hash_page.c File Reference

#include <sys/types.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "../include/db.h"
#include "hash.h"
#include "page.h"
#include "extern.h"

Include dependency graph for hash_page.c:

Go to the source code of this file.

Macros
#define	BYTE_MASK   ((1 << INT_BYTE_SHIFT) -1)
#define	OVMSG   "HASH: Out of overflow pages. Increase page size\n"
#define	PAGE_INIT(P)

Functions
BUFHEAD *	__add_ovflpage (HTAB *hashp, BUFHEAD *bufp)
int	__addel (HTAB *hashp, BUFHEAD *bufp, const DBT *key, const DBT *val)
int	__delpair (HTAB *hashp, BUFHEAD *bufp, int ndx)
void	__free_ovflpage (HTAB *hashp, BUFHEAD *obufp)
int	__get_page (HTAB *hashp, char *p, u_int32_t bucket, int is_bucket, int is_disk, int is_bitmap)
int	__ibitmap (HTAB *hashp, int pnum, int nbits, int ndx)
static void putpair	__P ((char *, const DBT *, const DBT *))
static int open_temp	__P ((HTAB *))
static u_int32_t *fetch_bitmap	__P ((HTAB *, int))
static int ugly_split	__P ((HTAB *, u_int32_t, BUFHEAD *, BUFHEAD *, int, int))
static void squeeze_key	__P ((u_int16_t *, const DBT *, const DBT *))
static u_int32_t first_free	__P ((u_int32_t))
int	__put_page (HTAB *hashp, char *p, u_int32_t bucket, int is_bucket, int is_bitmap)
int	__split_page (HTAB *hashp, u_int32_t obucket, u_int32_t nbucket)
static u_int32_t *	fetch_bitmap (HTAB *hashp, int ndx)
static u_int32_t	first_free (u_int32_t map)
static int	open_temp (HTAB *hashp)
static u_int16_t	overflow_page (HTAB *hashp)
static void	putpair (char *p, const DBT *key, const DBT *val)
static void	squeeze_key (u_int16_t *sp, const DBT *key, const DBT *val)
static int	ugly_split (HTAB *hashp, u_int32_t obucket, BUFHEAD *old_bufp, BUFHEAD *new_bufp, int copyto, int moved)

Macro Definition Documentation

BYTE_MASK

#define BYTE_MASK   ((1 << INT_BYTE_SHIFT) -1)

Definition at line 621 of file hash_page.c.

OVMSG

#define OVMSG   "HASH: Out of overflow pages. Increase page size\n"

PAGE_INIT

#define PAGE_INIT

(

P

)

Value:

    { \
    ((u_int16_t *)(P))[0] = 0; \
    ((u_int16_t *)(P))[1] = hashp->BSIZE - 3 * sizeof(u_int16_t); \
    ((u_int16_t *)(P))[2] = hashp->BSIZE; \
}

Definition at line 84 of file hash_page.c.

Function Documentation

__add_ovflpage()

BUFHEAD * __add_ovflpage	(	HTAB *	hashp,
		BUFHEAD *	bufp
	)

Definition at line 465 of file hash_page.c.

{
    register u_int16_t *sp;
    u_int16_t ndx, ovfl_num;
#ifdef DEBUG1
    int tmp1, tmp2;
#endif
    sp = (u_int16_t *)bufp->page;
 
    /* Check if we are dynamically determining the fill factor */
    if (hashp->FFACTOR == DEF_FFACTOR) {
        hashp->FFACTOR = sp[0] >> 1;
        if (hashp->FFACTOR < MIN_FFACTOR)
            hashp->FFACTOR = MIN_FFACTOR;
    }
    bufp->flags |= BUF_MOD;
    ovfl_num = overflow_page(hashp);
#ifdef DEBUG1
    tmp1 = bufp->addr;
    tmp2 = bufp->ovfl ? bufp->ovfl->addr : 0;
#endif
    if (!ovfl_num || !(bufp->ovfl = __get_buf(hashp, ovfl_num, bufp, 1)))
        return (NULL);
    bufp->ovfl->flags |= BUF_MOD;
#ifdef DEBUG1
    (void)fprintf(stderr, "ADDOVFLPAGE: %d->ovfl was %d is now %d\n",
        tmp1, tmp2, bufp->ovfl->addr);
#endif
    ndx = sp[0];
    /*
     * Since a pair is allocated on a page only if there's room to add
     * an overflow page, we know that the OVFL information will fit on
     * the page.
     */
    sp[ndx + 4] = OFFSET(sp);
    sp[ndx + 3] = FREESPACE(sp) - OVFLSIZE;
    sp[ndx + 1] = ovfl_num;
    sp[ndx + 2] = OVFLPAGE;
    sp[0] = ndx + 2;
#ifdef HASH_STATISTICS
    hash_overflows++;
#endif
    return (bufp->ovfl);
}

