src/db.c

   1 #include "redis.h"
   2
   3 #include <signal.h>
   4
   5 /*-----------------------------------------------------------------------------
   6  * C-level DB API
   7  *----------------------------------------------------------------------------*/
   8
   9 robj *lookupKey(redisDb *db, robj *key) {
  10     dictEntry *de = dictFind(db->dict,key->ptr);
  11     if (de) {
  12         robj *val = dictGetEntryVal(de);
  13
  14         if (server.vm_enabled) {
  15             if (val->storage == REDIS_VM_MEMORY ||
  16                 val->storage == REDIS_VM_SWAPPING)
  17             {
  18                 /* If we were swapping the object out, cancel the operation */
  19                 if (val->storage == REDIS_VM_SWAPPING)
  20                     vmCancelThreadedIOJob(val);
  21                 /* Update the access time for the aging algorithm. */
  22                 val->lru = server.lruclock;
  23             } else {
  24                 int notify = (val->storage == REDIS_VM_LOADING);
  25
  26                 /* Our value was swapped on disk. Bring it at home. */
  27                 redisAssert(val->type == REDIS_VMPOINTER);
  28                 val = vmLoadObject(val);
  29                 dictGetEntryVal(de) = val;
  30
  31                 /* Clients blocked by the VM subsystem may be waiting for
  32                  * this key... */
  33                 if (notify) handleClientsBlockedOnSwappedKey(db,key);
  34             }
  35         }
  36         return val;
  37     } else {
  38         return NULL;
  39     }
  40 }
  41
  42 robj *lookupKeyRead(redisDb *db, robj *key) {
  43     expireIfNeeded(db,key);
  44     return lookupKey(db,key);
  45 }
  46
  47 robj *lookupKeyWrite(redisDb *db, robj *key) {
  48     expireIfNeeded(db,key);
  49     return lookupKey(db,key);
  50 }
  51
  52 robj *lookupKeyReadOrReply(redisClient *c, robj *key, robj *reply) {
  53     robj *o = lookupKeyRead(c->db, key);
  54     if (!o) addReply(c,reply);
  55     return o;
  56 }
  57
  58 robj *lookupKeyWriteOrReply(redisClient *c, robj *key, robj *reply) {
  59     robj *o = lookupKeyWrite(c->db, key);
  60     if (!o) addReply(c,reply);
  61     return o;
  62 }
  63
  64 /* Add the key to the DB. If the key already exists REDIS_ERR is returned,
  65  * otherwise REDIS_OK is returned, and the caller should increment the
  66  * refcount of 'val'. */
  67 int dbAdd(redisDb *db, robj *key, robj *val) {
  68     /* Perform a lookup before adding the key, as we need to copy the
  69      * key value. */
  70     if (dictFind(db->dict, key->ptr) != NULL) {
  71         return REDIS_ERR;
  72     } else {
  73         sds copy = sdsdup(key->ptr);
  74         dictAdd(db->dict, copy, val);
  75         return REDIS_OK;
  76     }
  77 }
  78
  79 /* If the key does not exist, this is just like dbAdd(). Otherwise
  80  * the value associated to the key is replaced with the new one.
  81  *
  82  * On update (key already existed) 0 is returned. Otherwise 1. */
  83 int dbReplace(redisDb *db, robj *key, robj *val) {
  84     if (dictFind(db->dict,key->ptr) == NULL) {
  85         sds copy = sdsdup(key->ptr);
  86         dictAdd(db->dict, copy, val);
  87         return 1;
  88     } else {
  89         dictReplace(db->dict, key->ptr, val);
  90         return 0;
  91     }
  92 }
  93
  94 int dbExists(redisDb *db, robj *key) {
  95     return dictFind(db->dict,key->ptr) != NULL;
  96 }
  97
  98 /* Return a random key, in form of a Redis object.
  99  * If there are no keys, NULL is returned.
