Linux Certif

Toute la documentation sur la certification Linux LPI

dbopen

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dbopen - ¥Ç¡¼¥¿¥Ù¡¼¥¹¥¢¥¯¥»¥¹¥á¥½¥Ã¥É

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#include <sys/types.h>

#include <limits.h>

#include <db.h>



DB *dbopen(const char *file, int flags, int mode, DBTYPE type,

           const void *openinfo);

ÀâÌÀ

dbopen() ¤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¤Ï btree, hash, UNIX ¥Õ¥¡¥¤¥ë¤Ë»Ø¸þ¤·¤¿¥Õ¥©¡¼¥Þ¥Ã¥È, ¤Î 3 ¤Ä¤Ç¤¢¤ë¡£ btree ¥Õ¥©¡¼¥Þ¥Ã¥È¤Ï¡¢¥½¡¼¥È¤µ¤ì¤¿¥Ð¥é¥ó¥¹¥Ä¥ê¡¼¹½Â¤¤Ç¤¢¤ë¡£ hashed ¥Õ¥©¡¼¥Þ¥Ã¥È¤Ï¡¢³ÈÄ¥²Äǽ¤ÊưŪ hash ¥¹¥­¡¼¥à¤Ç¤¢¤ë¡£ ¥Õ¥é¥Ã¥È¥Õ¥¡¥¤¥ë (flat-file) ¥Õ¥©¡¼¥Þ¥Ã¥È¤Ï¡¢ ¸ÇÄêĹ/²ÄÊÑĹ¤Î¥ì¥³¡¼¥É¤«¤é¤Ê¤ë¥Ð¥¤¥È¥¹¥È¥ê¡¼¥à¥Õ¥¡¥¤¥ë¤Ç¤¢¤ë¡£ ¤½¤ì¤¾¤ì¤Î¥Õ¥©¡¼¥Þ¥Ã¥È¤È¡¢¥Õ¥¡¥¤¥ë¥Õ¥©¡¼¥Þ¥Ã¥È¤ËÆÃÍ­¤Î¾ðÊó¤Ï ¤½¤ì¤¾¤ìÂбþ¤¹¤ë¥Þ¥Ë¥å¥¢¥ë¥Ú¡¼¥¸ btree(3), hash(3), recno(3) ¤Ë¾ÜºÙ¤Ëµ­½Ò¤µ¤ì¤Æ¤¤¤ë¡£

dbopen() ¤Ï file ¤òÆɤ߹þ¤ß (Æɤ߽ñ¤­) ¤¹¤ë¤¿¤á¤Ë¥ª¡¼¥×¥ó¤¹¤ë¡£ file ¥Ñ¥é¥á¡¼¥¿¤ò NULL ¤Ë¤¹¤ì¤Ð¡¢ ¥Ç¥£¥¹¥¯¾å¤ËÊݸ¤·¤¿¤¯¤Ê¤¤¥Õ¥¡¥¤¥ë¤òºî¤ë¤³¤È¤â¤Ç¤­¤ë¡£

flags ¤È mode °ú¿ô¤Ï open(2) ¥ë¡¼¥Á¥ó¤Ç»ØÄꤹ¤ë¤Î¤ÈƱÍͤǤ¢¤ë¡£¤¿¤À¤· O_CREAT, O_EXCL, O_EXLOCK, O_NONBLOCK, O_RDONLY, O_RDWR, O_SHLOCK ¤È O_TRUNC ¥Õ¥é¥°¤À¤±¤¬°ÕÌ£¤ò»ý¤Ä¡£ (Ãí°Õ: O_WRONLY ¤Ç¥Ç¡¼¥¿¥Ù¡¼¥¹¥Õ¥¡¥¤¥ë¤ò³«¤¯»ö¤Ï½ÐÍè¤Ê¤¤)

