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 * $FreeBSD: src/lib/libc/db/mpool/mpool.c,v 1.5.2.1 2001/03/05 23:05:01 obrien Exp $ 34 */ 35 36 #if defined(LIBC_SCCS) && !defined(lint) 37 static char sccsid[] = "@(#)mpool.c 8.5 (Berkeley) 7/26/94"; 38 #endif /* LIBC_SCCS and not lint */ 39 40 #include <sys/param.h> 41 #include <sys/queue.h> 42 #include <sys/stat.h> 43 44 #include <errno.h> 45 #include <stdio.h> 46 #include <stdlib.h> 47 #include <string.h> 48 #include <unistd.h> 49 50 #include <db.h> 51 52 #define __MPOOLINTERFACE_PRIVATE 53 #include <mpool.h> 54 55 static BKT *mpool_bkt __P((MPOOL *)); 56 static BKT *mpool_look __P((MPOOL *, pgno_t)); 57 static int mpool_write __P((MPOOL *, BKT *)); 58 59 /* 60 * mpool_open -- 61 * Initialize a memory pool. 62 */ 63 MPOOL * 64 mpool_open(key, fd, pagesize, maxcache) 65 void *key; 66 int fd; 67 pgno_t pagesize, maxcache; 68 { 69 struct stat sb; 70 MPOOL *mp; 71 int entry; 72 73 /* 74 * Get information about the file. 75 * 76 * XXX 77 * We don't currently handle pipes, although we should. 78 */ 79 if (fstat(fd, &sb)) 80 return (NULL); 81 if (!S_ISREG(sb.st_mode)) { 82 errno = ESPIPE; 83 return (NULL); 84 } 85 86 /* Allocate and initialize the MPOOL cookie. */ 87 if ((mp = (MPOOL *)calloc(1, sizeof(MPOOL))) == NULL) 88 return (NULL); 89 TAILQ_INIT(&mp->lqh); 90 for (entry = 0; entry < HASHSIZE; ++entry) 91 TAILQ_INIT(&mp->hqh[entry]); 92 mp->maxcache = maxcache; 93 mp->npages = sb.st_size / pagesize; 94 mp->pagesize = pagesize; 95 mp->fd = fd; 96 return (mp); 97 } 98 99 /* 100 * mpool_filter -- 101 * Initialize input/output filters. 102 */ 103 void 104 mpool_filter(mp, pgin, pgout, pgcookie) 105 MPOOL *mp; 106 void (*pgin) __P((void *, pgno_t, void *)); 107 void (*pgout) __P((void *, pgno_t, void *)); 108 void *pgcookie; 109 { 110 mp->pgin = pgin; 111 mp->pgout = pgout; 112 mp->pgcookie = pgcookie; 113 } 114 115 /* 116 * mpool_new -- 117 * Get a new page of memory. 118 */ 119 void * 120 mpool_new(mp, pgnoaddr) 121 MPOOL *mp; 122 pgno_t *pgnoaddr; 123 { 124 struct _hqh *head; 125 BKT *bp; 126 127 if (mp->npages == MAX_PAGE_NUMBER) { 128 (void)fprintf(stderr, "mpool_new: page allocation overflow.\n"); 129 abort(); 130 } 131 #ifdef STATISTICS 132 ++mp->pagenew; 133 #endif 134 /* 135 * Get a BKT from the cache. Assign a new page number, attach 136 * it to the head of the hash chain, the tail of the lru chain, 137 * and return. 138 */ 139 if ((bp = mpool_bkt(mp)) == NULL) 140 return (NULL); 141 *pgnoaddr = bp->pgno = mp->npages++; 142 bp->flags = MPOOL_PINNED; 143 144 head = &mp->hqh[HASHKEY(bp->pgno)]; 145 TAILQ_INSERT_HEAD(head, bp, hq); 146 TAILQ_INSERT_TAIL(&mp->lqh, bp, q); 147 return (bp->page); 148 } 149 150 /* 151 * mpool_get 152 * Get a page. 153 */ 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 TAILQ_REMOVE(head, bp, hq); 190 TAILQ_INSERT_HEAD(head, bp, hq); 191 TAILQ_REMOVE(&mp->lqh, bp, q); 192 TAILQ_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 TAILQ_INSERT_HEAD(head, bp, hq); 226 TAILQ_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 int 240 mpool_put(mp, page, flags) 241 MPOOL *mp; 242 void *page; 243 u_int flags; 244 { 245 BKT *bp; 246 247 #ifdef STATISTICS 248 ++mp->pageput; 249 #endif 250 bp = (BKT *)((char *)page - sizeof(BKT)); 251 #ifdef DEBUG 252 if (!(bp->flags & MPOOL_PINNED)) { 253 (void)fprintf(stderr, 254 "mpool_put: page %d not pinned\n", bp->pgno); 255 abort(); 256 } 257 #endif 258 bp->flags &= ~MPOOL_PINNED; 259 bp->flags |= flags & MPOOL_DIRTY; 260 return (RET_SUCCESS); 261 } 262 263 /* 264 * mpool_close 265 * Close the buffer pool. 266 */ 267 int 268 mpool_close(mp) 269 MPOOL *mp; 270 { 271 BKT *bp; 272 273 /* Free up any space allocated to the lru pages. */ 274 while (!TAILQ_EMPTY(&mp->lqh)) { 275 bp = TAILQ_FIRST(&mp->lqh); 276 TAILQ_REMOVE(&mp->lqh, bp, 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 TAILQ_FOREACH(bp, &mp->lqh, q) 297 if (bp->flags & MPOOL_DIRTY && 298 mpool_write(mp, bp) == RET_ERROR) 299 return (RET_ERROR); 300 301 /* Sync the file descriptor. */ 302 return (_fsync(mp->fd) ? RET_ERROR : RET_SUCCESS); 303 } 304 305 /* 306 * mpool_bkt 307 * Get a page from the cache (or create one). 