hash.h

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996-2005
 *      Sleepycat Software.  All rights reserved.
 */
/*
 * Copyright (c) 1990, 1993, 1994
 *      Margo Seltzer.  All rights reserved.
 */
/*
 * Copyright (c) 1990, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Margo Seltzer.
 *
 * 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. 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.
 *
 * $Id: hash.h,v 12.1 2005/06/16 20:21:47 bostic Exp $
 */

#ifndef _DB_HASH_H_
#define _DB_HASH_H_

/* Hash internal structure. */
typedef struct hash_t {
        db_pgno_t meta_pgno;    /* Page number of the meta data page. */
        u_int32_t h_ffactor;    /* Fill factor. */
        u_int32_t h_nelem;      /* Number of elements. */
                                /* Hash function. */
        u_int32_t (*h_hash) __P((DB *, const void *, u_int32_t));
} HASH;

/* Cursor structure definitions. */
typedef struct cursor_t {
        /* struct __dbc_internal */
        __DBC_INTERNAL

        /* Hash private part */

        /* Per-thread information */
        DB_LOCK hlock;                  /* Metadata page lock. */
        HMETA *hdr;                     /* Pointer to meta-data page. */
        PAGE *split_buf;                /* Temporary buffer for splits. */

        /* Hash cursor information */
        db_pgno_t       bucket;         /* Bucket we are traversing. */
        db_pgno_t       lbucket;        /* Bucket for which we are locked. */
        db_indx_t       dup_off;        /* Offset within a duplicate set. */
        db_indx_t       dup_len;        /* Length of current duplicate. */
        db_indx_t       dup_tlen;       /* Total length of duplicate entry. */
        u_int32_t       seek_size;      /* Number of bytes we need for add. */
        db_pgno_t       seek_found_page;/* Page on which we can insert. */
        u_int32_t       order;          /* Relative order among deleted curs. */

#define H_CONTINUE      0x0001          /* Join--search strictly fwd for data */
#define H_DELETED       0x0002          /* Cursor item is deleted. */
#define H_DIRTY         0x0004          /* Meta-data page needs to be written */
#define H_DUPONLY       0x0008          /* Dups only; do not change key. */
#define H_EXPAND        0x0010          /* Table expanded. */
#define H_ISDUP         0x0020          /* Cursor is within duplicate set. */
#define H_NEXT_NODUP    0x0040          /* Get next non-dup entry. */
#define H_NOMORE        0x0080          /* No more entries in bucket. */
#define H_OK            0x0100          /* Request succeeded. */
        u_int32_t       flags;
} HASH_CURSOR;

/* Test string. */
#define CHARKEY                 "%$sniglet^&"

/* Overflow management */
/*
 * The spares table indicates the page number at which each doubling begins.
 * From this page number we subtract the number of buckets already allocated
 * so that we can do a simple addition to calculate the page number here.
 */
#define BS_TO_PAGE(bucket, spares)              \
        ((bucket) + (spares)[__db_log2((bucket) + 1)])
#define BUCKET_TO_PAGE(I, B)    (BS_TO_PAGE((B), (I)->hdr->spares))

/* Constraints about much data goes on a page. */

#define MINFILL         4
#define ISBIG(I, N)     (((N) > ((I)->hdr->dbmeta.pagesize / MINFILL)) ? 1 : 0)

/* Shorthands for accessing structure */
#define NDX_INVALID     0xFFFF
#define BUCKET_INVALID  0xFFFFFFFF

/* On page duplicates are stored as a string of size-data-size triples. */
#define DUP_SIZE(len)   ((len) + 2 * sizeof(db_indx_t))

/* Log messages types (these are subtypes within a record type) */
#define PAIR_KEYMASK            0x1
#define PAIR_DATAMASK           0x2
#define PAIR_DUPMASK            0x4
#define PAIR_MASK               0xf
#define PAIR_ISKEYBIG(N)        (N & PAIR_KEYMASK)
#define PAIR_ISDATABIG(N)       (N & PAIR_DATAMASK)
#define PAIR_ISDATADUP(N)       (N & PAIR_DUPMASK)
#define OPCODE_OF(N)    (N & ~PAIR_MASK)

#define PUTPAIR         0x20
#define DELPAIR         0x30
#define PUTOVFL         0x40
#define DELOVFL         0x50
#define HASH_UNUSED1    0x60
#define HASH_UNUSED2    0x70
#define SPLITOLD        0x80
#define SPLITNEW        0x90

typedef enum {
        DB_HAM_CHGPG = 1,
        DB_HAM_DELFIRSTPG = 2,
        DB_HAM_DELMIDPG = 3,
        DB_HAM_DELLASTPG = 4,
        DB_HAM_DUP   = 5,
        DB_HAM_SPLIT = 6
} db_ham_mode;

#include "dbinc_auto/hash_auto.h"
#include "dbinc_auto/hash_ext.h"
#include "dbinc/db_am.h"
#endif /* !_DB_HASH_H_ */

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