mpool.c revision 1.15
1 /* $NetBSD: mpool.c,v 1.15 2006/01/24 17:37:05 christos Exp $ */ 2 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 #include <sys/cdefs.h> 33 #if defined(LIBC_SCCS) && !defined(lint) 34 #if 0 35 static char sccsid[] = "@(#)mpool.c 8.5 (Berkeley) 7/26/94"; 36 #else 37 __RCSID("$NetBSD: mpool.c,v 1.15 2006/01/24 17:37:05 christos Exp $"); 38 #endif 39 #endif /* LIBC_SCCS and not lint */ 40 41 #include "namespace.h" 42 #include <sys/queue.h> 43 #include <sys/stat.h> 44 45 #include <errno.h> 46 #include <stdio.h> 47 #include <stdlib.h> 48 #include <string.h> 49 #include <unistd.h> 50 51 #include <db.h> 52 53 #define __MPOOLINTERFACE_PRIVATE 54 #include <mpool.h> 55 56 #ifdef __weak_alias 57 __weak_alias(mpool_close,_mpool_close) 58 __weak_alias(mpool_filter,_mpool_filter) 59 __weak_alias(mpool_get,_mpool_get) 60 __weak_alias(mpool_new,_mpool_new) 61 __weak_alias(mpool_open,_mpool_open) 62 __weak_alias(mpool_put,_mpool_put) 63 __weak_alias(mpool_sync,_mpool_sync) 64 #endif 65 66 static BKT *mpool_bkt __P((MPOOL *)); 67 static BKT *mpool_look __P((MPOOL *, pgno_t)); 68 static int mpool_write __P((MPOOL *, BKT *)); 69 70 /* 71 * mpool_open -- 72 * Initialize a memory pool. 73 */ 74 /*ARGSUSED*/ 75 MPOOL * 76 mpool_open(key, fd, pagesize, maxcache) 77 void *key; 78 int fd; 79 pgno_t pagesize, maxcache; 80 { 81 struct stat sb; 82 MPOOL *mp; 83 int entry; 84 85 /* 86 * Get information about the file. 87 * 88 * XXX 89 * We don't currently handle pipes, although we should. 90 */ 91 if (fstat(fd, &sb)) 92 return (NULL); 93 if (!S_ISREG(sb.st_mode)) { 94 errno = ESPIPE; 95 return (NULL); 96 } 97 98 /* Allocate and initialize the MPOOL cookie. */ 99 if ((mp = (MPOOL *)calloc(1, sizeof(MPOOL))) == NULL) 100 return (NULL); 101 CIRCLEQ_INIT(&mp->lqh); 102 for (entry = 0; entry < HASHSIZE; ++entry) 103 CIRCLEQ_INIT(&mp->hqh[entry]); 104 mp->maxcache = maxcache; 105 mp->npages = (pgno_t)(sb.st_size / pagesize); 106 mp->pagesize = pagesize; 107 mp->fd = fd; 108 return (mp); 109 } 110 111 /* 112 * mpool_filter -- 113 * Initialize input/output filters. 114 */ 115 void 116 mpool_filter(mp, pgin, pgout, pgcookie) 117 MPOOL *mp; 118 void (*pgin) __P((void *, pgno_t, void *)); 119 void (*pgout) __P((void *, pgno_t, void *)); 120 void *pgcookie; 121 { 122 mp->pgin = pgin; 123 mp->pgout = pgout; 124 mp->pgcookie = pgcookie; 125 } 126 127 /* 128 * mpool_new -- 129 * Get a new page of memory. 130 */ 131 void * 132 mpool_new(mp, pgnoaddr) 133 MPOOL *mp; 134 pgno_t *pgnoaddr; 135 { 136 struct _hqh *head; 137 BKT *bp; 138 139 if (mp->npages == MAX_PAGE_NUMBER) { 140 (void)fprintf(stderr, "mpool_new: page allocation overflow.