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. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * @(#)mpool.c 8.7 (Berkeley) 11/2/95
30 * $FreeBSD: head/lib/libc/db/mpool/mpool.c 194804 2009-06-24 01:15:10Z delphij $
31 */
32
33 #include "namespace.h"
34 #include <sys/param.h>
35 #include <sys/queue.h>
36 #include <sys/stat.h>
37
38 #include <errno.h>
39 #include <stdio.h>
40 #include <stdlib.h>
41 #include <string.h>
42 #include <unistd.h>
43 #include "un-namespace.h"
44
45 #include <db.h>
46
47 #define __MPOOLINTERFACE_PRIVATE
48 #include <mpool.h>
49
50 static BKT *mpool_bkt(MPOOL *);
51 static BKT *mpool_look(MPOOL *, pgno_t);
52 static int mpool_write(MPOOL *, BKT *);
53
54 /*
55 * mpool_open --
56 * Initialize a memory pool.
57 */
58 /* ARGSUSED */
59 MPOOL *
mpool_open(__unused void * key,int fd,pgno_t pagesize,pgno_t maxcache)60 mpool_open(__unused void *key, int fd, pgno_t pagesize, pgno_t maxcache)
61 {
62 struct stat sb;
63 MPOOL *mp;
64 int entry;
65
66 /*
67 * Get information about the file.
68 *
69 * XXX
70 * We don't currently handle pipes, although we should.
71 */
72 if (_fstat(fd, &sb))
73 return (NULL);
74 if (!S_ISREG(sb.st_mode)) {
75 errno = ESPIPE;
76 return (NULL);
77 }
78
79 /* Allocate and initialize the MPOOL cookie. */
80 if ((mp = (MPOOL *)calloc(1, sizeof(MPOOL))) == NULL)
81 return (NULL);
82 TAILQ_INIT(&mp->lqh);
83 for (entry = 0; entry < HASHSIZE; ++entry)
84 TAILQ_INIT(&mp->hqh[entry]);
85 mp->maxcache = maxcache;
86 mp->npages = sb.st_size / pagesize;
87 mp->pagesize = pagesize;
88 mp->fd = fd;
89 return (mp);
90 }
91
92 /*
93 * mpool_filter --
94 * Initialize input/output filters.
95 */
96 void
mpool_filter(MPOOL * mp,void (* pgin)(void *,pgno_t,void *),void (* pgout)(void *,pgno_t,void *),void * pgcookie)97 mpool_filter(MPOOL *mp, void (*pgin)(void *, pgno_t, void *),
98 void (*pgout) (void *, pgno_t, void *), void *pgcookie)
99 {
100 mp->pgin = pgin;
101 mp->pgout = pgout;
102 mp->pgcookie = pgcookie;
103 }
104
105 /*
106 * mpool_new --
107 * Get a new page of memory.
108 */
109 void *
mpool_new(MPOOL * mp,pgno_t * pgnoaddr,unsigned int flags)110 mpool_new(MPOOL *mp, pgno_t *pgnoaddr, unsigned int flags)
111 {
112 struct _hqh *head;
113 BKT *bp;
114
115 if (mp->npages == MAX_PAGE_NUMBER) {
116 fprintf(stderr, "mpool_new: page allocation overflow.\n");
117 abort();
118 }
119 #ifdef STATISTICS
120 ++mp->pagenew;
121 #endif
122 /*
123 * Get a BKT from the cache. Assign a new page number, attach
124 * it to the head of the hash chain, the tail of the lru chain,
125 * and return.
