]> git.saurik.com Git - redis.git/blob - src/db.c
A reimplementation of blocking operation internals.
[redis.git] / src / db.c
1 #include "redis.h"
2
3 #include <signal.h>
4 #include <ctype.h>
5
6 void SlotToKeyAdd(robj *key);
7 void SlotToKeyDel(robj *key);
8
9 /*-----------------------------------------------------------------------------
10 * C-level DB API
11 *----------------------------------------------------------------------------*/
12
13 robj *lookupKey(redisDb *db, robj *key) {
14 dictEntry *de = dictFind(db->dict,key->ptr);
15 if (de) {
16 robj *val = dictGetVal(de);
17
18 /* Update the access time for the aging algorithm.
19 * Don't do it if we have a saving child, as this will trigger
20 * a copy on write madness. */
21 if (server.rdb_child_pid == -1 && server.aof_child_pid == -1)
22 val->lru = server.lruclock;
23 return val;
24 } else {
25 return NULL;
26 }
27 }
28
29 robj *lookupKeyRead(redisDb *db, robj *key) {
30 robj *val;
31
32 expireIfNeeded(db,key);
33 val = lookupKey(db,key);
34 if (val == NULL)
35 server.stat_keyspace_misses++;
36 else
37 server.stat_keyspace_hits++;
38 return val;
39 }
40
41 robj *lookupKeyWrite(redisDb *db, robj *key) {
42 expireIfNeeded(db,key);
43 return lookupKey(db,key);
44 }
45
46 robj *lookupKeyReadOrReply(redisClient *c, robj *key, robj *reply) {
47 robj *o = lookupKeyRead(c->db, key);
48 if (!o) addReply(c,reply);
49 return o;
50 }
51
52 robj *lookupKeyWriteOrReply(redisClient *c, robj *key, robj *reply) {
53 robj *o = lookupKeyWrite(c->db, key);
54 if (!o) addReply(c,reply);
55 return o;
56 }
57
58 /* Add the key to the DB. It's up to the caller to increment the reference
59 * counte of the value if needed.
60 *
61 * The program is aborted if the key already exists. */
62 void dbAdd(redisDb *db, robj *key, robj *val) {
63 sds copy = sdsdup(key->ptr);
64 int retval = dictAdd(db->dict, copy, val);
65
66 redisAssertWithInfo(NULL,key,retval == REDIS_OK);
67 if (server.cluster_enabled) SlotToKeyAdd(key);
68 }
69
70 /* Overwrite an existing key with a new value. Incrementing the reference
71 * count of the new value is up to the caller.
72 * This function does not modify the expire time of the existing key.
73 *
74 * The program is aborted if the key was not already present. */
75 void dbOverwrite(redisDb *db, robj *key, robj *val) {
76 struct dictEntry *de = dictFind(db->dict,key->ptr);
77
78 redisAssertWithInfo(NULL,key,de != NULL);
79 dictReplace(db->dict, key->ptr, val);
80 }
81
82 /* High level Set operation. This function can be used in order to set
83 * a key, whatever it was existing or not, to a new object.
84 *
85 * 1) The ref count of the value object is incremented.
86 * 2) clients WATCHing for the destination key notified.
87 * 3) The expire time of the key is reset (the key is made persistent). */
88 void setKey(redisDb *db, robj *key, robj *val) {
89 if (lookupKeyWrite(db,key) == NULL) {
90 dbAdd(db,key,val);
91 } else {
92 dbOverwrite(db,key,val);
93 }
94 incrRefCount(val);
95 removeExpire(db,key);
96 signalModifiedKey(db,key);
97 }
98
99 int dbExists(redisDb *db, robj *key) {
100 return dictFind(db->dict,key->ptr) != NULL;
101 }
102
103 /* Return a random key, in form of a Redis object.
104 * If there are no keys, NULL is returned.