\n"); 141 abort(); 142 } 143 #ifdef STATISTICS 144 ++mp->pagenew; 145 #endif 146 /* 147 * Get a BKT from the cache. Assign a new page number, attach 148 * it to the head of the hash chain, the tail of the lru chain, 149 * and return. 150 */ 151 if ((bp = mpool_bkt(mp)) == NULL) 152 return (NULL); 153 *pgnoaddr = bp->pgno = mp->npages++; 154 bp->flags = MPOOL_PINNED; 155 156 head = &mp->hqh[HASHKEY(bp->pgno)]; 157 CIRCLEQ_INSERT_HEAD(head, bp, hq); 158 CIRCLEQ_INSERT_TAIL(&mp->lqh, bp, q); 159 return (bp->page); 160 } 161 162 /* 163 * mpool_get 164 * Get a page. 165 */ 166 /*ARGSUSED*/ 167 void * 168 mpool_get(mp, pgno, flags) 169 MPOOL *mp; 170 pgno_t pgno; 171 u_int flags; /* XXX not used? */ 172 { 173 struct _hqh *head; 174 BKT *bp; 175 off_t off; 176 int nr; 177 178 /* Check for attempt to retrieve a non-existent page. */ 179 if (pgno >= mp->npages) { 180 errno = EINVAL; 181 return (NULL); 182 } 183 184 #ifdef STATISTICS 185 ++mp->pageget; 186 #endif 187 188 /* Check for a page that is cached. */ 189 if ((bp = mpool_look(mp, pgno)) != NULL) { 190 #ifdef DEBUG 191 if (bp->flags & MPOOL_PINNED) { 192 (void)fprintf(stderr, 193 "mpool_get: page %d already pinned\n", bp->pgno); 194 abort(); 195 } 196 #endif 197 /* 198 * Move the page to the head of the hash chain and the tail 199 * of the lru chain. 200 */ 201 head = &mp->hqh[HASHKEY(bp->pgno)]; 202 CIRCLEQ_REMOVE(head, bp, hq); 203 CIRCLEQ_INSERT_HEAD(head, bp, hq); 204 CIRCLEQ_REMOVE(&mp->lqh, bp, q); 205 CIRCLEQ_INSERT_TAIL(&mp->lqh, bp, q); 206 207 /* Return a pinned page. */ 208 bp->flags |= MPOOL_PINNED; 209 return (bp->page); 210 } 211 212 /* Get a page from the cache. */ 213 if ((bp = mpool_bkt(mp)) == NULL) 214 return (NULL); 215 216 /* Read in the contents. */ 217 #ifdef STATISTICS 218 ++mp->pageread; 219 #endif 220 off = mp->pagesize * pgno; 221 if ((nr = pread(mp->fd, bp->page, (size_t)mp->pagesize, off)) != (int)mp->pagesize) { 222 if (nr >= 0) 223 errno = EFTYPE; 224 return (NULL); 225 } 226 227 /* Set the page number, pin the page. */ 228 bp->pgno = pgno; 229 bp->flags = MPOOL_PINNED; 230 231 /* 232 * Add the page to the head of the hash chain and the tail 233 * of the lru chain. 234 */ 235 head = &mp->hqh[HASHKEY(bp->pgno)]; 236 CIRCLEQ_INSERT_HEAD(head, bp, hq); 237 CIRCLEQ_INSERT_TAIL(&mp->lqh, bp, q); 238 239 /* Run through the user's filter. */ 240 if (mp->pgin != NULL) 241 (mp->pgin)(mp->pgcookie, bp->pgno, bp->page); 242 243 return (bp->page); 244 } 245 246 /* 247 * mpool_put 248 * Return a page. 249 */ 250 /*ARGSUSED*/ 251 int 252 mpool_put(mp, page, flags) 253 MPOOL *mp; 254 void *page; 255 u_int flags; 256 { 257 BKT *bp; 258 259 #ifdef STATISTICS 260 ++mp->pageput; 261 #endif 262 bp = (BKT *)(void *)((char *)page - sizeof(BKT)); 263 #ifdef DEBUG 264 if (!