villa.h

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/*************************************************************************************************
 * The advanced API of QDBM
 *                                                      Copyright (C) 2000-2003 Mikio Hirabayashi
 * This file is part of QDBM, Quick Database Manager.
 * QDBM is free software; you can redistribute it and/or modify it under the terms of the GNU
 * Lesser General Public License as published by the Free Software Foundation; either version
 * 2.1 of the License or any later version.  QDBM is distributed in the hope that it will be
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
 * details.
 * You should have received a copy of the GNU Lesser General Public License along with QDBM; if
 * not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
 * 02111-1307 USA.
 *************************************************************************************************/


#ifndef _VILLA_H                         /* duplication check */
#define _VILLA_H


#include <depot.h>
#include <cabin.h>
#include <stdlib.h>



/*************************************************************************************************
 * API
 *************************************************************************************************/


typedef struct {                         /* type of structure for a record */
  CBDATUM *key;                          /* datum of the key */
  CBDATUM *first;                        /* datum of the first value */
  CBLIST *rest;                          /* list of the rest values */
} VLREC;

typedef struct {                         /* type of structure for index of a page */
  int pid;                               /* ID number of the referring page */
  CBDATUM *key;                          /* threshold key of the page */
} VLIDX;

typedef struct {                         /* type of structure for a leaf page */
  int id;                                /* ID number of the leaf */
  int dirty;                             /* whether to be written back or not */
  CBLIST *recs;                          /* list of records */
  int prev;                              /* ID number of the previous leaf */
  int next;                              /* ID number of the next leaf */
} VLLEAF;

typedef struct {                         /* type of structure for a node page */
  int id;                                /* ID number of the node */
  int dirty;                             /* whether to be written back or not */
  int heir;                              /* ID of the child before the first index */
  CBLIST *idxs;                          /* list of indexes */
} VLNODE;

/* type of the pointer to a comparing function.
   `aptr' specifies the pointer to the region of one key.
   `asiz' specifies the size of the region of one key.
   `bptr' specifies the pointer to the region of the other key.
   `bsiz' specifies the size of the region of the other key.
   The return value is positive if the former is big, negative if the latter is big, 0 if both
   are equivalent. */
typedef int(*VLCFUNC)(const char *aptr, int asiz, const char *bptr, int bsiz);
extern VLCFUNC VL_CMPLEX;                /* lexical comparing function */
extern VLCFUNC VL_CMPINT;                /* native integer comparing function */
extern VLCFUNC VL_CMPNUM;                /* big endian number comparing function */
extern VLCFUNC VL_CMPDEC;                /* decimal string comparing function */

typedef struct {                         /* type of structure for a database handle */
  DEPOT *depot;                          /* internal database handle */
  VLCFUNC cmp;                           /* pointer to the comparing function */
  int wmode;                             /* whether writable or not */
  int root;                              /* ID number of the root page */
  int last;                              /* ID number of the last leaf */
  int lnum;                              /* number of leaves */
  int nnum;                              /* number of nodes */
  int rnum;                              /* number of records */
  CBMAP *leafc;                          /* cache for leaves */
  CBMAP *nodec;                          /* cache for nodes */
  int curleaf;                           /* ID number of the leaf where the cursor is */
  int curknum;                           /* index of the key where the cursor is */
  int curvnum;                           /* index of the value where the cursor is */
  int leafrecmax;                        /* max number of records in a leaf */
  int nodeidxmax;                        /* max number of indexes in a node */
  int leafcnum;                          /* max number of caching leaves */
  int nodecnum;                          /* max number of caching nodes */
  int avglsiz;                           /* average size of each leave */
  int avgnsiz;                           /* average size of each node */
  int tran;                              /* whether in the transaction or not */
  int rbroot;                            /* root for rollback */
  int rblast;                            /* last for rollback */
  int rblnum;                            /* lnum for rollback */
  int rbnnum;                            /* nnum for rollback */
  int rbrnum;                            /* rnum for rollback */
} VILLA;

enum {                                   /* enumeration for open modes */
  VL_OREADER = 1 << 0,                   /* open as a reader */
  VL_OWRITER = 1 << 1,                   /* open as a writer */
  VL_OCREAT = 1 << 2,                    /* a writer creating */
  VL_OTRUNC = 1 << 3,                    /* a writer truncating */
  VL_ONOLCK = 1 << 4                     /* open without locking */
};

enum {                                   /* enumeration for write modes */
  VL_DOVER,                              /* overwrite an existing value */
  VL_DKEEP,                              /* keep an existing value */
  VL_DDUP                                /* allow duplication of records */
};

enum {                                   /* enumeration for jump modes */
  VL_JFORWARD,                           /* step forward */
  VL_JBACKWARD                           /* step backward */
};


