Annotation of embedaddon/rsync/match.c, revision 1.1
1.1 ! misho 1: /*
! 2: * Block matching used by the file-transfer code.
! 3: *
! 4: * Copyright (C) 1996 Andrew Tridgell
! 5: * Copyright (C) 1996 Paul Mackerras
! 6: * Copyright (C) 2003-2009 Wayne Davison
! 7: *
! 8: * This program is free software; you can redistribute it and/or modify
! 9: * it under the terms of the GNU General Public License as published by
! 10: * the Free Software Foundation; either version 3 of the License, or
! 11: * (at your option) any later version.
! 12: *
! 13: * This program is distributed in the hope that it will be useful,
! 14: * but WITHOUT ANY WARRANTY; without even the implied warranty of
! 15: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
! 16: * GNU General Public License for more details.
! 17: *
! 18: * You should have received a copy of the GNU General Public License along
! 19: * with this program; if not, visit the http://fsf.org website.
! 20: */
! 21:
! 22: #include "rsync.h"
! 23:
! 24: extern int verbose;
! 25: extern int do_progress;
! 26: extern int checksum_seed;
! 27: extern int append_mode;
! 28:
! 29: int updating_basis_file;
! 30:
! 31: static int false_alarms;
! 32: static int hash_hits;
! 33: static int matches;
! 34: static int64 data_transfer;
! 35:
! 36: static int total_false_alarms;
! 37: static int total_hash_hits;
! 38: static int total_matches;
! 39:
! 40: extern struct stats stats;
! 41:
! 42: #define TRADITIONAL_TABLESIZE (1<<16)
! 43:
! 44: static uint32 tablesize;
! 45: static int32 *hash_table;
! 46:
! 47: #define SUM2HASH2(s1,s2) (((s1) + (s2)) & 0xFFFF)
! 48: #define SUM2HASH(sum) SUM2HASH2((sum)&0xFFFF,(sum)>>16)
! 49:
! 50: #define BIG_SUM2HASH(sum) ((sum)%tablesize)
! 51:
! 52: static void build_hash_table(struct sum_struct *s)
! 53: {
! 54: static uint32 alloc_size;
! 55: int32 i;
! 56:
! 57: /* Dynamically calculate the hash table size so that the hash load
! 58: * for big files is about 80%. A number greater than the traditional
! 59: * size must be odd or s2 will not be able to span the entire set. */
! 60: tablesize = (uint32)(s->count/8) * 10 + 11;
! 61: if (tablesize < TRADITIONAL_TABLESIZE)
! 62: tablesize = TRADITIONAL_TABLESIZE;
! 63: if (tablesize > alloc_size || tablesize < alloc_size - 16*1024) {
! 64: if (hash_table)
! 65: free(hash_table);
! 66: hash_table = new_array(int32, tablesize);
! 67: if (!hash_table)
! 68: out_of_memory("build_hash_table");
! 69: alloc_size = tablesize;
! 70: }
! 71:
! 72: memset(hash_table, 0xFF, tablesize * sizeof hash_table[0]);
! 73:
! 74: if (tablesize == TRADITIONAL_TABLESIZE) {
! 75: for (i = 0; i < s->count; i++) {
! 76: uint32 t = SUM2HASH(s->sums[i].sum1);
! 77: s->sums[i].chain = hash_table[t];
! 78: hash_table[t] = i;
! 79: }
! 80: } else {
! 81: for (i = 0; i < s->count; i++) {
! 82: uint32 t = BIG_SUM2HASH(s->sums[i].sum1);
! 83: s->sums[i].chain = hash_table[t];
! 84: hash_table[t] = i;
! 85: }
! 86: }
! 87: }
! 88:
! 89:
! 90: static OFF_T last_match;
! 91:
! 92:
! 93: /* Transmit a literal and/or match token.
! 94: *
! 95: * This delightfully-named function is called either when we find a
! 96: * match and need to transmit all the unmatched data leading up to it,
! 97: * or when we get bored of accumulating literal data and just need to
! 98: * transmit it. As a result of this second case, it is called even if
! 99: * we have not matched at all!