References __get_buf(), _bufhead::addr, BUF_MOD, DEF_FFACTOR, _bufhead::flags, FREESPACE, if(), MIN_FFACTOR, NULL, OFFSET, overflow_page(), _bufhead::ovfl, OVFLPAGE, OVFLSIZE, and _bufhead::page.

Referenced by __addel(), __big_insert(), __big_split(), and ugly_split().

__addel()

int __addel	(	HTAB *	hashp,
		BUFHEAD *	bufp,
		const DBT *	key,
		const DBT *	val
	)

Definition at line 398 of file hash_page.c.

{
    register u_int16_t *bp, *sop;
    int do_expand;
 
    bp = (u_int16_t *)bufp->page;
    do_expand = 0;
    while (bp[0] && (bp[2] < REAL_KEY || bp[bp[0]] < REAL_KEY))
        /* Exception case */
        if (bp[2] == FULL_KEY_DATA && bp[0] == 2)
            /* This is the last page of a big key/data pair
               and we need to add another page */
            break;
        else if (bp[2] < REAL_KEY && bp[bp[0]] != OVFLPAGE) {
            bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
            if (!bufp)
                return (-1);
            bp = (u_int16_t *)bufp->page;
        } else
            /* Try to squeeze key on this page */
            if (FREESPACE(bp) > PAIRSIZE(key, val)) {
                squeeze_key(bp, key, val);
                return (0);
            } else {
                bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
                if (!bufp)
                    return (-1);
                bp = (u_int16_t *)bufp->page;
            }
 
    if (PAIRFITS(bp, key, val))
        putpair(bufp->page, key, val);
    else {
        do_expand = 1;
        bufp = __add_ovflpage(hashp, bufp);
        if (!bufp)
            return (-1);
        sop = (u_int16_t *)bufp->page;
 
        if (PAIRFITS(sop, key, val))
            putpair((char *)sop, key, val);
        else
            if (__big_insert(hashp, bufp, key, val))
                return (-1);
    }
    bufp->flags |= BUF_MOD;
    /*
     * If the average number of keys per bucket exceeds the fill factor,
     * expand the table.
     */
    hashp->NKEYS++;
    if (do_expand ||
        (hashp->NKEYS / (hashp->MAX_BUCKET + 1) > hashp->FFACTOR))
        return (__expand_table(hashp));
    return (0);
}

References __add_ovflpage(), __big_insert(), __expand_table(), __get_buf(), BUF_MOD, _bufhead::flags, FREESPACE, FULL_KEY_DATA, if(), OVFLPAGE, _bufhead::page, PAIRFITS, PAIRSIZE, putpair(), REAL_KEY, squeeze_key(), and while().

Referenced by hash_access().

__delpair()

int __delpair	(	HTAB *	hashp,
		BUFHEAD *	bufp,
		int	ndx
	)

Definition at line 128 of file hash_page.c.