105 *
106 * The function makes sure to return keys not already expired. */
107 robj *dbRandomKey(redisDb *db) {
108 struct dictEntry *de;
109
110 while(1) {
111 sds key;
112 robj *keyobj;
113
114 de = dictGetRandomKey(db->dict);
115 if (de == NULL) return NULL;
116
117 key = dictGetKey(de);
118 keyobj = createStringObject(key,sdslen(key));
119 if (dictFind(db->expires,key)) {
120 if (expireIfNeeded(db,keyobj)) {
121 decrRefCount(keyobj);
122 continue; /* search for another key. This expired. */
123 }
124 }
125 return keyobj;
126 }
127 }
128
129 /* Delete a key, value, and associated expiration entry if any, from the DB */
130 int dbDelete(redisDb *db, robj *key) {
131 /* Deleting an entry from the expires dict will not free the sds of
132 * the key, because it is shared with the main dictionary. */
133 if (dictSize(db->expires) > 0) dictDelete(db->expires,key->ptr);
134 if (dictDelete(db->dict,key->ptr) == DICT_OK) {
135 if (server.cluster_enabled) SlotToKeyDel(key);
136 return 1;
137 } else {
138 return 0;
139 }
140 }
141
142 long long emptyDb() {
143 int j;
144 long long removed = 0;
145
146 for (j = 0; j < server.dbnum; j++) {
147 removed += dictSize(server.db[j].dict);
148 dictEmpty(server.db[j].dict);
149 dictEmpty(server.db[j].expires);
150 }
151 return removed;
152 }
153
154 int selectDb(redisClient *c, int id) {
155 if (id < 0 || id >= server.dbnum)
156 return REDIS_ERR;
157 c->db = &server.db[id];
158 return REDIS_OK;
159 }
160
161 /*-----------------------------------------------------------------------------
162 * Hooks for key space changes.
163 *
164 * Every time a key in the database is modified the function
165 * signalModifiedKey() is called.
166 *
167 * Every time a DB is flushed the function signalFlushDb() is called.
168 *----------------------------------------------------------------------------*/
169
170 void signalModifiedKey(redisDb *db, robj *key) {
171 touchWatchedKey(db,key);
172 }
173
174 void signalFlushedDb(int dbid) {
175 touchWatchedKeysOnFlush(dbid);
176 }
177
178 /*-----------------------------------------------------------------------------
179 * Type agnostic commands operating on the key space
180 *----------------------------------------------------------------------------*/
181
182 void flushdbCommand(redisClient *c) {
183 server.dirty += dictSize(c->db->dict);
184 signalFlushedDb(c->db->id);
185 dictEmpty(c->db->dict);
186 dictEmpty(c->db->expires);
187 addReply(c,shared.ok);
188 }
189
190 void flushallCommand(redisClient *c) {
191 signalFlushedDb(-1);
192 server.dirty += emptyDb();
193 addReply(c,shared.ok);
194 if (server.rdb_child_pid != -1) {
195 kill(server.rdb_child_pid,SIGKILL);
196 rdbRemoveTempFile(server.rdb_child_pid);
197 }
198 if (server.saveparamslen > 0) {
199 /* Normally rdbSave() will reset dirty, but we don't want this here
200 * as otherwise FLUSHALL will not be replicated nor put into the AOF. */
201 int saved_dirty = server.dirty;
202 rdbSave(server.rdb_filename);
203 server.dirty = saved_dirty;
204 }
205 server.dirty++;
206 }
207
208 void delCommand(redisClient *c) {
209 int deleted = 0, j;
210
211 for (j = 1; j < c->argc; j++) {
212 if (dbDelete(c->db,c->argv[j])) {
213 signalModifiedKey(c->db,c->argv[j]);
214 server.dirty++;
215 deleted++;
216 }
217 }
218 addReplyLongLong(c,deleted);
219 }
220
221 void existsCommand(redisClient *c) {
222 expireIfNeeded(c->db,c->argv[1]);
223 if (dbExists(c->db,c->argv[1])) {
224 addReply(c, shared.cone);
225 } else {
226 addReply(c, shared.czero);
227 }
228 }
229
230 void selectCommand(redisClient *c) {
231 long id;
232
233 if (getLongFromObjectOrReply(c, c->argv[1], &id,
234 "invalid DB index") != REDIS_OK)
235 return;
236
237 if (server.cluster_enabled && id != 0) {
