hash_buf.c revision 1.11.14.3
1 /* $NetBSD: hash_buf.c,v 1.11.14.3 2009/04/30 18:26:15 bouyer Exp $ */ 2 3 /*- 4 * Copyright (c) 1990, 1993, 1994 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Margo Seltzer. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #if HAVE_NBTOOL_CONFIG_H 36 #include "nbtool_config.h" 37 #endif 38 39 #include <sys/cdefs.h> 40 #if defined(LIBC_SCCS) && !defined(lint) 41 #if 0 42 static char sccsid[] = "@(#)hash_buf.c 8.5 (Berkeley) 7/15/94"; 43 #else 44 __RCSID("$NetBSD: hash_buf.c,v 1.11.14.3 2009/04/30 18:26:15 bouyer Exp $"); 45 #endif 46 #endif /* LIBC_SCCS and not lint */ 47 48 /* 49 * PACKAGE: hash 50 * 51 * DESCRIPTION: 52 * Contains buffer management 53 * 54 * ROUTINES: 55 * External 56 * __buf_init 57 * __get_buf 58 * __buf_free 59 * __reclaim_buf 60 * Internal 61 * newbuf 62 */ 63 64 #include <sys/param.h> 65 66 #include <errno.h> 67 #include <stddef.h> 68 #include <stdio.h> 69 #include <stdlib.h> 70 #include <string.h> 71 72 #ifdef DEBUG 73 #include <assert.h> 74 #endif 75 76 #include <db.h> 77 #include "hash.h" 78 #include "page.h" 79 #include "extern.h" 80 81 static BUFHEAD *newbuf __P((HTAB *, u_int32_t, BUFHEAD *)); 82 83 /* Unlink B from its place in the lru */ 84 #define BUF_REMOVE(B) { \ 85 (B)->prev->next = (B)->next; \ 86 (B)->next->prev = (B)->prev; \ 87 } 88 89 /* Insert B after P */ 90 #define BUF_INSERT(B, P) { \ 91 (B)->next = (P)->next; \ 92 (B)->prev = (P); \ 93 (P)->next = (B); \ 94 (B)->next->prev = (B); \ 95 } 96 97 #define MRU hashp->bufhead.next 98 #define LRU hashp->bufhead.prev 99 100 #define MRU_INSERT(B) BUF_INSERT((B), &hashp->bufhead) 101 #define LRU_INSERT(B) BUF_INSERT((B), LRU) 102 103 /* 104 * We are looking for a buffer with address "addr". If prev_bp is NULL, then 105 * address is a bucket index. If prev_bp is not NULL, then it points to the 106 * page previous to an overflow page that we are trying to find. 107 * 108 * CAVEAT: The buffer header accessed via prev_bp's ovfl field may no longer 109 * be valid. Therefore, you must always verify that its address matches the 110 * address you are seeking. 111 */ 112 extern BUFHEAD * 113 __get_buf(hashp, addr, prev_bp, newpage) 114 HTAB *hashp; 115 u_int32_t addr; 116 BUFHEAD *prev_bp; 117 int newpage; /* If prev_bp set, indicates a new overflow page. */ 118 { 119 register BUFHEAD *bp; 120 register u_int32_t is_disk_mask; 121 register int is_disk, segment_ndx = 0; /* pacify gcc */ 122 SEGMENT segp = NULL; /* pacify gcc */ 123 124 is_disk = 0; 125 is_disk_mask = 0; 126 if (prev_bp) { 127 bp = prev_bp->ovfl; 128 if (!bp || (bp->addr != addr)) 129 bp = NULL; 130 if (!newpage) 131 is_disk = BUF_DISK; 132 } else { 133 /* Grab buffer out of directory */ 134 segment_ndx = addr & (hashp->SGSIZE - 1); 135 136 /* valid segment ensured by __call_hash() */ 137 segp = hashp->dir[addr >> hashp->SSHIFT]; 138 #ifdef DEBUG 139 assert(segp != NULL); 140 #endif 141 bp = PTROF(segp[segment_ndx]); 142 is_disk_mask = ISDISK(segp[segment_ndx]); 143 is_disk = is_disk_mask || !hashp->new_file; 144 } 145 146 if (!bp) { 147 bp = newbuf(hashp, addr, prev_bp); 148 if (!bp || 149 __get_page(hashp, bp->page, addr, !prev_bp, is_disk, 0)) 150 return (NULL); 151 if (!prev_bp) 152 segp[segment_ndx] = 153 (BUFHEAD *)(void *)((u_long)bp | is_disk_mask); 154 } else { 155 BUF_REMOVE(bp); 156 MRU_INSERT(bp); 157 } 158 return (bp); 159 } 160 161 /* 162 * We need a buffer for this page. Either allocate one, or evict a resident 163 * one (if we have as many buffers as we're allowed) and put this one in. 164 * 165 * If newbuf finds an error (returning NULL), it also sets errno. 166 */ 167 static BUFHEAD * 168 newbuf(hashp, addr, prev_bp) 169 HTAB *hashp; 170 u_int32_t addr; 171 BUFHEAD *prev_bp; 172 { 173 register BUFHEAD *bp; /* The buffer we're going to use */ 174 register BUFHEAD *xbp; /* Temp pointer */ 175 register BUFHEAD *next_xbp; 176 SEGMENT segp; 177 int segment_ndx; 178 u_int16_t oaddr, *shortp; 179 180 oaddr = 0; 181 bp = LRU; 182 /* 183 * If LRU buffer is pinned, the buffer pool is too small. We need to 184 * allocate more buffers. 185 */ 186 if (hashp->nbufs || (bp->flags & BUF_PIN)) { 187 /* Allocate a new one */ 188 if ((bp = (BUFHEAD *)calloc(1, sizeof(BUFHEAD))) == NULL) 189 return (NULL); 190 if ((bp->page = calloc(1, (size_t)hashp->BSIZE)) == NULL) { 191 free(bp); 192 return (NULL); 193 } 194 if (hashp->nbufs) 195 hashp->nbufs--; 196 } else { 197 /* Kick someone out */ 198 BUF_REMOVE(bp); 199 /* 200 * If this is an overflow page with addr 0, it's already been 201 * flushed back in an overflow chain and initialized. 202 */ 203 if ((bp->addr != 0) || (bp->flags & BUF_BUCKET)) { 204 /* 205 * Set oaddr before __put_page so that you get it 206 * before bytes are swapped. 207 */ 208 shortp = (u_int16_t *)(void *)bp->page; 209 if (shortp[0]) 210 oaddr = shortp[shortp[0] - 1]; 211 if ((bp->flags & BUF_MOD) && __put_page(hashp, bp->page, 212 bp->addr, (int)IS_BUCKET(bp->flags), 0)) 213 return (NULL); 214 /* 215 * Update the pointer to this page (i.e. invalidate it). 216 * 217 * If this is a new file (i.e. we created it at open 218 * time), make sure that we mark pages which have been 219 * written to disk so we retrieve them from disk later, 220 * rather than allocating new pages. 221 */ 222 if (IS_BUCKET(bp->flags)) { 223 segment_ndx = bp->addr & (hashp->SGSIZE - 1); 224 segp = hashp->dir[bp->addr >> hashp->SSHIFT]; 225 #ifdef DEBUG 226 assert(segp != NULL); 227 #endif 228 229 if (hashp->new_file && 230 ((bp->flags & BUF_MOD) || 231 ISDISK(segp[segment_ndx]))) 232 segp[segment_ndx] = (BUFHEAD *)BUF_DISK; 233 else 234 segp[segment_ndx] = NULL; 235 } 236 /* 237 * Since overflow pages can only be access by means of 238 * their bucket, free overflow pages associated with 239 * this bucket. 