 100  *
 101  * The function makes sure to return keys not already expired. */
 102 robj *dbRandomKey(redisDb *db) {
 103     struct dictEntry *de;
 104
 105     while(1) {
 106         sds key;
 107         robj *keyobj;
 108
 109         de = dictGetRandomKey(db->dict);
 110         if (de == NULL) return NULL;
 111
 112         key = dictGetEntryKey(de);
 113         keyobj = createStringObject(key,sdslen(key));
 114         if (dictFind(db->expires,key)) {
 115             if (expireIfNeeded(db,keyobj)) {
 116                 decrRefCount(keyobj);
 117                 continue; /* search for another key. This expired. */
 118             }
 119         }
 120         return keyobj;
 121     }
 122 }
 123
 124 /* Delete a key, value, and associated expiration entry if any, from the DB */
 125 int dbDelete(redisDb *db, robj *key) {
 126     /* Deleting an entry from the expires dict will not free the sds of
 127      * the key, because it is shared with the main dictionary. */
 128     if (dictSize(db->expires) > 0) dictDelete(db->expires,key->ptr);
 129     return dictDelete(db->dict,key->ptr) == DICT_OK;
 130 }
 131
 132 /* Empty the whole database */
 133 long long emptyDb() {
 134     int j;
 135     long long removed = 0;
 136
 137     for (j = 0; j < server.dbnum; j++) {
 138         removed += dictSize(server.db[j].dict);
 139         dictEmpty(server.db[j].dict);
 140         dictEmpty(server.db[j].expires);
 141     }
 142     return removed;
 143 }
 144
 145 int selectDb(redisClient *c, int id) {
 146     if (id < 0 || id >= server.dbnum)
 147         return REDIS_ERR;
 148     c->db = &server.db[id];
 149     return REDIS_OK;
 150 }
 151
 152 /*-----------------------------------------------------------------------------
 153  * Type agnostic commands operating on the key space
 154  *----------------------------------------------------------------------------*/
 155
 156 void flushdbCommand(redisClient *c) {
 157     server.dirty += dictSize(c->db->dict);
 158     touchWatchedKeysOnFlush(c->db->id);
 159     dictEmpty(c->db->dict);
 160     dictEmpty(c->db->expires);
 161     addReply(c,shared.ok);
 162 }
 163
 164 void flushallCommand(redisClient *c) {
 165     touchWatchedKeysOnFlush(-1);
 166     server.dirty += emptyDb();
 167     addReply(c,shared.ok);
 168     if (server.bgsavechildpid != -1) {
 169         kill(server.bgsavechildpid,SIGKILL);
 170         rdbRemoveTempFile(server.bgsavechildpid);
 171     }
 172     rdbSave(server.dbfilename);
 173     server.dirty++;
 174 }
 175
 176 void delCommand(redisClient *c) {
 177     int deleted = 0, j;
 178
 179     for (j = 1; j < c->argc; j++) {
 180         if (dbDelete(c->db,c->argv[j])) {
 181             touchWatchedKey(c->db,c->argv[j]);
 182             server.dirty++;
 183             deleted++;
 184         }
 185     }
 186     addReplyLongLong(c,deleted);
 187 }
 188
 189 void existsCommand(redisClient *c) {
 190     expireIfNeeded(c->db,c->argv[1]);
 191     if (dbExists(c->db,c->argv[1])) {
 192         addReply(c, shared.cone);
 193     } else {
 194         addReply(c, shared.czero);
 195     }
 196 }
 197
 198 void selectCommand(redisClient *c) {
 199     int id = atoi(c->argv[1]->ptr);
 200
 201     if (selectDb(c,id) == REDIS_ERR) {
 202         addReplySds(c,sdsnew("-ERR invalid DB index\r\n"));
 203     } else {
 204         addReply(c,shared.ok);
 205     }
 206 }
 207
 208 void randomkeyCommand(redisClient *c) {
 209     robj *key;
 210
 211     if ((key = dbRandomKey(c->db)) == NULL) {
