lib/libc/db/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. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * $FreeBSD: src/lib/libc/db/mpool/mpool.c,v 1.5.2.1 2001/03/05 23:05:01 obrien Exp $
  30  * $DragonFly: src/lib/libc/db/mpool/mpool.c,v 1.7 2005/11/19 20:46:32 swildner Exp $
  31  *
  32  * @(#)mpool.c  8.5 (Berkeley) 7/26/94
  33  */
  34
  35 #include "namespace.h"
  36 #include <sys/param.h>
  37 #include <sys/queue.h>
  38 #include <sys/stat.h>
  39
  40 #include <errno.h>
  41 #include <stdio.h>
  42 #include <stdlib.h>
  43 #include <string.h>
  44 #include <unistd.h>
  45 #include "un-namespace.h"
  46
  47 #include <db.h>
  48
  49 #define __MPOOLINTERFACE_PRIVATE
  50 #include <mpool.h>
  51
  52 static BKT *mpool_bkt (MPOOL *);
  53 static BKT *mpool_look (MPOOL *, pgno_t);
  54 static int  mpool_write (MPOOL *, BKT *);
  55
  56 /*
  57  * mpool_open --
  58  *      Initialize a memory pool.
  59  */
  60 MPOOL *
  61 mpool_open(void *key __unused, int fd, pgno_t pagesize, pgno_t maxcache)
  62 {
  63         struct stat sb;
  64         MPOOL *mp;
  65         int entry;
  66
  67         /*
  68          * Get information about the file.
  69          *
  70          * XXX
  71          * We don't currently handle pipes, although we should.
  72          */
  73         if (_fstat(fd, &sb))
  74                 return (NULL);
  75         if (!S_ISREG(sb.st_mode)) {
  76                 errno = ESPIPE;
  77                 return (NULL);
  78         }
  79
  80         /* Allocate and initialize the MPOOL cookie. */
  81         if ((mp = (MPOOL *)calloc(1, sizeof(MPOOL))) == NULL)
  82                 return (NULL);
  83         TAILQ_INIT(&mp->lqh);
  84         for (entry = 0; entry < HASHSIZE; ++entry)
  85                 TAILQ_INIT(&mp->hqh[entry]);
  86         mp->maxcache = maxcache;
  87         mp->npages = sb.st_size / pagesize;
  88         mp->pagesize = pagesize;
  89         mp->fd = fd;
  90         return (mp);
  91 }
  92
  93 /*
  94  * mpool_filter --
  95  *      Initialize input/output filters.
  96  */
  97 void
  98 mpool_filter(MPOOL *mp, void (*pgin)(void *, pgno_t, void *),
  99              void (*pgout)(void *, pgno_t, void *), void *pgcookie)
 100 {
 101         mp->pgin = pgin;
 102         mp->pgout = pgout;
 103         mp->pgcookie = pgcookie;
 104 }
 105
 106 /*
 107  * mpool_new --
 108  *      Get a new page of memory.
 109  */
 110 void *
 111 mpool_new(MPOOL *mp, pgno_t *pgnoaddr)
 112 {
 113         struct _hqh *head;
 114         BKT *bp;
 115
 116         if (mp->npages == MAX_PAGE_NUMBER) {
 117                 fprintf(stderr, "mpool_new: page allocation overflow.\n");
 118                 abort();
 119         }
 120 #ifdef STATISTICS
 121         ++mp->pagenew;
 122 #endif
 123         /*
 124          * Get a BKT from the cache.  Assign a new page number, attach
 125          * it to the head of the hash chain, the tail of the lru chain,
 126          * and return.
 127          */
 128         if ((bp = mpool_bkt(mp)) == NULL)
 129                 return (NULL);
 130         *pgnoaddr = bp->pgno = mp->npages++;
 131         bp->flags = MPOOL_PINNED;
 132
 133         head = &mp->hqh[HASHKEY(bp->pgno)];
 134         TAILQ_INSERT_HEAD(head, bp, hq);
 135         TAILQ_INSERT_TAIL(&mp->lqh, bp, q);
 136         return (bp->page);
 137 }
 138
 139 /*
 140  * mpool_get
 141  *      Get a page.
 142  */
 143 void *
 144 mpool_get(MPOOL *mp, pgno_t pgno, u_int flags __unused)
 145 {
 146         struct _hqh *head;
 147         BKT *bp;
 148         off_t off;
 149         int nr;
 150
 151         /* Check for attempt to retrieve a non-existent page. */
 152         if (pgno >= mp->npages) {
 153                 errno = EINVAL;
 154                 return (NULL);
 155         }
 156
 157 #ifdef STATISTICS
 158         ++mp->pageget;
 159 #endif
 160
 161         /* Check for a page that is cached. */
 162         if ((bp = mpool_look(mp, pgno)) != NULL) {
 163 #ifdef DEBUG
 164                 if (bp->flags & MPOOL_PINNED) {
 165                         fprintf(stderr,
 166                             "mpool_get: page %d already pinned\n", bp->pgno);
 167                         abort();
 168                 }
 169 #endif
 170                 /*
 171                  * Move the page to the head of the hash chain and the tail
 172                  * of the lru chain.
