#include <string.h>
#include <fcntl.h>
#include <syslog.h>
+#include <time.h>
#include "configuration.h"
#include "log.h"
#include "trackdb.h"
#include "trackdb-int.h"
#include "version.h"
+#include "trackname.h"
+#include "queue.h"
+#include "server-queue.h"
static DB_TXN *global_tid;
/** @brief Count of tracks */
static long ntracks;
+static char **required_tags;
+static char **prohibited_tags;
+
+static int queue_contains(const struct queue_entry *head,
+ const char *track) {
+ const struct queue_entry *q;
+
+ for(q = head->next; q != head; q = q->next)
+ if(!strcmp(q->track, track))
+ return 1;
+ return 0;
+}
+
/** @brief Compute the weight of a track
* @param track Track name (UTF-8)
* @param data Track data
*
* Tracks to be excluded entirely are given a weight of 0.
*/
-static unsigned long compute_weight(const char attribute((unused)) *track,
- struct kvp attribute((unused)) *data,
+static unsigned long compute_weight(const char *track,
+ struct kvp *data,
struct kvp *prefs) {
const char *s;
+ char **track_tags;
+ time_t last, now;
- /* Firstly, tracks with random play disabled always have weight 0 and that's
- * that */
+ /* Reject tracks not in any collection (race between edit config and
+ * rescan) */
+ if(!find_track_root(track)) {
+ info("found track not in any collection: %s", track);
+ return 0;
+ }
+
+ /* Reject aliases to avoid giving aliased tracks extra weight */
+ if(kvp_get(data, "_alias_for"))
+ return 0;
+
+ /* Reject tracks with random play disabled */
if((s = kvp_get(prefs, "pick_at_random"))
&& !strcmp(s, "0"))
return 0;
+
+ /* Reject tracks played within the last 8 hours */
+ if((s = kvp_get(prefs, "played_time"))) {
+ last = atoll(s);
+ now = time(0);
+ if(now < last + config->replay_min)
+ return 0;
+ }
+
+ /* Reject tracks currently in the queue or in the recent list */
+ if(queue_contains(&qhead, track)
+ || queue_contains(&phead, track))
+ return 0;
+
+ /* We'll need tags for a number of things */
+ track_tags = parsetags(kvp_get(prefs, "tags"));
+
+ /* Reject tracks with prohibited tags */
+ if(prohibited_tags && tag_intersection(track_tags, prohibited_tags))
+ return 0;
+
+ /* Reject tracks that lack required tags */
+ if(*required_tags && !tag_intersection(track_tags, required_tags))
+ return 0;
+
+ /* Use the configured weight if available */
+ if((s = kvp_get(prefs, "weight"))) {
+ long n;
+ errno = 0;
+
+ n = strtol(s, 0, 10);
+ if((errno == 0 || errno == ERANGE) && n >= 0)
+ return n;
+ }
+
return 90000;
}
struct kvp *prefs,
void attribute((unused)) *u,
DB_TXN attribute((unused)) *tid) {
- const unsigned long weight = compute_weight(track, data, prefs);
+ unsigned long weight = compute_weight(track, data, prefs);
if(weight) {
struct weighted_track *const t = xmalloc(sizeof *t);
+ /* Clamp weight so that we can fit in billions of tracks when we do
+ * arithmetic in long long */
+ if(weight > 0x7fffffff)
+ weight = 0x7fffffff;
t->next = tracks;
t->track = track;
t->weight = weight;
}
/** @brief Pick a random integer uniformly from [0, limit) */
-static unsigned long long pick_weight(unsigned long long limit) {
- unsigned long long n;
+static void random_bytes(unsigned char *buf, size_t n) {
static int fd = -1;
int r;
if((fd = open("/dev/urandom", O_RDONLY)) < 0)
fatal(errno, "opening /dev/urandom");
}
- if((r = read(fd, &n, sizeof n)) < 0)
+ if((r = read(fd, buf, n)) < 0)
fatal(errno, "reading /dev/urandom");
- if((size_t)r < sizeof n)
+ if((size_t)r < n)
fatal(0, "short read from /dev/urandom");
- return n % limit;
+}
+
+/** @brief Pick a random integer uniformly from [0, limit) */
+static unsigned long long pick_weight(unsigned long long limit) {
+ unsigned char buf[(sizeof(unsigned long long) * CHAR_BIT + 7)/8], m;
+ unsigned long long t, r, slop;
+ int i, nby, nbi;
+
+ //info("pick_weight: limit = %llu", limit);
+
+ /* First, decide how many bits of output we actually need; do bytes first
+ * (they're quicker) and then bits.
