1 /* $NetBSD: hash_buf.c,v 1.14 2008/09/10 17:52:35 joerg 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 __RCSID("$NetBSD: hash_buf.c,v 1.14 2008/09/10 17:52:35 joerg Exp $"); 41 42 /* 43 * PACKAGE: hash 44 * 45 * DESCRIPTION: 46 * Contains buffer management 47 * 48 * ROUTINES: 49 * External 50 * __buf_init 51 * __get_buf 52 * __buf_free 53 * __reclaim_buf 54 * Internal 55 * newbuf 56 */ 57 58 #include <sys/param.h> 59 60 #include <errno.h> 61 #include <stddef.h> 62 #include <stdio.h> 63 #include <stdlib.h> 64 #include <assert.h> 65 66 #include <db.h> 67 #include "hash.h" 68 #include "page.h" 69 #include "extern.h" 70 71 static BUFHEAD *newbuf(HTAB *, uint32_t, BUFHEAD *); 72 73 /* Unlink B from its place in the lru */ 74 #define BUF_REMOVE(B) { \ 75 (B)->prev->next = (B)->next; \ 76 (B)->next->prev = (B)->prev; \ 77 } 78 79 /* Insert B after P */ 80 #define BUF_INSERT(B, P) { \ 81 (B)->next = (P)->next; \ 82 (B)->prev = (P); \ 83 (P)->next = (B); \ 84 (B)->next->prev = (B); \ 85 } 86 87 #define MRU hashp->bufhead.next 88 #define LRU hashp->bufhead.prev 89 90 #define MRU_INSERT(B) BUF_INSERT((B), &hashp->bufhead) 91 #define LRU_INSERT(B) BUF_INSERT((B), LRU) 92 93 /* 94 * We are looking for a buffer with address "addr". If prev_bp is NULL, then 95 * address is a bucket index. If prev_bp is not NULL, then it points to the 96 * page previous to an overflow page that we are trying to find. 97 * 98 * CAVEAT: The buffer header accessed via prev_bp's ovfl field may no longer 99 * be valid. Therefore, you must always verify that its address matches the 100 * address you are seeking. 101 */ 102 BUFHEAD * 103 __get_buf( 104 HTAB *hashp, 105 uint32_t addr, 106 BUFHEAD *prev_bp, 107 int newpage /* If prev_bp set, indicates a new overflow page. */ 108 ) 109 { 110 BUFHEAD *bp; 111 uint32_t is_disk_mask; 112 int is_disk, segment_ndx = 0; /* pacify gcc */ 113 SEGMENT segp = NULL; /* pacify gcc */ 114 115 is_disk = 0; 116 is_disk_mask = 0; 117 if (prev_bp) { 118 bp = prev_bp->ovfl; 119 if (!bp || (bp->addr != addr)) 120 bp = NULL; 121 if (!newpage) 122 is_disk = BUF_DISK; 123 } else { 124 /* Grab buffer out of directory */ 125 segment_ndx = addr & (hashp->SGSIZE - 1); 126 127 /* valid segment ensured by __call_hash() */ 128 segp = hashp->dir[addr >> hashp->SSHIFT]; 129 _DIAGASSERT(segp != NULL); 130 bp = PTROF(segp[segment_ndx]); 131 is_disk_mask = ISDISK(segp[segment_ndx]); 132 is_disk = is_disk_mask || !hashp->new_file; 133 } 134 135 if (!bp) { 136 bp = newbuf(hashp, addr, prev_bp); 137 if (!bp || 138 __get_page(hashp, bp->page, addr, !prev_bp, is_disk, 0)) 139 return (NULL); 140 if (!prev_bp) 141 segp[segment_ndx] = 142 (BUFHEAD *)(void *)((u_long)bp | is_disk_mask); 143 } else { 144 BUF_REMOVE(bp); 145 MRU_INSERT(bp); 146 } 147 return (bp); 148 } 149 150 /* 151 * We need a buffer for this page. Either allocate one, or evict a resident 152 * one (if we have as many buffers as we're allowed) and put this one in. 153 * 154 * If newbuf finds an error (returning NULL), it also sets errno. 155 */ 156 static BUFHEAD * 157 newbuf(HTAB *hashp, uint32_t addr, BUFHEAD *prev_bp) 158 { 159 BUFHEAD *bp; /* The buffer we're going to use */ 160 BUFHEAD *xbp; /* Temp pointer */ 161 BUFHEAD *next_xbp; 162 SEGMENT segp; 163 int segment_ndx; 164 uint16_t oaddr, *shortp; 165 166 oaddr = 0; 167 bp = LRU; 168 /* 169 * If LRU buffer is pinned, the buffer pool is too small. We need to 170 * allocate more buffers. 171 */ 172 if (hashp->nbufs || (bp->flags & BUF_PIN)) { 173 /* Allocate a new one */ 174 if ((bp = calloc(1, sizeof(BUFHEAD))) == NULL) 175 return (NULL); 176 if ((bp->page = calloc(1, (size_t)hashp->BSIZE)) == NULL) { 177 free(bp); 178 return (NULL); 179 } 180 if (hashp->nbufs) 181 hashp->nbufs--; 182 } else { 183 /* Kick someone out */ 184 BUF_REMOVE(bp); 185 /* 186 * If this is an overflow page with addr 0, it's already been 187 * flushed back in an overflow chain and initialized. 