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bea6f6d5 RK |
1 | /* |
2 | * This file is part of DisOrder | |
3 | * Copyright (C) 2008 Richard Kettlewell | |
4 | * | |
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. | |
9 | * | |
10 | * This program is distributed in the hope that it will be useful, but | |
11 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | * General Public License for more details. | |
14 | * | |
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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 | |
18 | * USA | |
19 | */ | |
20 | /** @file choose.c | |
21 | * @brief Random track chooser | |
22 | * | |
23 | * Picks a track at random and writes it to standard output. If for | |
24 | * any reason no track can be picked - even a trivial reason like a | |
25 | * deadlock - it just exits and expects the server to try again. | |
26 | */ | |
27 | ||
28 | #include <config.h> | |
29 | #include "types.h" | |
30 | ||
31 | #include <getopt.h> | |
32 | #include <stdio.h> | |
33 | #include <stdlib.h> | |
34 | #include <db.h> | |
35 | #include <locale.h> | |
36 | #include <errno.h> | |
37 | #include <sys/types.h> | |
38 | #include <unistd.h> | |
39 | #include <pcre.h> | |
40 | #include <string.h> | |
41 | #include <fcntl.h> | |
42 | #include <syslog.h> | |
91c9324a | 43 | #include <time.h> |
bea6f6d5 RK |
44 | |
45 | #include "configuration.h" | |
46 | #include "log.h" | |
47 | #include "defs.h" | |
48 | #include "mem.h" | |
49 | #include "kvp.h" | |
50 | #include "syscalls.h" | |
51 | #include "printf.h" | |
52 | #include "trackdb.h" | |
53 | #include "trackdb-int.h" | |
54 | #include "version.h" | |
91c9324a | 55 | #include "trackname.h" |
28dc2d22 RK |
56 | #include "queue.h" |
57 | #include "server-queue.h" | |
bea6f6d5 RK |
58 | |
59 | static DB_TXN *global_tid; | |
60 | ||
61 | static const struct option options[] = { | |
62 | { "help", no_argument, 0, 'h' }, | |
63 | { "version", no_argument, 0, 'V' }, | |
64 | { "config", required_argument, 0, 'c' }, | |
65 | { "debug", no_argument, 0, 'd' }, | |
66 | { "no-debug", no_argument, 0, 'D' }, | |
67 | { "syslog", no_argument, 0, 's' }, | |
68 | { "no-syslog", no_argument, 0, 'S' }, | |
69 | { 0, 0, 0, 0 } | |
70 | }; | |
71 | ||
72 | /* display usage message and terminate */ | |
73 | static void help(void) { | |
74 | xprintf("Usage:\n" | |
75 | " disorder-choose [OPTIONS]\n" | |
76 | "Options:\n" | |
77 | " --help, -h Display usage message\n" | |
78 | " --version, -V Display version number\n" | |
79 | " --config PATH, -c PATH Set configuration file\n" | |
80 | " --debug, -d Turn on debugging\n" | |
81 | " --[no-]syslog Enable/disable logging to syslog\n" | |
82 | "\n" | |
83 | "Track choose for DisOrder. Not intended to be run\n" | |
84 | "directly.\n"); | |
85 | xfclose(stdout); | |
86 | exit(0); | |
87 | } | |
88 | ||
89 | /** @brief Weighted track record */ | |
90 | struct weighted_track { | |
91 | /** @brief Next track in the list */ | |
92 | struct weighted_track *next; | |
93 | /** @brief Track name */ | |
94 | const char *track; | |
95 | /** @brief Weight for this track (always positive) */ | |
96 | unsigned long weight; | |
97 | }; | |
98 | ||
99 | /** @brief List of tracks with nonzero weight */ | |
100 | static struct weighted_track *tracks; | |
