mpool.c revision 1.8
1 /* $NetBSD: mpool.c,v 1.8 1997/07/21 14:06:41 jtc 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. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #include <sys/cdefs.h> 37 #if defined(LIBC_SCCS) && !defined(lint) 38 #if 0 39 static char sccsid[] = "@(#)mpool.c 8.5 (Berkeley) 7/26/94"; 40 #else 41 __RCSID("$NetBSD: mpool.c,v 1.8 1997/07/21 14:06:41 jtc Exp $"); 42 #endif 43 #endif /* LIBC_SCCS and not lint */ 44 45 #include "namespace.h" 46 #include <sys/param.h> 47 #include <sys/queue.h> 48 #include <sys/stat.h> 49 50 #include <errno.h> 51 #include <stdio.h> 52 #include <stdlib.h> 53 #include <string.h> 54 #include <unistd.h> 55 56 #include <db.h> 57 58 #define __MPOOLINTERFACE_PRIVATE 59 #include <mpool.h> 60 61 #ifdef __weak_alias 62 __weak_alias(mpool_close,_mpool_close); 63 __weak_alias(mpool_filter,_mpool_filter); 64 __weak_alias(mpool_get,_mpool_get); 65 __weak_alias(mpool_new,_mpool_new); 66 __weak_alias(mpool_open,_mpool_open); 67 __weak_alias(mpool_put,_mpool_put); 68 __weak_alias(mpool_sync,_mpool_sync); 69 #endif 70 71 static BKT *mpool_bkt __P((MPOOL *)); 72 static BKT *mpool_look __P((MPOOL *, pgno_t)); 73 static int mpool_write __P((MPOOL *, BKT *)); 74 75 /* 76 * mpool_open -- 77 * Initialize a memory pool. 78 */ 79 MPOOL * 80 mpool_open(key, fd, pagesize, maxcache) 81 void *key; 82 int fd; 83 pgno_t pagesize, maxcache; 84 { 85 struct stat sb; 86 MPOOL *mp; 87 int entry; 88 89 /* 90 * Get information about the file. 91 * 92 * XXX 93 * We don't currently handle pipes, although we should. 94 */ 95 if (fstat(fd, &sb)) 96 return (NULL); 97 if (!S_ISREG(sb.st_mode)) { 98 errno = ESPIPE; 99 return (NULL); 100 } 101 102 /* Allocate and initialize the MPOOL cookie. */ 103 if ((mp = (MPOOL *)calloc(1, sizeof(MPOOL))) == NULL) 104 return (NULL); 105 CIRCLEQ_INIT(&mp->lqh); 106 for (entry = 0; entry < HASHSIZE; ++entry) 107 CIRCLEQ_INIT(&mp->hqh[entry]); 108 mp->maxcache = maxcache; 109 mp->npages = sb.st_size / pagesize; 110 mp->pagesize = pagesize; 111 mp->fd = fd; 112 return (mp); 113 } 114 115 /* 116 * mpool_filter -- 117 * Initialize input/output filters. 118 */ 119 void 120 mpool_filter(mp, pgin, pgout, pgcookie) 121 MPOOL *mp; 122 void (*pgin) __P((void *, pgno_t, void *)); 123 void (*pgout) __P((void *, pgno_t, void *)); 124 void *pgcookie; 125 { 126 mp->pgin = pgin; 127 mp->pgout = pgout; 128 mp->pgcookie = pgcookie; 129 } 130 131 /* 132 * mpool_new -- 133 * Get a new page of memory. 134 */ 135 void * 136 mpool_new(mp, pgnoaddr) 137 MPOOL *mp; 138 pgno_t *pgnoaddr; 139 { 140 struct _hqh *head; 141 BKT *bp; 142 143 if (mp->npages == MAX_PAGE_NUMBER) { 144 (void)fprintf(stderr, "mpool_new: page allocation overflow.\n"); 145 abort(); 146 } 147 #ifdef STATISTICS 148 ++mp->pagenew; 149 #endif 150 /* 151 * Get a BKT from the cache. Assign a new page number, attach 152 * it to the head of the hash chain, the tail of the lru chain, 153 * and return. 154 */ 155 if ((bp = mpool_bkt(mp)) == NULL) 156 return (NULL); 157 *pgnoaddr = bp->pgno = mp->npages++; 158 bp->flags = MPOOL_PINNED; 159 160 head = &mp->hqh[HASHKEY(bp->pgno)]; 161 CIRCLEQ_INSERT_HEAD(head, bp, hq); 162 CIRCLEQ_INSERT_TAIL(&mp->lqh, bp, q); 163 return (bp->page); 164 } 165 166 /* 167 * mpool_get 168 * Get a page. 169 */ 170 void * 171 mpool_get(mp, pgno, flags) 172 MPOOL *mp; 173 pgno_t pgno; 174 u_int flags; /* XXX not used? */ 175 { 176 struct _hqh *head; 177 BKT *bp; 178 off_t off; 179 int nr; 180 181 /* Check for attempt to retrieve a non-existent page. */ 182 if (pgno >= mp->npages) { 183 errno = EINVAL; 184 return (NULL); 185 } 186 187 #ifdef STATISTICS 188 ++mp->pageget; 189 #endif 190 191 /* Check for a page that is cached. */ 192 if ((bp = mpool_look(mp, pgno)) != NULL) { 193 #ifdef DEBUG 194 if (bp->flags & MPOOL_PINNED) { 195 (void)fprintf(stderr, 196 "mpool_get: page %d already pinned\n", bp->pgno); 197 abort(); 198 } 199 #endif 200 /* 201 * Move the page to the head of the hash chain and the tail 202 * of the lru chain. 