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