126 */
127 if ((bp = mpool_bkt(mp)) == NULL)
128 return (NULL);
129 if (flags == MPOOL_PAGE_REQUEST) {
130 mp->npages++;
131 bp->pgno = *pgnoaddr;
132 } else
133 bp->pgno = *pgnoaddr = mp->npages++;
134
135 bp->flags = MPOOL_PINNED | MPOOL_INUSE;
136
137 head = &mp->hqh[HASHKEY(bp->pgno)];
138 TAILQ_INSERT_HEAD(head, bp, hq);
139 TAILQ_INSERT_TAIL(&mp->lqh, bp, q);
140 return (bp->page);
141 }
142
143 int
mpool_delete(MPOOL * mp,void * page)144 mpool_delete(MPOOL *mp, void *page)
145 {
146 struct _hqh *head;
147 BKT *bp;
148
149 bp = (BKT *)((char *)page - sizeof(BKT));
150
151 #ifdef DEBUG
152 if (!(bp->flags & MPOOL_PINNED)) {
153 fprintf(stderr,
154 "mpool_delete: page %d not pinned\n", bp->pgno);
155 abort();
156 }
157 #endif
158
159 /* Remove from the hash and lru queues. */
160 head = &mp->hqh[HASHKEY(bp->pgno)];
161 TAILQ_REMOVE(head, bp, hq);
162 TAILQ_REMOVE(&mp->lqh, bp, q);
163
164 free(bp);
165 mp->curcache--;
166 return (RET_SUCCESS);
167 }
168
169 /*
170 * mpool_get
171 * Get a page.
172 */
173 /* ARGSUSED */
174 void *
mpool_get(MPOOL * mp,pgno_t pgno,unsigned int flags)175 mpool_get(MPOOL *mp, pgno_t pgno,
176 unsigned int flags) /* XXX not used? */
177 {
178 struct _hqh *head;
179 BKT *bp;
180 off_t off;
181 int nr;
182
183 #ifdef STATISTICS
184 ++mp->pageget;
185 #endif
186
187 /* Check for a page that is cached. */
188 if ((bp = mpool_look(mp, pgno)) != NULL) {
189 #ifdef DEBUG
190 if (!(flags & MPOOL_IGNOREPIN) && bp->flags & MPOOL_PINNED) {
191 fprintf(stderr,
192 "mpool_get: page %d already pinned\n", bp->pgno);
193 abort();
194 }
195 #endif
196 /*
197 * Move the page to the head of the hash chain and the tail
198 * of the lru chain.
199 */
200 head = &mp->hqh[HASHKEY(bp->pgno)];
201 TAILQ_REMOVE(head, bp, hq);
202 TAILQ_INSERT_HEAD(head, bp, hq);
203 TAILQ_REMOVE(&mp->lqh, bp, q);
204 TAILQ_INSERT_TAIL(&mp->lqh, bp, q);
205
206 /* Return a pinned page. */
207 bp->flags |= MPOOL_PINNED;
208 return (bp->page);
209 }
210
211 /* Get a page from the cache. */
212 if ((bp = mpool_bkt(mp)) == NULL)
213 return (NULL);
214
215 /* Read in the contents. */
216 off = mp->pagesize * pgno;
217 if ((nr = pread(mp->fd, bp->page, mp->pagesize, off)) != (ssize_t)mp->pagesize) {
218 switch (nr) {
219 case -1:
220 /* errno is set for us by pread(). */
221 free(bp);
222 mp->curcache--;
223 return (NULL);
224 case 0:
225 /*
226 * A zero-length read means you need to create a
227 * new page.
228 */
229 memset(bp->page, 0, mp->pagesize);
230 break;
231 default:
232 /* A partial read is definitely bad. */
233 free(bp);
234 mp->curcache--;
235 errno = EINVAL;
236 return (NULL);
237 }
238 }
239 #ifdef STATISTICS
240 ++mp->pageread;
241 #endif
242
243 /* Set the page number, pin the page. */
244 bp->pgno = pgno;
245 if (!(flags & MPOOL_IGNOREPIN))
246 bp->flags = MPOOL_PINNED;
247 bp->flags |= MPOOL_INUSE;
248
249 /*
250 * Add the page to the head of the hash chain and the tail
251 * of the lru chain.
252 */
253 head = &mp->hqh[HASHKEY(bp->pgno)];
254 TAILQ_INSERT_HEAD(head, bp, hq);
255 TAILQ_INSERT_TAIL(&mp->lqh, bp, q);
256
257 /* Run through the user's filter. */
258 if (mp->pgin != NULL)
259 (mp->pgin)(mp->pgcookie, bp->pgno, bp->page);
260
261 return (bp->page);
262 }
263
264 /*
265 * mpool_put
266 * Return a page.
