diff options
Diffstat (limited to 'db/hash/hash_page.c')
| -rw-r--r-- | db/hash/hash_page.c | 944 |
1 files changed, 944 insertions, 0 deletions
diff --git a/db/hash/hash_page.c b/db/hash/hash_page.c new file mode 100644 index 0000000000..e1dfe6b8d6 --- /dev/null +++ b/db/hash/hash_page.c @@ -0,0 +1,944 @@ +/*- + * 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. 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. + */ + +#if defined(LIBC_SCCS) && !defined(lint) +static char sccsid[] = "@(#)hash_page.c 8.7 (Berkeley) 8/16/94"; +#endif /* LIBC_SCCS and not lint */ + +/* + * PACKAGE: hashing + * + * DESCRIPTION: + * Page manipulation for hashing package. + * + * ROUTINES: + * + * External + * __get_page + * __add_ovflpage + * Internal + * overflow_page + * open_temp + */ + +#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> +#ifdef DEBUG +#include <assert.h> +#endif + +#include <db.h> +#include "hash.h" +#include "page.h" +#include "extern.h" + +static u_int32_t *fetch_bitmap __P((HTAB *, int)); +static u_int32_t first_free __P((u_int32_t)); +static int open_temp __P((HTAB *)); +static u_int16_t overflow_page __P((HTAB *)); +static void putpair __P((char *, const DBT *, const DBT *)); +static void squeeze_key __P((u_int16_t *, const DBT *, const DBT *)); +static int ugly_split + __P((HTAB *, u_int32_t, BUFHEAD *, BUFHEAD *, int, int)); + +#define PAGE_INIT(P) { \ + ((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; \ +} + +/* + * This is called AFTER we have verified that there is room on the page for + * the pair (PAIRFITS has returned true) so we go right ahead and start moving + * stuff on. + */ +static void +putpair(p, key, val) + char *p; + const DBT *key, *val; +{ + 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; +} + +/* + * Returns: + * 0 OK + * -1 error + */ +extern int +__delpair(hashp, bufp, ndx) + HTAB *hashp; + BUFHEAD *bufp; + register int ndx; +{ + 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); +} +/* + * Returns: + * 0 ==> OK + * -1 ==> Error + */ +extern int +__split_page(hashp, obucket, nbucket) + HTAB *hashp; + u_int32_t obucket, nbucket; +{ + 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); +} + +/* + * Called when we encounter an overflow or big key/data page during split + * handling. This is special cased since we have to begin checking whether + * the key/data pairs fit on their respective pages and because we may need + * overflow pages for both the old and new pages. + * + * The first page might be a page with regular key/data pairs in which case + * we have a regular overflow condition and just need to go on to the next + * page or it might be a big key/data pair in which case we need to fix the + * big key/data pair. + * + * Returns: + * 0 ==> success + * -1 ==> failure + */ +static int +ugly_split(hashp, obucket, old_bufp, new_bufp, copyto, moved) + HTAB *hashp; + u_int32_t obucket; /* Same as __split_page. */ + BUFHEAD *old_bufp, *new_bufp; + int copyto; /* First byte on page which contains key/data values. */ + int moved; /* Number of pairs moved to new page. */ +{ + 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); +} + +/* + * Add the given pair to the page + * + * Returns: + * 0 ==> OK + * 1 ==> failure + */ +extern int +__addel(hashp, bufp, key, val) + HTAB *hashp; + BUFHEAD *bufp; + const DBT *key, *val; +{ + 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); +} + +/* + * + * Returns: + * pointer on success + * NULL on error + */ +extern BUFHEAD * +__add_ovflpage(hashp, bufp) + HTAB *hashp; + BUFHEAD *bufp; +{ + 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); +} + +/* + * Returns: + * 0 indicates SUCCESS + * -1 indicates FAILURE + */ +extern int +__get_page(hashp, p, bucket, is_bucket, is_disk, is_bitmap) + HTAB *hashp; + char *p; + u_int32_t bucket; + int is_bucket, is_disk, is_bitmap; +{ + 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); +} + +/* + * Write page p to disk + * + * Returns: + * 0 ==> OK + * -1 ==>failure + */ +extern int +__put_page(hashp, p, bucket, is_bucket, is_bitmap) + HTAB *hashp; + char *p; + u_int32_t bucket; + int is_bucket, is_bitmap; +{ + 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); +} + +#define BYTE_MASK ((1 << INT_BYTE_SHIFT) -1) +/* + * Initialize a new bitmap page. Bitmap pages are left in memory + * once they are read in. + */ +extern int +__ibitmap(hashp, pnum, nbits, ndx) + HTAB *hashp; + int pnum, nbits, ndx; +{ + 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); +} + +static u_int32_t +first_free(map) + u_int32_t map; +{ + 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); +} + +static u_int16_t +overflow_page(hashp) + HTAB *hashp; +{ + register u_int32_t *freep; + 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) { + (void)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1); + 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) { + (void)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1); + 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) { + (void)write(STDERR_FILENO, OVMSG, + sizeof(OVMSG) - 1); + 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); +} + +/* + * Mark this overflow page as free. + */ +extern void +__free_ovflpage(hashp, obufp) + HTAB *hashp; + BUFHEAD *obufp; +{ + 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); +} + +/* + * Returns: + * 0 success + * -1 failure + */ +static int +open_temp(hashp) + HTAB *hashp; +{ + 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); +} + +/* + * We have to know that the key will fit, but the last entry on the page is + * an overflow pair, so we need to shift things. + */ +static void +squeeze_key(sp, key, val) + u_int16_t *sp; + const DBT *key, *val; +{ + 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; +} + +static u_int32_t * +fetch_bitmap(hashp, ndx) + HTAB *hashp; + int ndx; +{ + 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]); +} + +#ifdef DEBUG4 +int +print_chain(addr) + int addr; +{ + BUFHEAD *bufp; + short *bp, oaddr; + + (void)fprintf(stderr, "%d ", addr); + bufp = __get_buf(hashp, addr, NULL, 0); + bp = (short *)bufp->page; + while (bp[0] && ((bp[bp[0]] == OVFLPAGE) || + ((bp[0] > 2) && bp[2] < REAL_KEY))) { + oaddr = bp[bp[0] - 1]; + (void)fprintf(stderr, "%d ", (int)oaddr); + bufp = __get_buf(hashp, (int)oaddr, bufp, 0); + bp = (short *)bufp->page; + } + (void)fprintf(stderr, "\n"); +} +#endif |