1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
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 #if defined(LIBC_SCCS) && !defined(lint)
33 static char sccsid[] = "@(#)mpool.c 8.7 (Berkeley) 11/2/95";
34 #endif /* LIBC_SCCS and not lint */
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD$");
37
38 #include "namespace.h"
39 #include <sys/param.h>
40 #include <sys/queue.h>
41 #include <sys/stat.h>
42
43 #include <errno.h>
44 #include <stdio.h>
45 #include <stdlib.h>
46 #include <string.h>
47 #include <unistd.h>
48 #include "un-namespace.h"
49
50 #include <db.h>
51
52 #define __MPOOLINTERFACE_PRIVATE
53 #include <mpool.h>
54
55 static BKT *mpool_bkt(MPOOL *);
56 static BKT *mpool_look(MPOOL *, pgno_t);
57 static int mpool_write(MPOOL *, BKT *);
58
59 /*
60 * mpool_open --
61 * Initialize a memory pool.
62 */
63 /* ARGSUSED */
64 MPOOL *
mpool_open(void * key,int fd,pgno_t pagesize,pgno_t maxcache)65 mpool_open(void *key, int fd, pgno_t pagesize, pgno_t 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 TAILQ_INIT(&mp->lqh);
88 for (entry = 0; entry < HASHSIZE; ++entry)
89 TAILQ_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
mpool_filter(MPOOL * mp,void (* pgin)(void *,pgno_t,void *),void (* pgout)(void *,pgno_t,void *),void * pgcookie)102 mpool_filter(MPOOL *mp, void (*pgin) (void *, pgno_t, void *),
103 void (*pgout) (void *, pgno_t, void *), void *pgcookie)
104 {
105 mp->pgin = pgin;
106 mp->pgout = pgout;
107 mp->pgcookie = pgcookie;
108 }
109
110 /*
111 * mpool_new --
112 * Get a new page of memory.
113 */
114 void *
mpool_new(MPOOL * mp,pgno_t * pgnoaddr,u_int flags)115 mpool_new(MPOOL *mp, pgno_t *pgnoaddr, u_int flags)
116 {
117 struct _hqh *head;
118 BKT *bp;
119
120 if (mp->npages == MAX_PAGE_NUMBER) {
121 (void)fprintf(stderr, "mpool_new: page allocation overflow.\n");
122 abort();
123 }
124 #ifdef STATISTICS
125 ++mp->pagenew;
126 #endif
127 /*
128 * Get a BKT from the cache. Assign a new page number, attach
129 * it to the head of the hash chain, the tail of the lru chain,
130 * and return.
131 */
132 if ((bp = mpool_bkt(mp)) == NULL)
133 return (NULL);
134 if (flags == MPOOL_PAGE_REQUEST) {
135 mp->npages++;
136 bp->pgno = *pgnoaddr;
137 } else
138 bp->pgno = *pgnoaddr = mp->npages++;
139
140 bp->flags = MPOOL_PINNED | MPOOL_INUSE;
141
142 head = &mp->hqh[HASHKEY(bp->pgno)];
143 TAILQ_INSERT_HEAD(head, bp, hq);
144 TAILQ_INSERT_TAIL(&mp->lqh, bp, q);
145 return (bp->page);
146 }
147
148 int
mpool_delete(MPOOL * mp,void * page)149 mpool_delete(MPOOL *mp, void *page)
150 {
151 struct _hqh *head;
152 BKT *bp;
153
154 bp = (BKT *)((char *)page - sizeof(BKT));
155
156 #ifdef DEBUG
157 if (!(bp->flags & MPOOL_PINNED)) {
158 (void)fprintf(stderr,
159 "mpool_delete: page %d not pinned\n", bp->pgno);
160 abort();
161 }
162 #endif
163
164 /* Remove from the hash and lru queues. */
165 head = &mp->hqh[HASHKEY(bp->pgno)];
166 TAILQ_REMOVE(head, bp, hq);
167 TAILQ_REMOVE(&mp->lqh, bp, q);
168
169 free(bp);
170 mp->curcache--;
171 return (RET_SUCCESS);
172 }
173
174 /*
175 * mpool_get
176 * Get a page.
177 */
178 /* ARGSUSED */
179 void *
mpool_get(MPOOL * mp,pgno_t pgno,u_int flags)180 mpool_get(MPOOL *mp, pgno_t pgno,
181 u_int flags) /* XXX not used? */
182 {
183 struct _hqh *head;
184 BKT *bp;
185 off_t off;
186 int nr;
187
188 #ifdef STATISTICS
189 ++mp->pageget;
190 #endif
191
192 /* Check for a page that is cached. */
193 if ((bp = mpool_look(mp, pgno)) != NULL) {
194 #ifdef DEBUG
195 if (!(flags & MPOOL_IGNOREPIN) && bp->flags & MPOOL_PINNED) {
196 (void)fprintf(stderr,
197 "mpool_get: page %d already pinned\n", bp->pgno);
198 abort();
199 }
200 #endif
201 /*
202 * Move the page to the head of the hash chain and the tail
203 * of the lru chain.
