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 * 4. 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
30#if defined(LIBC_SCCS) && !defined(lint)
31static char sccsid[] = "@(#)mpool.c	8.7 (Berkeley) 11/2/95";
32#endif /* LIBC_SCCS and not lint */
33#include <sys/cdefs.h>
34__FBSDID("$FreeBSD$");
35
36#include "namespace.h"
37#include <sys/param.h>
38#include <sys/queue.h>
39#include <sys/stat.h>
40
41#include <errno.h>
42#include <stdio.h>
43#include <stdlib.h>
44#include <string.h>
45#include <unistd.h>
46#include "un-namespace.h"
47
48#include <db.h>
49
50#define	__MPOOLINTERFACE_PRIVATE
51#include <mpool.h>
52
53static BKT *mpool_bkt(MPOOL *);
54static BKT *mpool_look(MPOOL *, pgno_t);
55static int  mpool_write(MPOOL *, BKT *);
56
57/*
58 * mpool_open --
59 *	Initialize a memory pool.
60 */
61/* ARGSUSED */
62MPOOL *
63mpool_open(void *key, int fd, pgno_t pagesize, pgno_t maxcache)
64{
65	struct stat sb;
66	MPOOL *mp;
67	int entry;
68
69	/*
70	 * Get information about the file.
71	 *
72	 * XXX
73	 * We don't currently handle pipes, although we should.
74	 */
75	if (_fstat(fd, &sb))
76		return (NULL);
77	if (!S_ISREG(sb.st_mode)) {
78		errno = ESPIPE;
79		return (NULL);
80	}
81
82	/* Allocate and initialize the MPOOL cookie. */
83	if ((mp = (MPOOL *)calloc(1, sizeof(MPOOL))) == NULL)
84		return (NULL);
85	TAILQ_INIT(&mp->lqh);
86	for (entry = 0; entry < HASHSIZE; ++entry)
87		TAILQ_INIT(&mp->hqh[entry]);
88	mp->maxcache = maxcache;
89	mp->npages = sb.st_size / pagesize;
90	mp->pagesize = pagesize;
91	mp->fd = fd;
92	return (mp);
93}
94
95/*
96 * mpool_filter --
97 *	Initialize input/output filters.
98 */
99void
100mpool_filter(MPOOL *mp, void (*pgin) (void *, pgno_t, void *),
101    void (*pgout) (void *, pgno_t, void *), void *pgcookie)
102{
103	mp->pgin = pgin;
104	mp->pgout = pgout;
105	mp->pgcookie = pgcookie;
106}
107
108/*
109 * mpool_new --
110 *	Get a new page of memory.
111 */
112void *
113mpool_new(MPOOL *mp, pgno_t *pgnoaddr, u_int flags)
114{
115	struct _hqh *head;
116	BKT *bp;
117
118	if (mp->npages == MAX_PAGE_NUMBER) {
119		(void)fprintf(stderr, "mpool_new: page allocation overflow.\n");
120		abort();
121	}
122#ifdef STATISTICS
123	++mp->pagenew;
124#endif
125	/*
126	 * Get a BKT from the cache.  Assign a new page number, attach
127	 * it to the head of the hash chain, the tail of the lru chain,
128	 * and return.
129	 */
130	if ((bp = mpool_bkt(mp)) == NULL)
131		return (NULL);
132	if (flags == MPOOL_PAGE_REQUEST) {
133		mp->npages++;
134		bp->pgno = *pgnoaddr;
135	} else
136		bp->pgno = *pgnoaddr = mp->npages++;
137
138	bp->flags = MPOOL_PINNED | MPOOL_INUSE;
139
140	head = &mp->hqh[HASHKEY(bp->pgno)];
141	TAILQ_INSERT_HEAD(head, bp, hq);
142	TAILQ_INSERT_TAIL(&mp->lqh, bp, q);
143	return (bp->page);
144}
145
146int
147mpool_delete(MPOOL *mp, void *page)
148{
149	struct _hqh *head;
150	BKT *bp;
151
152	bp = (BKT *)((char *)page - sizeof(BKT));
153
154#ifdef DEBUG
155	if (!(bp->flags & MPOOL_PINNED)) {
156		(void)fprintf(stderr,
157		    "mpool_delete: page %d not pinned\n", bp->pgno);
158		abort();
159	}
160#endif
161
162	/* Remove from the hash and lru queues. */
163	head = &mp->hqh[HASHKEY(bp->pgno)];
164	TAILQ_REMOVE(head, bp, hq);
165	TAILQ_REMOVE(&mp->lqh, bp, q);
166
167	free(bp);
168	mp->curcache--;
169	return (RET_SUCCESS);
170}
171
172/*
173 * mpool_get
174 *	Get a page.
