2 Copyright (C) Andrew Tridgell 1996
3 Copyright (C) Paul Mackerras 1996
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software
17 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 extern int do_progress;
25 extern int checksum_seed;
27 typedef unsigned short tag;
29 #define TABLESIZE (1<<16)
30 #define NULL_TAG ((size_t)-1)
32 static int false_alarms;
35 static int64 data_transfer;
37 static int total_false_alarms;
38 static int total_tag_hits;
39 static int total_matches;
41 extern struct stats stats;
48 static struct target *targets;
50 static size_t *tag_table;
52 #define gettag2(s1,s2) (((s1) + (s2)) & 0xFFFF)
53 #define gettag(sum) gettag2((sum)&0xFFFF,(sum)>>16)
55 static int compare_targets(struct target *t1,struct target *t2)
57 return (int)t1->t - (int)t2->t;
61 static void build_hash_table(struct sum_struct *s)
66 tag_table = new_array(size_t, TABLESIZE);
68 targets = new_array(struct target, s->count);
69 if (!tag_table || !targets)
70 out_of_memory("build_hash_table");
72 for (i = 0; i < s->count; i++) {
74 targets[i].t = gettag(s->sums[i].sum1);
77 qsort(targets,s->count,sizeof(targets[0]),(int (*)())compare_targets);
79 for (i = 0; i < TABLESIZE; i++)
80 tag_table[i] = NULL_TAG;
82 for (i = s->count; i-- > 0; )
83 tag_table[targets[i].t] = i;
87 static OFF_T last_match;
91 * Transmit a literal and/or match token.
93 * This delightfully-named function is called either when we find a
94 * match and need to transmit all the unmatched data leading up to it,
95 * or when we get bored of accumulating literal data and just need to
96 * transmit it. As a result of this second case, it is called even if
97 * we have not matched at all!
99 * @param i If >0, the number of a matched token. If 0, indicates we
100 * have only literal data.
102 static void matched(int f,struct sum_struct *s,struct map_struct *buf,
105 OFF_T n = offset - last_match;
108 if (verbose > 2 && i >= 0)
109 rprintf(FINFO,"match at %.0f last_match=%.0f j=%d len=%u n=%.0f\n",
110 (double)offset,(double)last_match,i,s->sums[i].len,(double)n);
112 send_token(f,i,buf,last_match,n,i<0?0:s->sums[i].len);
116 stats.matched_data += s->sums[i].len;
120 for (j = 0; j < n; j += CHUNK_SIZE) {
121 int n1 = MIN(CHUNK_SIZE,n-j);
122 sum_update(map_ptr(buf,last_match+j,n1),n1);
127 last_match = offset + s->sums[i].len;
131 if (buf && do_progress) {
132 show_progress(last_match, buf->file_size);
135 end_progress(buf->file_size);
140 static void hash_search(int f,struct sum_struct *s,
141 struct map_struct *buf, OFF_T len)
146 char sum2[SUM_LENGTH];
150 /* last_i is used to encourage adjacent matches, allowing the RLL coding of the
151 output to work more efficiently */
155 rprintf(FINFO,"hash search b=%u len=%.0f\n",
156 s->blength, (double)len);
159 k = MIN(len, s->blength);
161 map = (schar *)map_ptr(buf, 0, k);
163 sum = get_checksum1((char *)map, k);
167 rprintf(FINFO, "sum=%.8x k=%u\n", sum, k);
171 end = len + 1 - s->sums[s->count-1].len;
174 rprintf(FINFO, "hash search s->blength=%u len=%.0f count=%.0f\n",
175 s->blength, (double)len, (double)s->count);
179 tag t = gettag2(s1,s2);
181 size_t j = tag_table[t];
184 rprintf(FINFO,"offset=%.0f sum=%08x\n",(double)offset,sum);
189 sum = (s1 & 0xffff) | (s2 << 16);
193 size_t i = targets[j].i;
195 if (sum != s->sums[i].sum1)