238 addReplyError(c,"SELECT is not allowed in cluster mode");
239 return;
240 }
241 if (selectDb(c,id) == REDIS_ERR) {
242 addReplyError(c,"invalid DB index");
243 } else {
244 addReply(c,shared.ok);
245 }
246 }
247
248 void randomkeyCommand(redisClient *c) {
249 robj *key;
250
251 if ((key = dbRandomKey(c->db)) == NULL) {
252 addReply(c,shared.nullbulk);
253 return;
254 }
255
256 addReplyBulk(c,key);
257 decrRefCount(key);
258 }
259
260 void keysCommand(redisClient *c) {
261 dictIterator *di;
262 dictEntry *de;
263 sds pattern = c->argv[1]->ptr;
264 int plen = sdslen(pattern), allkeys;
265 unsigned long numkeys = 0;
266 void *replylen = addDeferredMultiBulkLength(c);
267
268 di = dictGetSafeIterator(c->db->dict);
269 allkeys = (pattern[0] == '*' && pattern[1] == '\0');
270 while((de = dictNext(di)) != NULL) {
271 sds key = dictGetKey(de);
272 robj *keyobj;
273
274 if (allkeys || stringmatchlen(pattern,plen,key,sdslen(key),0)) {
275 keyobj = createStringObject(key,sdslen(key));
276 if (expireIfNeeded(c->db,keyobj) == 0) {
277 addReplyBulk(c,keyobj);
278 numkeys++;
279 }
280 decrRefCount(keyobj);
281 }
282 }
283 dictReleaseIterator(di);
284 setDeferredMultiBulkLength(c,replylen,numkeys);
285 }
286
287 void dbsizeCommand(redisClient *c) {
288 addReplyLongLong(c,dictSize(c->db->dict));
289 }
290
291 void lastsaveCommand(redisClient *c) {
292 addReplyLongLong(c,server.lastsave);
293 }
294
295 void typeCommand(redisClient *c) {
296 robj *o;
297 char *type;
298
299 o = lookupKeyRead(c->db,c->argv[1]);
300 if (o == NULL) {
301 type = "none";
302 } else {
303 switch(o->type) {
304 case REDIS_STRING: type = "string"; break;
305 case REDIS_LIST: type = "list"; break;
306 case REDIS_SET: type = "set"; break;
307 case REDIS_ZSET: type = "zset"; break;
308 case REDIS_HASH: type = "hash"; break;
309 default: type = "unknown"; break;
310 }
311 }
312 addReplyStatus(c,type);
313 }
314
315 void shutdownCommand(redisClient *c) {
316 int flags = 0;
317
318 if (c->argc > 2) {
319 addReply(c,shared.syntaxerr);
320 return;
321 } else if (c->argc == 2) {
322 if (!strcasecmp(c->argv[1]->ptr,"nosave")) {
323 flags |= REDIS_SHUTDOWN_NOSAVE;
324 } else if (!strcasecmp(c->argv[1]->ptr,"save")) {
325 flags |= REDIS_SHUTDOWN_SAVE;
326 } else {
327 addReply(c,shared.syntaxerr);
328 return;
329 }
330 }
331 if (prepareForShutdown(flags) == REDIS_OK) exit(0);
332 addReplyError(c,"Errors trying to SHUTDOWN. Check logs.");
333 }
334
335 void renameGenericCommand(redisClient *c, int nx) {
336 robj *o;
337 long long expire;
338
339 /* To use the same key as src and dst is probably an error */
340 if (sdscmp(c->argv[1]->ptr,c->argv[2]->ptr) == 0) {
341 addReply(c,shared.sameobjecterr);
342 return;
343 }
344
345 if ((o = lookupKeyWriteOrReply(c,c->argv[1],shared.nokeyerr)) == NULL)
346 return;
347
348 incrRefCount(o);
349 expire = getExpire(c->db,c->argv[1]);
350 if (lookupKeyWrite(c->db,c->argv[2]) != NULL) {
351 if (nx) {
352 decrRefCount(o);
353 addReply(c,shared.czero);
354 return;
355 }
356 /* Overwrite: delete the old key before creating the new one with the same name. */
357 dbDelete(c->db,c->argv[2]);
358 }
359 dbAdd(c->db,c->argv[2],o);
360 if (expire != -1) setExpire(c->db,c->argv[2],expire);
361 dbDelete(c->db,c->argv[1]);
362 signalModifiedKey(c->db,c->argv[1]);
363 signalModifiedKey(c->db,c->argv[2]);
364 server.dirty++;
365 addReply(c,nx ? shared.cone : shared.ok);
366 }
367
368 void renameCommand(redisClient *c) {
369 renameGenericCommand(c,0);
370 }
371
372 void renamenxCommand(redisClient *c) {
373 renameGenericCommand(c,1);
374 }
375
376 void moveCommand(redisClient *c) {
377 robj *o;
378 redisDb *src, *dst;
379 int srcid;
380
381 if (server.cluster_enabled) {
382 addReplyError(c,"MOVE is not allowed in cluster mode");
383 return;
384 }
385
