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 rcsid[] = "$OpenBSD: mpool.c,v 1.4 1996/09/15 09:30:51 tholo Exp $"; 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 /* ARGSUSED */ 62 MPOOL * 63 mpool_open(key, fd, pagesize, maxcache) 64 void *key; 65 int fd; 66 pgno_t pagesize, maxcache; 67 { 68 struct stat sb; 69 MPOOL *mp; 70 int entry; 71 72 /* 73 * Get information about the file. 74 * 75 * XXX 76 * We don't currently handle pipes, although we should. 77 */ 78 if (fstat(fd, &sb)) 79 return (NULL); 80 if (!S_ISREG(sb.st_mode)) { 81 errno = ESPIPE; 82 return (NULL); 83 } 84 85 /* Allocate and initialize the MPOOL cookie. */ 86 if ((mp = (MPOOL *)calloc(1, sizeof(MPOOL))) == NULL) 87 return (NULL); 88 CIRCLEQ_INIT(&mp->lqh); 89 for (entry = 0; entry < HASHSIZE; ++entry) 90 CIRCLEQ_INIT(&mp->hqh[entry]); 91 mp->maxcache = maxcache; 92 mp->npages = sb.st_size / pagesize; 93 mp->pagesize = pagesize; 94 mp->fd = fd; 95 return (mp); 96 } 97 98 /* 99 * mpool_filter -- 100 * Initialize input/output filters. 101 */ 102 void 103 mpool_filter(mp, pgin, pgout, pgcookie) 104 MPOOL *mp; 105 void (*pgin) __P((void *, pgno_t, void *)); 106 void (*pgout) __P((void *, pgno_t, void *)); 107 void *pgcookie; 108 { 109 mp->pgin = pgin; 110 mp->pgout = pgout; 111 mp->pgcookie = pgcookie; 112 } 113 114 /* 115 * mpool_new -- 116 * Get a new page of memory. 117 */ 118 void * 119 mpool_new(mp, pgnoaddr) 120 MPOOL *mp; 121 pgno_t *pgnoaddr; 122 { 123 struct _hqh *head; 124 BKT *bp; 125 126 if (mp->npages == MAX_PAGE_NUMBER) { 127 (void)fprintf(stderr, "mpool_new: page allocation overflow.\n"); 128 abort(); 129 } 130 #ifdef STATISTICS 131 ++mp->pagenew; 132 #endif 133 /* 134 * Get a BKT from the cache. Assign a new page number, attach 135 * it to the head of the hash chain, the tail of the lru chain, 136 * and return. 137 */ 138 if ((bp = mpool_bkt(mp)) == NULL) 139 return (NULL); 140 *pgnoaddr = bp->pgno = mp->npages++; 141 bp->flags = MPOOL_PINNED; 142 143 head = &mp->hqh[HASHKEY(bp->pgno)]; 144 CIRCLEQ_INSERT_HEAD(head, bp, hq); 145 CIRCLEQ_INSERT_TAIL(&mp->lqh, bp, q); 146 return (bp->page); 147 } 148 149 /* 150 * mpool_get 151 * Get a page. 152 */ 153 /* ARGSUSED */ 154 void * 155 mpool_get(mp, pgno, flags) 156 MPOOL *mp; 157 pgno_t pgno; 158 u_int flags; /* XXX not used? */ 159 { 160 struct _hqh *head; 161 BKT *bp; 162 off_t off; 163 int nr; 164 165 /* Check for attempt to retrieve a non-existent page. */ 166 if (pgno >= mp->npages) { 167 errno = EINVAL; 168 return (NULL); 169 } 170 171 #ifdef STATISTICS 172 ++mp->pageget; 173 #endif 174 175 /* Check for a page that is cached. */ 176 if ((bp = mpool_look(mp, pgno)) != NULL) { 177 #ifdef DEBUG 178 if (bp->flags & MPOOL_PINNED) { 179 (void)fprintf(stderr, 180 "mpool_get: page %d already pinned\n", bp->pgno); 181 abort(); 182 } 183 #endif 184 /* 185 * Move the page to the head of the hash chain and the tail 186 * of the lru chain. 