db.1.85/mpool/mpool.c

   1 /*-
   2  * Copyright (c) 1990, 1993, 1994
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #if defined(LIBC_SCCS) && !defined(lint)
  35 static char sccsid[] = "@(#)mpool.c     8.5 (Berkeley) 7/26/94";
  36 #endif /* LIBC_SCCS and not lint */
  37
  38 #include <sys/param.h>
  39 #include <sys/queue.h>
  40 #include <sys/stat.h>
  41
  42 #include <errno.h>
  43 #include <stdio.h>
  44 #include <stdlib.h>
  45 #include <string.h>
  46 #include <unistd.h>
  47
  48 #include <db.h>
  49
  50 #define __MPOOLINTERFACE_PRIVATE
  51 #include <mpool.h>
  52
  53 static BKT *mpool_bkt __P((MPOOL *));
  54 static BKT *mpool_look __P((MPOOL *, pgno_t));
  55 static int  mpool_write __P((MPOOL *, BKT *));
  56
  57 /*
  58  * mpool_open --
  59  *      Initialize a memory pool.
  60  */
  61 MPOOL *
  62 mpool_open(key, fd, pagesize, maxcache)
  63         void *key;
  64         int fd;
  65         pgno_t pagesize, maxcache;
  66 {
  67         struct stat sb;
  68         MPOOL *mp;
  69         int entry;
  70
  71         /*
  72          * Get information about the file.
  73          *
  74          * XXX
  75          * We don't currently handle pipes, although we should.
  76          */
  77         if (fstat(fd, &sb))
  78                 return (NULL);
  79         if (!S_ISREG(sb.st_mode)) {
  80                 errno = ESPIPE;
  81                 return (NULL);
  82         }
  83
  84         /* Allocate and initialize the MPOOL cookie. */
  85         if ((mp = (MPOOL *)calloc(1, sizeof(MPOOL))) == NULL)
  86                 return (NULL);
  87         CIRCLEQ_INIT(&mp->lqh);
  88         for (entry = 0; entry < HASHSIZE; ++entry)
  89                 CIRCLEQ_INIT(&mp->hqh[entry]);
  90         mp->maxcache = maxcache;
  91         mp->npages = sb.st_size / pagesize;
  92         mp->pagesize = pagesize;
  93         mp->fd = fd;
  94         return (mp);
  95 }
  96
  97 /*
  98  * mpool_filter --
  99  *      Initialize input/output filters.
 100  */
 101 void
 102 mpool_filter(mp, pgin, pgout, pgcookie)
 103         MPOOL *mp;
 104         void (*pgin) __P((void *, pgno_t, void *));
 105         void (*pgout) __P((void *, pgno_t, void *));
 106         void *pgcookie;
 107 {
 108         mp->pgin = pgin;
 109         mp->pgout = pgout;
 110         mp->pgcookie = pgcookie;
 111 }
 112
 113 /*
 114  * mpool_new --
 115  *      Get a new page of memory.
 116  */
 117 void *
 118 mpool_new(mp, pgnoaddr)
 119         MPOOL *mp;
 120         pgno_t *pgnoaddr;
 121 {
 122         struct _hqh *head;
 123         BKT *bp;
 124
 125         if (mp->npages == MAX_PAGE_NUMBER) {
 126                 (void)fprintf(stderr, "mpool_new: page allocation overflow.\n");
 127                 abort();
 128         }
 129 #ifdef STATISTICS
 130         ++mp->pagenew;
 131 #endif
 132         /*
 133          * Get a BKT from the cache.  Assign a new page number, attach
 134          * it to the head of the hash chain, the tail of the lru chain,
 135          * and return.