(bp->flags & MPOOL_PINNED)) { 265 (void)fprintf(stderr, 266 "mpool_put: page %d not pinned\n", bp->pgno); 267 abort(); 268 } 269 #endif 270 bp->flags &= ~MPOOL_PINNED; 271 bp->flags |= flags & MPOOL_DIRTY; 272 return (RET_SUCCESS); 273 } 274 275 /* 276 * mpool_close 277 * Close the buffer pool. 278 */ 279 int 280 mpool_close(mp) 281 MPOOL *mp; 282 { 283 BKT *bp; 284 285 /* Free up any space allocated to the lru pages. */ 286 while ((bp = mp->lqh.cqh_first) != (void *)&mp->lqh) { 287 CIRCLEQ_REMOVE(&mp->lqh, mp->lqh.cqh_first, q); 288 free(bp); 289 } 290 291 /* Free the MPOOL cookie. */ 292 free(mp); 293 return (RET_SUCCESS); 294 } 295 296 /* 297 * mpool_sync 298 * Sync the pool to disk. 299 */ 300 int 301 mpool_sync(mp) 302 MPOOL *mp; 303 { 304 BKT *bp; 305 306 /* Walk the lru chain, flushing any dirty pages to disk. */ 307 for (bp = mp->lqh.cqh_first; 308 bp != (void *)&mp->lqh; bp = bp->q.cqe_next) 309 if (bp->flags & MPOOL_DIRTY && 310 mpool_write(mp, bp) == RET_ERROR) 311 return (RET_ERROR); 312 313 /* Sync the file descriptor. */ 314 return (fsync(mp->fd) ? RET_ERROR : RET_SUCCESS); 315 } 316 317 /* 318 * mpool_bkt 319 * Get a page from the cache (or create one). 320 */ 321 static BKT * 322 mpool_bkt(mp) 323 MPOOL *mp; 324 { 325 struct _hqh *head; 326 BKT *bp; 327 328 /* If under the max cached, always create a new page. */ 329 if (mp->curcache < mp->maxcache) 330 goto new; 331 332 /* 333 * If the cache is max'd out, walk the lru list for a buffer we 334 * can flush. If we find one, write it (if necessary) and take it 335 * off any lists. If we don't find anything we grow the cache anyway. 336 * The cache never shrinks. 337 */ 338 for (bp = mp->lqh.cqh_first; 339 bp != (void *)&mp->lqh; bp = bp->q.cqe_next) 340 if (!(bp->flags & MPOOL_PINNED)) { 341 /* Flush if dirty. */ 342 if (bp->flags & MPOOL_DIRTY && 343 mpool_write(mp, bp) == RET_ERROR) 344 return (NULL); 345 #ifdef STATISTICS 346 ++mp->pageflush; 347 #endif 348 /* Remove from the hash and lru queues. */ 349 head = &mp->hqh[HASHKEY(bp->pgno)]; 350 CIRCLEQ_REMOVE(head, bp, hq); 351 CIRCLEQ_REMOVE(&mp->lqh, bp, q); 352 #ifdef DEBUG 353 { 354 void *spage = bp->page; 355 (void)memset(bp, 0xff, 356 (size_t)(sizeof(BKT) + mp->pagesize)); 357 bp->page = spage; 358 } 359 #endif 360 return (bp); 361 } 362 363 new: if ((bp = (BKT *)malloc((size_t)(sizeof(BKT) + mp->pagesize))) == NULL) 364 return (NULL); 365 #ifdef STATISTICS 366 ++mp->pagealloc; 367 #endif 368 #if defined(DEBUG) || defined(PURIFY) 369 (void)memset(bp, 0xff, (size_t)(sizeof(BKT) + mp->pagesize)); 370 #endif 371 bp->page = (char *)(void *)bp + sizeof(BKT); 372 ++mp->curcache; 373 return (bp); 374 } 375 376 /* 377 * mpool_write 