1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1990, 1993, 1994 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #if defined(LIBC_SCCS) && !defined(lint) 33 static char sccsid[] = "@(#)mpool.c 8.7 (Berkeley) 11/2/95"; 34 #endif /* LIBC_SCCS and not lint */ 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 /* ARGSUSED */ 61 MPOOL * 62 mpool_open(void *key, int fd, pgno_t pagesize, pgno_t maxcache) 63 { 64 struct stat sb; 65 MPOOL *mp; 66 int entry; 67 68 /* 69 * Get information about the file. 70 * 71 * XXX 72 * We don't currently handle pipes, although we should. 73 */ 74 if (_fstat(fd, &sb)) 75 return (NULL); 76 if (!S_ISREG(sb.st_mode)) { 77 errno = ESPIPE; 78 return (NULL); 79 } 80 81 /* Allocate and initialize the MPOOL cookie. */ 82 if ((mp = (MPOOL *)calloc(1, sizeof(MPOOL))) == NULL) 83 return (NULL); 84 TAILQ_INIT(&mp->lqh); 85 for (entry = 0; entry < HASHSIZE; ++entry) 86 TAILQ_INIT(&mp->hqh[entry]); 87 mp->maxcache = maxcache; 88 mp->npages = sb.st_size / pagesize; 89 mp->pagesize = pagesize; 90 mp->fd = fd; 91 return (mp); 92 } 93 94 /* 95 * mpool_filter -- 96 * Initialize input/output filters. 97 */ 98 void 99 mpool_filter(MPOOL *mp, void (*pgin) (void *, pgno_t, void *), 100 void (*pgout) (void *, pgno_t, void *), void *pgcookie) 101 { 102 mp->pgin = pgin; 103 mp->pgout = pgout; 104 mp->pgcookie = pgcookie; 105 } 106 107 /* 108 * mpool_new -- 109 * Get a new page of memory. 110 */ 111 void * 112 mpool_new(MPOOL *mp, pgno_t *pgnoaddr, u_int flags) 113 { 114 struct _hqh *head; 115 BKT *bp; 116 117 if (mp->npages == MAX_PAGE_NUMBER) { 118 (void)fprintf(stderr, "mpool_new: page allocation overflow.\n"); 119 abort(); 120 } 121 #ifdef STATISTICS 122 ++mp->pagenew; 123 #endif 124 /* 125 * Get a BKT from the cache. Assign a new page number, attach 126 * it to the head of the hash chain, the tail of the lru chain, 127 * and return. 128 */ 129 if ((bp = mpool_bkt(mp)) == NULL) 130 return (NULL); 131 if (flags == MPOOL_PAGE_REQUEST) { 132 mp->npages++; 133 bp->pgno = *pgnoaddr; 134 } else 135 bp->pgno = *pgnoaddr = mp->npages++; 136 137 bp->flags = MPOOL_PINNED | MPOOL_INUSE; 138 139 head = &mp->hqh[HASHKEY(bp->pgno)]; 140 TAILQ_INSERT_HEAD(head, bp, hq); 141 TAILQ_INSERT_TAIL(&mp->lqh, bp, q); 142 return (bp->page); 143 } 144 145 int 146 mpool_delete(MPOOL *mp, void *page) 147 { 148 struct _hqh *head; 149 BKT *bp; 150 151 bp = (BKT *)((char *)page - sizeof(BKT)); 152 153 #ifdef DEBUG 154 if (!(bp->flags & MPOOL_PINNED)) { 155 (void)fprintf(stderr, 156 "mpool_delete: page %d not pinned\n", bp->pgno); 157 abort(); 158 } 159 #endif 160 161 /* Remove from the hash and lru queues. */ 162 head = &mp->hqh[HASHKEY(bp->pgno)]; 163 TAILQ_REMOVE(head, bp, hq); 164 TAILQ_REMOVE(&mp->lqh, bp, q); 165 166 free(bp); 167 mp->curcache--; 168 return (RET_SUCCESS); 169 } 170 171 /* 172 * mpool_get 173 * Get a page. 174 */ 175 /* ARGSUSED */ 176 void * 177 mpool_get(MPOOL *mp, pgno_t pgno, 178 u_int flags) /* XXX not used? */ 179 { 180 struct _hqh *head; 181 BKT *bp; 182 off_t off; 183 int nr; 184 185 #ifdef STATISTICS 186 ++mp->pageget; 187 #endif 188 189 /* Check for a page that is cached. */ 190 if ((bp = mpool_look(mp, pgno)) != NULL) { 191 #ifdef DEBUG 192 if (!(flags & MPOOL_IGNOREPIN) && bp->flags & MPOOL_PINNED) { 193 (void)fprintf(stderr, 194 "mpool_get: page %d already pinned\n", bp->pgno); 195 abort(); 196 } 197 #endif 198 /* 199 * Move the page to the head of the hash chain and the tail 200 * of the lru chain. 