 136          */
 137         if ((bp = mpool_bkt(mp)) == NULL)
 138                 return (NULL);
 139         *pgnoaddr = bp->pgno = mp->npages++;
 140         bp->flags = MPOOL_PINNED;
 141
 142         head = &mp->hqh[HASHKEY(bp->pgno)];
 143         CIRCLEQ_INSERT_HEAD(head, bp, hq);
 144         CIRCLEQ_INSERT_TAIL(&mp->lqh, bp, q);
 145         return (bp->page);
 146 }
 147
 148 /*
 149  * mpool_get
 150  *      Get a page.
 151  */
 152 void *
 153 mpool_get(mp, pgno, flags)
 154         MPOOL *mp;
 155         pgno_t pgno;
 156         u_int flags;                            /* XXX not used? */
 157 {
 158         struct _hqh *head;
 159         BKT *bp;
 160         off_t off;
 161         int nr;
 162
 163         /* Check for attempt to retrieve a non-existent page. */
 164         if (pgno >= mp->npages) {
 165                 errno = EINVAL;
 166                 return (NULL);
 167         }
 168
 169 #ifdef STATISTICS
 170         ++mp->pageget;
 171 #endif
 172
 173         /* Check for a page that is cached. */
 174         if ((bp = mpool_look(mp, pgno)) != NULL) {
 175 #ifdef DEBUG
 176                 if (bp->flags & MPOOL_PINNED) {
 177                         (void)fprintf(stderr,
 178                             "mpool_get: page %d already pinned\n", bp->pgno);
 179                         abort();
 180                 }
 181 #endif
 182                 /*
 183                  * Move the page to the head of the hash chain and the tail
 184                  * of the lru chain.
 185                  */
 186                 head = &mp->hqh[HASHKEY(bp->pgno)];
 187                 CIRCLEQ_REMOVE(head, bp, hq);
 188                 CIRCLEQ_INSERT_HEAD(head, bp, hq);
 189                 CIRCLEQ_REMOVE(&mp->lqh, bp, q);
 190                 CIRCLEQ_INSERT_TAIL(&mp->lqh, bp, q);
 191
 192                 /* Return a pinned page. */
 193                 bp->flags |= MPOOL_PINNED;
 194                 return (bp->page);
 195         }
 196
 197         /* Get a page from the cache. */
 198         if ((bp = mpool_bkt(mp)) == NULL)
 199                 return (NULL);
 200
 201         /* Read in the contents. */
 202 #ifdef STATISTICS
 203         ++mp->pageread;
 204 #endif
 205         off = mp->pagesize * pgno;
 206         if (lseek(mp->fd, off, SEEK_SET) != off)
 207                 return (NULL);
 208         if ((nr = read(mp->fd, bp->page, mp->pagesize)) != mp->pagesize) {
 209                 if (nr >= 0)
 210                         errno = EFTYPE;
 211                 return (NULL);
 212         }
 213
 214         /* Set the page number, pin the page. */
 215         bp->pgno = pgno;
 216         bp->flags = MPOOL_PINNED;
 217
 218         /*
 219          * Add the page to the head of the hash chain and the tail
 220          * of the lru chain.
 221          */
 222         head = &mp->hqh[HASHKEY(bp->pgno)];
 223         CIRCLEQ_INSERT_HEAD(head, bp, hq);
 224         CIRCLEQ_INSERT_TAIL(&mp->lqh, bp, q);
 225
 226         /* Run through the user's filter. */
 227         if (mp->pgin != NULL)
 228                 (mp->pgin)(mp->pgcookie, bp->pgno, bp->page);
 229
 230         return (bp->page);
 231 }
 232
 233 /*
 234  * mpool_put
 235  *      Return a page.
 236  */
 237 int
 238 mpool_put(mp, page, flags)
 239         MPOOL *mp;
 240         void *page;
 241         u_int flags;
 242 {
 243         BKT *bp;
 244
 245 #ifdef STATISTICS
 246         ++mp->pageput;
 247 #endif
 248         bp = (BKT *)((char *)page - sizeof(BKT));
 249 #ifdef DEBUG
 250         if (!(bp->flags & MPOOL_PINNED)) {
 251                 (void)fprintf(stderr,
 252                     "mpool_put: page %d not pinned\n", bp->pgno);
 253                 abort();
 254         }
 255 #endif
 256         bp->flags &= ~MPOOL_PINNED;
 257         bp->flags |= flags & MPOOL_DIRTY;
 258         return (RET_SUCCESS);
 259 }
 260
 261 /*
 262  * mpool_close
 263  *      Close the buffer pool.