! 100: *
! 101: * If i >= 0, the number of a matched token. If < 0, indicates we have
! 102: * only literal data. A -1 will send a 0-token-int too, and a -2 sends
! 103: * only literal data, w/o any token-int. */
! 104: static void matched(int f, struct sum_struct *s, struct map_struct *buf,
! 105: OFF_T offset, int32 i)
! 106: {
! 107: int32 n = (int32)(offset - last_match); /* max value: block_size (int32) */
! 108: int32 j;
! 109:
! 110: if (verbose > 2 && i >= 0) {
! 111: rprintf(FINFO,
! 112: "match at %.0f last_match=%.0f j=%d len=%ld n=%ld\n",
! 113: (double)offset, (double)last_match, i,
! 114: (long)s->sums[i].len, (long)n);
! 115: }
! 116:
! 117: send_token(f, i, buf, last_match, n, i < 0 ? 0 : s->sums[i].len);
! 118: data_transfer += n;
! 119:
! 120: if (i >= 0) {
! 121: stats.matched_data += s->sums[i].len;
! 122: n += s->sums[i].len;
! 123: }
! 124:
! 125: for (j = 0; j < n; j += CHUNK_SIZE) {
! 126: int32 n1 = MIN(CHUNK_SIZE, n - j);
! 127: sum_update(map_ptr(buf, last_match + j, n1), n1);
! 128: }
! 129:
! 130: if (i >= 0)
! 131: last_match = offset + s->sums[i].len;
! 132: else
! 133: last_match = offset;
! 134:
! 135: if (buf && do_progress)
! 136: show_progress(last_match, buf->file_size);
! 137: }
! 138:
! 139:
! 140: static void hash_search(int f,struct sum_struct *s,
! 141: struct map_struct *buf, OFF_T len)
! 142: {
! 143: OFF_T offset, aligned_offset, end;
! 144: int32 k, want_i, aligned_i, backup;
! 145: char sum2[SUM_LENGTH];
! 146: uint32 s1, s2, sum;
! 147: int more;
! 148: schar *map;
! 149:
! 150: /* want_i is used to encourage adjacent matches, allowing the RLL
! 151: * coding of the output to work more efficiently. */
! 152: want_i = 0;
! 153:
! 154: if (verbose > 2) {
! 155: rprintf(FINFO, "hash search b=%ld len=%.0f\n",
! 156: (long)s->blength, (double)len);
! 157: }
! 158:
! 159: k = (int32)MIN(len, (OFF_T)s->blength);
! 160:
! 161: map = (schar *)map_ptr(buf, 0, k);
! 162:
! 163: sum = get_checksum1((char *)map, k);
! 164: s1 = sum & 0xFFFF;
! 165: s2 = sum >> 16;
! 166: if (verbose > 3)
! 167: rprintf(FINFO, "sum=%.8x k=%ld\n", sum, (long)k);
! 168:
! 169: offset = aligned_offset = aligned_i = 0;
! 170:
! 171: end = len + 1 - s->sums[s->count-1].len;
! 172:
! 173: if (verbose > 3) {
! 174: rprintf(FINFO, "hash search s->blength=%ld len=%.0f count=%.0f\n",
! 175: (long)s->blength, (double)len, (double)s->count);
! 176: }
! 177:
! 178: do {
! 179: int done_csum2 = 0;
! 180: int32 i;
! 181:
! 182: if (verbose > 4) {
! 183: rprintf(FINFO, "offset=%.0f sum=%04x%04x\n",
! 184: (double)offset, s2 & 0xFFFF, s1 & 0xFFFF);
! 185: }
! 186:
! 187: if (tablesize == TRADITIONAL_TABLESIZE) {
! 188: if ((i = hash_table[SUM2HASH2(s1,s2)]) < 0)
! 189: goto null_hash;
! 190: sum = (s1 & 0xffff) | (s2 << 16);
! 191: } else {
! 192: sum = (s1 & 0xffff) | (s2 << 16);
! 193: if ((i = hash_table[BIG_SUM2HASH(sum)]) < 0)
! 194: goto null_hash;
! 195: }
! 196:
! 197: hash_hits++;
! 198: do {
! 199: int32 l;
! 200:
! 201: if (sum != s->sums[i].sum1)
! 202: continue;
! 203:
! 204: /* also make sure the two blocks are the same length */
! 205: l = (int32)MIN((OFF_T)s->blength, len-offset);
! 206: if (l != s->sums[i].len)
! 207: continue;
! 208:
! 209: /* in-place: ensure chunk's offset is either >= our
! 210: * offset or that the data didn't move. */
! 211: if (updating_basis_file && s->sums[i].offset < offset
! 212: && !(s->sums[i].flags & SUMFLG_SAME_OFFSET))
! 213: continue;