type °ú¿ô¤Ï DBTYPE ·¿¤Ç¤¢¤ë (¥¤¥ó¥¯¥ë¡¼¥É¥Õ¥¡¥¤¥ë <db.h> ¤ÇÄêµÁ¤µ¤ì¤Æ¤¤¤ë)¡£ DB_BTREE, DB_HASH, DB_RECNO ¤Î¤¤¤º¤ì¤«¤ò¥»¥Ã¥È¤Ç¤­¤ë¡£

openinfo °ú¿ô¤Ï¥¢¥¯¥»¥¹¥á¥½¥Ã¥É¤Ë¸ÇÍ­¤Ê¹½Â¤ÂΤؤΥݥ¤¥ó¥¿¤Ç¤¢¤ë¡£ ¤½¤ì¤¾¤ì¤Î¹½Â¤ÂΤ˴ؤ·¤Æ¤Ï³Æ¥¢¥¯¥»¥¹¥á¥½¥Ã¥É¤Î ¥Þ¥Ë¥å¥¢¥ë¥Ú¡¼¥¸¤Ëµ­½Ò¤µ¤ì¤Æ¤¤¤ë¡£ openinfo ¤¬ NULL ¤Î¾ì¹ç¡¢¤½¤ì¤¾¤ì¤Î¥¢¥¯¥»¥¹¥á¥½¥Ã¥É¤È¥·¥¹¥Æ¥à¤È¤ËŬ¹ç¤·¤¿ ¥Ç¥Õ¥©¥ë¥È¤¬ÍѤ¤¤é¤ì¤ë¡£

dbopen() ¤Ï¡¢À®¸ù¤·¤¿¾ì¹ç DB ¹½Â¤ÂΤؤΥݥ¤¥ó¥¿¤ò¡¢¥¨¥é¡¼¤Î¾ì¹ç NULL ¤òÊÖ¤¹¡£ DB ¹½Â¤ÂÎ¤Ï <db.h> ¥¤¥ó¥¯¥ë¡¼¥É¥Õ¥¡¥¤¥ë¤ÎÃæ¤ÇÄêµÁ¤µ¤ì¤Æ¤ª¤ê¡¢ ¾¯¤Ê¤¯¤È¤â°Ê²¼¤Î¤è¤¦¤Ê¥Õ¥£¡¼¥ë¥É¤ò»ý¤Ã¤Æ¤¤¤ë¡£

typedef struct {

    DBTYPE type;

    int (*close)(const DB *db);

    int (*del)(const DB *db, const DBT *key, u_int flags);

    int (*fd)(const DB *db);

    int (*get)(const DB *db, DBT *key, DBT *data, u_int flags);

    int (*put)(const DB *db, DBT *key, const DBT *data,

               u_int flags);

    int (*sync)(const DB *db, u_int flags);

    int (*seq)(const DB *db, DBT *key, DBT *data, u_int flags);

} DB;

³ÆÍ×ÁǤˤϡ¢¥Ç¡¼¥¿¥Ù¡¼¥¹¤Î¥¿¥¤¥×¤È¡¢ ÍÍ¡¹¤ÊÆ°ºî¤ò¤¹¤ë´Ø¿ô¤Î¥»¥Ã¥È¤¬µ­½Ò¤µ¤ì¤Æ¤¤¤ë¡£ ¤³¤ì¤é¤Î´Ø¿ô¤Ï dbopen() ¤Ë¤è¤Ã¤ÆÊÖ¤µ¤ì¤ë¹½Â¤ÂΤؤΥݥ¤¥ó¥¿¤ò°ú¿ô¤Ë¤È¤ë¡£ ¥­¡¼/¥Ç¡¼¥¿¹½Â¤ÂΤؤΥݥ¤¥ó¥¿¤ä¥Õ¥é¥°Ãͤò¼è¤ë¤â¤Î¤â¤¢¤ë¡£

type

ÍѤ¤¤é¤ì¤Æ¤¤¤ë¥¢¥¯¥»¥¹¥á¥½¥Ã¥É (¤È¥Õ¥¡¥¤¥ë¥Õ¥©¡¼¥Þ¥Ã¥È) ¤Î·¿¡£

close

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del

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flag °ú¿ô¤Ï¼¡¤ÎÃͤ¬¥»¥Ã¥È¤Ç¤­¤ë¡£