187 */ 188 head = &mp->hqh[HASHKEY(bp->pgno)]; 189 CIRCLEQ_REMOVE(head, bp, hq); 190 CIRCLEQ_INSERT_HEAD(head, bp, hq); 191 CIRCLEQ_REMOVE(&mp->lqh, bp, q); 192 CIRCLEQ_INSERT_TAIL(&mp->lqh, bp, q); 193 194 /* Return a pinned page. */ 195 bp->flags |= MPOOL_PINNED; 196 return (bp->page); 197 } 198 199 /* Get a page from the cache. */ 200 if ((bp = mpool_bkt(mp)) == NULL) 201 return (NULL); 202 203 /* Read in the contents. */ 204 #ifdef STATISTICS 205 ++mp->pageread; 206 #endif 207 off = mp->pagesize * pgno; 208 if (lseek(mp->fd, off, SEEK_SET) != off) 209 return (NULL); 210 if ((nr = read(mp->fd, bp->page, mp->pagesize)) != mp->pagesize) { 211 if (nr >= 0) 212 errno = EFTYPE; 213 return (NULL); 214 } 215 216 /* Set the page number, pin the page. */ 217 bp->pgno = pgno; 218 bp->flags = MPOOL_PINNED; 219 220 /* 221 * Add the page to the head of the hash chain and the tail 222 * of the lru chain. 223 */ 224 head = &mp->hqh[HASHKEY(bp->pgno)]; 225 CIRCLEQ_INSERT_HEAD(head, bp, hq); 226 CIRCLEQ_INSERT_TAIL(&mp->lqh, bp, q); 227 228 /* Run through the user's filter. */ 229 if (mp->pgin != NULL) 230 (mp->pgin)(mp->pgcookie, bp->pgno, bp->page); 231 232 return (bp->page); 233 } 234 235 /* 236 * mpool_put 237 * Return a page. 238 */ 239 /* ARGSUSED */ 240 int 241 mpool_put(mp, page, flags) 242 MPOOL *mp; 243 void *page; 244 u_int flags; 245 { 246 BKT *bp; 247 248 #ifdef STATISTICS 249 ++mp->pageput; 250 #endif 251 bp = (BKT *)((char *)page - sizeof(BKT)); 252 #ifdef DEBUG 253 if (!(bp->flags & MPOOL_PINNED)) { 254 (void)fprintf(stderr, 255 "mpool_put: page %d not pinned\n", bp->pgno); 256 abort(); 257 } 258 #endif 259 bp->flags &= ~MPOOL_PINNED; 260 bp->flags |= flags & MPOOL_DIRTY; 261 return (RET_SUCCESS); 262 } 263 264 /* 265 * mpool_close 266 * Close the buffer pool. 267 */ 268 int 269 mpool_close(mp) 270 MPOOL *mp; 271 { 272 BKT *bp; 273 274 /* Free up any space allocated to the lru pages. */ 275 while ((bp = mp->lqh.cqh_first) != (void *)&mp->lqh) { 276 CIRCLEQ_REMOVE(&mp->lqh, mp->lqh.cqh_first, q); 277 free(bp); 278 } 279 280 /* Free the MPOOL cookie. */ 281 free(mp); 282 return (RET_SUCCESS); 283 } 284 285 /* 286 * mpool_sync 287 * Sync the pool to disk. 288 */ 289 int 290 mpool_sync(mp) 291 MPOOL *mp; 292 { 293 BKT *bp; 294 295 /* Walk the lru chain, flushing any dirty pages to disk. */ 296 for (bp = mp->lqh.cqh_first; 297 bp != (void *)&mp->lqh; bp = bp->q.cqe_next) 298 if (bp->flags & MPOOL_DIRTY && 299 mpool_write(mp, bp) == RET_ERROR) 300 return (RET_ERROR); 301 302 /* Sync the file descriptor. */ 303 return (fsync(mp->fd) ? RET_ERROR : RET_SUCCESS); 304 } 305 306 /* 307 * mpool_bkt 308 * Get a page from the cache (or create one). 309 */ 310 static BKT * 311 mpool_bkt(mp) 312 MPOOL *mp; 313 { 314 struct _hqh *head; 315 BKT *bp; 316 317 /* If under the max cached, always create a new page. */ 318 if (mp->curcache < mp->maxcache) 319 goto new; 320 321 /* 322 * If the cache is max'd out, walk the lru list for a buffer we 323 * can flush. If we find one, write it (if necessary) and take it 324 * off any lists. If we don't find anything we grow the cache anyway. 325 * The cache never shrinks. 326 */ 327 for (bp = mp->lqh.cqh_first; 328 bp != (void *)&mp->lqh; bp = bp->q.cqe_next) 329 if (!