! 214:
! 215: if (verbose > 3) {
! 216: rprintf(FINFO,
! 217: "potential match at %.0f i=%ld sum=%08x\n",
! 218: (double)offset, (long)i, sum);
! 219: }
! 220:
! 221: if (!done_csum2) {
! 222: map = (schar *)map_ptr(buf,offset,l);
! 223: get_checksum2((char *)map,l,sum2);
! 224: done_csum2 = 1;
! 225: }
! 226:
! 227: if (memcmp(sum2,s->sums[i].sum2,s->s2length) != 0) {
! 228: false_alarms++;
! 229: continue;
! 230: }
! 231:
! 232: /* When updating in-place, the best possible match is
! 233: * one with an identical offset, so we prefer that over
! 234: * the adjacent want_i optimization. */
! 235: if (updating_basis_file) {
! 236: /* All the generator's chunks start at blength boundaries. */
! 237: while (aligned_offset < offset) {
! 238: aligned_offset += s->blength;
! 239: aligned_i++;
! 240: }
! 241: if (offset == aligned_offset && aligned_i < s->count) {
! 242: if (i != aligned_i) {
! 243: if (sum != s->sums[aligned_i].sum1
! 244: || l != s->sums[aligned_i].len
! 245: || memcmp(sum2, s->sums[aligned_i].sum2, s->s2length) != 0)
! 246: goto check_want_i;
! 247: i = aligned_i;
! 248: }
! 249: /* This identical chunk is in the same spot in the old and new file. */
! 250: s->sums[i].flags |= SUMFLG_SAME_OFFSET;
! 251: want_i = i;
! 252: }
! 253: }
! 254:
! 255: check_want_i:
! 256: /* we've found a match, but now check to see
! 257: * if want_i can hint at a better match. */
! 258: if (i != want_i && want_i < s->count
! 259: && (!updating_basis_file || s->sums[want_i].offset >= offset
! 260: || s->sums[want_i].flags & SUMFLG_SAME_OFFSET)
! 261: && sum == s->sums[want_i].sum1
! 262: && memcmp(sum2, s->sums[want_i].sum2, s->s2length) == 0) {
! 263: /* we've found an adjacent match - the RLL coder
! 264: * will be happy */
! 265: i = want_i;
! 266: }
! 267: want_i = i + 1;
! 268:
! 269: matched(f,s,buf,offset,i);
! 270: offset += s->sums[i].len - 1;
! 271: k = (int32)MIN((OFF_T)s->blength, len-offset);
! 272: map = (schar *)map_ptr(buf, offset, k);
! 273: sum = get_checksum1((char *)map, k);
! 274: s1 = sum & 0xFFFF;
! 275: s2 = sum >> 16;
! 276: matches++;
! 277: break;
! 278: } while ((i = s->sums[i].chain) >= 0);
! 279:
! 280: null_hash:
! 281: backup = (int32)(offset - last_match);
! 282: /* We sometimes read 1 byte prior to last_match... */
! 283: if (backup < 0)
! 284: backup = 0;
! 285:
! 286: /* Trim off the first byte from the checksum */
! 287: more = offset + k < len;
! 288: map = (schar *)map_ptr(buf, offset - backup, k + more + backup)
! 289: + backup;
! 290: s1 -= map[0] + CHAR_OFFSET;
! 291: s2 -= k * (map[0]+CHAR_OFFSET);
! 292:
! 293: /* Add on the next byte (if there is one) to the checksum */
! 294: if (more) {
! 295: s1 += map[k] + CHAR_OFFSET;
! 296: s2 += s1;
! 297: } else
! 298: --k;
! 299:
! 300: /* By matching early we avoid re-reading the
! 301: data 3 times in the case where a token
! 302: match comes a long way after last
! 303: match. The 3 reads are caused by the
! 304: running match, the checksum update and the
! 305: literal send. */
! 306: if (backup >= s->blength+CHUNK_SIZE && end-offset > CHUNK_SIZE)
! 307: matched(f, s, buf, offset - s->blength, -2);
! 308: } while (++offset < end);
! 309:
! 310: matched(f, s, buf, len, -1);
! 311: map_ptr(buf, len-1, 1);
! 312: }
! 313:
! 314:
! 315: /**
! 316: * Scan through a origin file, looking for sections that match
! 317: * checksums from the generator, and transmit either literal or token
! 318: * data.