/* Get a database handle.
   `name' specifies the name of a database file.
   `omode' specifies the connection mode: `VL_OWRITER' as a writer, `VL_OREADER' as a reader.
   If the mode is `VL_OWRITER', the following may be added by bitwise or: `VL_OCREAT', which
   means it creates a new database if not exist, `VL_OTRUNC', which means it creates a new
   database regardless if one exists.  Both of `VL_OREADER' and `VL_OWRITER' can be added to by
   bitwise or: `VL_ONOLCK', which means it opens a database file without file locking.
   `cmp' specifies a comparing function: `VL_CMPLEX' comparing keys in lexical order,
   `VL_CMPINT' comparing keys as objects of `int' in native byte order, `VL_CMPNUM' comparing
   keys as numbers of big endian, `VL_CMPDEC' comparing keys as decimal strings.  Any function
   based on the declaration of the type `VLCFUNC' can be assigned to the comparing function.
   The comparing function should be kept same in  the life of a database.
   The return value is the database handle or `NULL' if it is not successful.
   While connecting as a writer, an exclusive lock is invoked to the database file.
   While connecting as a reader, a shared lock is invoked to the database file.  The thread
   blocks until the lock is achieved. If `VL_ONOLCK' is used, the application is responsible
   for exclusion control. */
VILLA *vlopen(const char *name, int omode, VLCFUNC cmp);


/* Close a database handle.
   `villa' specifies a database handle.
   If successful, the return value is true, else, it is false.
   Because the region of a closed handle is released, it becomes impossible to use the handle.
   Updating a database is assured to be written when the handle is closed.  If a writer opens
   a database but does not close it appropriately, the database will be broken.  If the
   transaction is activated and not committed, it is aborted. */
int vlclose(VILLA *villa);


/* Store a record.
   `villa' specifies a database handle connected as a writer.
   `kbuf' specifies the pointer to the region of a key.
   `ksiz' specifies the size of the region of the key.  If it is negative, the size is assigned
   with `strlen(kbuf)'.
   `vbuf' specifies the pointer to the region of a value.
   `vsiz' specifies the size of the region of the value.  If it is negative, the size is
   assigned with `strlen(vbuf)'.
   `dmode' specifies behavior when the key overlaps, by the following values: `VL_DOVER',
   which means the specified value overwrites the existing one, `VL_DKEEP', which means the
   existing value is kept, `VL_DDUP', which means duplication of keys is allowed.
   If successful, the return value is true, else, it is false.
   A duplicated record is stored at the tail of the records of the same key.  The cursor becomes
   unavailable due to updating database. */
int vlput(VILLA *villa, const char *kbuf, int ksiz, const char *vbuf, int vsiz, int dmode);


/* Delete a record.
   `villa' specifies a database handle connected as a writer.
   `kbuf' specifies the pointer to the region of a key.
   `ksiz' specifies the size of the region of the key.  If it is negative, the size is assigned
   with `strlen(kbuf)'.
   If successful, the return value is true, else, it is false.  False is returned when no
   record corresponds to the specified key.
   When the key of duplicated records is specified, the first record of the same key is deleted.
   The cursor becomes unavailable due to updating database. */
int vlout(VILLA *villa, const char *kbuf, int ksiz);


/* Retrieve a record.
   `villa' specifies a database handle.
   `kbuf' specifies the pointer to the region of a key.
   `ksiz' specifies the size of the region of the key.  If it is negative, the size is assigned
   with `strlen(kbuf)'.
   `sp' specifies the pointer to a variable to which the size of the region of the return
   value is assigned.  If it is `NULL', it is not used.
   If successful, the return value is the pointer to the region of the value of the
   corresponding record, else, it is `NULL'.  `NULL' is returned when no record corresponds to
   the specified key.
   When the key of duplicated records is specified, the value of the first record of the same
   key is selected.  Because an additional zero code is appended at the end of the region of the
   return value, the return value can be treated as a character string.  Because the region of
   the return value is allocated with the `malloc' call, it should be released with the `free'
   call if it is no longer in use. */
char *vlget(VILLA *villa, const char *kbuf, int ksiz, int *sp);


/* Get the number of records corresponding a key.
   `villa' specifies a database handle.
   `kbuf' specifies the pointer to the region of a key.
   `ksiz' specifies the size of the region of the key.  If it is negative, the size is assigned
   with `strlen(kbuf)'.
   The return value is the number of corresponding records.  If no record corresponds, 0 is
   returned. */
int vlvnum(VILLA *villa, const char *kbuf, int ksiz);


/* Store plural records corresponding a key.
   `villa' specifies a database handle connected as a writer.
   `kbuf' specifies the pointer to the region of a key.
   `ksiz' specifies the size of the region of the key.  If it is negative, the size is assigned
   with `strlen(kbuf)'.
   `vals' specifies a list handle of values.  The list should not be empty.
   If successful, the return value is true, else, it is false.
   The cursor becomes unavailable due to updating database. */
int vlputlist(VILLA *villa, const char *kbuf, int ksiz, CBLIST *vals);