 264  */
 265 int
 266 mpool_close(mp)
 267         MPOOL *mp;
 268 {
 269         BKT *bp;
 270
 271         /* Free up any space allocated to the lru pages. */
 272         while ((bp = mp->lqh.cqh_first) != (void *)&mp->lqh) {
 273                 CIRCLEQ_REMOVE(&mp->lqh, mp->lqh.cqh_first, q);
 274                 free(bp);
 275         }
 276
 277         /* Free the MPOOL cookie. */
 278         free(mp);
 279         return (RET_SUCCESS);
 280 }
 281
 282 /*
 283  * mpool_sync
 284  *      Sync the pool to disk.
 285  */
 286 int
 287 mpool_sync(mp)
 288         MPOOL *mp;
 289 {
 290         BKT *bp;
 291
 292         /* Walk the lru chain, flushing any dirty pages to disk. */
 293         for (bp = mp->lqh.cqh_first;
 294             bp != (void *)&mp->lqh; bp = bp->q.cqe_next)
 295                 if (bp->flags & MPOOL_DIRTY &&
 296                     mpool_write(mp, bp) == RET_ERROR)
 297                         return (RET_ERROR);
 298
 299         /* Sync the file descriptor. */
 300         return (fsync(mp->fd) ? RET_ERROR : RET_SUCCESS);
 301 }
 302
 303 /*
 304  * mpool_bkt
 305  *      Get a page from the cache (or create one).
 306  */
 307 static BKT *
 308 mpool_bkt(mp)
 309         MPOOL *mp;
 310 {
 311         struct _hqh *head;
 312         BKT *bp;
 313
 314         /* If under the max cached, always create a new page. */
 315         if (mp->curcache < mp->maxcache)
 316                 goto new;
 317
 318         /*
 319          * If the cache is max'd out, walk the lru list for a buffer we
 320          * can flush.  If we find one, write it (if necessary) and take it
 321          * off any lists.  If we don't find anything we grow the cache anyway.
 322          * The cache never shrinks.
 323          */
 324         for (bp = mp->lqh.cqh_first;
 325             bp != (void *)&mp->lqh; bp = bp->q.cqe_next)
 326                 if (!(bp->flags & MPOOL_PINNED)) {
 327                         /* Flush if dirty. */
 328                         if (bp->flags & MPOOL_DIRTY &&
 329                             mpool_write(mp, bp) == RET_ERROR)
 330                                 return (NULL);
 331 #ifdef STATISTICS
 332                         ++mp->pageflush;
 333 #endif
 334                         /* Remove from the hash and lru queues. */
 335                         head = &mp->hqh[HASHKEY(bp->pgno)];
 336                         CIRCLEQ_REMOVE(head, bp, hq);
 337                         CIRCLEQ_REMOVE(&mp->lqh, bp, q);
 338 #ifdef DEBUG
 339                         { void *spage;
 340                                 spage = bp->page;
 341                                 memset(bp, 0xff, sizeof(BKT) + mp->pagesize);
 342                                 bp->page = spage;
 343                         }
 344 #endif
 345                         return (bp);
 346                 }
 347
 348 new:    if ((bp = (BKT *)malloc(sizeof(BKT) + mp->pagesize)) == NULL)
 349                 return (NULL);
 350 #ifdef STATISTICS
 351         ++mp->pagealloc;
 352 #endif
 353 #if defined(DEBUG) || defined(PURIFY)
 354         memset(bp, 0xff, sizeof(BKT) + mp->pagesize);
 355 #endif
 356         bp->page = (char *)bp + sizeof(BKT);
 357         ++mp->curcache;
 358         return (bp);
 359 }
 360
 361 /*
 362  * mpool_write
 363  *      Write a page to disk.