203 */ 204 head = &mp->hqh[HASHKEY(bp->pgno)]; 205 CIRCLEQ_REMOVE(head, bp, hq); 206 CIRCLEQ_INSERT_HEAD(head, bp, hq); 207 CIRCLEQ_REMOVE(&mp->lqh, bp, q); 208 CIRCLEQ_INSERT_TAIL(&mp->lqh, bp, q); 209 210 /* Return a pinned page. */ 211 bp->flags |= MPOOL_PINNED; 212 return (bp->page); 213 } 214 215 /* Get a page from the cache. */ 216 if ((bp = mpool_bkt(mp)) == NULL) 217 return (NULL); 218 219 /* Read in the contents. */ 220 #ifdef STATISTICS 221 ++mp->pageread; 222 #endif 223 off = mp->pagesize * pgno; 224 if (lseek(mp->fd, off, SEEK_SET) != off) 225 return (NULL); 226 if ((nr = read(mp->fd, bp->page, mp->pagesize)) != mp->pagesize) { 227 if (nr >= 0) 228 errno = EFTYPE; 229 return (NULL); 230 } 231 232 /* Set the page number, pin the page. */ 233 bp->pgno = pgno; 234 bp->flags = MPOOL_PINNED; 235 236 /* 237 * Add the page to the head of the hash chain and the tail 238 * of the lru chain. 239 */ 240 head = &mp->hqh[HASHKEY(bp->pgno)]; 241 CIRCLEQ_INSERT_HEAD(head, bp, hq); 242 CIRCLEQ_INSERT_TAIL(&mp->lqh, bp, q); 243 244 /* Run through the user's filter. */ 245 if (mp->pgin != NULL) 246 (mp->pgin)(mp->pgcookie, bp->pgno, bp->page); 247 248 return (bp->page); 249 } 250 251 /* 252 * mpool_put 253 * Return a page. 254 */ 255 int 256 mpool_put(mp, page, flags) 257 MPOOL *mp; 258 void *page; 259 u_int flags; 260 { 261 BKT *bp; 262 263 #ifdef STATISTICS 264 ++mp->pageput; 265 #endif 266 bp = (BKT *)((char *)page - sizeof(BKT)); 267 #ifdef DEBUG 268 if (!(bp->flags & MPOOL_PINNED)) { 269 (void)fprintf(stderr, 270 "mpool_put: page %d not pinned\n", bp->pgno); 271 abort(); 272 } 273 #endif 274 bp->flags &= ~MPOOL_PINNED; 275 bp->flags |= flags & MPOOL_DIRTY; 276 return (RET_SUCCESS); 277 } 278 279 /* 280 * mpool_close 281 * Close the buffer pool. 282 */ 283 int 284 mpool_close(mp) 285 MPOOL *mp; 286 { 287 BKT *bp; 288 289 /* Free up any space allocated to the lru pages. */ 290 while ((bp = mp->lqh.cqh_first) != (void *)&mp->lqh) { 291 CIRCLEQ_REMOVE(&mp->lqh, mp->lqh.cqh_first, q); 292 free(bp); 293 } 294 295 /* Free the MPOOL cookie. */ 296 free(mp); 297 return (RET_SUCCESS); 298 } 299 300 /* 301 * mpool_sync 302 * Sync the pool to disk. 303 */ 304 int 305 mpool_sync(mp) 306 MPOOL *mp; 307 { 308 BKT *bp; 309 310 /* Walk the lru chain, flushing any dirty pages to disk. */ 311 for (bp = mp->lqh.cqh_first; 312 bp != (void *)&mp->lqh; bp = bp->q.cqe_next) 313 if (bp->flags & MPOOL_DIRTY && 314 mpool_write(mp, bp) == RET_ERROR) 315 return (RET_ERROR); 316 317 /* Sync the file descriptor. */ 318 return (fsync(mp->fd) ? RET_ERROR : RET_SUCCESS); 319 } 320 321 /* 322 * mpool_bkt 323 * Get a page from the cache (or create one). 324 */ 325 static BKT * 326 mpool_bkt(mp) 327 MPOOL *mp; 328 { 329 struct _hqh *head; 330 BKT *bp; 331 332 /* If under the max cached, always create a new page. */ 333 if (mp->curcache < mp->maxcache) 334 goto new; 335 336 /* 337 * If the cache is max'd out, walk the lru list for a buffer we 338 * can flush. If we find one, write it (if necessary) and take it 339 * off any lists. If we don't find anything we grow the cache anyway. 