db/hash/hash_buf-fbsd.c

   1 /*-
   2  * Copyright (c) 1990, 1993, 1994
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Margo Seltzer.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #if defined(LIBC_SCCS) && !defined(lint)
  38 static char sccsid[] = "@(#)hash_buf.c  8.5 (Berkeley) 7/15/94";
  39 #endif /* LIBC_SCCS and not lint */
  40 #include <sys/cdefs.h>
  41 __FBSDID("$FreeBSD: src/lib/libc/db/hash/hash_buf.c,v 1.7 2002/03/21 22:46:26 obrien Exp $");
  42
  43 /*
  44  * PACKAGE: hash
  45  *
  46  * DESCRIPTION:
  47  *      Contains buffer management
  48  *
  49  * ROUTINES:
  50  * External
  51  *      __buf_init
  52  *      __get_buf
  53  *      __buf_free
  54  *      __reclaim_buf
  55  * Internal
  56  *      newbuf
  57  */
  58
  59 #include <sys/param.h>
  60
  61 #include <stddef.h>
  62 #include <stdio.h>
  63 #include <stdlib.h>
  64
  65 #ifdef DEBUG
  66 #include <assert.h>
  67 #endif
  68
  69 #include <db.h>
  70 #include "hash.h"
  71 #include "page.h"
  72 #include "hash_extern.h"
  73
  74 static BUFHEAD *newbuf(HTAB *, u_int32_t, BUFHEAD *);
  75
  76 /* Unlink B from its place in the lru */
  77 #define BUF_REMOVE(B) { \
  78         (B)->prev->next = (B)->next; \
  79         (B)->next->prev = (B)->prev; \
  80 }
  81
  82 /* Insert B after P */
  83 #define BUF_INSERT(B, P) { \
  84         (B)->next = (P)->next; \
  85         (B)->prev = (P); \
  86         (P)->next = (B); \
  87         (B)->next->prev = (B); \
  88 }
  89
  90 #define MRU     hashp->bufhead.next
  91 #define LRU     hashp->bufhead.prev
  92
  93 #define MRU_INSERT(B)   BUF_INSERT((B), &hashp->bufhead)
  94 #define LRU_INSERT(B)   BUF_INSERT((B), LRU)
  95
  96 /*
  97  * We are looking for a buffer with address "addr".  If prev_bp is NULL, then
  98  * address is a bucket index.  If prev_bp is not NULL, then it points to the
  99  * page previous to an overflow page that we are trying to find.
 100  *
 101  * CAVEAT:  The buffer header accessed via prev_bp's ovfl field may no longer
 102  * be valid.  Therefore, you must always verify that its address matches the
 103  * address you are seeking.
 104  */
 105 extern BUFHEAD *
 106 __get_buf(hashp, addr, prev_bp, newpage)
 107         HTAB *hashp;
 108         u_int32_t addr;
 109         BUFHEAD *prev_bp;
 110         int newpage;    /* If prev_bp set, indicates a new overflow page. */
 111 {
 112         BUFHEAD *bp;
 113         u_int32_t is_disk_mask;
 114         int is_disk, segment_ndx;
 115         SEGMENT segp;
 116
 117         is_disk = 0;
 118         is_disk_mask = 0;
 119         if (prev_bp) {
 120                 bp = prev_bp->ovfl;
 121                 if (!bp || (bp->addr != addr))
 122                         bp = NULL;
 123                 if (!newpage)
 124                         is_disk = BUF_DISK;
 125         } else {
 126                 /* Grab buffer out of directory */
 127                 segment_ndx = addr & (hashp->SGSIZE - 1);
 128
 129                 /* valid segment ensured by __call_hash() */
 130                 segp = hashp->dir[addr >> hashp->SSHIFT];
 131 #ifdef DEBUG
 132                 assert(segp != NULL);
 133 #endif
 134                 bp = PTROF(segp[segment_ndx]);
 135                 is_disk_mask = ISDISK(segp[segment_ndx]);
 136                 is_disk = is_disk_mask || !hashp->new_file;
 137         }
 138
 139         if (!bp) {
 140                 bp = newbuf(hashp, addr, prev_bp);
 141                 if (!bp ||
 142                     __get_page(hashp, bp->page, addr, !prev_bp, is_disk, 0))
 143                         return (NULL);
 144                 if (!prev_bp)
 145                         segp[segment_ndx] =
 146                             (BUFHEAD *)((ptrdiff_t)bp | is_disk_mask);
 147         } else {
 148                 BUF_REMOVE(bp);
 149                 MRU_INSERT(bp);
 150         }
 151         return (bp);
 152 }
 153
 154 /*
 155  * We need a buffer for this page. Either allocate one, or evict a resident
 156  * one (if we have as many buffers as we're allowed) and put this one in.