{
    register u_int16_t *bp, newoff;
    register int n;
    u_int16_t pairlen;
 
    bp = (u_int16_t *)bufp->page;
    n = bp[0];
 
    if (bp[ndx + 1] < REAL_KEY)
        return (__big_delete(hashp, bufp));
    if (ndx != 1)
        newoff = bp[ndx - 1];
    else
        newoff = hashp->BSIZE;
    pairlen = newoff - bp[ndx + 1];
 
    if (ndx != (n - 1)) {
        /* Hard Case -- need to shuffle keys */
        register int i;
        register char *src = bufp->page + (int)OFFSET(bp);
        register char *dst = src + (int)pairlen;
        memmove(dst, src, bp[ndx + 1] - OFFSET(bp));
 
        /* Now adjust the pointers */
        for (i = ndx + 2; i <= n; i += 2) {
            if (bp[i + 1] == OVFLPAGE) {
                bp[i - 2] = bp[i];
                bp[i - 1] = bp[i + 1];
            } else {
                bp[i - 2] = bp[i] + pairlen;
                bp[i - 1] = bp[i + 1] + pairlen;
            }
        }
    }
    /* Finally adjust the page data */
    bp[n] = OFFSET(bp) + pairlen;
    bp[n - 1] = bp[n + 1] + pairlen + 2 * sizeof(u_int16_t);
    bp[0] = n - 2;
    hashp->NKEYS--;
 
    bufp->flags |= BUF_MOD;
    return (0);
}

References __big_delete(), BUF_MOD, _bufhead::flags, if(), OFFSET, OVFLPAGE, _bufhead::page, and REAL_KEY.

Referenced by hash_access().

__free_ovflpage()

void __free_ovflpage	(	HTAB *	hashp,
		BUFHEAD *	obufp
	)

Definition at line 815 of file hash_page.c.

{
    register u_int16_t addr;
    u_int32_t *freep;
    int bit_address, free_page, free_bit;
    u_int16_t ndx;
 
    addr = obufp->addr;
#ifdef DEBUG1
    (void)fprintf(stderr, "Freeing %d\n", addr);
#endif
    ndx = (((u_int16_t)addr) >> SPLITSHIFT);
    bit_address =
        (ndx ? hashp->SPARES[ndx - 1] : 0) + (addr & SPLITMASK) - 1;
     if (bit_address < hashp->LAST_FREED)
        hashp->LAST_FREED = bit_address;
    free_page = (bit_address >> (hashp->BSHIFT + BYTE_SHIFT));
    free_bit = bit_address & ((hashp->BSIZE << BYTE_SHIFT) - 1);
 
    if (!(freep = hashp->mapp[free_page]))
        freep = fetch_bitmap(hashp, free_page);
#ifdef DEBUG
    /*
     * This had better never happen.  It means we tried to read a bitmap
     * that has already had overflow pages allocated off it, and we
     * failed to read it from the file.
     */
    if (!freep)
        assert(0);
#endif
    CLRBIT(freep, free_bit);
#ifdef DEBUG2
    (void)fprintf(stderr, "FREE_OVFLPAGE: ADDR: %d BIT: %d PAGE %d\n",
        obufp->addr, free_bit, free_page);
#endif
    __reclaim_buf(hashp, obufp);
}

References __reclaim_buf(), _bufhead::addr, BYTE_SHIFT, CLRBIT, fetch_bitmap(), LAST_FREED, htab::mapp, SPLITMASK, and SPLITSHIFT.

Referenced by __big_delete(), and ugly_split().

__get_page()

int __get_page	(	HTAB *	hashp,
		char *	p,
		u_int32_t	bucket,
		int	is_bucket,
		int	is_disk,
		int	is_bitmap
	)

Definition at line 518 of file hash_page.c.

{
    register int fd, page, size;
    int rsize;
    u_int16_t *bp;
 
    fd = hashp->fp;
    size = hashp->BSIZE;
 
    if ((fd == -1) || !is_disk) {
        PAGE_INIT(p);
        return (0);
    }
    if (is_bucket)
        page = BUCKET_TO_PAGE(bucket);
    else
        page = OADDR_TO_PAGE(bucket);
    if ((lseek(fd, (off_t)page << hashp->BSHIFT, SEEK_SET) == -1) ||
        ((rsize = read(fd, p, size)) == -1))
        return (-1);
    bp = (u_int16_t *)p;
    if (!rsize)
        bp[0] = 0;  /* We hit the EOF, so initialize a new page */
    else
        if (rsize != size) {
            errno = EFTYPE;
            return (-1);
        }
    if (!is_bitmap && !bp[0]) {
        PAGE_INIT(p);
    } else
        if (hashp->LORDER != BYTE_ORDER) {
            register int i, max;
 
            if (is_bitmap) {
                max = hashp->BSIZE >> 2; /* divide by 4 */
                for (i = 0; i < max; i++)
                    M_32_SWAP(((int *)p)[i]);
            } else {
                M_16_SWAP(bp[0]);
                max = bp[0] + 2;
                for (i = 1; i <= max; i++)
                    M_16_SWAP(bp[i]);
            }
        }
    return (0);
}

References BUCKET_TO_PAGE, BYTE_ORDER, EFTYPE, errno, htab::fp, max, OADDR_TO_PAGE, and PAGE_INIT.