 212         addReply(c,shared.nullbulk);
 213         return;
 214     }
 215
 216     addReplyBulk(c,key);
 217     decrRefCount(key);
 218 }
 219
 220 void keysCommand(redisClient *c) {
 221     dictIterator *di;
 222     dictEntry *de;
 223     sds pattern = c->argv[1]->ptr;
 224     int plen = sdslen(pattern);
 225     unsigned long numkeys = 0;
 226     void *replylen = addDeferredMultiBulkLength(c);
 227
 228     di = dictGetIterator(c->db->dict);
 229     while((de = dictNext(di)) != NULL) {
 230         sds key = dictGetEntryKey(de);
 231         robj *keyobj;
 232
 233         if ((pattern[0] == '*' && pattern[1] == '\0') ||
 234             stringmatchlen(pattern,plen,key,sdslen(key),0)) {
 235             keyobj = createStringObject(key,sdslen(key));
 236             if (expireIfNeeded(c->db,keyobj) == 0) {
 237                 addReplyBulk(c,keyobj);
 238                 numkeys++;
 239             }
 240             decrRefCount(keyobj);
 241         }
 242     }
 243     dictReleaseIterator(di);
 244     setDeferredMultiBulkLength(c,replylen,numkeys);
 245 }
 246
 247 void dbsizeCommand(redisClient *c) {
 248     addReplySds(c,
 249         sdscatprintf(sdsempty(),":%lu\r\n",dictSize(c->db->dict)));
 250 }
 251
 252 void lastsaveCommand(redisClient *c) {
 253     addReplySds(c,
 254         sdscatprintf(sdsempty(),":%lu\r\n",server.lastsave));
 255 }
 256
 257 void typeCommand(redisClient *c) {
 258     robj *o;
 259     char *type;
 260
 261     o = lookupKeyRead(c->db,c->argv[1]);
 262     if (o == NULL) {
 263         type = "+none";
 264     } else {
 265         switch(o->type) {
 266         case REDIS_STRING: type = "+string"; break;
 267         case REDIS_LIST: type = "+list"; break;
 268         case REDIS_SET: type = "+set"; break;
 269         case REDIS_ZSET: type = "+zset"; break;
 270         case REDIS_HASH: type = "+hash"; break;
 271         default: type = "+unknown"; break;
 272         }
 273     }
 274     addReplySds(c,sdsnew(type));
 275     addReply(c,shared.crlf);
 276 }
 277
 278 void saveCommand(redisClient *c) {
 279     if (server.bgsavechildpid != -1) {
 280         addReplySds(c,sdsnew("-ERR background save in progress\r\n"));
 281         return;
 282     }
 283     if (rdbSave(server.dbfilename) == REDIS_OK) {
 284         addReply(c,shared.ok);
 285     } else {
 286         addReply(c,shared.err);
 287     }
 288 }
 289
 290 void bgsaveCommand(redisClient *c) {
 291     if (server.bgsavechildpid != -1) {
 292         addReplySds(c,sdsnew("-ERR background save already in progress\r\n"));
 293         return;
 294     }
 295     if (rdbSaveBackground(server.dbfilename) == REDIS_OK) {
 296         char *status = "+Background saving started\r\n";
 297         addReplySds(c,sdsnew(status));
 298     } else {
 299         addReply(c,shared.err);
 300     }
 301 }
 302
 303 void shutdownCommand(redisClient *c) {
 304     if (prepareForShutdown() == REDIS_OK)
 305         exit(0);
 306     addReplySds(c, sdsnew("-ERR Errors trying to SHUTDOWN. Check logs.\r\n"));
 307 }
 308
 309 void renameGenericCommand(redisClient *c, int nx) {
 310     robj *o;
 311
 312     /* To use the same key as src and dst is probably an error */
 313     if (sdscmp(c->argv[1]->ptr,c->argv[2]->ptr) == 0) {
 314         addReply(c,shared.sameobjecterr);
 315         return;
 316     }
 317
 318     if ((o = lookupKeyWriteOrReply(c,c->argv[1],shared.nokeyerr)) == NULL)
 319         return;
 320
 321     incrRefCount(o);
