤¤¤ë (¤Þ¤¿¤Ï
.B O_TRUNC
¥Õ¥é¥°¤¬»ØÄꤵ¤ì¤Æ¤¤¤Ê¤¤) ¤È¡¢
.IR bsize ,
.IR ffactor ,
.IR lorder ,
.I nelem
¤Ë»ØÄꤵ¤ì¤¿ÃͤÏ̵»ë¤µ¤ì¡¢
¥Ï¥Ã¥·¥å¤¬ºî¤é¤ì¤¿»þ¤Ë»È¤Ã¤¿Ãͤ¬»È¤ï¤ì¤ë¡£
.PP
.\"O If a hash function is specified,
hash ´Ø¿ô¤¬»ØÄꤵ¤ì¤ë¤È¡¢
.I hash_open
.\"O will attempt to determine if the hash function specified is the same as
.\"O the one with which the database was created, and will fail if it is not.
¤Ï¥Ç¡¼¥¿¥Ù¡¼¥¹¤¬ºî¤é¤ì¤¿»þ¤Ë»ØÄꤵ¤ì¤Æ¤¤¤¿
hash ´Ø¿ô¤Èº£²ó»ØÄꤵ¤ì¤¿ hash ´Ø¿ô¤¬Æ±¤¸¤«¤É¤¦¤«¤òÄ´¤Ù¡¢
Ʊ¤¸¤Ç¤Ê¤¤¾ì¹ç¤Ë¤Ï¼ºÇÔ¤¹¤ë¡£
.PP
.\"O Backward-compatible interfaces to the routines described in
.BR dbm (3),
¤È
.\"O and
.BR ndbm (3)
¤Ëµ­½Ò¤µ¤ì¤Æ¤¤¤ë¥ë¡¼¥Á¥ó¤Ø¤Î²áµî¸ß´¹¤ò¼è¤ë¤¿¤á¤Î¥¤¥ó¥¿¡¼¥Õ¥§¥¤¥¹¤¬
¸ºß¤¹¤ë¡£¤·¤«¤·¤³¤ì¤é¤Î¥¤¥ó¥¿¡¼¥Õ¥§¥¤¥¹¤Ï°ÊÁ°¤Î¥Õ¥¡¥¤¥ë¥Õ¥©¡¼
¥Þ¥Ã¥È¤È¤Ï¸ß´¹À­¤¬¤Ê¤¤¡£
.\"O are provided, however these interfaces are not compatible with
.\"O previous file formats.
.SH ¥¨¥é¡¼
.\"O The
.\"O .I hash
.\"O access method routines may fail and set
.\"O .I errno
.\"O for any of the errors specified for the library routine
.\"O .BR dbopen (3).
.I hash
¥¢¥¯¥»¥¹¥á¥½¥Ã¥É¥ë¡¼¥Á¥ó¤Ï¡¢¼ºÇÔ¤¹¤ë¤È¥é¥¤¥Ö¥é¥ê¥ë¡¼¥Á¥ó
.BR dbopen (3)
¤Ç»ØÄꤵ¤ì¤Æ¤¤¤ë¥¨¥é¡¼¤Ë±þ¤¸¤¿
.I errno
¤ò¥»¥Ã¥È¤¹¤ë¡£
.SH ¥Ð¥°
.\"O Only big and little endian byte order are supported.
¥Ð¥¤¥È¥ª¡¼¥À¡¼¤È¤·¤Æ¤Ï¥Ó¥Ã¥°¥¨¥ó¥Ç¥£¥¢¥ó¤È¥ê¥È¥ë¥¨¥ó¥Ç¥£¥¢¥ó¤Î¤ß¤¬
¥µ¥Ý¡¼¥È¤µ¤ì¤Æ¤¤¤ë¡£
.SH ´ØÏ¢¹àÌÜ
.BR btree (3),
.BR dbopen (3),
.BR mpool (3),
.BR recno (3)
.sp
.IR "Dynamic Hash Tables" ,
Per-Ake Larson, Communications of the ACM, April 1988.
.sp
.IR "A New Hash Package for UNIX" ,
Margo Seltzer, USENIX Proceedings, Winter 1991.