Referenced by __get_buf(), and fetch_bitmap().

__ibitmap()

int __ibitmap	(	HTAB *	hashp,
		int	pnum,
		int	nbits,
		int	ndx
	)

Definition at line 627 of file hash_page.c.

{
    u_int32_t *ip;
    int clearbytes, clearints;
 
    if ((ip = (u_int32_t *)malloc(hashp->BSIZE)) == NULL)
        return (1);
    hashp->nmaps++;
    clearints = ((nbits - 1) >> INT_BYTE_SHIFT) + 1;
    clearbytes = clearints << INT_TO_BYTE;
    (void)memset((char *)ip, 0, clearbytes);
    (void)memset(((char *)ip) + clearbytes, 0xFF,
        hashp->BSIZE - clearbytes);
    ip[clearints - 1] = ALL_SET << (nbits & BYTE_MASK);
    SETBIT(ip, 0);
    hashp->BITMAPS[ndx] = (u_int16_t)pnum;
    hashp->mapp[ndx] = ip;
    return (0);
}

References ALL_SET, BYTE_MASK, INT_BYTE_SHIFT, INT_TO_BYTE, malloc(), htab::mapp, htab::nmaps, NULL, and SETBIT.

Referenced by init_htab(), and overflow_page().

__P() [1/6]

static void putpair __P ( (char *, const DBT *, const DBT *)  )

static

__P() [2/6]

static int open_temp __P ( (HTAB *)  )

static

__P() [3/6]

static u_int32_t *fetch_bitmap __P ( (HTAB *, int)  )

static

__P() [4/6]

static int ugly_split __P ( (HTAB *, u_int32_t, BUFHEAD *, BUFHEAD *, int, int)  )

static

__P() [5/6]

static void squeeze_key __P ( (u_int16_t *, const DBT *, const DBT *)  )

static

__P() [6/6]

static u_int32_t first_free __P ( (u_int32_t)  )

static

__put_page()

int __put_page	(	HTAB *	hashp,
		char *	p,
		u_int32_t	bucket,
		int	is_bucket,
		int	is_bitmap
	)

Definition at line 578 of file hash_page.c.

{
    register int fd, page, size;
    int wsize;
 
    size = hashp->BSIZE;
    if ((hashp->fp == -1) && open_temp(hashp))
        return (-1);
    fd = hashp->fp;
 
    if (hashp->LORDER != BYTE_ORDER) {
        register int i;
        register int max;
 
        if (is_bitmap) {
            max = hashp->BSIZE >> 2;    /* divide by 4 */
            for (i = 0; i < max; i++)
                M_32_SWAP(((int *)p)[i]);
        } else {
            max = ((u_int16_t *)p)[0] + 2;
            for (i = 0; i <= max; i++)
                M_16_SWAP(((u_int16_t *)p)[i]);
        }
    }
    if (is_bucket)
        page = BUCKET_TO_PAGE(bucket);
    else
        page = OADDR_TO_PAGE(bucket);
    if ((lseek(fd, (off_t)page << hashp->BSHIFT, SEEK_SET) == -1) ||
        ((wsize = write(fd, p, size)) == -1))
        /* Errno is set */
        return (-1);
    if (wsize != size) {
        errno = EFTYPE;
        return (-1);
    }
    return (0);
}

References BUCKET_TO_PAGE, BYTE_ORDER, EFTYPE, errno, htab::fp, max, OADDR_TO_PAGE, and open_temp().

Referenced by __buf_free(), flush_meta(), and newbuf().

__split_page()

int __split_page	(	HTAB *	hashp,
		u_int32_t	obucket,
		u_int32_t	nbucket
	)

Definition at line 181 of file hash_page.c.