101 | ||
102 | /** @brief Sum of all weights */ | |
103 | static unsigned long long total_weight; | |
104 | ||
105 | /** @brief Count of tracks */ | |
106 | static long ntracks; | |
107 | ||
91c9324a RK |
108 | static char **required_tags; |
109 | static char **prohibited_tags; | |
110 | ||
28dc2d22 RK |
111 | static int queue_contains(const struct queue_entry *head, |
112 | const char *track) { | |
113 | const struct queue_entry *q; | |
114 | ||
115 | for(q = head->next; q != head; q = q->next) | |
116 | if(!strcmp(q->track, track)) | |
117 | return 1; | |
118 | return 0; | |
119 | } | |
120 | ||
bea6f6d5 RK |
121 | /** @brief Compute the weight of a track |
122 | * @param track Track name (UTF-8) | |
123 | * @param data Track data | |
124 | * @param prefs Track preferences | |
125 | * @return Track weight (non-negative) | |
126 | * | |
127 | * Tracks to be excluded entirely are given a weight of 0. | |
128 | */ | |
91c9324a RK |
129 | static unsigned long compute_weight(const char *track, |
130 | struct kvp *data, | |
bea6f6d5 RK |
131 | struct kvp *prefs) { |
132 | const char *s; | |
91c9324a RK |
133 | char **track_tags; |
134 | time_t last, now; | |
135 | ||
136 | /* Reject tracks not in any collection (race between edit config and | |
137 | * rescan) */ | |
138 | if(!find_track_root(track)) { | |
139 | info("found track not in any collection: %s", track); | |
140 | return 0; | |
141 | } | |
bea6f6d5 | 142 | |
91c9324a RK |
143 | /* Reject aliases to avoid giving aliased tracks extra weight */ |
144 | if(kvp_get(data, "_alias_for")) | |
145 | return 0; | |
146 | ||
147 | /* Reject tracks with random play disabled */ | |
bea6f6d5 RK |
148 | if((s = kvp_get(prefs, "pick_at_random")) |
149 | && !strcmp(s, "0")) | |
150 | return 0; | |
91c9324a RK |
151 | |
152 | /* Reject tracks played within the last 8 hours */ | |
153 | if((s = kvp_get(prefs, "played_time"))) { | |
154 | last = atoll(s); | |
155 | now = time(0); | |
cebe3127 | 156 | if(now < last + config->replay_min) |
91c9324a RK |
157 | return 0; |
158 | } | |
159 | ||
28dc2d22 RK |
160 | /* Reject tracks currently in the queue or in the recent list */ |
161 | if(queue_contains(&qhead, track) | |
162 | || queue_contains(&phead, track)) | |
163 | return 0; | |
164 | ||
91c9324a RK |
165 | /* We'll need tags for a number of things */ |
166 | track_tags = parsetags(kvp_get(prefs, "tags")); | |
167 | ||
168 | /* Reject tracks with prohibited tags */ | |
169 | if(prohibited_tags && tag_intersection(track_tags, prohibited_tags)) | |
170 | return 0; | |
171 | ||
172 | /* Reject tracks that lack required tags */ | |
173 | if(*required_tags && !tag_intersection(track_tags, required_tags)) | |
174 | return 0; | |
175 | ||
36a1a882 RK |
176 | /* Use the configured weight if available */ |
177 | if((s = kvp_get(prefs, "weight"))) { | |
178 | long n; | |
179 | errno = 0; | |
180 | ||
181 | n = strtol(s, 0, 10); | |
182 | if((errno == 0 || errno == ERANGE) && n >= 0) | |
183 | return n; | |
184 | } | |
185 | ||
bea6f6d5 RK |
186 | return 90000; |
187 | } | |
188 | ||
189 | /** @brief Called for each track */ | |
190 | static int collect_tracks_callback(const char *track, | |
191 | struct kvp *data, | |
192 | struct kvp *prefs, | |
193 | void attribute((unused)) *u, | |