 322     if (dbAdd(c->db,c->argv[2],o) == REDIS_ERR) {
 323         if (nx) {
 324             decrRefCount(o);
 325             addReply(c,shared.czero);
 326             return;
 327         }
 328         dbReplace(c->db,c->argv[2],o);
 329     }
 330     dbDelete(c->db,c->argv[1]);
 331     touchWatchedKey(c->db,c->argv[1]);
 332     touchWatchedKey(c->db,c->argv[2]);
 333     server.dirty++;
 334     addReply(c,nx ? shared.cone : shared.ok);
 335 }
 336
 337 void renameCommand(redisClient *c) {
 338     renameGenericCommand(c,0);
 339 }
 340
 341 void renamenxCommand(redisClient *c) {
 342     renameGenericCommand(c,1);
 343 }
 344
 345 void moveCommand(redisClient *c) {
 346     robj *o;
 347     redisDb *src, *dst;
 348     int srcid;
 349
 350     /* Obtain source and target DB pointers */
 351     src = c->db;
 352     srcid = c->db->id;
 353     if (selectDb(c,atoi(c->argv[2]->ptr)) == REDIS_ERR) {
 354         addReply(c,shared.outofrangeerr);
 355         return;
 356     }
 357     dst = c->db;
 358     selectDb(c,srcid); /* Back to the source DB */
 359
 360     /* If the user is moving using as target the same
 361      * DB as the source DB it is probably an error. */
 362     if (src == dst) {
 363         addReply(c,shared.sameobjecterr);
 364         return;
 365     }
 366
 367     /* Check if the element exists and get a reference */
 368     o = lookupKeyWrite(c->db,c->argv[1]);
 369     if (!o) {
 370         addReply(c,shared.czero);
 371         return;
 372     }
 373
 374     /* Try to add the element to the target DB */
 375     if (dbAdd(dst,c->argv[1],o) == REDIS_ERR) {
 376         addReply(c,shared.czero);
 377         return;
 378     }
 379     incrRefCount(o);
 380
 381     /* OK! key moved, free the entry in the source DB */
 382     dbDelete(src,c->argv[1]);
 383     server.dirty++;
 384     addReply(c,shared.cone);
 385 }
 386
 387 /*-----------------------------------------------------------------------------
 388  * Expires API
 389  *----------------------------------------------------------------------------*/
 390
 391 int removeExpire(redisDb *db, robj *key) {
 392     /* An expire may only be removed if there is a corresponding entry in the
 393      * main dict. Otherwise, the key will never be freed. */
 394     redisAssert(dictFind(db->dict,key->ptr) != NULL);
 395     return dictDelete(db->expires,key->ptr) == DICT_OK;
 396 }
 397
 398 void setExpire(redisDb *db, robj *key, time_t when) {
 399     dictEntry *de;
 400
 401     /* Reuse the sds from the main dict in the expire dict */
 402     de = dictFind(db->dict,key->ptr);
 403     redisAssert(de != NULL);
 404     dictReplace(db->expires,dictGetEntryKey(de),(void*)when);
 405 }
 406
 407 /* Return the expire time of the specified key, or -1 if no expire
 408  * is associated with this key (i.e. the key is non volatile) */
 409 time_t getExpire(redisDb *db, robj *key) {
 410     dictEntry *de;
 411
 412     /* No expire? return ASAP */
 413     if (dictSize(db->expires) == 0 ||
 414        (de = dictFind(db->expires,key->ptr)) == NULL) return -1;
 415
 416     /* The entry was found in the expire dict, this means it should also
 417      * be present in the main dict (safety check). */
 418     redisAssert(dictFind(db->dict,key->ptr) != NULL);
 419     return (time_t) dictGetEntryVal(de);
 420 }
 421
 422 /* Propagate expires into slaves and the AOF file.
 423  * When a key expires in the master, a DEL operation for this key is sent
 424  * to all the slaves and the AOF file if enabled.