308 */ 309 static BKT * 310 mpool_bkt(mp) 311 MPOOL *mp; 312 { 313 struct _hqh *head; 314 BKT *bp; 315 316 /* If under the max cached, always create a new page. */ 317 if (mp->curcache < mp->maxcache) 318 goto new; 319 320 /* 321 * If the cache is max'd out, walk the lru list for a buffer we 322 * can flush. If we find one, write it (if necessary) and take it 323 * off any lists. If we don't find anything we grow the cache anyway. 324 * The cache never shrinks. 325 */ 326 TAILQ_FOREACH(bp, &mp->lqh, q) 327 if (!(bp->flags & MPOOL_PINNED)) { 328 /* Flush if dirty. */ 329 if (bp->flags & MPOOL_DIRTY && 330 mpool_write(mp, bp) == RET_ERROR) 331 return (NULL); 332 #ifdef STATISTICS 333 ++mp->pageflush; 334 #endif 335 /* Remove from the hash and lru queues. */ 336 head = &mp->hqh[HASHKEY(bp->pgno)]; 337 TAILQ_REMOVE(head, bp, hq); 338 TAILQ_REMOVE(&mp->lqh, bp, q); 339 #ifdef DEBUG 340 { void *spage; 341 spage = bp->page; 342 memset(bp, 0xff, sizeof(BKT) + mp->pagesize); 343 bp->page = spage; 344 } 345 #endif 346 return (bp); 347 } 348 349 new: if ((bp = (BKT *)malloc(sizeof(BKT) + mp->pagesize)) == NULL) 350 return (NULL); 351 #ifdef STATISTICS 352 ++mp->pagealloc; 353 #endif 354 #if defined(DEBUG) || defined(PURIFY) 355 memset(bp, 0xff, sizeof(BKT) + mp->pagesize); 356 #endif 357 bp->page = (char *)bp + sizeof(BKT); 358 ++mp->curcache; 359 return (bp); 360 } 361 362 /* 363 * mpool_write 364 * Write a page to disk. 365 */ 366 static int 367 mpool_write(mp, bp) 368 MPOOL *mp; 369 BKT *bp; 370 { 371 off_t off; 372 373 #ifdef STATISTICS 374 ++mp->pagewrite; 375 #endif 376 377 /* Run through the user's filter. */ 378 if (mp->pgout) 379 (mp->pgout)(mp->pgcookie, bp->pgno, bp->page); 380 381 off = mp->pagesize * bp->pgno; 382 if (lseek(mp->fd, off, SEEK_SET) != off) 383 return (RET_ERROR); 384 if (_write(mp->fd, bp->page, mp->pagesize) != mp->pagesize) 385 return (RET_ERROR); 386 387 bp->flags &= ~MPOOL_DIRTY; 388 return (RET_SUCCESS); 389 } 390 391 /* 392 * mpool_look 393 * Lookup a page in the cache. 394 */ 395 static BKT * 396 mpool_look(mp, pgno) 397 MPOOL *mp; 398 pgno_t pgno; 399 { 400 struct _hqh *head; 401 BKT *bp; 402 403 head = &mp->hqh[HASHKEY(pgno)]; 404 TAILQ_FOREACH(bp, head, hq) 405 if (bp->pgno == pgno) { 406 #ifdef STATISTICS 407 ++mp->cachehit; 408 #endif 409 return (bp); 410 } 411 #ifdef STATISTICS 412 ++mp->cachemiss; 413 #endif 414 return (NULL); 415 } 416 417 #ifdef STATISTICS 418 /* 419 * mpool_stat 420 * Print out cache statistics. 421 */ 422 void 423 mpool_stat(mp) 424 MPOOL *mp; 425 { 426 BKT *bp; 427 int cnt; 428 char *sep; 429 430 (void)fprintf(stderr, "%lu pages in the file\n", mp->npages); 431 (void)fprintf(stderr, 432 "page size %lu, cacheing %lu pages of %lu page max cache\n", 433 mp->pagesize, mp->curcache, mp->maxcache); 434 (void)fprintf(stderr, "%lu page puts, %lu page gets, %lu page new\n", 435 mp->pageput, mp->pageget, mp->pagenew); 436 (void)fprintf(stderr, "%lu page allocs, %lu page flushes\n", 437 mp->pagealloc, mp->pageflush); 438 if (mp->cachehit + mp->cachemiss) 439 (void)fprintf(stderr, 440 "%.0f%% cache hit rate (%lu hits, %lu misses)\n", 441 ((double)mp->cachehit / (mp->cachehit + mp->cachemiss)) 442 * 100, mp->cachehit, mp->cachemiss); 443 (void)fprintf(stderr, "%lu page reads, %lu page writes\n", 444 mp->pageread, mp->pagewrite); 445 446 sep = ""; 447 cnt = 0; 448 TAILQ_FOREACH(bp, &mp->lqh, q) { 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