175 */
176/* ARGSUSED */
177void *
178mpool_get(MPOOL *mp, pgno_t pgno,
179    u_int flags)		/* XXX not used? */
180{
181	struct _hqh *head;
182	BKT *bp;
183	off_t off;
184	int nr;
185
186#ifdef STATISTICS
187	++mp->pageget;
188#endif
189
190	/* Check for a page that is cached. */
191	if ((bp = mpool_look(mp, pgno)) != NULL) {
192#ifdef DEBUG
193		if (!(flags & MPOOL_IGNOREPIN) && bp->flags & MPOOL_PINNED) {
194			(void)fprintf(stderr,
195			    "mpool_get: page %d already pinned\n", bp->pgno);
196			abort();
197		}
198#endif
199		/*
200		 * Move the page to the head of the hash chain and the tail
201		 * of the lru chain.
202		 */
203		head = &mp->hqh[HASHKEY(bp->pgno)];
204		TAILQ_REMOVE(head, bp, hq);
205		TAILQ_INSERT_HEAD(head, bp, hq);
206		TAILQ_REMOVE(&mp->lqh, bp, q);
207		TAILQ_INSERT_TAIL(&mp->lqh, bp, q);
208
209		/* Return a pinned page. */
210		bp->flags |= MPOOL_PINNED;
211		return (bp->page);
212	}
213
214	/* Get a page from the cache. */
215	if ((bp = mpool_bkt(mp)) == NULL)
216		return (NULL);
217
218	/* Read in the contents. */
219	off = mp->pagesize * pgno;
220	if ((nr = pread(mp->fd, bp->page, mp->pagesize, off)) != (ssize_t)mp->pagesize) {
221		switch (nr) {
222		case -1:
223			/* errno is set for us by pread(). */
224			free(bp);
225			mp->curcache--;
226			return (NULL);
227		case 0:
228			/*
229			 * A zero-length read means you need to create a
230			 * new page.
231			 */
232			memset(bp->page, 0, mp->pagesize);
233			break;
234		default:
235			/* A partial read is definitely bad. */
236			free(bp);
237			mp->curcache--;
238			errno = EINVAL;
239			return (NULL);
240		}
241	}
242#ifdef STATISTICS
243	++mp->pageread;
244#endif
245
246	/* Set the page number, pin the page. */
247	bp->pgno = pgno;
248	if (!(flags & MPOOL_IGNOREPIN))
249		bp->flags = MPOOL_PINNED;
250	bp->flags |= MPOOL_INUSE;
251
252	/*
253	 * Add the page to the head of the hash chain and the tail
254	 * of the lru chain.
255	 */
256	head = &mp->hqh[HASHKEY(bp->pgno)];
257	TAILQ_INSERT_HEAD(head, bp, hq);
258	TAILQ_INSERT_TAIL(&mp->lqh, bp, q);
259
260	/* Run through the user's filter. */
261	if (mp->pgin != NULL)
262		(mp->pgin)(mp->pgcookie, bp->pgno, bp->page);
263
264	return (bp->page);
265}
266
267/*
268 * mpool_put
269 *	Return a page.
270 */
271/* ARGSUSED */
272int
273mpool_put(MPOOL *mp, void *page, u_int flags)
274{
275	BKT *bp;
276
277#ifdef STATISTICS
278	++mp->pageput;
279#endif
280	bp = (BKT *)((char *)page - sizeof(BKT));
281#ifdef DEBUG
282	if (!(bp->flags & MPOOL_PINNED)) {
283		(void)fprintf(stderr,
284		    "mpool_put: page %d not pinned\n", bp->pgno);
285		abort();
286	}
287#endif
288	bp->flags &= ~MPOOL_PINNED;
289	if (flags & MPOOL_DIRTY)
290		bp->flags |= flags & MPOOL_DIRTY;
291	return (RET_SUCCESS);
292}
293
294/*
295 * mpool_close
296 *	Close the buffer pool.
297 */
298int
299mpool_close(MPOOL *mp)
300{
301	BKT *bp;
302
303	/* Free up any space allocated to the lru pages. */
304	while (!TAILQ_EMPTY(&mp->lqh)) {
305		bp = TAILQ_FIRST(&mp->lqh);
306		TAILQ_REMOVE(&mp->lqh, bp, q);
307		free(bp);
308	}
309
310	/* Free the MPOOL cookie. */
311	free(mp);
312	return (RET_SUCCESS);
313}
314
315/*
316 * mpool_sync
317 *	Sync the pool to disk.
318 */
319int
320mpool_sync(MPOOL *mp)
321{
322	BKT *bp;
323
324	/* Walk the lru chain, flushing any dirty pages to disk. */
325	TAILQ_FOREACH(bp, &mp->lqh, q)
326		if (bp->flags & MPOOL_DIRTY &&
327		    mpool_write(mp, bp) == RET_ERROR)
328			return (RET_ERROR);
329
330	/* Sync the file descriptor. */
331	return (_fsync(mp->fd) ? RET_ERROR : RET_SUCCESS);
332}
333
334/*
335 * mpool_bkt
336 *	Get a page from the cache (or create one).
337 */
338static BKT *
339mpool_bkt(MPOOL *mp)
340{
341	struct _hqh *head;
342	BKT *bp;
343
344	/* If under the max cached, always create a new page. */
345	if (mp->curcache < mp->maxcache)
346		goto new;
347
348	/*
349	 * If the cache is max'd out, walk the lru list for a buffer we
350	 * can flush.  If we find one, write it (if necessary) and take it
351	 * off any lists.  If we don't find anything we grow the cache anyway.