201 */ 202 head = &mp->hqh[HASHKEY(bp->pgno)]; 203 TAILQ_REMOVE(head, bp, hq); 204 TAILQ_INSERT_HEAD(head, bp, hq); 205 TAILQ_REMOVE(&mp->lqh, bp, q); 206 TAILQ_INSERT_TAIL(&mp->lqh, bp, q); 207 208 /* Return a pinned page. */ 209 bp->flags |= MPOOL_PINNED; 210 return (bp->page); 211 } 212 213 /* Get a page from the cache. */ 214 if ((bp = mpool_bkt(mp)) == NULL) 215 return (NULL); 216 217 /* Read in the contents. */ 218 off = mp->pagesize * pgno; 219 if ((nr = pread(mp->fd, bp->page, mp->pagesize, off)) != (ssize_t)mp->pagesize) { 220 switch (nr) { 221 case -1: 222 /* errno is set for us by pread(). */ 223 free(bp); 224 mp->curcache--; 225 return (NULL); 226 case 0: 227 /* 228 * A zero-length read means you need to create a 229 * new page. 230 */ 231 memset(bp->page, 0, mp->pagesize); 232 break; 233 default: 234 /* A partial read is definitely bad. */ 235 free(bp); 236 mp->curcache--; 237 errno = EINVAL; 238 return (NULL); 239 } 240 } 241 #ifdef STATISTICS 242 ++mp->pageread; 243 #endif 244 245 /* Set the page number, pin the page. */ 246 bp->pgno = pgno; 247 if (!(flags & MPOOL_IGNOREPIN)) 248 bp->flags = MPOOL_PINNED; 249 bp->flags |= MPOOL_INUSE; 250 251 /* 252 * Add the page to the head of the hash chain and the tail 253 * of the lru chain. 254 */ 255 head = &mp->hqh[HASHKEY(bp->pgno)]; 256 TAILQ_INSERT_HEAD(head, bp, hq); 257 TAILQ_INSERT_TAIL(&mp->lqh, bp, q); 258 259 /* Run through the user's filter. */ 260 if (mp->pgin != NULL) 261 (mp->pgin)(mp->pgcookie, bp->pgno, bp->page); 262 263 return (bp->page); 264 } 265 266 /* 267 * mpool_put 268 * Return a page. 269 */ 270 /* ARGSUSED */ 271 int 272 mpool_put(MPOOL *mp, void *page, u_int flags) 273 { 274 BKT *bp; 275 276 #ifdef STATISTICS 277 ++mp->pageput; 278 #endif 279 bp = (BKT *)((char *)page - sizeof(BKT)); 280 #ifdef DEBUG 281 if (!(bp->flags & MPOOL_PINNED)) { 282 (void)fprintf(stderr, 283 "mpool_put: page %d not pinned\n", bp->pgno); 284 abort(); 285 } 286 #endif 287 bp->flags &= ~MPOOL_PINNED; 288 if (flags & MPOOL_DIRTY) 289 bp->flags |= flags & MPOOL_DIRTY; 290 return (RET_SUCCESS); 291 } 292 293 /* 294 * mpool_close 295 * Close the buffer pool. 296 */ 297 int 298 mpool_close(MPOOL *mp) 299 { 300 BKT *bp; 301 302 /* Free up any space allocated to the lru pages. */ 303 while (!TAILQ_EMPTY(&mp->lqh)) { 304 bp = TAILQ_FIRST(&mp->lqh); 305 TAILQ_REMOVE(&mp->lqh, bp, q); 306 free(bp); 307 } 308 309 /* Free the MPOOL cookie. */ 310 free(mp); 311 return (RET_SUCCESS); 312 } 313 314 /* 315 * mpool_sync 316 * Sync the pool to disk. 317 */ 318 int 319 mpool_sync(MPOOL *mp) 320 { 321 BKT *bp; 322 323 /* Walk the lru chain, flushing any dirty pages to disk. */ 324 TAILQ_FOREACH(bp, &mp->lqh, q) 325 if (bp->flags & MPOOL_DIRTY && 326 mpool_write(mp, bp) == RET_ERROR) 327 return (RET_ERROR); 328 329 /* Sync the file descriptor. */ 330 return (_fsync(mp->fd) ? RET_ERROR : RET_SUCCESS); 331 } 332 333 /* 334 * mpool_bkt 335 * Get a page from the cache (or create one). 336 */ 337 static BKT * 338 mpool_bkt(MPOOL *mp) 339 { 340 struct _hqh *head; 341 BKT *bp; 342 343 /* If under the max cached, always create a new page. */ 344 if (mp->curcache < mp->maxcache) 345 goto new; 346 347 /* 348 * If the cache is max'd out, walk the lru list for a buffer we 349 * can flush. If we find one, write it (if necessary) and take it 350 * off any lists. If we don't find anything we grow the cache anyway. 351 * The cache never shrinks. 