 157  *
 158  * If newbuf finds an error (returning NULL), it also sets errno.
 159  */
 160 static BUFHEAD *
 161 newbuf(hashp, addr, prev_bp)
 162         HTAB *hashp;
 163         u_int32_t addr;
 164         BUFHEAD *prev_bp;
 165 {
 166         BUFHEAD *bp;            /* The buffer we're going to use */
 167         BUFHEAD *xbp;           /* Temp pointer */
 168         BUFHEAD *next_xbp;
 169         SEGMENT segp;
 170         int segment_ndx;
 171         u_int16_t oaddr, *shortp;
 172
 173         oaddr = 0;
 174         bp = LRU;
 175         /*
 176          * If LRU buffer is pinned, the buffer pool is too small. We need to
 177          * allocate more buffers.
 178          */
 179         if (hashp->nbufs || (bp->flags & BUF_PIN)) {
 180                 /* Allocate a new one */
 181                 if ((bp = (BUFHEAD *)malloc(sizeof(BUFHEAD))) == NULL)
 182                         return (NULL);
 183 #ifdef PURIFY
 184                 memset(bp, 0xff, sizeof(BUFHEAD));
 185 #endif
 186                 if ((bp->page = (char *)malloc(hashp->BSIZE)) == NULL) {
 187                         free(bp);
 188                         return (NULL);
 189                 }
 190 #ifdef PURIFY
 191                 memset(bp->page, 0xff, hashp->BSIZE);
 192 #endif
 193                 if (hashp->nbufs)
 194                         hashp->nbufs--;
 195         } else {
 196                 /* Kick someone out */
 197                 BUF_REMOVE(bp);
 198                 /*
 199                  * If this is an overflow page with addr 0, it's already been
 200                  * flushed back in an overflow chain and initialized.
 201                  */
 202                 if ((bp->addr != 0) || (bp->flags & BUF_BUCKET)) {
 203                         /*
 204                          * Set oaddr before __put_page so that you get it
 205                          * before bytes are swapped.
 206                          */
 207                         shortp = (u_int16_t *)bp->page;
 208                         if (shortp[0])
 209                                 oaddr = shortp[shortp[0] - 1];
 210                         if ((bp->flags & BUF_MOD) && __put_page(hashp, bp->page,
 211                             bp->addr, (int)IS_BUCKET(bp->flags), 0))
 212                                 return (NULL);
 213                         /*
 214                          * Update the pointer to this page (i.e. invalidate it).
 215                          *
 216                          * If this is a new file (i.e. we created it at open
 217                          * time), make sure that we mark pages which have been
 218                          * written to disk so we retrieve them from disk later,
 219                          * rather than allocating new pages.
 220                          */
 221                         if (IS_BUCKET(bp->flags)) {
 222                                 segment_ndx = bp->addr & (hashp->SGSIZE - 1);
 223                                 segp = hashp->dir[bp->addr >> hashp->SSHIFT];
 224 #ifdef DEBUG
 225                                 assert(segp != NULL);
 226 #endif
 227
 228                                 if (hashp->new_file &&
 229                                     ((bp->flags & BUF_MOD) ||
 230                                     ISDISK(segp[segment_ndx])))
 231                                         segp[segment_ndx] = (BUFHEAD *)BUF_DISK;
 232                                 else
 233                                         segp[segment_ndx] = NULL;
 234                         }
 235                         /*
 236                          * Since overflow pages can only be access by means of
 237                          * their bucket, free overflow pages associated with
 238                          * this bucket.