 364  */
 365 static int
 366 mpool_write(mp, bp)
 367         MPOOL *mp;
 368         BKT *bp;
 369 {
 370         off_t off;
 371
 372 #ifdef STATISTICS
 373         ++mp->pagewrite;
 374 #endif
 375
 376         /* Run through the user's filter. */
 377         if (mp->pgout)
 378                 (mp->pgout)(mp->pgcookie, bp->pgno, bp->page);
 379
 380         off = mp->pagesize * bp->pgno;
 381         if (lseek(mp->fd, off, SEEK_SET) != off)
 382                 return (RET_ERROR);
 383         if (write(mp->fd, bp->page, mp->pagesize) != mp->pagesize)
 384                 return (RET_ERROR);
 385
 386         bp->flags &= ~MPOOL_DIRTY;
 387         return (RET_SUCCESS);
 388 }
 389
 390 /*
 391  * mpool_look
 392  *      Lookup a page in the cache.
 393  */
 394 static BKT *
 395 mpool_look(mp, pgno)
 396         MPOOL *mp;
 397         pgno_t pgno;
 398 {
 399         struct _hqh *head;
 400         BKT *bp;
 401
 402         head = &mp->hqh[HASHKEY(pgno)];
 403         for (bp = head->cqh_first; bp != (void *)head; bp = bp->hq.cqe_next)
 404                 if (bp->pgno == pgno) {
 405 #ifdef STATISTICS
 406                         ++mp->cachehit;
 407 #endif
 408                         return (bp);
 409                 }
 410 #ifdef STATISTICS
 411         ++mp->cachemiss;
 412 #endif
 413         return (NULL);
 414 }
 415
 416 #ifdef STATISTICS
 417 /*
 418  * mpool_stat
 419  *      Print out cache statistics.
 420  */
 421 void
 422 mpool_stat(mp)
 423         MPOOL *mp;
 424 {
 425         BKT *bp;
 426         int cnt;
 427         char *sep;
 428
 429         (void)fprintf(stderr, "%lu pages in the file\n", mp->npages);
 430         (void)fprintf(stderr,
 431             "page size %lu, cacheing %lu pages of %lu page max cache\n",
 432             mp->pagesize, mp->curcache, mp->maxcache);
 433         (void)fprintf(stderr, "%lu page puts, %lu page gets, %lu page new\n",
 434             mp->pageput, mp->pageget, mp->pagenew);
 435         (void)fprintf(stderr, "%lu page allocs, %lu page flushes\n",
 436             mp->pagealloc, mp->pageflush);
 437         if (mp->cachehit + mp->cachemiss)
 438                 (void)fprintf(stderr,
 439                     "%.0f%% cache hit rate (%lu hits, %lu misses)\n",
 440                     ((double)mp->cachehit / (mp->cachehit + mp->cachemiss))
 441                     * 100, mp->cachehit, mp->cachemiss);
 442         (void)fprintf(stderr, "%lu page reads, %lu page writes\n",
 443             mp->pageread, mp->pagewrite);
 444
 445         sep = "";
 446         cnt = 0;
 447         for (bp = mp->lqh.cqh_first;
 448             bp != (void *)&mp->lqh; bp = bp->q.cqe_next) {
 449                 (void)fprintf(stderr, "%s%d", sep, bp->pgno);
 450                 if (bp->flags & MPOOL_DIRTY)
 451                         (void)fprintf(stderr, "d");
 452                 if (bp->flags & MPOOL_PINNED)
 453                         (void)fprintf(stderr, "P");
 454                 if (++cnt == 10) {
 455                         sep = "\n";
 456                         cnt = 0;
 457                 } else
 458                         sep = ", ";
 459
 460         }
 461         (void)fprintf(stderr, "\n");
 462 }
 463 #endif