194 | DB_TXN attribute((unused)) *tid) { | |
36a1a882 | 195 | unsigned long weight = compute_weight(track, data, prefs); |
bea6f6d5 RK |
196 | |
197 | if(weight) { | |
198 | struct weighted_track *const t = xmalloc(sizeof *t); | |
199 | ||
36a1a882 RK |
200 | /* Clamp weight so that we can fit in billions of tracks when we do |
201 | * arithmetic in long long */ | |
202 | if(weight > 0x7fffffff) | |
203 | weight = 0x7fffffff; | |
bea6f6d5 RK |
204 | t->next = tracks; |
205 | t->track = track; | |
206 | t->weight = weight; | |
207 | tracks = t; | |
208 | total_weight += weight; | |
209 | ++ntracks; | |
210 | } | |
211 | return 0; | |
212 | } | |
213 | ||
214 | /** @brief Pick a random integer uniformly from [0, limit) */ | |
4005a0d6 | 215 | static void random_bytes(unsigned char *buf, size_t n) { |
bea6f6d5 RK |
216 | static int fd = -1; |
217 | int r; | |
218 | ||
219 | if(fd < 0) { | |
220 | if((fd = open("/dev/urandom", O_RDONLY)) < 0) | |
221 | fatal(errno, "opening /dev/urandom"); | |
222 | } | |
4005a0d6 | 223 | if((r = read(fd, buf, n)) < 0) |
bea6f6d5 | 224 | fatal(errno, "reading /dev/urandom"); |
4005a0d6 | 225 | if((size_t)r < n) |
bea6f6d5 | 226 | fatal(0, "short read from /dev/urandom"); |
4005a0d6 | 227 | } |
228 | ||
229 | /** @brief Pick a random integer uniformly from [0, limit) */ | |
230 | static unsigned long long pick_weight(unsigned long long limit) { | |
231 | unsigned char buf[(sizeof(unsigned long long) * CHAR_BIT + 7)/8], m; | |
232 | unsigned long long t, r, slop; | |
233 | int i, nby, nbi; | |
234 | ||
235 | //info("pick_weight: limit = %llu", limit); | |
236 | ||
237 | /* First, decide how many bits of output we actually need; do bytes first | |
238 | * (they're quicker) and then bits. | |
239 | * | |
240 | * To speed this up, we could use a binary search if we knew where to | |
241 | * start. (Note that shifting by ULLONG_BITS or more (if such a constant | |
242 | * existed) is undefined behaviour, so we mustn't do that.) Figuring out a | |
243 | * start point involves preprocessor and/or autoconf magic. | |
244 | */ | |
245 | for (nby = 1, t = (limit - 1) >> 8; t; nby++, t >>= 8) | |
246 | ; | |
247 | nbi = (nby - 1) << 3; t = limit >> nbi; | |
248 | if (t >> 4) { t >>= 4; nbi += 4; } | |
249 | if (t >> 2) { t >>= 2; nbi += 2; } | |
250 | if (t >> 1) { t >>= 1; nbi += 1; } | |
251 | nbi++; | |
252 | //info("nby = %d; nbi = %d", nby, nbi); | |
253 | ||
254 | /* Main randomness collection loop. We read a number of bytes from the | |
255 | * randomness source, and glue them together into an integer (dropping | |
256 | * bits off the top byte as necessary). Call the result r; we have | |
257 | * 2^{nbi - 1) <= limit < 2^nbi and r < 2^nbi. If r < limit then we win; | |
258 | * otherwise we try again. Given the above bounds, we expect fewer than 2 | |
259 | * iterations. | |
260 | * | |
261 | * Unfortunately there are subtleties. In particular, 2^nbi may in fact be | |
262 | * zero due to overflow. So in fact what we do is compute slop = 2^nbi - | |
263 | * limit > 0; if r < slop then we try again, otherwise r - slop is our | |
264 | * winner. | |
265 | */ | |
266 | slop = (2 << (nbi - 1)) - limit; | |
267 | m = nbi & 7 ? (1 << (nbi & 7)) - 1 : 0xff; | |
268 | //info("slop = %llu", slop); | |