 425  *
 426  * This way the key expiry is centralized in one place, and since both
 427  * AOF and the master->slave link guarantee operation ordering, everything
 428  * will be consistent even if we allow write operations against expiring
 429  * keys. */
 430 void propagateExpire(redisDb *db, robj *key) {
 431     struct redisCommand *cmd;
 432     robj *argv[2];
 433
 434     cmd = lookupCommand("del");
 435     argv[0] = createStringObject("DEL",3);
 436     argv[1] = key;
 437     incrRefCount(key);
 438
 439     if (server.appendonly)
 440         feedAppendOnlyFile(cmd,db->id,argv,2);
 441     if (listLength(server.slaves))
 442         replicationFeedSlaves(server.slaves,db->id,argv,2);
 443
 444     decrRefCount(argv[0]);
 445     decrRefCount(argv[1]);
 446 }
 447
 448 int expireIfNeeded(redisDb *db, robj *key) {
 449     time_t when = getExpire(db,key);
 450
 451     /* If we are running in the context of a slave, return ASAP:
 452      * the slave key expiration is controlled by the master that will
 453      * send us synthesized DEL operations for expired keys.
 454      *
 455      * Still we try to return the right information to the caller,
 456      * that is, 0 if we think the key should be still valid, 1 if
 457      * we think the key is expired at this time. */
 458     if (server.masterhost != NULL) {
 459         return time(NULL) > when;
 460     }
 461
 462     if (when < 0) return 0;
 463
 464     /* Return when this key has not expired */
 465     if (time(NULL) <= when) return 0;
 466
 467     /* Delete the key */
 468     server.stat_expiredkeys++;
 469     server.dirty++;
 470     propagateExpire(db,key);
 471     return dbDelete(db,key);
 472 }
 473
 474 /*-----------------------------------------------------------------------------
 475  * Expires Commands
 476  *----------------------------------------------------------------------------*/
 477
 478 void expireGenericCommand(redisClient *c, robj *key, robj *param, long offset) {
 479     dictEntry *de;
 480     time_t seconds;
 481
 482     if (getLongFromObjectOrReply(c, param, &seconds, NULL) != REDIS_OK) return;
 483
 484     seconds -= offset;
 485
 486     de = dictFind(c->db->dict,key->ptr);
 487     if (de == NULL) {
 488         addReply(c,shared.czero);
 489         return;
 490     }
 491     if (seconds <= 0) {
 492         if (dbDelete(c->db,key)) server.dirty++;
 493         addReply(c, shared.cone);
 494         touchWatchedKey(c->db,key);
 495         return;
 496     } else {
 497         time_t when = time(NULL)+seconds;
 498         setExpire(c->db,key,when);
 499         addReply(c,shared.cone);
 500         touchWatchedKey(c->db,key);
 501         server.dirty++;
 502         return;
 503     }
 504 }
 505
 506 void expireCommand(redisClient *c) {
 507     expireGenericCommand(c,c->argv[1],c->argv[2],0);
 508 }
 509
 510 void expireatCommand(redisClient *c) {
 511     expireGenericCommand(c,c->argv[1],c->argv[2],time(NULL));
 512 }
 513
 514 void ttlCommand(redisClient *c) {
 515     time_t expire, ttl = -1;
 516
 517     expire = getExpire(c->db,c->argv[1]);
 518     if (expire != -1) {
 519         ttl = (expire-time(NULL));
 520         if (ttl < 0) ttl = -1;
 521     }
 522     addReplyLongLong(c,(long long)ttl);
 523 }
 524
 525 void persistCommand(redisClient *c) {
 526     dictEntry *de;
 527
 528     de = dictFind(c->db->dict,c->argv[1]->ptr);
 529     if (de == NULL) {
 530         addReply(c,shared.czero);
 531     } else {
 532         if (removeExpire(c->db,c->argv[1])) {
 533             addReply(c,shared.cone);
 534             server.dirty++;
 535         } else {
 536             addReply(c,shared.czero);
 537         }
 538     }
 539 }