{
    register BUFHEAD *new_bufp, *old_bufp;
    register u_int16_t *ino;
    register char *np;
    DBT key, val;
    int n, ndx, retval;
    u_int16_t copyto, diff, off, moved;
    char *op;
 
    copyto = (u_int16_t)hashp->BSIZE;
    off = (u_int16_t)hashp->BSIZE;
    old_bufp = __get_buf(hashp, obucket, NULL, 0);
    if (old_bufp == NULL)
        return (-1);
    new_bufp = __get_buf(hashp, nbucket, NULL, 0);
    if (new_bufp == NULL)
        return (-1);
 
    old_bufp->flags |= (BUF_MOD | BUF_PIN);
    new_bufp->flags |= (BUF_MOD | BUF_PIN);
 
    ino = (u_int16_t *)(op = old_bufp->page);
    np = new_bufp->page;
 
    moved = 0;
 
    for (n = 1, ndx = 1; n < ino[0]; n += 2) {
        if (ino[n + 1] < REAL_KEY) {
            retval = ugly_split(hashp, obucket, old_bufp, new_bufp,
                (int)copyto, (int)moved);
            old_bufp->flags &= ~BUF_PIN;
            new_bufp->flags &= ~BUF_PIN;
            return (retval);
 
        }
        key.data = (u_char *)op + ino[n];
        key.size = off - ino[n];
 
        if (__call_hash(hashp, key.data, key.size) == obucket) {
            /* Don't switch page */
            diff = copyto - off;
            if (diff) {
                copyto = ino[n + 1] + diff;
                memmove(op + copyto, op + ino[n + 1],
                    off - ino[n + 1]);
                ino[ndx] = copyto + ino[n] - ino[n + 1];
                ino[ndx + 1] = copyto;
            } else
                copyto = ino[n + 1];
            ndx += 2;
        } else {
            /* Switch page */
            val.data = (u_char *)op + ino[n + 1];
            val.size = ino[n] - ino[n + 1];
            putpair(np, &key, &val);
            moved += 2;
        }
 
        off = ino[n + 1];
    }
 
    /* Now clean up the page */
    ino[0] -= moved;
    FREESPACE(ino) = copyto - sizeof(u_int16_t) * (ino[0] + 3);
    OFFSET(ino) = copyto;
 
#ifdef DEBUG3
    (void)fprintf(stderr, "split %d/%d\n",
        ((u_int16_t *)np)[0] / 2,
        ((u_int16_t *)op)[0] / 2);
#endif
    /* unpin both pages */
    old_bufp->flags &= ~BUF_PIN;
    new_bufp->flags &= ~BUF_PIN;
    return (0);
}

References __call_hash(), __get_buf(), BUF_MOD, BUF_PIN, DBT::data, _bufhead::flags, FREESPACE, NULL, OFFSET, _bufhead::page, putpair(), REAL_KEY, retval, DBT::size, and ugly_split().

Referenced by __expand_table().

fetch_bitmap()

static u_int32_t * fetch_bitmap ( HTAB *  hashp, int  ndx  )

static

Definition at line 910 of file hash_page.c.

{
    if (ndx >= hashp->nmaps)
        return (NULL);
    if ((hashp->mapp[ndx] = (u_int32_t *)malloc(hashp->BSIZE)) == NULL)
        return (NULL);
    if (__get_page(hashp,
        (char *)hashp->mapp[ndx], hashp->BITMAPS[ndx], 0, 1, 1)) {
        free(hashp->mapp[ndx]);
        return (NULL);
    }
    return (hashp->mapp[ndx]);
}

References __get_page(), free(), malloc(), htab::mapp, htab::nmaps, and NULL.

Referenced by __free_ovflpage(), and overflow_page().

first_free()

static u_int32_t first_free ( u_int32_t  map )

static

Definition at line 650 of file hash_page.c.

{
    register u_int32_t i, mask;
 
    mask = 0x1;
    for (i = 0; i < BITS_PER_MAP; i++) {
        if (!(mask & map))
            return (i);
        mask = mask << 1;
    }
    return (i);
}

References BITS_PER_MAP.