204 */
205 head = &mp->hqh[HASHKEY(bp->pgno)];
206 TAILQ_REMOVE(head, bp, hq);
207 TAILQ_INSERT_HEAD(head, bp, hq);
208 TAILQ_REMOVE(&mp->lqh, bp, q);
209 TAILQ_INSERT_TAIL(&mp->lqh, bp, q);
210
211 /* Return a pinned page. */
212 bp->flags |= MPOOL_PINNED;
213 return (bp->page);
214 }
215
216 /* Get a page from the cache. */
217 if ((bp = mpool_bkt(mp)) == NULL)
218 return (NULL);
219
220 /* Read in the contents. */
221 off = mp->pagesize * pgno;
222 if ((nr = pread(mp->fd, bp->page, mp->pagesize, off)) != (ssize_t)mp->pagesize) {
223 switch (nr) {
224 case -1:
225 /* errno is set for us by pread(). */
226 free(bp);
227 mp->curcache--;
228 return (NULL);
229 case 0:
230 /*
231 * A zero-length read means you need to create a
232 * new page.
233 */
234 memset(bp->page, 0, mp->pagesize);
235 break;
236 default:
237 /* A partial read is definitely bad. */
238 free(bp);
239 mp->curcache--;
240 errno = EINVAL;
241 return (NULL);
242 }
243 }
244 #ifdef STATISTICS
245 ++mp->pageread;
246 #endif
247
248 /* Set the page number, pin the page. */
249 bp->pgno = pgno;
250 if (!(flags & MPOOL_IGNOREPIN))
251 bp->flags = MPOOL_PINNED;
252 bp->flags |= MPOOL_INUSE;
253
254 /*
255 * Add the page to the head of the hash chain and the tail
256 * of the lru chain.
257 */
258 head = &mp->hqh[HASHKEY(bp->pgno)];
259 TAILQ_INSERT_HEAD(head, bp, hq);
260 TAILQ_INSERT_TAIL(&mp->lqh, bp, q);
261
262 /* Run through the user's filter. */
263 if (mp->pgin != NULL)
264 (mp->pgin)(mp->pgcookie, bp->pgno, bp->page);
265
266 return (bp->page);
267 }
268
269 /*
270 * mpool_put
271 * Return a page.
272 */
273 /* ARGSUSED */
274 int
mpool_put(MPOOL * mp,void * page,u_int flags)275 mpool_put(MPOOL *mp, void *page, u_int flags)
276 {
277 BKT *bp;
278
279 #ifdef STATISTICS
280 ++mp->pageput;
281 #endif
282 bp = (BKT *)((char *)page - sizeof(BKT));
283 #ifdef DEBUG
284 if (!(bp->flags & MPOOL_PINNED)) {
285 (void)fprintf(stderr,
286 "mpool_put: page %d not pinned\n", bp->pgno);
287 abort();
288 }
289 #endif
290 bp->flags &= ~MPOOL_PINNED;
291 if (flags & MPOOL_DIRTY)
292 bp->flags |= flags & MPOOL_DIRTY;
293 return (RET_SUCCESS);
294 }
295
296 /*
297 * mpool_close
298 * Close the buffer pool.
299 */
300 int
mpool_close(MPOOL * mp)301 mpool_close(MPOOL *mp)
302 {
303 BKT *bp;
304
305 /* Free up any space allocated to the lru pages. */
306 while (!TAILQ_EMPTY(&mp->lqh)) {
307 bp = TAILQ_FIRST(&mp->lqh);
308 TAILQ_REMOVE(&mp->lqh, bp, q);
309 free(bp);
310 }
311
312 /* Free the MPOOL cookie. */
313 free(mp);
314 return (RET_SUCCESS);
315 }
316
317 /*
318 * mpool_sync
319 * Sync the pool to disk.
320 */
321 int
mpool_sync(MPOOL * mp)322 mpool_sync(MPOOL *mp)
323 {
324 BKT *bp;
325
326 /* Walk the lru chain, flushing any dirty pages to disk. */
327 TAILQ_FOREACH(bp, &mp->lqh, q)
328 if (bp->flags & MPOOL_DIRTY &&
329 mpool_write(mp, bp) == RET_ERROR)
330 return (RET_ERROR);
331
332 /* Sync the file descriptor. */
333 return (_fsync(mp->fd) ? RET_ERROR : RET_SUCCESS);
334 }
335
336 /*
337 * mpool_bkt
338 * Get a page from the cache (or create one).
339 */
340 static BKT *
mpool_bkt(MPOOL * mp)341 mpool_bkt(MPOOL *mp)
342 {
343 struct _hqh *head;
344 BKT *bp;
345
346 /* If under the max cached, always create a new page. */
347 if (mp->curcache < mp->maxcache)
348 goto new;
349
350 /*
351 * If the cache is max'd out, walk the lru list for a buffer we
352 * can flush. If we find one, write it (if necessary) and take it
353 * off any lists. If we don't find anything we grow the cache anyway.
354 * The cache never shrinks.