267 */
268 /* ARGSUSED */
269 int
mpool_put(MPOOL * mp,void * page,unsigned int flags)270 mpool_put(MPOOL *mp, void *page, unsigned int flags)
271 {
272 BKT *bp;
273
274 #ifdef STATISTICS
275 ++mp->pageput;
276 #endif
277 bp = (BKT *)((char *)page - sizeof(BKT));
278 #ifdef DEBUG
279 if (!(bp->flags & MPOOL_PINNED)) {
280 fprintf(stderr,
281 "mpool_put: page %d not pinned\n", bp->pgno);
282 abort();
283 }
284 #endif
285 bp->flags &= ~MPOOL_PINNED;
286 if (flags & MPOOL_DIRTY)
287 bp->flags |= flags & MPOOL_DIRTY;
288 return (RET_SUCCESS);
289 }
290
291 /*
292 * mpool_close
293 * Close the buffer pool.
294 */
295 int
mpool_close(MPOOL * mp)296 mpool_close(MPOOL *mp)
297 {
298 BKT *bp;
299
300 /* Free up any space allocated to the lru pages. */
301 while (!TAILQ_EMPTY(&mp->lqh)) {
302 bp = TAILQ_FIRST(&mp->lqh);
303 TAILQ_REMOVE(&mp->lqh, bp, q);
304 free(bp);
305 }
306
307 /* Free the MPOOL cookie. */
308 free(mp);
309 return (RET_SUCCESS);
310 }
311
312 /*
313 * mpool_sync
314 * Sync the pool to disk.
315 */
316 int
mpool_sync(MPOOL * mp)317 mpool_sync(MPOOL *mp)
318 {
319 BKT *bp;
320
321 /* Walk the lru chain, flushing any dirty pages to disk. */
322 TAILQ_FOREACH(bp, &mp->lqh, q)
323 if (bp->flags & MPOOL_DIRTY &&
324 mpool_write(mp, bp) == RET_ERROR)
325 return (RET_ERROR);
326
327 /* Sync the file descriptor. */
328 return (_fsync(mp->fd) ? RET_ERROR : RET_SUCCESS);
329 }
330
331 /*
332 * mpool_bkt
333 * Get a page from the cache (or create one).
334 */
335 static BKT *
mpool_bkt(MPOOL * mp)336 mpool_bkt(MPOOL *mp)
337 {
338 struct _hqh *head;
339 BKT *bp;
340
341 /* If under the max cached, always create a new page. */
342 if (mp->curcache < mp->maxcache)
343 goto new;
344
345 /*
346 * If the cache is max'd out, walk the lru list for a buffer we
347 * can flush. If we find one, write it (if necessary) and take it
348 * off any lists. If we don't find anything we grow the cache anyway.
349 * The cache never shrinks.
350 */
351 TAILQ_FOREACH(bp, &mp->lqh, q)
352 if (!(bp->flags & MPOOL_PINNED)) {
353 /* Flush if dirty. */
354 if (bp->flags & MPOOL_DIRTY &&
355 mpool_write(mp, bp) == RET_ERROR)
356 return (NULL);
357 #ifdef STATISTICS
358 ++mp->pageflush;
359 #endif
360 /* Remove from the hash and lru queues. */
361 head = &mp->hqh[HASHKEY(bp->pgno)];
362 TAILQ_REMOVE(head, bp, hq);
363 TAILQ_REMOVE(&mp->lqh, bp, q);
364 #ifdef DEBUG
365 { void *spage;
366 spage = bp->page;
367 memset(bp, 0xff, sizeof(BKT) + mp->pagesize);
368 bp->page = spage;
369 }
370 #endif
371 bp->flags = 0;
372 return (bp);
373 }
374
375 new: if ((bp = (BKT *)calloc(1, sizeof(BKT) + mp->pagesize)) == NULL)
376 return (NULL);
377 #ifdef STATISTICS
378 ++mp->pagealloc;
379 #endif
380 bp->page = (char *)bp + sizeof(BKT);
381 bp->flags = 0;
382 ++mp->curcache;
383 return (bp);
384 }
385
386 /*
387 * mpool_write
388 * Write a page to disk.