+ *
+ * To speed this up, we could use a binary search if we knew where to
+ * start. (Note that shifting by ULLONG_BITS or more (if such a constant
+ * existed) is undefined behaviour, so we mustn't do that.) Figuring out a
+ * start point involves preprocessor and/or autoconf magic.
+ */
+ for (nby = 1, t = (limit - 1) >> 8; t; nby++, t >>= 8)
+ ;
+ nbi = (nby - 1) << 3; t = limit >> nbi;
+ if (t >> 4) { t >>= 4; nbi += 4; }
+ if (t >> 2) { t >>= 2; nbi += 2; }
+ if (t >> 1) { t >>= 1; nbi += 1; }
+ nbi++;
+ //info("nby = %d; nbi = %d", nby, nbi);
+
+ /* Main randomness collection loop. We read a number of bytes from the
+ * randomness source, and glue them together into an integer (dropping
+ * bits off the top byte as necessary). Call the result r; we have
+ * 2^{nbi - 1) <= limit < 2^nbi and r < 2^nbi. If r < limit then we win;
+ * otherwise we try again. Given the above bounds, we expect fewer than 2
+ * iterations.
+ *
+ * Unfortunately there are subtleties. In particular, 2^nbi may in fact be
+ * zero due to overflow. So in fact what we do is compute slop = 2^nbi -
+ * limit > 0; if r < slop then we try again, otherwise r - slop is our
+ * winner.
+ */
+ slop = (2 << (nbi - 1)) - limit;
+ m = nbi & 7 ? (1 << (nbi & 7)) - 1 : 0xff;
+ //info("slop = %llu", slop);
+ //info("m = 0x%02x", m);
+
+ do {
+ /* Actually get some random data. */
+ random_bytes(buf, nby);
+
+ /* Clobber the top byte. */
+ buf[0] &= m;
+
+ /* Turn it into an integer. */
+ for (r = 0, i = 0; i < nby; i++)
+ r = (r << 8) | buf[i];
+ //info("r = %llu", r);
+ } while (r < slop);
+
+ return r - slop;
}
/** @brief Pick a track at random and write it to stdout */
}
int main(int argc, char **argv) {
- int n, logsyslog = !isatty(2);
+ int n, logsyslog = !isatty(2), err;
+ const char *tags;
set_progname(argv);
mem_init();
log_default = &log_syslog;
}
if(config_read(0)) fatal(0, "cannot read configuration");
+ /* Find out current queue/recent list */
+ queue_read();
+ recent_read();
/* Generate the candidate track list */
trackdb_init(TRACKDB_NO_RECOVER);
trackdb_open(TRACKDB_NO_UPGRADE|TRACKDB_READ_ONLY);
global_tid = trackdb_begin_transaction();
+ if((err = trackdb_get_global_tid("required-tags", global_tid, &tags)))
+ fatal(0, "error getting required-tags: %s", db_strerror(err));
+ required_tags = parsetags(tags);
+ if((err = trackdb_get_global_tid("prohibited-tags", global_tid, &tags)))
+ fatal(0, "error getting prohibited-tags: %s", db_strerror(err));
+ prohibited_tags = parsetags(tags);
if(trackdb_scan(0, collect_tracks_callback, 0, global_tid))
exit(1);
trackdb_commit_transaction(global_tid);
~mdw / disorder / blobdiff