Referenced by overflow_page().

open_temp()

static int open_temp ( HTAB *  hashp )

static

Definition at line 861 of file hash_page.c.

{
    sigset_t set, oset;
    static char namestr[] = "_hashXXXXXX";
 
    /* Block signals; make sure file goes away at process exit. */
    (void)sigfillset(&set);
    (void)sigprocmask(SIG_BLOCK, &set, &oset);
    if ((hashp->fp = mkstemp(namestr)) != -1) {
        (void)unlink(namestr);
        (void)fcntl(hashp->fp, F_SETFD, 1);
    }
    (void)sigprocmask(SIG_SETMASK, &oset, (sigset_t *)NULL);
    return (hashp->fp != -1 ? 0 : -1);
}

References htab::fp, NULL, and set().

Referenced by __put_page().

overflow_page()

static u_int16_t overflow_page ( HTAB *  hashp )

static

Definition at line 665 of file hash_page.c.

{
    register u_int32_t *freep = 0;
    register int max_free, offset, splitnum;
    u_int16_t addr;
    int bit, first_page, free_bit, free_page, i, in_use_bits, j;
#ifdef DEBUG2
    int tmp1, tmp2;
#endif
    splitnum = hashp->OVFL_POINT;
    max_free = hashp->SPARES[splitnum];
 
    free_page = (max_free - 1) >> (hashp->BSHIFT + BYTE_SHIFT);
    free_bit = (max_free - 1) & ((hashp->BSIZE << BYTE_SHIFT) - 1);
 
    /* Look through all the free maps to find the first free block */
    first_page = hashp->LAST_FREED >>(hashp->BSHIFT + BYTE_SHIFT);
    for ( i = first_page; i <= free_page; i++ ) {
        if (!(freep = (u_int32_t *)hashp->mapp[i]) &&
            !(freep = fetch_bitmap(hashp, i)))
            return (0);
        if (i == free_page)
            in_use_bits = free_bit;
        else
            in_use_bits = (hashp->BSIZE << BYTE_SHIFT) - 1;
 
        if (i == first_page) {
            bit = hashp->LAST_FREED &
                ((hashp->BSIZE << BYTE_SHIFT) - 1);
            j = bit / BITS_PER_MAP;
            bit = bit & ~(BITS_PER_MAP - 1);
        } else {
            bit = 0;
            j = 0;
        }
        for (; bit <= in_use_bits; j++, bit += BITS_PER_MAP)
            if (freep[j] != ALL_SET)
                goto found;
    }
 
    /* No Free Page Found */
    hashp->LAST_FREED = hashp->SPARES[splitnum];
    hashp->SPARES[splitnum]++;
    offset = hashp->SPARES[splitnum] -
        (splitnum ? hashp->SPARES[splitnum - 1] : 0);
 
#define OVMSG   "HASH: Out of overflow pages.  Increase page size\n"
    if (offset > SPLITMASK) {
        if (++splitnum >= NCACHED) {
            if (write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1) < 0) {
            }
            return (0);
        }
        hashp->OVFL_POINT = splitnum;
        hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1];
        hashp->SPARES[splitnum-1]--;
        offset = 1;
    }
 
    /* Check if we need to allocate a new bitmap page */
    if (free_bit == (hashp->BSIZE << BYTE_SHIFT) - 1) {
        free_page++;
        if (free_page >= NCACHED) {
            if (write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1) < 0) {
            }
            return (0);
        }
        /*
         * This is tricky.  The 1 indicates that you want the new page
         * allocated with 1 clear bit.  Actually, you are going to
         * allocate 2 pages from this map.  The first is going to be
         * the map page, the second is the overflow page we were
         * looking for.  The init_bitmap routine automatically, sets
         * the first bit of itself to indicate that the bitmap itself
         * is in use.  We would explicitly set the second bit, but
         * don't have to if we tell init_bitmap not to leave it clear
         * in the first place.
         */
        if (__ibitmap(hashp,
            (int)OADDR_OF(splitnum, offset), 1, free_page))
            return (0);
        hashp->SPARES[splitnum]++;
#ifdef DEBUG2
        free_bit = 2;
#endif
        offset++;
        if (offset > SPLITMASK) {
            if (++splitnum >= NCACHED) {
                if (write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1) < 0) {
                }
                return (0);
            }
            hashp->OVFL_POINT = splitnum;
            hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1];
            hashp->SPARES[splitnum-1]--;
            offset = 0;
        }
    } else {
        /*
         * Free_bit addresses the last used bit.  Bump it to address
         * the first available bit.
         */
        free_bit++;
        SETBIT(freep, free_bit);
    }
 