269 | //info("m = 0x%02x", m); | |
270 | ||
271 | do { | |
272 | /* Actually get some random data. */ | |
273 | random_bytes(buf, nby); | |
274 | ||
275 | /* Clobber the top byte. */ | |
276 | buf[0] &= m; | |
277 | ||
278 | /* Turn it into an integer. */ | |
279 | for (r = 0, i = 0; i < nby; i++) | |
280 | r = (r << 8) | buf[i]; | |
281 | //info("r = %llu", r); | |
282 | } while (r < slop); | |
283 | ||
284 | return r - slop; | |
bea6f6d5 RK |
285 | } |
286 | ||
287 | /** @brief Pick a track at random and write it to stdout */ | |
288 | static void pick_track(void) { | |
289 | long long w; | |
290 | struct weighted_track *t; | |
291 | ||
292 | w = pick_weight(total_weight); | |
293 | t = tracks; | |
294 | while(t && w >= t->weight) { | |
295 | w -= t->weight; | |
296 | t = t->next; | |
297 | } | |
298 | if(!t) | |
299 | fatal(0, "ran out of tracks but %lld weighting left", w); | |
300 | xprintf("%s", t->track); | |
301 | } | |
302 | ||
303 | int main(int argc, char **argv) { | |
91c9324a RK |
304 | int n, logsyslog = !isatty(2), err; |
305 | const char *tags; | |
bea6f6d5 RK |
306 | |
307 | set_progname(argv); | |
308 | mem_init(); | |
309 | if(!setlocale(LC_CTYPE, "")) fatal(errno, "error calling setlocale"); | |
310 | while((n = getopt_long(argc, argv, "hVc:dDSs", options, 0)) >= 0) { | |
311 | switch(n) { | |
312 | case 'h': help(); | |
313 | case 'V': version("disorder-choose"); | |
314 | case 'c': configfile = optarg; break; | |
315 | case 'd': debugging = 1; break; | |
316 | case 'D': debugging = 0; break; | |
317 | case 'S': logsyslog = 0; break; | |
318 | case 's': logsyslog = 1; break; | |
319 | default: fatal(0, "invalid option"); | |
320 | } | |
321 | } | |
322 | if(logsyslog) { | |
323 | openlog(progname, LOG_PID, LOG_DAEMON); | |
324 | log_default = &log_syslog; | |
325 | } | |
326 | if(config_read(0)) fatal(0, "cannot read configuration"); | |
28dc2d22 RK |
327 | /* Find out current queue/recent list */ |
328 | queue_read(); | |
329 | recent_read(); | |
bea6f6d5 RK |
330 | /* Generate the candidate track list */ |
331 | trackdb_init(TRACKDB_NO_RECOVER); | |
332 | trackdb_open(TRACKDB_NO_UPGRADE|TRACKDB_READ_ONLY); | |
333 | global_tid = trackdb_begin_transaction(); | |
91c9324a RK |
334 | if((err = trackdb_get_global_tid("required-tags", global_tid, &tags))) |
335 | fatal(0, "error getting required-tags: %s", db_strerror(err)); | |
336 | required_tags = parsetags(tags); | |
337 | if((err = trackdb_get_global_tid("prohibited-tags", global_tid, &tags))) | |
338 | fatal(0, "error getting prohibited-tags: %s", db_strerror(err)); | |
339 | prohibited_tags = parsetags(tags); | |
bea6f6d5 RK |
340 | if(trackdb_scan(0, collect_tracks_callback, 0, global_tid)) |
341 | exit(1); | |
342 | trackdb_commit_transaction(global_tid); | |
343 | trackdb_close(); | |
344 | trackdb_deinit(); | |
345 | //info("ntracks=%ld total_weight=%lld", ntracks, total_weight); | |
346 | if(!total_weight) | |
347 | fatal(0, "no tracks match random choice criteria"); | |
348 | /* Pick a track */ | |
349 | pick_track(); | |
350 | xfclose(stdout); | |
351 | return 0; | |
352 | } | |
353 | ||
354 | /* | |
355 | Local Variables: | |
356 | c-basic-offset:2 | |
357 | comment-column:40 | |
358 | fill-column:79 | |
359 | indent-tabs-mode:nil | |
360 | End: | |
361 | */ |