240 */ 241 for (xbp = bp; xbp->ovfl;) { 242 next_xbp = xbp->ovfl; 243 xbp->ovfl = 0; 244 xbp = next_xbp; 245 246 /* Check that ovfl pointer is up date. */ 247 if (IS_BUCKET(xbp->flags) || 248 (oaddr != xbp->addr)) 249 break; 250 251 shortp = (u_int16_t *)(void *)xbp->page; 252 if (shortp[0]) 253 /* set before __put_page */ 254 oaddr = shortp[shortp[0] - 1]; 255 if ((xbp->flags & BUF_MOD) && __put_page(hashp, 256 xbp->page, xbp->addr, 0, 0)) 257 return (NULL); 258 xbp->addr = 0; 259 xbp->flags = 0; 260 BUF_REMOVE(xbp); 261 LRU_INSERT(xbp); 262 } 263 } 264 } 265 266 /* Now assign this buffer */ 267 bp->addr = addr; 268 #ifdef DEBUG1 269 (void)fprintf(stderr, "NEWBUF1: %d->ovfl was %d is now %d\n", 270 bp->addr, (bp->ovfl ? bp->ovfl->addr : 0), 0); 271 #endif 272 bp->ovfl = NULL; 273 if (prev_bp) { 274 /* 275 * If prev_bp is set, this is an overflow page, hook it in to 276 * the buffer overflow links. 277 */ 278 #ifdef DEBUG1 279 (void)fprintf(stderr, "NEWBUF2: %d->ovfl was %d is now %d\n", 280 prev_bp->addr, (prev_bp->ovfl ? bp->ovfl->addr : 0), 281 (bp ? bp->addr : 0)); 282 #endif 283 prev_bp->ovfl = bp; 284 bp->flags = 0; 285 } else 286 bp->flags = BUF_BUCKET; 287 MRU_INSERT(bp); 288 return (bp); 289 } 290 291 extern void 292 __buf_init(hashp, nbytes) 293 HTAB *hashp; 294 u_int nbytes; 295 { 296 BUFHEAD *bfp; 297 int npages; 298 299 bfp = &(hashp->bufhead); 300 npages = (unsigned int)(nbytes + hashp->BSIZE - 1) >> hashp->BSHIFT; 301 npages = MAX(npages, MIN_BUFFERS); 302 303 hashp->nbufs = npages; 304 bfp->next = bfp; 305 bfp->prev = bfp; 306 /* 307 * This space is calloc'd so these are already null. 308 * 309 * bfp->ovfl = NULL; 310 * bfp->flags = 0; 311 * bfp->page = NULL; 312 * bfp->addr = 0; 313 */ 314 } 315 316 extern int 317 __buf_free(hashp, do_free, to_disk) 318 HTAB *hashp; 319 int do_free, to_disk; 320 { 321 BUFHEAD *bp; 322 323 /* Need to make sure that buffer manager has been initialized */ 324 if (!LRU) 325 return (0); 326 for (bp = LRU; bp != &hashp->bufhead;) { 327 /* Check that the buffer is valid */ 328 if (bp->addr || IS_BUCKET(bp->flags)) { 329 if (to_disk && (bp->flags & BUF_MOD) && 330 __put_page(hashp, bp->page, 331 bp->addr, IS_BUCKET(bp->flags), 0)) 332 return (-1); 333 } 334 /* Check if we are freeing stuff */ 335 if (do_free) { 336 if (bp->page) { 337 (void)memset(bp->page, 0, (size_t)hashp->BSIZE); 338 free(bp->page); 339 } 340 BUF_REMOVE(bp); 341 free(bp); 342 bp = LRU; 343 } else 344 bp = bp->prev; 345 } 346 return (0); 347 } 348 349 extern void 350 __reclaim_buf(hashp, bp) 351 HTAB *hashp; 352 BUFHEAD *bp; 353 { 354 bp->ovfl = 0; 355 bp->addr = 0; 356 bp->flags = 0; 357 BUF_REMOVE(bp); 358 LRU_INSERT(bp); 359 } 360
Indexes created Fri Oct 03 14:09:59 GMT 2025