mpool.c revision 1.1.1.2
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 sccsid[] = "@(#)mpool.c 8.5 (Berkeley) 7/26/94"; 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 MPOOL * 62 mpool_open(key, fd, pagesize, maxcache) 63 void *key; 64 int fd; 65 pgno_t pagesize, maxcache; 66 { 67 struct stat sb; 68 MPOOL *mp; 69 int entry; 70 71 /* 72 * Get information about the file. 73 * 74 * XXX 75 * We don't currently handle pipes, although we should. 76 */ 77 if (fstat(fd, &sb)) 78 return (NULL); 79 if (!S_ISREG(sb.st_mode)) { 80 errno = ESPIPE; 81 return (NULL); 82 } 83 84 /* Allocate and initialize the MPOOL cookie. */ 85 if ((mp = (MPOOL *)calloc(1, sizeof(MPOOL))) == NULL) 86 return (NULL); 87 CIRCLEQ_INIT(&mp->lqh); 88 for (entry = 0; entry < HASHSIZE; ++entry) 89 CIRCLEQ_INIT(&mp->hqh[entry]); 90 mp->maxcache = maxcache; 91 mp->npages = sb.st_size / pagesize; 92 mp->pagesize = pagesize; 93 mp->fd = fd; 94 return (mp); 95 } 96 97 /* 98 * mpool_filter -- 99 * Initialize input/output filters. 100 */ 101 void 102 mpool_filter(mp, pgin, pgout, pgcookie) 103 MPOOL *mp; 104 void (*pgin) __P((void *, pgno_t, void *)); 105 void (*pgout) __P((void *, pgno_t, void *)); 106 void *pgcookie; 107 { 108 mp->pgin = pgin; 109 mp->pgout = pgout; 110 mp->pgcookie = pgcookie; 111 } 112 113 /* 114 * mpool_new -- 115 * Get a new page of memory. 116 */ 117 void * 118 mpool_new(mp, pgnoaddr) 119 MPOOL *mp; 120 pgno_t *pgnoaddr; 121 { 122 struct _hqh *head; 123 BKT *bp; 124 125 if (mp->npages == MAX_PAGE_NUMBER) { 126 (void)fprintf(stderr, "mpool_new: page allocation overflow.\n"); 127 abort(); 128 } 129 #ifdef STATISTICS 130 ++mp->pagenew; 131 #endif 132 /* 133 * Get a BKT from the cache. Assign a new page number, attach 134 * it to the head of the hash chain, the tail of the lru chain, 135 * and return. 136 */ 137 if ((bp = mpool_bkt(mp)) == NULL) 138 return (NULL); 139 *pgnoaddr = bp->pgno = mp->npages++; 140 bp->flags = MPOOL_PINNED; 141 142 head = &mp->hqh[HASHKEY(bp->pgno)]; 143 CIRCLEQ_INSERT_HEAD(head, bp, hq); 144 CIRCLEQ_INSERT_TAIL(&mp->lqh, bp, q); 145 return (bp->page); 146 } 147 148 /* 149 * mpool_get 150 * Get a page. 151 */ 152 void * 153 mpool_get(mp, pgno, flags) 154 MPOOL *mp; 155 pgno_t pgno; 156 u_int flags; /* XXX not used? */ 157 { 158 struct _hqh *head; 159 BKT *bp; 160 off_t off; 161 int nr; 162 163 /* Check for attempt to retrieve a non-existent page. */ 164 if (pgno >= mp->npages) { 165 errno = EINVAL; 166 return (NULL); 167 } 168 169 #ifdef STATISTICS 170 ++mp->pageget; 171 #endif 172 173 /* Check for a page that is cached. */ 174 if ((bp = mpool_look(mp, pgno)) != NULL) { 175 #ifdef DEBUG 176 if (bp->flags & MPOOL_PINNED) { 177 (void)fprintf(stderr, 178 "mpool_get: page %d already pinned\n", bp->pgno); 179 abort(); 180 } 181 #endif 182 /* 183 * Move the page to the head of the hash chain and the tail 184 * of the lru chain. 