 173                  */
 174                 head = &mp->hqh[HASHKEY(bp->pgno)];
 175                 TAILQ_REMOVE(head, bp, hq);
 176                 TAILQ_INSERT_HEAD(head, bp, hq);
 177                 TAILQ_REMOVE(&mp->lqh, bp, q);
 178                 TAILQ_INSERT_TAIL(&mp->lqh, bp, q);
 179
 180                 /* Return a pinned page. */
 181                 bp->flags |= MPOOL_PINNED;
 182                 return (bp->page);
 183         }
 184
 185         /* Get a page from the cache. */
 186         if ((bp = mpool_bkt(mp)) == NULL)
 187                 return (NULL);
 188
 189         /* Read in the contents. */
 190 #ifdef STATISTICS
 191         ++mp->pageread;
 192 #endif
 193         off = mp->pagesize * pgno;
 194         nr = pread(mp->fd, bp->page, mp->pagesize, off);
 195         if (nr != mp->pagesize) {
 196                 if (nr >= 0)
 197                         errno = EFTYPE;
 198                 return (NULL);
 199         }
 200
 201         /* Set the page number, pin the page. */
 202         bp->pgno = pgno;
 203         bp->flags = MPOOL_PINNED;
 204
 205         /*
 206          * Add the page to the head of the hash chain and the tail
 207          * of the lru chain.
 208          */
 209         head = &mp->hqh[HASHKEY(bp->pgno)];
 210         TAILQ_INSERT_HEAD(head, bp, hq);
 211         TAILQ_INSERT_TAIL(&mp->lqh, bp, q);
 212
 213         /* Run through the user's filter. */
 214         if (mp->pgin != NULL)
 215                 (mp->pgin)(mp->pgcookie, bp->pgno, bp->page);
 216
 217         return (bp->page);
 218 }
 219
 220 /*
 221  * mpool_put
 222  *      Return a page.
 223  */
 224 int
 225 mpool_put(MPOOL *mp __unused, void *page, u_int flags)
 226 {
 227         BKT *bp;
 228
 229 #ifdef STATISTICS
 230         ++mp->pageput;
 231 #endif
 232         bp = (BKT *)((char *)page - sizeof(BKT));
 233 #ifdef DEBUG
 234         if (!(bp->flags & MPOOL_PINNED)) {
 235                 fprintf(stderr,
 236                     "mpool_put: page %d not pinned\n", bp->pgno);
 237                 abort();
 238         }
 239 #endif
 240         bp->flags &= ~MPOOL_PINNED;
 241         bp->flags |= flags & MPOOL_DIRTY;
 242         return (RET_SUCCESS);
 243 }
 244
 245 /*
 246  * mpool_close
 247  *      Close the buffer pool.
 248  */
 249 int
 250 mpool_close(MPOOL *mp)
 251 {
 252         BKT *bp;
 253
 254         /* Free up any space allocated to the lru pages. */
 255         while (!TAILQ_EMPTY(&mp->lqh)) {
 256                 bp = TAILQ_FIRST(&mp->lqh);
 257                 TAILQ_REMOVE(&mp->lqh, bp, q);
 258                 free(bp);
 259         }
 260
 261         /* Free the MPOOL cookie. */
 262         free(mp);
 263         return (RET_SUCCESS);
 264 }
 265
 266 /*
 267  * mpool_sync
 268  *      Sync the pool to disk.
 269  */
 270 int
 271 mpool_sync(MPOOL *mp)
 272 {
 273         BKT *bp;
 274
 275         /* Walk the lru chain, flushing any dirty pages to disk. */
 276         TAILQ_FOREACH(bp, &mp->lqh, q)
 277                 if (bp->flags & MPOOL_DIRTY &&
 278                     mpool_write(mp, bp) == RET_ERROR)
 279                         return (RET_ERROR);
 280
 281         /* Sync the file descriptor. */
 282         return (_fsync(mp->fd) ? RET_ERROR : RET_SUCCESS);
 283 }
 284
 285 /*
 286  * mpool_bkt
 287  *      Get a page from the cache (or create one).
 288  */
 289 static BKT *
 290 mpool_bkt(MPOOL *mp)
 291 {
 292         struct _hqh *head;
 293         BKT *bp;
 294
 295         /* If under the max cached, always create a new page. */
 296         if (mp->curcache < mp->maxcache)
 297                 goto new;
 298
 299         /*
 300          * If the cache is max'd out, walk the lru list for a buffer we
 301          * can flush.  If we find one, write it (if necessary) and take it
 302          * off any lists.  If we don't find anything we grow the cache anyway.
 303          * The cache never shrinks.