188 */ 189 if ((bp->addr != 0) || (bp->flags & BUF_BUCKET)) { 190 /* 191 * Set oaddr before __put_page so that you get it 192 * before bytes are swapped. 193 */ 194 shortp = (uint16_t *)(void *)bp->page; 195 if (shortp[0]) 196 oaddr = shortp[shortp[0] - 1]; 197 if ((bp->flags & BUF_MOD) && __put_page(hashp, bp->page, 198 bp->addr, (int)IS_BUCKET(bp->flags), 0)) 199 return (NULL); 200 /* 201 * Update the pointer to this page (i.e. invalidate it). 202 * 203 * If this is a new file (i.e. we created it at open 204 * time), make sure that we mark pages which have been 205 * written to disk so we retrieve them from disk later, 206 * rather than allocating new pages. 207 */ 208 if (IS_BUCKET(bp->flags)) { 209 segment_ndx = bp->addr & (hashp->SGSIZE - 1); 210 segp = hashp->dir[bp->addr >> hashp->SSHIFT]; 211 _DIAGASSERT(segp != NULL); 212 213 if (hashp->new_file && 214 ((bp->flags & BUF_MOD) || 215 ISDISK(segp[segment_ndx]))) 216 segp[segment_ndx] = (BUFHEAD *)BUF_DISK; 217 else 218 segp[segment_ndx] = NULL; 219 } 220 /* 221 * Since overflow pages can only be access by means of 222 * their bucket, free overflow pages associated with 223 * this bucket. 224 */ 225 for (xbp = bp; xbp->ovfl;) { 226 next_xbp = xbp->ovfl; 227 xbp->ovfl = 0; 228 xbp = next_xbp; 229 230 /* Check that ovfl pointer is up date. */ 231 if (IS_BUCKET(xbp->flags) || 232 (oaddr != xbp->addr)) 233 break; 234 235 shortp = (uint16_t *)(void *)xbp->page; 236 if (shortp[0]) 237 /* set before __put_page */ 238 oaddr = shortp[shortp[0] - 1]; 239 if ((xbp->flags & BUF_MOD) && __put_page(hashp, 240 xbp->page, xbp->addr, 0, 0)) 241 return (NULL); 242 xbp->addr = 0; 243 xbp->flags = 0; 244 BUF_REMOVE(xbp); 245 LRU_INSERT(xbp); 246 } 247 } 248 } 249 250 /* Now assign this buffer */ 251 bp->addr = addr; 252 #ifdef DEBUG1 253 (void)fprintf(stderr, "NEWBUF1: %d->ovfl was %d is now %d\n", 254 bp->addr, (bp->ovfl ? bp->ovfl->addr : 0), 0); 255 #endif 256 bp->ovfl = NULL; 257 if (prev_bp) { 258 /* 259 * If prev_bp is set, this is an overflow page, hook it in to 260 * the buffer overflow links. 261 */ 262 #ifdef DEBUG1 263 (void)fprintf(stderr, "NEWBUF2: %d->ovfl was %d is now %d\n", 264 prev_bp->addr, (prev_bp->ovfl ? prev_bp->ovfl->addr : 0), 265 (bp ? bp->addr : 0)); 266 #endif 267 prev_bp->ovfl = bp; 268 bp->flags = 0; 269 } else 270 bp->flags = BUF_BUCKET; 271 MRU_INSERT(bp); 272 return (bp); 273 } 274 275 void 276 __buf_init(HTAB *hashp, u_int nbytes) 277 { 278 BUFHEAD *bfp; 279 int npages; 280 281 bfp = &(hashp->bufhead); 282 npages = (unsigned int)(nbytes + hashp->BSIZE - 1) >> hashp->BSHIFT; 283 npages = MAX(npages, MIN_BUFFERS); 284 285 hashp->nbufs = npages; 286 bfp->next = bfp; 287 bfp->prev = bfp; 288 /* 289 * This space is calloc'd so these are already null. 290 * 291 * bfp->ovfl = NULL; 292 * bfp->flags = 0; 293 * bfp->page = NULL; 294 * bfp->addr = 0; 295 */ 296 } 297 298 int 299 __buf_free(HTAB *hashp, int do_free, int to_disk) 300 { 301 BUFHEAD *bp; 302 303 /* Need to make sure that buffer manager has been initialized */ 304 if (!LRU) 305 return (0); 306 for (bp = LRU; bp != &hashp->bufhead;) { 307 /* Check that the buffer is valid */ 308 if (bp->addr || IS_BUCKET(bp->flags)) { 309 if (to_disk && (bp->flags & BUF_MOD) && 310 __put_page(hashp, bp->page, 311 bp->addr, IS_BUCKET(bp->flags), 0)) 312 return (-1); 313 } 314 /* Check if we are freeing stuff */ 315 if (do_free) { 316 if (bp->page) 317 free(bp->page); 318 BUF_REMOVE(bp); 319 free(bp); 320 bp = LRU; 321 } else 322 bp = bp->prev; 323 } 324 return (0); 325 } 326 327 void 328 __reclaim_buf(HTAB *hashp, BUFHEAD *bp) 329 { 330 bp->ovfl = 0; 331 bp->addr = 0; 332 bp->flags = 0; 333 BUF_REMOVE(bp); 334 LRU_INSERT(bp); 335 } 336