198 /* also make sure the two blocks are the same length */
199 l = MIN((OFF_T)s->blength, len-offset);
200 if (l != s->sums[i].len)
204 rprintf(FINFO,"potential match at %.0f target=%.0f %.0f sum=%08x\n",
205 (double)offset,(double)j,(double)i,sum);
208 map = (schar *)map_ptr(buf,offset,l);
209 get_checksum2((char *)map,l,sum2);
213 if (memcmp(sum2,s->sums[i].sum2,s->s2length) != 0) {
218 /* we've found a match, but now check to see
219 * if last_i can hint at a better match */
220 if (i != last_i + 1 && last_i + 1 < s->count
221 && sum == s->sums[last_i+1].sum1
222 && memcmp(sum2, s->sums[last_i+1].sum2, s->s2length) == 0) {
223 /* we've found an adjacent match - the RLL coder
229 matched(f,s,buf,offset,i);
230 offset += s->sums[i].len - 1;
231 k = MIN(s->blength, len-offset);
232 map = (schar *)map_ptr(buf, offset, k);
233 sum = get_checksum1((char *)map, k);
238 } while (++j < s->count && targets[j].t == t);
241 /* Trim off the first byte from the checksum */
242 map = (schar *)map_ptr(buf, offset, k+1);
243 s1 -= map[0] + CHAR_OFFSET;
244 s2 -= k * (map[0]+CHAR_OFFSET);
246 /* Add on the next byte (if there is one) to the checksum */
247 if (k < (len-offset)) {
248 s1 += (map[k]+CHAR_OFFSET);
253 /* By matching early we avoid re-reading the
254 data 3 times in the case where a token
255 match comes a long way after last
256 match. The 3 reads are caused by the
257 running match, the checksum update and the
259 if (offset > last_match
260 && offset-last_match >= CHUNK_SIZE+s->blength
261 && end-offset > CHUNK_SIZE) {
262 matched(f,s,buf,offset - s->blength, -2);
264 } while (++offset < end);
266 matched(f,s,buf,len,-1);
267 map_ptr(buf,len-1,1);
272 * Scan through a origin file, looking for sections that match
273 * checksums from the generator, and transmit either literal or token
276 * Also calculates the MD4 checksum of the whole file, using the md
277 * accumulator. This is transmitted with the file as protection
278 * against corruption on the wire.
280 * @param s Checksums received from the generator. If <tt>s->count ==
281 * 0</tt>, then there are actually no checksums for this file.
283 * @param len Length of the file to send.
285 void match_sums(int f, struct sum_struct *s, struct map_struct *buf, OFF_T len)
287 char file_sum[MD4_SUM_LENGTH];
288 extern int write_batch;
296 sum_init(checksum_seed);
298 if (len > 0 && s->count>0) {
302 rprintf(FINFO,"built hash table\n");
304 hash_search(f,s,buf,len);
307 rprintf(FINFO,"done hash search\n");
310 /* by doing this in pieces we avoid too many seeks */
311 for (j = 0; j < len-CHUNK_SIZE; j += CHUNK_SIZE) {
312 int n1 = MIN(CHUNK_SIZE,(len-CHUNK_SIZE)-j);
313 matched(f,s,buf,j+n1,-2);
315 matched(f,s,buf,len,-1);
319 /* If we had a read error, send a bad checksum. */
320 if (buf && buf->status != 0)
324 rprintf(FINFO,"sending file_sum\n");
325 write_buf(f,file_sum,MD4_SUM_LENGTH);
327 write_batch_delta_file(file_sum, MD4_SUM_LENGTH);
335 rprintf(FINFO, "false_alarms=%d tag_hits=%d matches=%d\n",
336 false_alarms, tag_hits, matches);
338 total_tag_hits += tag_hits;
339 total_false_alarms += false_alarms;
340 total_matches += matches;
341 stats.literal_data += data_transfer;
344 void match_report(void)
350 "total: matches=%d tag_hits=%d false_alarms=%d data=%.0f\n",
351 total_matches,total_tag_hits,
353 (double)stats.literal_data);