    /* Calculate address of the new overflow page */
    addr = OADDR_OF(splitnum, offset);
#ifdef DEBUG2
    (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",
        addr, free_bit, free_page);
#endif
    return (addr);
 
found:
    bit = bit + first_free(freep[j]);
    SETBIT(freep, bit);
#ifdef DEBUG2
    tmp1 = bit;
    tmp2 = i;
#endif
    /*
     * Bits are addressed starting with 0, but overflow pages are addressed
     * beginning at 1. Bit is a bit addressnumber, so we need to increment
     * it to convert it to a page number.
     */
    bit = 1 + bit + (i * (hashp->BSIZE << BYTE_SHIFT));
    if (bit >= hashp->LAST_FREED)
        hashp->LAST_FREED = bit - 1;
 
    /* Calculate the split number for this page */
    for (i = 0; (i < splitnum) && (bit > hashp->SPARES[i]); i++);
    offset = (i ? bit - hashp->SPARES[i - 1] : bit);
    if (offset >= SPLITMASK)
        return (0); /* Out of overflow pages */
    addr = OADDR_OF(i, offset);
#ifdef DEBUG2
    (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",
        addr, tmp1, tmp2);
#endif
 
    /* Allocate and return the overflow page */
    return (addr);
}

References __ibitmap(), ALL_SET, BITS_PER_MAP, BYTE_SHIFT, fetch_bitmap(), first_free(), htab::mapp, NCACHED, OADDR_OF, OVMSG, SETBIT, and SPLITMASK.

Referenced by __add_ovflpage().

putpair()

static void putpair ( char *  p, const DBT *  key, const DBT *  val  )

static

Definition at line 96 of file hash_page.c.

{
    register u_int16_t *bp, n, off;
 
    bp = (u_int16_t *)p;
 
    /* Enter the key first. */
    n = bp[0];
 
    off = OFFSET(bp) - key->size;
    memmove(p + off, key->data, key->size);
    bp[++n] = off;
 
    /* Now the data. */
    off -= val->size;
    memmove(p + off, val->data, val->size);
    bp[++n] = off;
 
    /* Adjust page info. */
    bp[0] = n;
    bp[n + 1] = off - ((n + 3) * sizeof(u_int16_t));
    bp[n + 2] = off;
}

References DBT::data, OFFSET, and DBT::size.

Referenced by __addel(), __split_page(), and ugly_split().

squeeze_key()

static void squeeze_key ( u_int16_t *  sp, const DBT *  key, const DBT *  val  )

static

Definition at line 883 of file hash_page.c.

{
    register char *p;
    u_int16_t free_space, n, off, pageno;
 
    p = (char *)sp;
    n = sp[0];
    free_space = FREESPACE(sp);
    off = OFFSET(sp);
 
    pageno = sp[n - 1];
    off -= key->size;
    sp[n - 1] = off;
    memmove(p + off, key->data, key->size);
    off -= val->size;
    sp[n] = off;
    memmove(p + off, val->data, val->size);
    sp[0] = n + 2;
    sp[n + 1] = pageno;
    sp[n + 2] = OVFLPAGE;
    FREESPACE(sp) = free_space - PAIRSIZE(key, val);
    OFFSET(sp) = off;
}

References DBT::data, FREESPACE, OFFSET, OVFLPAGE, PAIRSIZE, and DBT::size.

Referenced by __addel().

ugly_split()

static int ugly_split ( HTAB *  hashp, u_int32_t  obucket, BUFHEAD *  old_bufp, BUFHEAD *  new_bufp, int  copyto, int  moved  )

static

Definition at line 277 of file hash_page.c.