185 */ 186 head = &mp->hqh[HASHKEY(bp->pgno)]; 187 CIRCLEQ_REMOVE(head, bp, hq); 188 CIRCLEQ_INSERT_HEAD(head, bp, hq); 189 CIRCLEQ_REMOVE(&mp->lqh, bp, q); 190 CIRCLEQ_INSERT_TAIL(&mp->lqh, bp, q); 191 192 /* Return a pinned page. */ 193 bp->flags |= MPOOL_PINNED; 194 return (bp->page); 195 } 196 197 /* Get a page from the cache. */ 198 if ((bp = mpool_bkt(mp)) == NULL) 199 return (NULL); 200 201 /* Read in the contents. */ 202 #ifdef STATISTICS 203 ++mp->pageread; 204 #endif 205 off = mp->pagesize * pgno; 206 if (lseek(mp->fd, off, SEEK_SET) != off) 207 return (NULL); 208 if ((nr = read(mp->fd, bp->page, mp->pagesize)) != mp->pagesize) { 209 if (nr >= 0) 210 errno = EFTYPE; 211 return (NULL); 212 } 213 214 /* Set the page number, pin the page. */ 215 bp->pgno = pgno; 216 bp->flags = MPOOL_PINNED; 217 218 /* 219 * Add the page to the head of the hash chain and the tail 220 * of the lru chain. 221 */ 222 head = &mp->hqh[HASHKEY(bp->pgno)]; 223 CIRCLEQ_INSERT_HEAD(head, bp, hq); 224 CIRCLEQ_INSERT_TAIL(&mp->lqh, bp, q); 225 226 /* Run through the user's filter. */ 227 if (mp->pgin != NULL) 228 (mp->pgin)(mp->pgcookie, bp->pgno, bp->page); 229 230 return (bp->page); 231 } 232 233 /* 234 * mpool_put 235 * Return a page. 236 */ 237 int 238 mpool_put(mp, page, flags) 239 MPOOL *mp; 240 void *page; 241 u_int flags; 242 { 243 BKT *bp; 244 245 #ifdef STATISTICS 246 ++mp->pageput; 247 #endif 248 bp = (BKT *)((char *)page - sizeof(BKT)); 249 #ifdef DEBUG 250 if (!(bp->flags & MPOOL_PINNED)) { 251 (void)fprintf(stderr, 252 "mpool_put: page %d not pinned\n", bp->pgno); 253 abort(); 254 } 255 #endif 256 bp->flags &= ~MPOOL_PINNED; 257 bp->flags |= flags & MPOOL_DIRTY; 258 return (RET_SUCCESS); 259 } 260 261 /* 262 * mpool_close 263 * Close the buffer pool. 264 */ 265 int 266 mpool_close(mp) 267 MPOOL *mp; 268 { 269 BKT *bp; 270 271 /* Free up any space allocated to the lru pages. */ 272 while ((bp = mp->lqh.cqh_first) != (void *)&mp->lqh) { 273 CIRCLEQ_REMOVE(&mp->lqh, mp->lqh.cqh_first, q); 274 free(bp); 275 } 276 277 /* Free the MPOOL cookie. */ 278 free(mp); 279 return (RET_SUCCESS); 280 } 281 282 /* 283 * mpool_sync 284 * Sync the pool to disk. 285 */ 286 int 287 mpool_sync(mp) 288 MPOOL *mp; 289 { 290 BKT *bp; 291 292 /* Walk the lru chain, flushing any dirty pages to disk. */ 293 for (bp = mp->lqh.cqh_first; 294 bp != (void *)&mp->lqh; bp = bp->q.cqe_next) 295 if (bp->flags & MPOOL_DIRTY && 296 mpool_write(mp, bp) == RET_ERROR) 297 return (RET_ERROR); 298 299 /* Sync the file descriptor. */ 300 return (fsync(mp->fd) ? RET_ERROR : RET_SUCCESS); 301 } 302 303 /* 304 * mpool_bkt 305 * Get a page from the cache (or create one). 306 */ 307 static BKT * 308 mpool_bkt(mp) 309 MPOOL *mp; 310 { 311 struct _hqh *head; 312 BKT *bp; 313 314 /* If under the max cached, always create a new page. */ 315 if (mp->curcache < mp->maxcache) 316 goto new; 317 318 /* 319 * If the cache is max'd out, walk the lru list for a buffer we 320 * can flush. If we find one, write it (if necessary) and take it 321 * off any lists. If we don't find anything we grow the cache anyway. 322 * The cache never shrinks. 323 */ 324 for (bp = mp->lqh.cqh_first; 325 bp != (void *)&mp->lqh; bp = bp->q.cqe_next) 326 if (!