352	 * The cache never shrinks.
353	 */
354	TAILQ_FOREACH(bp, &mp->lqh, q)
355		if (!(bp->flags & MPOOL_PINNED)) {
356			/* Flush if dirty. */
357			if (bp->flags & MPOOL_DIRTY &&
358			    mpool_write(mp, bp) == RET_ERROR)
359				return (NULL);
360#ifdef STATISTICS
361			++mp->pageflush;
362#endif
363			/* Remove from the hash and lru queues. */
364			head = &mp->hqh[HASHKEY(bp->pgno)];
365			TAILQ_REMOVE(head, bp, hq);
366			TAILQ_REMOVE(&mp->lqh, bp, q);
367#ifdef DEBUG
368			{ void *spage;
369				spage = bp->page;
370				memset(bp, 0xff, sizeof(BKT) + mp->pagesize);
371				bp->page = spage;
372			}
373#endif
374			bp->flags = 0;
375			return (bp);
376		}
377
378new:	if ((bp = (BKT *)calloc(1, sizeof(BKT) + mp->pagesize)) == NULL)
379		return (NULL);
380#ifdef STATISTICS
381	++mp->pagealloc;
382#endif
383	bp->page = (char *)bp + sizeof(BKT);
384	bp->flags = 0;
385	++mp->curcache;
386	return (bp);
387}
388
389/*
390 * mpool_write
391 *	Write a page to disk.
392 */
393static int
394mpool_write(MPOOL *mp, BKT *bp)
395{
396	off_t off;
397
398#ifdef STATISTICS
399	++mp->pagewrite;
400#endif
401
402	/* Run through the user's filter. */
403	if (mp->pgout)
404		(mp->pgout)(mp->pgcookie, bp->pgno, bp->page);
405
406	off = mp->pagesize * bp->pgno;
407	if (pwrite(mp->fd, bp->page, mp->pagesize, off) != (ssize_t)mp->pagesize)
408		return (RET_ERROR);
409
410	/*
411	 * Re-run through the input filter since this page may soon be
412	 * accessed via the cache, and whatever the user's output filter
413	 * did may screw things up if we don't let the input filter
414	 * restore the in-core copy.
415	 */
416	if (mp->pgin)
417		(mp->pgin)(mp->pgcookie, bp->pgno, bp->page);
418
419	bp->flags &= ~MPOOL_DIRTY;
420	return (RET_SUCCESS);
421}
422
423/*
424 * mpool_look
425 *	Lookup a page in the cache.
426 */
427static BKT *
428mpool_look(MPOOL *mp, pgno_t pgno)
429{
430	struct _hqh *head;
431	BKT *bp;
432
433	head = &mp->hqh[HASHKEY(pgno)];
434	TAILQ_FOREACH(bp, head, hq)
435		if ((bp->pgno == pgno) &&
436			((bp->flags & MPOOL_INUSE) == MPOOL_INUSE)) {
437#ifdef STATISTICS
438			++mp->cachehit;
439#endif
440			return (bp);
441		}
442#ifdef STATISTICS
443	++mp->cachemiss;
444#endif
445	return (NULL);
446}
447
448#ifdef STATISTICS
449/*
450 * mpool_stat
451 *	Print out cache statistics.
452 */
453void
454mpool_stat(MPOOL *mp)
455{
456	BKT *bp;
457	int cnt;
458	char *sep;
459
460	(void)fprintf(stderr, "%lu pages in the file\n", mp->npages);
461	(void)fprintf(stderr,
462	    "page size %lu, cacheing %lu pages of %lu page max cache\n",
463	    mp->pagesize, mp->curcache, mp->maxcache);
464	(void)fprintf(stderr, "%lu page puts, %lu page gets, %lu page new\n",
465	    mp->pageput, mp->pageget, mp->pagenew);
466	(void)fprintf(stderr, "%lu page allocs, %lu page flushes\n",
467	    mp->pagealloc, mp->pageflush);
468	if (mp->cachehit + mp->cachemiss)
469		(void)fprintf(stderr,
470		    "%.0f%% cache hit rate (%lu hits, %lu misses)\n",
471		    ((double)mp->cachehit / (mp->cachehit + mp->cachemiss))
472		    * 100, mp->cachehit, mp->cachemiss);
473	(void)fprintf(stderr, "%lu page reads, %lu page writes\n",
474	    mp->pageread, mp->pagewrite);
475
476	sep = "";
477	cnt = 0;
478	TAILQ_FOREACH(bp, &mp->lqh, q) {
479		(void)fprintf(stderr, "%s%d", sep, bp->pgno);
480		if (bp->flags & MPOOL_DIRTY)
481			(void)fprintf(stderr, "d");
482		if (bp->flags & MPOOL_PINNED)
483			(void)fprintf(stderr, "P");
484		if (++cnt == 10) {
485			sep = "\n";
486			cnt = 0;
487		} else
488			sep = ", ";
489
490	}
491	(void)fprintf(stderr, "\n");
492}
493#endif
494