352 */ 353 TAILQ_FOREACH(bp, &mp->lqh, q) 354 if (!(bp->flags & MPOOL_PINNED)) { 355 /* Flush if dirty. */ 356 if (bp->flags & MPOOL_DIRTY && 357 mpool_write(mp, bp) == RET_ERROR) 358 return (NULL); 359 #ifdef STATISTICS 360 ++mp->pageflush; 361 #endif 362 /* Remove from the hash and lru queues. */ 363 head = &mp->hqh[HASHKEY(bp->pgno)]; 364 TAILQ_REMOVE(head, bp, hq); 365 TAILQ_REMOVE(&mp->lqh, bp, q); 366 #ifdef DEBUG 367 { void *spage; 368 spage = bp->page; 369 memset(bp, 0xff, sizeof(BKT) + mp->pagesize); 370 bp->page = spage; 371 } 372 #endif 373 bp->flags = 0; 374 return (bp); 375 } 376 377 new: if ((bp = (BKT *)calloc(1, sizeof(BKT) + mp->pagesize)) == NULL) 378 return (NULL); 379 #ifdef STATISTICS 380 ++mp->pagealloc; 381 #endif 382 bp->page = (char *)bp + sizeof(BKT); 383 bp->flags = 0; 384 ++mp->curcache; 385 return (bp); 386 } 387 388 /* 389 * mpool_write 390 * Write a page to disk. 391 */ 392 static int 393 mpool_write(MPOOL *mp, BKT *bp) 394 { 395 off_t off; 396 397 #ifdef STATISTICS 398 ++mp->pagewrite; 399 #endif 400 401 /* Run through the user's filter. */ 402 if (mp->pgout) 403 (mp->pgout)(mp->pgcookie, bp->pgno, bp->page); 404 405 off = mp->pagesize * bp->pgno; 406 if (pwrite(mp->fd, bp->page, mp->pagesize, off) != (ssize_t)mp->pagesize) 407 return (RET_ERROR); 408 409 /* 410 * Re-run through the input filter since this page may soon be 411 * accessed via the cache, and whatever the user's output filter 412 * did may screw things up if we don't let the input filter 413 * restore the in-core copy. 414 */ 415 if (mp->pgin) 416 (mp->pgin)(mp->pgcookie, bp->pgno, bp->page); 417 418 bp->flags &= ~MPOOL_DIRTY; 419 return (RET_SUCCESS); 420 } 421 422 /* 423 * mpool_look 424 * Lookup a page in the cache. 425 */ 426 static BKT * 427 mpool_look(MPOOL *mp, pgno_t pgno) 428 { 429 struct _hqh *head; 430 BKT *bp; 431 432 head = &mp->hqh[HASHKEY(pgno)]; 433 TAILQ_FOREACH(bp, head, hq) 434 if ((bp->pgno == pgno) && 435 ((bp->flags & MPOOL_INUSE) == MPOOL_INUSE)) { 436 #ifdef STATISTICS 437 ++mp->cachehit; 438 #endif 439 return (bp); 440 } 441 #ifdef STATISTICS 442 ++mp->cachemiss; 443 #endif 444 return (NULL); 445 } 446 447 #ifdef STATISTICS 448 /* 449 * mpool_stat 450 * Print out cache statistics. 451 */ 452 void 453 mpool_stat(MPOOL *mp) 454 { 455 BKT *bp; 456 int cnt; 457 char *sep; 458 459 (void)fprintf(stderr, "%lu pages in the file\n", mp->npages); 460 (void)fprintf(stderr, 461 "page size %lu, cacheing %lu pages of %lu page max cache\n", 462 mp->pagesize, mp->curcache, mp->maxcache); 463 (void)fprintf(stderr, "%lu page puts, %lu page gets, %lu page new\n", 464 mp->pageput, mp->pageget, mp->pagenew); 465 (void)fprintf(stderr, "%lu page allocs, %lu page flushes\n", 466 mp->pagealloc, mp->pageflush); 467 if (mp->cachehit + mp->cachemiss) 468 (void)fprintf(stderr, 469 "%.0f%% cache hit rate (%lu hits, %lu misses)\n", 470 ((double)mp->cachehit / (mp->cachehit + mp->cachemiss)) 471 * 100, mp->cachehit, mp->cachemiss); 472 (void)fprintf(stderr, "%lu page reads, %lu page writes\n", 473 mp->pageread, mp->pagewrite); 474 475 sep = ""; 476 cnt = 0; 477 TAILQ_FOREACH(bp, &mp->lqh, q) { 478 (void)fprintf(stderr, "%s%d", sep, bp->pgno); 479 if (bp->flags & MPOOL_DIRTY) 480 (void)fprintf(stderr, "d"); 481 if (bp->flags & MPOOL_PINNED) 482 (void)fprintf(stderr, "P"); 483 if (++cnt == 10) { 484 sep = "\n"; 485 cnt = 0; 486 } else 487 sep = ", "; 488 489 } 490 (void)fprintf(stderr, "\n"); 491 } 492 #endif 493