340 * The cache never shrinks. 341 */ 342 for (bp = mp->lqh.cqh_first; 343 bp != (void *)&mp->lqh; bp = bp->q.cqe_next) 344 if (!(bp->flags & MPOOL_PINNED)) { 345 /* Flush if dirty. */ 346 if (bp->flags & MPOOL_DIRTY && 347 mpool_write(mp, bp) == RET_ERROR) 348 return (NULL); 349 #ifdef STATISTICS 350 ++mp->pageflush; 351 #endif 352 /* Remove from the hash and lru queues. */ 353 head = &mp->hqh[HASHKEY(bp->pgno)]; 354 CIRCLEQ_REMOVE(head, bp, hq); 355 CIRCLEQ_REMOVE(&mp->lqh, bp, q); 356 #ifdef DEBUG 357 { void *spage; 358 spage = bp->page; 359 memset(bp, 0xff, sizeof(BKT) + mp->pagesize); 360 bp->page = spage; 361 } 362 #endif 363 return (bp); 364 } 365 366 new: if ((bp = (BKT *)malloc(sizeof(BKT) + mp->pagesize)) == NULL) 367 return (NULL); 368 #ifdef STATISTICS 369 ++mp->pagealloc; 370 #endif 371 #if defined(DEBUG) || defined(PURIFY) 372 memset(bp, 0xff, sizeof(BKT) + mp->pagesize); 373 #endif 374 bp->page = (char *)bp + sizeof(BKT); 375 ++mp->curcache; 376 return (bp); 377 } 378 379 /* 380 * mpool_write 381 * Write a page to disk. 382 */ 383 static int 384 mpool_write(mp, bp) 385 MPOOL *mp; 386 BKT *bp; 387 { 388 off_t off; 389 390 #ifdef STATISTICS 391 ++mp->pagewrite; 392 #endif 393 394 /* Run through the user's filter. */ 395 if (mp->pgout) 396 (mp->pgout)(mp->pgcookie, bp->pgno, bp->page); 397 398 off = mp->pagesize * bp->pgno; 399 if (lseek(mp->fd, off, SEEK_SET) != off) 400 return (RET_ERROR); 401 if (write(mp->fd, bp->page, mp->pagesize) != mp->pagesize) 402 return (RET_ERROR); 403 404 bp->flags &= ~MPOOL_DIRTY; 405 return (RET_SUCCESS); 406 } 407 408 /* 409 * mpool_look 410 * Lookup a page in the cache. 411 */ 412 static BKT * 413 mpool_look(mp, pgno) 414 MPOOL *mp; 415 pgno_t pgno; 416 { 417 struct _hqh *head; 418 BKT *bp; 419 420 head = &mp->hqh[HASHKEY(pgno)]; 421 for (bp = head->cqh_first; bp != (void *)head; bp = bp->hq.cqe_next) 422 if (bp->pgno == pgno) { 423 #ifdef STATISTICS 424 ++mp->cachehit; 425 #endif 426 return (bp); 427 } 428 #ifdef STATISTICS 429 ++mp->cachemiss; 430 #endif 431 return (NULL); 432 } 433 434 #ifdef STATISTICS 435 /* 436 * mpool_stat 437 * Print out cache statistics. 438 */ 439 void 440 mpool_stat(mp) 441 MPOOL *mp; 442 { 443 BKT *bp; 444 int cnt; 445 char *sep; 446 447 (void)fprintf(stderr, "%lu pages in the file\n", mp->npages); 448 (void)fprintf(stderr, 449 "page size %lu, cacheing %lu pages of %lu page max cache\n", 450 mp->pagesize, mp->curcache, mp->maxcache); 451 (void)fprintf(stderr, "%lu page puts, %lu page gets, %lu page new\n", 452 mp->pageput, mp->pageget, mp->pagenew); 453 (void)fprintf(stderr, "%lu page allocs, %lu page flushes\n", 454 mp->pagealloc, mp->pageflush); 455 if (mp->cachehit + mp->cachemiss) 456 (void)fprintf(stderr, 457 "%.0f%% cache hit rate (%lu hits, %lu misses)\n", 458 ((double)mp->cachehit / (mp->cachehit + mp->cachemiss)) 459 * 100, mp->cachehit, mp->cachemiss); 460 (void)fprintf(stderr, "%lu page reads, %lu page writes\n", 461 mp->pageread, mp->pagewrite); 462 463 sep = ""; 464 cnt = 0; 465 for (bp = mp->lqh.cqh_first; 466 bp != (void *)&mp->lqh; bp = bp->q.cqe_next) { 467 (void)fprintf(stderr, "%s%d", sep, bp->pgno); 468 if (bp->flags & MPOOL_DIRTY) 469 (void)fprintf(stderr, "d"); 470 if (bp->flags & MPOOL_PINNED) 471 (void)fprintf(stderr, "P"); 472 if (++cnt == 10) { 473 sep = "\n"; 474 cnt = 0; 475 } else 476 sep = ", "; 477 478 } 479 (void)fprintf(stderr, "\n"); 480 } 481 #endif 482
Indexes created Wed Sep 24 14:09:57 GMT 2025