 304          */
 305         TAILQ_FOREACH(bp, &mp->lqh, q)
 306                 if (!(bp->flags & MPOOL_PINNED)) {
 307                         /* Flush if dirty. */
 308                         if (bp->flags & MPOOL_DIRTY &&
 309                             mpool_write(mp, bp) == RET_ERROR)
 310                                 return (NULL);
 311 #ifdef STATISTICS
 312                         ++mp->pageflush;
 313 #endif
 314                         /* Remove from the hash and lru queues. */
 315                         head = &mp->hqh[HASHKEY(bp->pgno)];
 316                         TAILQ_REMOVE(head, bp, hq);
 317                         TAILQ_REMOVE(&mp->lqh, bp, q);
 318 #ifdef DEBUG
 319                         { void *spage;
 320                                 spage = bp->page;
 321                                 memset(bp, 0xff, sizeof(BKT) + mp->pagesize);
 322                                 bp->page = spage;
 323                         }
 324 #endif
 325                         return (bp);
 326                 }
 327
 328 new:    if ((bp = (BKT *)malloc(sizeof(BKT) + mp->pagesize)) == NULL)
 329                 return (NULL);
 330 #ifdef STATISTICS
 331         ++mp->pagealloc;
 332 #endif
 333 #if defined(DEBUG) || defined(PURIFY)
 334         memset(bp, 0xff, sizeof(BKT) + mp->pagesize);
 335 #endif
 336         bp->page = (char *)bp + sizeof(BKT);
 337         ++mp->curcache;
 338         return (bp);
 339 }
 340
 341 /*
 342  * mpool_write
 343  *      Write a page to disk.
 344  */
 345 static int
 346 mpool_write(MPOOL *mp, BKT *bp)
 347 {
 348         off_t off;
 349
 350 #ifdef STATISTICS
 351         ++mp->pagewrite;
 352 #endif
 353
 354         /* Run through the user's filter. */
 355         if (mp->pgout)
 356                 (mp->pgout)(mp->pgcookie, bp->pgno, bp->page);
 357
 358         off = mp->pagesize * bp->pgno;
 359         if (pwrite(mp->fd, bp->page, mp->pagesize, off) != mp->pagesize)
 360                 return (RET_ERROR);
 361
 362         bp->flags &= ~MPOOL_DIRTY;
 363         return (RET_SUCCESS);
 364 }
 365
 366 /*
 367  * mpool_look
 368  *      Lookup a page in the cache.
 369  */
 370 static BKT *
 371 mpool_look(MPOOL *mp, pgno_t pgno)
 372 {
 373         struct _hqh *head;
 374         BKT *bp;
 375
 376         head = &mp->hqh[HASHKEY(pgno)];
 377         TAILQ_FOREACH(bp, head, hq)
 378                 if (bp->pgno == pgno) {
 379 #ifdef STATISTICS
 380                         ++mp->cachehit;
 381 #endif
 382                         return (bp);
 383                 }
 384 #ifdef STATISTICS
 385         ++mp->cachemiss;
 386 #endif
 387         return (NULL);
 388 }
 389
 390 #ifdef STATISTICS
 391 /*
 392  * mpool_stat
 393  *      Print out cache statistics.
 394  */
 395 void
 396 mpool_stat(MPOOL *mp)
 397 {
 398         BKT *bp;
 399         int cnt;
 400         char *sep;
 401
 402         fprintf(stderr, "%lu pages in the file\n", mp->npages);
 403         fprintf(stderr,
 404             "page size %lu, cacheing %lu pages of %lu page max cache\n",
 405             mp->pagesize, mp->curcache, mp->maxcache);
 406         fprintf(stderr, "%lu page puts, %lu page gets, %lu page new\n",
 407             mp->pageput, mp->pageget, mp->pagenew);
 408         fprintf(stderr, "%lu page allocs, %lu page flushes\n",
 409             mp->pagealloc, mp->pageflush);
 410         if (mp->cachehit + mp->cachemiss)
 411                 fprintf(stderr,
 412                     "%.0f%% cache hit rate (%lu hits, %lu misses)\n",
 413                     ((double)mp->cachehit / (mp->cachehit + mp->cachemiss))
 414                     * 100, mp->cachehit, mp->cachemiss);
 415         fprintf(stderr, "%lu page reads, %lu page writes\n",
 416             mp->pageread, mp->pagewrite);
 417
 418         sep = "";
 419         cnt = 0;
 420         TAILQ_FOREACH(bp, &mp->lqh, q) {
 421                 fprintf(stderr, "%s%d", sep, bp->pgno);
 422                 if (bp->flags & MPOOL_DIRTY)
 423                         fprintf(stderr, "d");
 424                 if (bp->flags & MPOOL_PINNED)
 425                         fprintf(stderr, "P");
 426                 if (++cnt == 10) {
 427                         sep = "\n";
 428                         cnt = 0;
 429                 } else
 430                         sep = ", ";
 431
 432         }
 433         fprintf(stderr, "\n");
 434 }
 435 #endif