355 */
356 TAILQ_FOREACH(bp, &mp->lqh, q)
357 if (!(bp->flags & MPOOL_PINNED)) {
358 /* Flush if dirty. */
359 if (bp->flags & MPOOL_DIRTY &&
360 mpool_write(mp, bp) == RET_ERROR)
361 return (NULL);
362 #ifdef STATISTICS
363 ++mp->pageflush;
364 #endif
365 /* Remove from the hash and lru queues. */
366 head = &mp->hqh[HASHKEY(bp->pgno)];
367 TAILQ_REMOVE(head, bp, hq);
368 TAILQ_REMOVE(&mp->lqh, bp, q);
369 #ifdef DEBUG
370 { void *spage;
371 spage = bp->page;
372 memset(bp, 0xff, sizeof(BKT) + mp->pagesize);
373 bp->page = spage;
374 }
375 #endif
376 bp->flags = 0;
377 return (bp);
378 }
379
380 new: if ((bp = (BKT *)calloc(1, sizeof(BKT) + mp->pagesize)) == NULL)
381 return (NULL);
382 #ifdef STATISTICS
383 ++mp->pagealloc;
384 #endif
385 bp->page = (char *)bp + sizeof(BKT);
386 bp->flags = 0;
387 ++mp->curcache;
388 return (bp);
389 }
390
391 /*
392 * mpool_write
393 * Write a page to disk.
394 */
395 static int
mpool_write(MPOOL * mp,BKT * bp)396 mpool_write(MPOOL *mp, BKT *bp)
397 {
398 off_t off;
399
400 #ifdef STATISTICS
401 ++mp->pagewrite;
402 #endif
403
404 /* Run through the user's filter. */
405 if (mp->pgout)
406 (mp->pgout)(mp->pgcookie, bp->pgno, bp->page);
407
408 off = mp->pagesize * bp->pgno;
409 if (pwrite(mp->fd, bp->page, mp->pagesize, off) != (ssize_t)mp->pagesize)
410 return (RET_ERROR);
411
412 /*
413 * Re-run through the input filter since this page may soon be
414 * accessed via the cache, and whatever the user's output filter
415 * did may screw things up if we don't let the input filter
416 * restore the in-core copy.
417 */
418 if (mp->pgin)
419 (mp->pgin)(mp->pgcookie, bp->pgno, bp->page);
420
421 bp->flags &= ~MPOOL_DIRTY;
422 return (RET_SUCCESS);
423 }
424
425 /*
426 * mpool_look
427 * Lookup a page in the cache.
428 */
429 static BKT *
mpool_look(MPOOL * mp,pgno_t pgno)430 mpool_look(MPOOL *mp, pgno_t pgno)
431 {
432 struct _hqh *head;
433 BKT *bp;
434
435 head = &mp->hqh[HASHKEY(pgno)];
436 TAILQ_FOREACH(bp, head, hq)
437 if ((bp->pgno == pgno) &&
438 ((bp->flags & MPOOL_INUSE) == MPOOL_INUSE)) {
439 #ifdef STATISTICS
440 ++mp->cachehit;
441 #endif
442 return (bp);
443 }
444 #ifdef STATISTICS
445 ++mp->cachemiss;
446 #endif
447 return (NULL);
448 }
449
450 #ifdef STATISTICS
451 /*
452 * mpool_stat
453 * Print out cache statistics.
454 */
455 void
mpool_stat(MPOOL * mp)456 mpool_stat(MPOOL *mp)
457 {
458 BKT *bp;
459 int cnt;
460 char *sep;
461
462 (void)fprintf(stderr, "%lu pages in the file\n", mp->npages);
463 (void)fprintf(stderr,
464 "page size %lu, cacheing %lu pages of %lu page max cache\n",
465 mp->pagesize, mp->curcache, mp->maxcache);
466 (void)fprintf(stderr, "%lu page puts, %lu page gets, %lu page new\n",
467 mp->pageput, mp->pageget, mp->pagenew);
468 (void)fprintf(stderr, "%lu page allocs, %lu page flushes\n",
469 mp->pagealloc, mp->pageflush);
470 if (mp->cachehit + mp->cachemiss)
471 (void)fprintf(stderr,
472 "%.0f%% cache hit rate (%lu hits, %lu misses)\n",
473 ((double)mp->cachehit / (mp->cachehit + mp->cachemiss))
474 * 100, mp->cachehit, mp->cachemiss);
475 (void)fprintf(stderr, "%lu page reads, %lu page writes\n",
476 mp->pageread, mp->pagewrite);
477
478 sep = "";
479 cnt = 0;
480 TAILQ_FOREACH(bp, &mp->lqh, q) {
481 (void)fprintf(stderr, "%s%d", sep, bp->pgno);
482 if (bp->flags & MPOOL_DIRTY)
483 (void)fprintf(stderr, "d");
484 if (bp->flags & MPOOL_PINNED)
485 (void)fprintf(stderr, "P");
486 if (++cnt == 10) {
487 sep = "\n";
488 cnt = 0;
489 } else
490 sep = ", ";
491
492 }
493 (void)fprintf(stderr, "\n");
494 }
495 #endif
496