! 319: *
! 320: * Also calculates the MD4 checksum of the whole file, using the md
! 321: * accumulator. This is transmitted with the file as protection
! 322: * against corruption on the wire.
! 323: *
! 324: * @param s Checksums received from the generator. If <tt>s->count ==
! 325: * 0</tt>, then there are actually no checksums for this file.
! 326: *
! 327: * @param len Length of the file to send.
! 328: **/
! 329: void match_sums(int f, struct sum_struct *s, struct map_struct *buf, OFF_T len)
! 330: {
! 331: char file_sum[MAX_DIGEST_LEN];
! 332: int sum_len;
! 333:
! 334: last_match = 0;
! 335: false_alarms = 0;
! 336: hash_hits = 0;
! 337: matches = 0;
! 338: data_transfer = 0;
! 339:
! 340: sum_init(checksum_seed);
! 341:
! 342: if (append_mode > 0) {
! 343: if (append_mode == 2) {
! 344: OFF_T j = 0;
! 345: for (j = CHUNK_SIZE; j < s->flength; j += CHUNK_SIZE) {
! 346: if (buf && do_progress)
! 347: show_progress(last_match, buf->file_size);
! 348: sum_update(map_ptr(buf, last_match, CHUNK_SIZE),
! 349: CHUNK_SIZE);
! 350: last_match = j;
! 351: }
! 352: if (last_match < s->flength) {
! 353: int32 n = (int32)(s->flength - last_match);
! 354: if (buf && do_progress)
! 355: show_progress(last_match, buf->file_size);
! 356: sum_update(map_ptr(buf, last_match, n), n);
! 357: }
! 358: }
! 359: last_match = s->flength;
! 360: s->count = 0;
! 361: }
! 362:
! 363: if (len > 0 && s->count > 0) {
! 364: build_hash_table(s);
! 365:
! 366: if (verbose > 2)
! 367: rprintf(FINFO,"built hash table\n");
! 368:
! 369: hash_search(f, s, buf, len);
! 370:
! 371: if (verbose > 2)
! 372: rprintf(FINFO,"done hash search\n");
! 373: } else {
! 374: OFF_T j;
! 375: /* by doing this in pieces we avoid too many seeks */
! 376: for (j = last_match + CHUNK_SIZE; j < len; j += CHUNK_SIZE)
! 377: matched(f, s, buf, j, -2);
! 378: matched(f, s, buf, len, -1);
! 379: }
! 380:
! 381: sum_len = sum_end(file_sum);
! 382: /* If we had a read error, send a bad checksum. */
! 383: if (buf && buf->status != 0)
! 384: file_sum[0]++;
! 385:
! 386: if (verbose > 2)
! 387: rprintf(FINFO,"sending file_sum\n");
! 388: write_buf(f, file_sum, sum_len);
! 389:
! 390: if (verbose > 2)
! 391: rprintf(FINFO, "false_alarms=%d hash_hits=%d matches=%d\n",
! 392: false_alarms, hash_hits, matches);
! 393:
! 394: total_hash_hits += hash_hits;
! 395: total_false_alarms += false_alarms;
! 396: total_matches += matches;
! 397: stats.literal_data += data_transfer;
! 398: }
! 399:
! 400: void match_report(void)
! 401: {
! 402: if (verbose <= 1)
! 403: return;
! 404:
! 405: rprintf(FINFO,
! 406: "total: matches=%d hash_hits=%d false_alarms=%d data=%.0f\n",
! 407: total_matches, total_hash_hits, total_false_alarms,
! 408: (double)stats.literal_data);
! 409: }
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