386 /* Obtain source and target DB pointers */
387 src = c->db;
388 srcid = c->db->id;
389 if (selectDb(c,atoi(c->argv[2]->ptr)) == REDIS_ERR) {
390 addReply(c,shared.outofrangeerr);
391 return;
392 }
393 dst = c->db;
394 selectDb(c,srcid); /* Back to the source DB */
395
396 /* If the user is moving using as target the same
397 * DB as the source DB it is probably an error. */
398 if (src == dst) {
399 addReply(c,shared.sameobjecterr);
400 return;
401 }
402
403 /* Check if the element exists and get a reference */
404 o = lookupKeyWrite(c->db,c->argv[1]);
405 if (!o) {
406 addReply(c,shared.czero);
407 return;
408 }
409
410 /* Return zero if the key already exists in the target DB */
411 if (lookupKeyWrite(dst,c->argv[1]) != NULL) {
412 addReply(c,shared.czero);
413 return;
414 }
415 dbAdd(dst,c->argv[1],o);
416 incrRefCount(o);
417
418 /* OK! key moved, free the entry in the source DB */
419 dbDelete(src,c->argv[1]);
420 server.dirty++;
421 addReply(c,shared.cone);
422 }
423
424 /*-----------------------------------------------------------------------------
425 * Expires API
426 *----------------------------------------------------------------------------*/
427
428 int removeExpire(redisDb *db, robj *key) {
429 /* An expire may only be removed if there is a corresponding entry in the
430 * main dict. Otherwise, the key will never be freed. */
431 redisAssertWithInfo(NULL,key,dictFind(db->dict,key->ptr) != NULL);
432 return dictDelete(db->expires,key->ptr) == DICT_OK;
433 }
434
435 void setExpire(redisDb *db, robj *key, long long when) {
436 dictEntry *kde, *de;
437
438 /* Reuse the sds from the main dict in the expire dict */
439 kde = dictFind(db->dict,key->ptr);
440 redisAssertWithInfo(NULL,key,kde != NULL);
441 de = dictReplaceRaw(db->expires,dictGetKey(kde));
442 dictSetSignedIntegerVal(de,when);
443 }
444
445 /* Return the expire time of the specified key, or -1 if no expire
446 * is associated with this key (i.e. the key is non volatile) */
447 long long getExpire(redisDb *db, robj *key) {
448 dictEntry *de;
449
450 /* No expire? return ASAP */
451 if (dictSize(db->expires) == 0 ||
452 (de = dictFind(db->expires,key->ptr)) == NULL) return -1;
453
454 /* The entry was found in the expire dict, this means it should also
455 * be present in the main dict (safety check). */
456 redisAssertWithInfo(NULL,key,dictFind(db->dict,key->ptr) != NULL);
457 return dictGetSignedIntegerVal(de);
458 }
459
460 /* Propagate expires into slaves and the AOF file.
461 * When a key expires in the master, a DEL operation for this key is sent
462 * to all the slaves and the AOF file if enabled.
463 *
464 * This way the key expiry is centralized in one place, and since both
465 * AOF and the master->slave link guarantee operation ordering, everything
466 * will be consistent even if we allow write operations against expiring
467 * keys. */
468 void propagateExpire(redisDb *db, robj *key) {
469 robj *argv[2];
470
471 argv[0] = shared.del;
472 argv[1] = key;
473 incrRefCount(argv[0]);
474 incrRefCount(argv[1]);
475
476 if (server.aof_state != REDIS_AOF_OFF)
477 feedAppendOnlyFile(server.delCommand,db->id,argv,2);
478 if (listLength(server.slaves))
479 replicationFeedSlaves(server.slaves,db->id,argv,2);
480
481 decrRefCount(argv[0]);
482 decrRefCount(argv[1]);
483 }
484
485 int expireIfNeeded(redisDb *db, robj *key) {
486 long long when = getExpire(db,key);
487
488 if (when < 0) return 0; /* No expire for this key */
489
490 /* Don't expire anything while loading. It will be done later. */
491 if (server.loading) return 0;
492
493 /* If we are running in the context of a slave, return ASAP:
494 * the slave key expiration is controlled by the master that will
495 * send us synthesized DEL operations for expired keys.