{
    register BUFHEAD *bufp; /* Buffer header for ino */
    register u_int16_t *ino;    /* Page keys come off of */
    register u_int16_t *np; /* New page */
    register u_int16_t *op; /* Page keys go on to if they aren't moving */
 
    BUFHEAD *last_bfp;  /* Last buf header OVFL needing to be freed */
    DBT key, val;
    SPLIT_RETURN ret;
    u_int16_t n, off, ov_addr, scopyto;
    char *cino;     /* Character value of ino */
 
    bufp = old_bufp;
    ino = (u_int16_t *)old_bufp->page;
    np = (u_int16_t *)new_bufp->page;
    op = (u_int16_t *)old_bufp->page;
    last_bfp = NULL;
    scopyto = (u_int16_t)copyto;    /* ANSI */
 
    n = ino[0] - 1;
    while (n < ino[0]) {
        if (ino[2] < REAL_KEY && ino[2] != OVFLPAGE) {
            if (__big_split(hashp, old_bufp,
                new_bufp, bufp, bufp->addr, obucket, &ret))
                return (-1);
            old_bufp = ret.oldp;
            if (!old_bufp)
                return (-1);
            op = (u_int16_t *)old_bufp->page;
            new_bufp = ret.newp;
            if (!new_bufp)
                return (-1);
            np = (u_int16_t *)new_bufp->page;
            bufp = ret.nextp;
            if (!bufp)
                return (0);
            cino = (char *)bufp->page;
            ino = (u_int16_t *)cino;
            last_bfp = ret.nextp;
        } else if (ino[n + 1] == OVFLPAGE) {
            ov_addr = ino[n];
            /*
             * Fix up the old page -- the extra 2 are the fields
             * which contained the overflow information.
             */
            ino[0] -= (moved + 2);
            FREESPACE(ino) =
                scopyto - sizeof(u_int16_t) * (ino[0] + 3);
            OFFSET(ino) = scopyto;
 
            bufp = __get_buf(hashp, ov_addr, bufp, 0);
            if (!bufp)
                return (-1);
 
            ino = (u_int16_t *)bufp->page;
            n = 1;
            scopyto = hashp->BSIZE;
            moved = 0;
 
            if (last_bfp)
                __free_ovflpage(hashp, last_bfp);
            last_bfp = bufp;
        }
        /* Move regular sized pairs of there are any */
        off = hashp->BSIZE;
        for (n = 1; (n < ino[0]) && (ino[n + 1] >= REAL_KEY); n += 2) {
            cino = (char *)ino;
            key.data = (u_char *)cino + ino[n];
            key.size = off - ino[n];
            val.data = (u_char *)cino + ino[n + 1];
            val.size = ino[n] - ino[n + 1];
            off = ino[n + 1];
 
            if (__call_hash(hashp, key.data, key.size) == obucket) {
                /* Keep on old page */
                if (PAIRFITS(op, (&key), (&val)))
                    putpair((char *)op, &key, &val);
                else {
                    old_bufp =
                        __add_ovflpage(hashp, old_bufp);
                    if (!old_bufp)
                        return (-1);
                    op = (u_int16_t *)old_bufp->page;
                    putpair((char *)op, &key, &val);
                }
                old_bufp->flags |= BUF_MOD;
            } else {
                /* Move to new page */
                if (PAIRFITS(np, (&key), (&val)))
                    putpair((char *)np, &key, &val);
                else {
                    new_bufp =
                        __add_ovflpage(hashp, new_bufp);
                    if (!new_bufp)
                        return (-1);
                    np = (u_int16_t *)new_bufp->page;
                    putpair((char *)np, &key, &val);
                }
                new_bufp->flags |= BUF_MOD;
            }
        }
    }
    if (last_bfp)
        __free_ovflpage(hashp, last_bfp);
    return (0);
}

References __add_ovflpage(), __big_split(), __call_hash(), __free_ovflpage(), __get_buf(), _bufhead::addr, BUF_MOD, DBT::data, _bufhead::flags, FREESPACE, if(), SPLIT_RETURN::newp, SPLIT_RETURN::nextp, NULL, OFFSET, SPLIT_RETURN::oldp, OVFLPAGE, _bufhead::page, PAIRFITS, putpair(), REAL_KEY, and DBT::size.

Referenced by __split_page().