 239                          */
 240                         for (xbp = bp; xbp->ovfl;) {
 241                                 next_xbp = xbp->ovfl;
 242                                 xbp->ovfl = 0;
 243                                 xbp = next_xbp;
 244
 245                                 /* Check that ovfl pointer is up date. */
 246                                 if (IS_BUCKET(xbp->flags) ||
 247                                     (oaddr != xbp->addr))
 248                                         break;
 249
 250                                 shortp = (u_int16_t *)xbp->page;
 251                                 if (shortp[0])
 252                                         /* set before __put_page */
 253                                         oaddr = shortp[shortp[0] - 1];
 254                                 if ((xbp->flags & BUF_MOD) && __put_page(hashp,
 255                                     xbp->page, xbp->addr, 0, 0))
 256                                         return (NULL);
 257                                 xbp->addr = 0;
 258                                 xbp->flags = 0;
 259                                 BUF_REMOVE(xbp);
 260                                 LRU_INSERT(xbp);
 261                         }
 262                 }
 263         }
 264
 265         /* Now assign this buffer */
 266         bp->addr = addr;
 267 #ifdef DEBUG1
 268         (void)fprintf(stderr, "NEWBUF1: %d->ovfl was %d is now %d\n",
 269             bp->addr, (bp->ovfl ? bp->ovfl->addr : 0), 0);
 270 #endif
 271         bp->ovfl = NULL;
 272         if (prev_bp) {
 273                 /*
 274                  * If prev_bp is set, this is an overflow page, hook it in to
 275                  * the buffer overflow links.
 276                  */
 277 #ifdef DEBUG1
 278                 (void)fprintf(stderr, "NEWBUF2: %d->ovfl was %d is now %d\n",
 279                     prev_bp->addr, (prev_bp->ovfl ? bp->ovfl->addr : 0),
 280                     (bp ? bp->addr : 0));
 281 #endif
 282                 prev_bp->ovfl = bp;
 283                 bp->flags = 0;
 284         } else
 285                 bp->flags = BUF_BUCKET;
 286         MRU_INSERT(bp);
 287         return (bp);
 288 }
 289
 290 extern void
 291 __buf_init(hashp, nbytes)
 292         HTAB *hashp;
 293         int nbytes;
 294 {
 295         BUFHEAD *bfp;
 296         int npages;
 297
 298         bfp = &(hashp->bufhead);
 299         npages = (nbytes + hashp->BSIZE - 1) >> hashp->BSHIFT;
 300         npages = MAX(npages, MIN_BUFFERS);
 301
 302         hashp->nbufs = npages;
 303         bfp->next = bfp;
 304         bfp->prev = bfp;
 305         /*
 306          * This space is calloc'd so these are already null.
 307          *
 308          * bfp->ovfl = NULL;
 309          * bfp->flags = 0;
 310          * bfp->page = NULL;
 311          * bfp->addr = 0;
 312          */
 313 }
 314
 315 extern int
 316 __buf_free(hashp, do_free, to_disk)
 317         HTAB *hashp;
 318         int do_free, to_disk;
 319 {
 320         BUFHEAD *bp;
 321
 322         /* Need to make sure that buffer manager has been initialized */
 323         if (!LRU)
 324                 return (0);
 325         for (bp = LRU; bp != &hashp->bufhead;) {
 326                 /* Check that the buffer is valid */
 327                 if (bp->addr || IS_BUCKET(bp->flags)) {
 328                         if (to_disk && (bp->flags & BUF_MOD) &&
 329                             __put_page(hashp, bp->page,
 330                             bp->addr, IS_BUCKET(bp->flags), 0))
 331                                 return (-1);
 332                 }
 333                 /* Check if we are freeing stuff */
 334                 if (do_free) {
 335                         if (bp->page)
 336                                 free(bp->page);
 337                         BUF_REMOVE(bp);
 338                         free(bp);
 339                         bp = LRU;
 340                 } else
 341                         bp = bp->prev;
 342         }
 343         return (0);
 344 }
 345
 346 extern void
 347 __reclaim_buf(hashp, bp)
 348         HTAB *hashp;
 349         BUFHEAD *bp;
 350 {
 351         bp->ovfl = 0;
 352         bp->addr = 0;
 353         bp->flags = 0;
 354         BUF_REMOVE(bp);
 355         LRU_INSERT(bp);
 356 }