(bp->flags & MPOOL_PINNED)) { 327 /* Flush if dirty. */ 328 if (bp->flags & MPOOL_DIRTY && 329 mpool_write(mp, bp) == RET_ERROR) 330 return (NULL); 331 #ifdef STATISTICS 332 ++mp->pageflush; 333 #endif 334 /* Remove from the hash and lru queues. */ 335 head = &mp->hqh[HASHKEY(bp->pgno)]; 336 CIRCLEQ_REMOVE(head, bp, hq); 337 CIRCLEQ_REMOVE(&mp->lqh, bp, q); 338 #ifdef DEBUG 339 { void *spage; 340 spage = bp->page; 341 memset(bp, 0xff, sizeof(BKT) + mp->pagesize); 342 bp->page = spage; 343 } 344 #endif 345 return (bp); 346 } 347 348 new: if ((bp = (BKT *)malloc(sizeof(BKT) + mp->pagesize)) == NULL) 349 return (NULL); 350 #ifdef STATISTICS 351 ++mp->pagealloc; 352 #endif 353 #if defined(DEBUG) || defined(PURIFY) 354 memset(bp, 0xff, sizeof(BKT) + mp->pagesize); 355 #endif 356 bp->page = (char *)bp + sizeof(BKT); 357 ++mp->curcache; 358 return (bp); 359 } 360 361 /* 362 * mpool_write 363 * Write a page to disk. 364 */ 365 static int 366 mpool_write(mp, bp) 367 MPOOL *mp; 368 BKT *bp; 369 { 370 off_t off; 371 372 #ifdef STATISTICS 373 ++mp->pagewrite; 374 #endif 375 376 /* Run through the user's filter. */ 377 if (mp->pgout) 378 (mp->pgout)(mp->pgcookie, bp->pgno, bp->page); 379 380 off = mp->pagesize * bp->pgno; 381 if (lseek(mp->fd, off, SEEK_SET) != off) 382 return (RET_ERROR); 383 if (write(mp->fd, bp->page, mp->pagesize) != mp->pagesize) 384 return (RET_ERROR); 385 386 bp->flags &= ~MPOOL_DIRTY; 387 return (RET_SUCCESS); 388 } 389 390 /* 391 * mpool_look 392 * Lookup a page in the cache. 393 */ 394 static BKT * 395 mpool_look(mp, pgno) 396 MPOOL *mp; 397 pgno_t pgno; 398 { 399 struct _hqh *head; 400 BKT *bp; 401 402 head = &mp->hqh[HASHKEY(pgno)]; 403 for (bp = head->cqh_first; bp != (void *)head; bp = bp->hq.cqe_next) 404 if (bp->pgno == pgno) { 405 #ifdef STATISTICS 406 ++mp->cachehit; 407 #endif 408 return (bp); 409 } 410 #ifdef STATISTICS 411 ++mp->cachemiss; 412 #endif 413 return (NULL); 414 } 415 416 #ifdef STATISTICS 417 /* 418 * mpool_stat 419 * Print out cache statistics. 420 */ 421 void 422 mpool_stat(mp) 423 MPOOL *mp; 424 { 425 BKT *bp; 426 int cnt; 427 char *sep; 428 429 (void)fprintf(stderr, "%lu pages in the file\n", mp->npages); 430 (void)fprintf(stderr, 431 "page size %lu, cacheing %lu pages of %lu page max cache\n", 432 mp->pagesize, mp->curcache, mp->maxcache); 433 (void)fprintf(stderr, "%lu page puts, %lu page gets, %lu page new\n", 434 mp->pageput, mp->pageget, mp->pagenew); 435 (void)fprintf(stderr, "%lu page allocs, %lu page flushes\n", 436 mp->pagealloc, mp->pageflush); 437 if (mp->cachehit + mp->cachemiss) 438 (void)fprintf(stderr, 439 "%.0f%% cache hit rate (%lu hits, %lu misses)\n", 440 ((double)mp->cachehit / (mp->cachehit + mp->cachemiss)) 441 * 100, mp->cachehit, mp->cachemiss); 442 (void)fprintf(stderr, "%lu page reads, %lu page writes\n", 443 mp->pageread, mp->pagewrite); 444 445 sep = ""; 446 cnt = 0; 447 for (bp = mp->lqh.cqh_first; 448 bp != (void *)&mp->lqh; bp = bp->q.cqe_next) { 449 (void)fprintf(stderr, "%s%d", sep, bp->pgno); 450 if (bp->flags & MPOOL_DIRTY) 451 (void)fprintf(stderr, "d"); 452 if (bp->flags & MPOOL_PINNED) 453 (void)fprintf(stderr, "P"); 454 if (++cnt == 10) { 455 sep = "\n"; 456 cnt = 0; 457 } else 458 sep = ", "; 459 460 } 461 (void)fprintf(stderr, "\n"); 462 } 463 #endif 464
Indexes created Tue Sep 30 06:09:59 GMT 2025