496 *
497 * Still we try to return the right information to the caller,
498 * that is, 0 if we think the key should be still valid, 1 if
499 * we think the key is expired at this time. */
500 if (server.masterhost != NULL) {
501 return mstime() > when;
502 }
503
504 /* Return when this key has not expired */
505 if (mstime() <= when) return 0;
506
507 /* Delete the key */
508 server.stat_expiredkeys++;
509 propagateExpire(db,key);
510 return dbDelete(db,key);
511 }
512
513 /*-----------------------------------------------------------------------------
514 * Expires Commands
515 *----------------------------------------------------------------------------*/
516
517 /* This is the generic command implementation for EXPIRE, PEXPIRE, EXPIREAT
518 * and PEXPIREAT. Because the commad second argument may be relative or absolute
519 * the "basetime" argument is used to signal what the base time is (either 0
520 * for *AT variants of the command, or the current time for relative expires).
521 *
522 * unit is either UNIT_SECONDS or UNIT_MILLISECONDS, and is only used for
523 * the argv[2] parameter. The basetime is always specified in milliesconds. */
524 void expireGenericCommand(redisClient *c, long long basetime, int unit) {
525 dictEntry *de;
526 robj *key = c->argv[1], *param = c->argv[2];
527 long long when; /* unix time in milliseconds when the key will expire. */
528
529 if (getLongLongFromObjectOrReply(c, param, &when, NULL) != REDIS_OK)
530 return;
531
532 if (unit == UNIT_SECONDS) when *= 1000;
533 when += basetime;
534
535 de = dictFind(c->db->dict,key->ptr);
536 if (de == NULL) {
537 addReply(c,shared.czero);
538 return;
539 }
540 /* EXPIRE with negative TTL, or EXPIREAT with a timestamp into the past
541 * should never be executed as a DEL when load the AOF or in the context
542 * of a slave instance.
543 *
544 * Instead we take the other branch of the IF statement setting an expire
545 * (possibly in the past) and wait for an explicit DEL from the master. */
546 if (when <= mstime() && !server.loading && !server.masterhost) {
547 robj *aux;
548
549 redisAssertWithInfo(c,key,dbDelete(c->db,key));
550 server.dirty++;
551
552 /* Replicate/AOF this as an explicit DEL. */
553 aux = createStringObject("DEL",3);
554 rewriteClientCommandVector(c,2,aux,key);
555 decrRefCount(aux);
556 signalModifiedKey(c->db,key);
557 addReply(c, shared.cone);
558 return;
559 } else {
560 setExpire(c->db,key,when);
561 addReply(c,shared.cone);
562 signalModifiedKey(c->db,key);
563 server.dirty++;
564 return;
565 }
566 }
567
568 void expireCommand(redisClient *c) {
569 expireGenericCommand(c,mstime(),UNIT_SECONDS);
570 }
571
572 void expireatCommand(redisClient *c) {
573 expireGenericCommand(c,0,UNIT_SECONDS);
574 }
575
576 void pexpireCommand(redisClient *c) {
577 expireGenericCommand(c,mstime(),UNIT_MILLISECONDS);
578 }
579
580 void pexpireatCommand(redisClient *c) {
581 expireGenericCommand(c,0,UNIT_MILLISECONDS);
582 }
583
584 void ttlGenericCommand(redisClient *c, int output_ms) {
585 long long expire, ttl = -1;
586
587 expire = getExpire(c->db,c->argv[1]);
588 if (expire != -1) {
589 ttl = expire-mstime();
590 if (ttl < 0) ttl = -1;
591 }
592 if (ttl == -1) {
593 addReplyLongLong(c,-1);
594 } else {
595 addReplyLongLong(c,output_ms ? ttl : ((ttl+500)/1000));
596 }
597 }
598
599 void ttlCommand(redisClient *c) {
600 ttlGenericCommand(c, 0);
601 }
602
603 void pttlCommand(redisClient *c) {
604 ttlGenericCommand(c, 1);
605 }
606