378 * Write a page to disk. 379 */ 380 static int 381 mpool_write(mp, bp) 382 MPOOL *mp; 383 BKT *bp; 384 { 385 off_t off; 386 387 #ifdef STATISTICS 388 ++mp->pagewrite; 389 #endif 390 391 /* Run through the user's filter. */ 392 if (mp->pgout) 393 (mp->pgout)(mp->pgcookie, bp->pgno, bp->page); 394 395 off = mp->pagesize * bp->pgno; 396 if (pwrite(mp->fd, bp->page, (size_t)mp->pagesize, off) != (int)mp->pagesize) 397 return (RET_ERROR); 398 399 /* 400 * Re-run through the input filter since this page may soon be 401 * accessed via the cache, and whatever the user's output filter 402 * did may screw things up if we don't let the input filter 403 * restore the in-core copy. 404 */ 405 if (mp->pgin) 406 (mp->pgin)(mp->pgcookie, bp->pgno, bp->page); 407 408 bp->flags &= ~MPOOL_DIRTY; 409 return (RET_SUCCESS); 410 } 411 412 /* 413 * mpool_look 414 * Lookup a page in the cache. 415 */ 416 static BKT * 417 mpool_look(mp, pgno) 418 MPOOL *mp; 419 pgno_t pgno; 420 { 421 struct _hqh *head; 422 BKT *bp; 423 424 head = &mp->hqh[HASHKEY(pgno)]; 425 for (bp = head->cqh_first; bp != (void *)head; bp = bp->hq.cqe_next) 426 if (bp->pgno == pgno) { 427 #ifdef STATISTICS 428 ++mp->cachehit; 429 #endif 430 return (bp); 431 } 432 #ifdef STATISTICS 433 ++mp->cachemiss; 434 #endif 435 return (NULL); 436 } 437 438 #ifdef STATISTICS 439 /* 440 * mpool_stat 441 * Print out cache statistics. 442 */ 443 void 444 mpool_stat(mp) 445 MPOOL *mp; 446 { 447 BKT *bp; 448 int cnt; 449 char *sep; 450 451 (void)fprintf(stderr, "%lu pages in the file\n", mp->npages); 452 (void)fprintf(stderr, 453 "page size %lu, cacheing %lu pages of %lu page max cache\n", 454 mp->pagesize, mp->curcache, mp->maxcache); 455 (void)fprintf(stderr, "%lu page puts, %lu page gets, %lu page new\n", 456 mp->pageput, mp->pageget, mp->pagenew); 457 (void)fprintf(stderr, "%lu page allocs, %lu page flushes\n", 458 mp->pagealloc, mp->pageflush); 459 if (mp->cachehit + mp->cachemiss) 460 (void)fprintf(stderr, 461 "%.0f%% cache hit rate (%lu hits, %lu misses)\n", 462 ((double)mp->cachehit / (mp->cachehit + mp->cachemiss)) 463 * 100, mp->cachehit, mp->cachemiss); 464 (void)fprintf(stderr, "%lu page reads, %lu page writes\n", 465 mp->pageread, mp->pagewrite); 466 467 sep = ""; 468 cnt = 0; 469 for (bp = mp->lqh.cqh_first; 470 bp != (void *)&mp->lqh; bp = bp->q.cqe_next) { 471 (void)fprintf(stderr, "%s%d", sep, bp->pgno); 472 if (bp->flags & MPOOL_DIRTY) 473 (void)fprintf(stderr, "d"); 474 if (bp->flags & MPOOL_PINNED) 475 (void)fprintf(stderr, "P"); 476 if (++cnt == 10) { 477 sep = "\n"; 478 cnt = 0; 479 } else 480 sep = ", "; 481 482 } 483 (void)fprintf(stderr, "\n"); 484 } 485 #endif 486
Indexes created Wed Sep 24 05:09:52 GMT 2025