R_CURSOR

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delete ¥ë¡¼¥Á¥ó¤Ï¥¨¥é¡¼¤Î¾ì¹ç -1 ¤òÊÖ¤· (errno ¤ò¥»¥Ã¥È¤¹¤ë)¡¢À®¸ù¤¹¤ë¤È 0 ¤òÊÖ¤¹¡£¤Þ¤¿»ØÄê¤Î key ¤¬¥Õ¥¡¥¤¥ëÃæ¤Ë̵¤¤¾ì¹ç 1 ¤òÊÖ¤¹¡£

fd

ÍѤ¤¤Æ¤¤¤ë¥Ç¡¼¥¿¥Ù¡¼¥¹¤Î¥Õ¥¡¥¤¥ë¥Ç¥¹¥¯¥ê¥×¥¿¤òÊÖ¤¹¥ë¡¼¥Á¥ó ¤Ø¤Î¥Ý¥¤¥ó¥¿¡£ Ʊ¤¸¥Õ¥¡¥¤¥ë̾ file ¤Ç dbopen() ¤ò¸Æ¤Ó½Ð¤·¤¿Á´¤Æ¤Î¥×¥í¥»¥¹¤ËÂФ·¤Æ¡¢ ¤½¤Î¥Õ¥¡¥¤¥ë¤ò¼¨¤¹Ã±°ì¤Î¥Õ¥¡¥¤¥ë¥Ç¥¹¥¯¥ê¥×¥¿¤¬ÊÖ¤µ¤ì¤ë¡£ ¤³¤Î¥Õ¥¡¥¤¥ë¥Ç¥¹¥¯¥ê¥×¥¿¤Ï¥í¥Ã¥¯´Ø¿ô fcntl(2) ¤È flock(2) ¤Ø¤Î°ú¿ô¤È¤·¤Æ°ÂÁ´¤Ë»ÈÍѤǤ­¤ë¡£ ¤³¤Î¥Õ¥¡¥¤¥ë¥Ç¥¹¥¯¥ê¥×¥¿¤Ï¡¢É¬¤º¤·¤â¥¢¥¯¥»¥¹¥á¥½¥Ã¥É¤Ç ÍѤ¤¤é¤ì¤Æ¤¤¤ë¥Õ¥¡¥¤¥ë¤Î¤¤¤º¤ì¤«¤Ë´ØÏ¢¤Å¤±¤é¤ì¤Æ¤¤¤Ê¤¯¤Æ¤âÎɤ¤¡£ ¥á¥â¥êÆâ¤Î¥Ç¡¼¥¿¥Ù¡¼¥¹¤Ë¤Ï¥Õ¥¡¥¤¥ë¥Ç¥¹¥¯¥ê¥×¥¿¤Ï̵¤¤¡£ fd ¥ë¡¼¥Á¥ó¤Ï¥¨¥é¡¼¤Î¾ì¹ç -1 ¤òÊÖ¤· (errno ¤ò¥»¥Ã¥È¤¹¤ë)¡¢À®¸ù¤¹¤ë¤È¥Õ¥¡¥¤¥ë¥Ç¥¹¥¯¥ê¥×¥¿¤òÊÖ¤¹¡£

get

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put

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R_IAFTER

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R_NOOVERWRITE

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seq

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R_NEXT

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R_PREV

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sync

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R_RECNOSYNC

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typedef struct {

void *data;
size_t size;

} DBT;

DBT ¹½Â¤ÂΤγÆÍ×ÁǤϼ¡¤Î¤è¤¦¤ËÄêµÁ¤µ¤ì¤Æ¤¤¤ë¡£

data

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btree(3), hash(3), mpool(3), recno(3)

LIBTP: Portable, Modular Transactions for UNIX, Margo Seltzer, Michael Olson, USENIX proceedings, Winter 1992.