607 void persistCommand(redisClient *c) {
608 dictEntry *de;
609
610 de = dictFind(c->db->dict,c->argv[1]->ptr);
611 if (de == NULL) {
612 addReply(c,shared.czero);
613 } else {
614 if (removeExpire(c->db,c->argv[1])) {
615 addReply(c,shared.cone);
616 server.dirty++;
617 } else {
618 addReply(c,shared.czero);
619 }
620 }
621 }
622
623 /* -----------------------------------------------------------------------------
624 * API to get key arguments from commands
625 * ---------------------------------------------------------------------------*/
626
627 int *getKeysUsingCommandTable(struct redisCommand *cmd,robj **argv, int argc, int *numkeys) {
628 int j, i = 0, last, *keys;
629 REDIS_NOTUSED(argv);
630
631 if (cmd->firstkey == 0) {
632 *numkeys = 0;
633 return NULL;
634 }
635 last = cmd->lastkey;
636 if (last < 0) last = argc+last;
637 keys = zmalloc(sizeof(int)*((last - cmd->firstkey)+1));
638 for (j = cmd->firstkey; j <= last; j += cmd->keystep) {
639 redisAssert(j < argc);
640 keys[i++] = j;
641 }
642 *numkeys = i;
643 return keys;
644 }
645
646 int *getKeysFromCommand(struct redisCommand *cmd,robj **argv, int argc, int *numkeys, int flags) {
647 if (cmd->getkeys_proc) {
648 return cmd->getkeys_proc(cmd,argv,argc,numkeys,flags);
649 } else {
650 return getKeysUsingCommandTable(cmd,argv,argc,numkeys);
651 }
652 }
653
654 void getKeysFreeResult(int *result) {
655 zfree(result);
656 }
657
658 int *noPreloadGetKeys(struct redisCommand *cmd,robj **argv, int argc, int *numkeys, int flags) {
659 if (flags & REDIS_GETKEYS_PRELOAD) {
660 *numkeys = 0;
661 return NULL;
662 } else {
663 return getKeysUsingCommandTable(cmd,argv,argc,numkeys);
664 }
665 }
666
667 int *renameGetKeys(struct redisCommand *cmd,robj **argv, int argc, int *numkeys, int flags) {
668 if (flags & REDIS_GETKEYS_PRELOAD) {
669 int *keys = zmalloc(sizeof(int));
670 *numkeys = 1;
671 keys[0] = 1;
672 return keys;
673 } else {
674 return getKeysUsingCommandTable(cmd,argv,argc,numkeys);
675 }
676 }
677
678 int *zunionInterGetKeys(struct redisCommand *cmd,robj **argv, int argc, int *numkeys, int flags) {
679 int i, num, *keys;
680 REDIS_NOTUSED(cmd);
681 REDIS_NOTUSED(flags);
682
683 num = atoi(argv[2]->ptr);
684 /* Sanity check. Don't return any key if the command is going to
685 * reply with syntax error. */
686 if (num > (argc-3)) {
687 *numkeys = 0;
688 return NULL;
689 }
690 keys = zmalloc(sizeof(int)*num);
691 for (i = 0; i < num; i++) keys[i] = 3+i;
692 *numkeys = num;
693 return keys;
694 }
695
696 /* Slot to Key API. This is used by Redis Cluster in order to obtain in
697 * a fast way a key that belongs to a specified hash slot. This is useful
698 * while rehashing the cluster. */
699 void SlotToKeyAdd(robj *key) {
700 unsigned int hashslot = keyHashSlot(key->ptr,sdslen(key->ptr));
701
702 zslInsert(server.cluster.slots_to_keys,hashslot,key);
703 incrRefCount(key);
704 }
705
706 void SlotToKeyDel(robj *key) {
707 unsigned int hashslot = keyHashSlot(key->ptr,sdslen(key->ptr));
708
709 zslDelete(server.cluster.slots_to_keys,hashslot,key);
710 }
711
712 unsigned int GetKeysInSlot(unsigned int hashslot, robj **keys, unsigned int count) {
713 zskiplistNode *n;
714 zrangespec range;
715 int j = 0;
716
717 range.min = range.max = hashslot;
718 range.minex = range.maxex = 0;
719
720 n = zslFirstInRange(server.cluster.slots_to_keys, range);
721 while(n && n->score == hashslot && count--) {
722 keys[j++] = n->obj;
723 n = n->level[0].forward;
724 }
725 return j;
726 }