389 */
390 static int
mpool_write(MPOOL * mp,BKT * bp)391 mpool_write(MPOOL *mp, BKT *bp)
392 {
393 off_t off;
394
395 #ifdef STATISTICS
396 ++mp->pagewrite;
397 #endif
398
399 /* Run through the user's filter. */
400 if (mp->pgout)
401 (mp->pgout)(mp->pgcookie, bp->pgno, bp->page);
402
403 off = mp->pagesize * bp->pgno;
404 if (pwrite(mp->fd, bp->page, mp->pagesize, off) != (ssize_t)mp->pagesize)
405 return (RET_ERROR);
406
407 /*
408 * Re-run through the input filter since this page may soon be
409 * accessed via the cache, and whatever the user's output filter
410 * did may screw things up if we don't let the input filter
411 * restore the in-core copy.
412 */
413 if (mp->pgin)
414 (mp->pgin)(mp->pgcookie, bp->pgno, bp->page);
415
416 bp->flags &= ~MPOOL_DIRTY;
417 return (RET_SUCCESS);
418 }
419
420 /*
421 * mpool_look
422 * Lookup a page in the cache.
423 */
424 static BKT *
mpool_look(MPOOL * mp,pgno_t pgno)425 mpool_look(MPOOL *mp, pgno_t pgno)
426 {
427 struct _hqh *head;
428 BKT *bp;
429
430 head = &mp->hqh[HASHKEY(pgno)];
431 TAILQ_FOREACH(bp, head, hq)
432 if ((bp->pgno == pgno) &&
433 ((bp->flags & MPOOL_INUSE) == MPOOL_INUSE)) {
434 #ifdef STATISTICS
435 ++mp->cachehit;
436 #endif
437 return (bp);
438 }
439 #ifdef STATISTICS
440 ++mp->cachemiss;
441 #endif
442 return (NULL);
443 }
444
445 #ifdef STATISTICS
446 /*
447 * mpool_stat
448 * Print out cache statistics.
449 */
450 void
mpool_stat(MPOOL * mp)451 mpool_stat(MPOOL *mp)
452 {
453 BKT *bp;
454 int cnt;
455 char *sep;
456
457 fprintf(stderr, "%lu pages in the file\n", mp->npages);
458 fprintf(stderr,
459 "page size %lu, caching %lu pages of %lu page max cache\n",
460 mp->pagesize, mp->curcache, mp->maxcache);
461 fprintf(stderr, "%lu page puts, %lu page gets, %lu page new\n",
462 mp->pageput, mp->pageget, mp->pagenew);
463 fprintf(stderr, "%lu page allocs, %lu page flushes\n",
464 mp->pagealloc, mp->pageflush);
465 if (mp->cachehit + mp->cachemiss)
466 fprintf(stderr,
467 "%.0f%% cache hit rate (%lu hits, %lu misses)\n",
468 ((double)mp->cachehit / (mp->cachehit + mp->cachemiss))
469 * 100, mp->cachehit, mp->cachemiss);
470 fprintf(stderr, "%lu page reads, %lu page writes\n",
471 mp->pageread, mp->pagewrite);
472
473 sep = "";
474 cnt = 0;
475 TAILQ_FOREACH(bp, &mp->lqh, q) {
476 fprintf(stderr, "%s%d", sep, bp->pgno);
477 if (bp->flags & MPOOL_DIRTY)
478 fprintf(stderr, "d");
479 if (bp->flags & MPOOL_PINNED)
480 fprintf(stderr, "P");
481 if (++cnt == 10) {
482 sep = "\n";
483 cnt = 0;
484 } else
485 sep = ", ";
486 }
487 fprintf(stderr, "\n");
488 }
489 #endif
490