(bp->flags & MPOOL_PINNED)) { 330 /* Flush if dirty. */ 331 if (bp->flags & MPOOL_DIRTY && 332 mpool_write(mp, bp) == RET_ERROR) 333 return (NULL); 334 #ifdef STATISTICS 335 ++mp->pageflush; 336 #endif 337 /* Remove from the hash and lru queues. */ 338 head = &mp->hqh[HASHKEY(bp->pgno)]; 339 CIRCLEQ_REMOVE(head, bp, hq); 340 CIRCLEQ_REMOVE(&mp->lqh, bp, q); 341 #ifdef DEBUG 342 { void *spage; 343 spage = bp->page; 344 memset(bp, 0xff, sizeof(BKT) + mp->pagesize); 345 bp->page = spage; 346 } 347 #endif 348 return (bp); 349 } 350 351 new: if ((bp = (BKT *)malloc(sizeof(BKT) + mp->pagesize)) == NULL) 352 return (NULL); 353 #ifdef STATISTICS 354 ++mp->pagealloc; 355 #endif 356 #if defined(DEBUG) || defined(PURIFY) 357 memset(bp, 0xff, sizeof(BKT) + mp->pagesize); 358 #endif 359 bp->page = (char *)bp + sizeof(BKT); 360 ++mp->curcache; 361 return (bp); 362 } 363 364 /* 365 * mpool_write 366 * Write a page to disk. 367 */ 368 static int 369 mpool_write(mp, bp) 370 MPOOL *mp; 371 BKT *bp; 372 { 373 off_t off; 374 375 #ifdef STATISTICS 376 ++mp->pagewrite; 377 #endif 378 379 /* Run through the user's filter. */ 380 if (mp->pgout) 381 (mp->pgout)(mp->pgcookie, bp->pgno, bp->page); 382 383 off = mp->pagesize * bp->pgno; 384 if (lseek(mp->fd, off, SEEK_SET) != off) 385 return (RET_ERROR); 386 if (write(mp->fd, bp->page, mp->pagesize) != mp->pagesize) 387 return (RET_ERROR); 388 389 bp->flags &= ~MPOOL_DIRTY; 390 return (RET_SUCCESS); 391 } 392 393 /* 394 * mpool_look 395 * Lookup a page in the cache. 396 */ 397 static BKT * 398 mpool_look(mp, pgno) 399 MPOOL *mp; 400 pgno_t pgno; 401 { 402 struct _hqh *head; 403 BKT *bp; 404 405 head = &mp->hqh[HASHKEY(pgno)]; 406 for (bp = head->cqh_first; bp != (void *)head; bp = bp->hq.cqe_next) 407 if (bp->pgno == pgno) { 408 #ifdef STATISTICS 409 ++mp->cachehit; 410 #endif 411 return (bp); 412 } 413 #ifdef STATISTICS 414 ++mp->cachemiss; 415 #endif 416 return (NULL); 417 } 418 419 #ifdef STATISTICS 420 /* 421 * mpool_stat 422 * Print out cache statistics. 423 */ 424 void 425 mpool_stat(mp) 426 MPOOL *mp; 427 { 428 BKT *bp; 429 int cnt; 430 char *sep; 431 432 (void)fprintf(stderr, "%lu pages in the file\n", mp->npages); 433 (void)fprintf(stderr, 434 "page size %lu, cacheing %lu pages of %lu page max cache\n", 435 mp->pagesize, mp->curcache, mp->maxcache); 436 (void)fprintf(stderr, "%lu page puts, %lu page gets, %lu page new\n", 437 mp->pageput, mp->pageget, mp->pagenew); 438 (void)fprintf(stderr, "%lu page allocs, %lu page flushes\n", 439 mp->pagealloc, mp->pageflush); 440 if (mp->cachehit + mp->cachemiss) 441 (void)fprintf(stderr, 442 "%.0f%% cache hit rate (%lu hits, %lu misses)\n", 443 ((double)mp->cachehit / (mp->cachehit + mp->cachemiss)) 444 * 100, mp->cachehit, mp->cachemiss); 445 (void)fprintf(stderr, "%lu page reads, %lu page writes\n", 446 mp->pageread, mp->pagewrite); 447 448 sep = ""; 449 cnt = 0; 450 for (bp = mp->lqh.cqh_first; 451 bp != (void *)&mp->lqh; bp = bp->q.cqe_next) { 452 (void)fprintf(stderr, "%s%d", sep, bp->pgno); 453 if (bp->flags & MPOOL_DIRTY) 454 (void)fprintf(stderr, "d"); 455 if (bp->flags & MPOOL_PINNED) 456 (void)fprintf(stderr, "P"); 457 if (++cnt == 10) { 458 sep = "\n"; 459 cnt = 0; 460 } else 461 sep = ", "; 462 463 } 464 (void)fprintf(stderr, "\n"); 465 } 466 #endif 467