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     /* If VM is enabled make sure to awake waiting clients for this key:
 127      * deleting the key will kill the I/O thread bringing the key from swap
 128      * to memory, so the client will never be notified and unblocked if we
 129      * don't do it now. */
 130     handleClientsBlockedOnSwappedKey(db,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     return dictDelete(db->dict,key->ptr) == DICT_OK;
 135 }
 136
 137 /* Empty the whole database */
 138 long long emptyDb() {
 139     int j;
 140     long long removed = 0;
 141
 142     for (j = 0; j < server.dbnum; j++) {
 143         removed += dictSize(server.db[j].dict);
 144         dictEmpty(server.db[j].dict);
 145         dictEmpty(server.db[j].expires);
 146     }
 147     return removed;
 148 }
 149
 150 int selectDb(redisClient *c, int id) {
 151     if (id < 0 || id >= server.dbnum)
 152         return REDIS_ERR;
 153     c->db = &server.db[id];
 154     return REDIS_OK;
 155 }
 156
 157 /*-----------------------------------------------------------------------------
 158  * Type agnostic commands operating on the key space
 159  *----------------------------------------------------------------------------*/
 160
 161 void flushdbCommand(redisClient *c) {
 162     server.dirty += dictSize(c->db->dict);
 163     touchWatchedKeysOnFlush(c->db->id);
 164     dictEmpty(c->db->dict);
 165     dictEmpty(c->db->expires);
 166     addReply(c,shared.ok);
 167 }
 168
 169 void flushallCommand(redisClient *c) {
 170     touchWatchedKeysOnFlush(-1);
 171     server.dirty += emptyDb();
 172     addReply(c,shared.ok);
 173     if (server.bgsavechildpid != -1) {
 174         kill(server.bgsavechildpid,SIGKILL);
 175         rdbRemoveTempFile(server.bgsavechildpid);
 176     }
 177     rdbSave(server.dbfilename);
 178     server.dirty++;
 179 }
 180
 181 void delCommand(redisClient *c) {
 182     int deleted = 0, j;
 183
 184     for (j = 1; j < c->argc; j++) {
 185         if (dbDelete(c->db,c->argv[j])) {
 186             touchWatchedKey(c->db,c->argv[j]);
 187             server.dirty++;
 188             deleted++;
 189         }
 190     }
 191     addReplyLongLong(c,deleted);
 192 }
 193
 194 void existsCommand(redisClient *c) {
 195     expireIfNeeded(c->db,c->argv[1]);
 196     if (dbExists(c->db,c->argv[1])) {
 197         addReply(c, shared.cone);
 198     } else {
 199         addReply(c, shared.czero);
 200     }
 201 }
 202
 203 void selectCommand(redisClient *c) {
 204     int id = atoi(c->argv[1]->ptr);
 205
 206     if (selectDb(c,id) == REDIS_ERR) {
 207         addReplySds(c,sdsnew("-ERR invalid DB index\r\n"));
 208     } else {
 209         addReply(c,shared.ok);
 210     }
 211 }
 212
 213 void randomkeyCommand(redisClient *c) {
 214     robj *key;
 215
 216     if ((key = dbRandomKey(c->db)) == NULL) {
 217         addReply(c,shared.nullbulk);
 218         return;
 219     }
 220
 221     addReplyBulk(c,key);
 222     decrRefCount(key);
 223 }
 224
 225 void keysCommand(redisClient *c) {
 226     dictIterator *di;
 227     dictEntry *de;
 228     sds pattern = c->argv[1]->ptr;
 229     int plen = sdslen(pattern), allkeys;
 230     unsigned long numkeys = 0;
 231     robj *lenobj = createObject(REDIS_STRING,NULL);
 232
 233     di = dictGetIterator(c->db->dict);
 234     addReply(c,lenobj);
 235     decrRefCount(lenobj);
 236     allkeys = (pattern[0] == '*' && pattern[1] == '\0');
 237     while((de = dictNext(di)) != NULL) {
 238         sds key = dictGetEntryKey(de);
 239         robj *keyobj;
 240
 241         if (allkeys || stringmatchlen(pattern,plen,key,sdslen(key),0)) {
 242             keyobj = createStringObject(key,sdslen(key));
 243             if (expireIfNeeded(c->db,keyobj) == 0) {
 244                 addReplyBulk(c,keyobj);
 245                 numkeys++;
 246             }
 247             decrRefCount(keyobj);
 248         }
 249     }
 250     dictReleaseIterator(di);
 251     lenobj->ptr = sdscatprintf(sdsempty(),"*%lu\r\n",numkeys);
 252 }
 253
 254 void dbsizeCommand(redisClient *c) {
 255     addReplySds(c,
 256         sdscatprintf(sdsempty(),":%lu\r\n",dictSize(c->db->dict)));
 257 }
 258
 259 void lastsaveCommand(redisClient *c) {
 260     addReplySds(c,
 261         sdscatprintf(sdsempty(),":%lu\r\n",server.lastsave));
 262 }
 263
 264 void typeCommand(redisClient *c) {
 265     robj *o;
 266     char *type;
 267
 268     o = lookupKeyRead(c->db,c->argv[1]);
 269     if (o == NULL) {
 270         type = "+none";
 271     } else {
 272         switch(o->type) {
 273         case REDIS_STRING: type = "+string"; break;
 274         case REDIS_LIST: type = "+list"; break;
 275         case REDIS_SET: type = "+set"; break;
 276         case REDIS_ZSET: type = "+zset"; break;
 277         case REDIS_HASH: type = "+hash"; break;
 278         default: type = "+unknown"; break;
 279         }
 280     }
 281     addReplySds(c,sdsnew(type));
 282     addReply(c,shared.crlf);
 283 }
 284
 285 void saveCommand(redisClient *c) {
 286     if (server.bgsavechildpid != -1) {
 287         addReplySds(c,sdsnew("-ERR background save in progress\r\n"));
 288         return;
 289     }
 290     if (rdbSave(server.dbfilename) == REDIS_OK) {
 291         addReply(c,shared.ok);
 292     } else {
 293         addReply(c,shared.err);
 294     }
 295 }
 296
 297 void bgsaveCommand(redisClient *c) {
 298     if (server.bgsavechildpid != -1) {
 299         addReplySds(c,sdsnew("-ERR background save already in progress\r\n"));
 300         return;
 301     }
 302     if (rdbSaveBackground(server.dbfilename) == REDIS_OK) {
 303         char *status = "+Background saving started\r\n";
 304         addReplySds(c,sdsnew(status));
 305     } else {
 306         addReply(c,shared.err);
 307     }
 308 }
 309
 310 void shutdownCommand(redisClient *c) {
 311     if (prepareForShutdown() == REDIS_OK)
 312         exit(0);
 313     addReplySds(c, sdsnew("-ERR Errors trying to SHUTDOWN. Check logs.\r\n"));
 314 }
 315
 316 void renameGenericCommand(redisClient *c, int nx) {
 317     robj *o;
 318
 319     /* To use the same key as src and dst is probably an error */
 320     if (sdscmp(c->argv[1]->ptr,c->argv[2]->ptr) == 0) {
 321         addReply(c,shared.sameobjecterr);
 322         return;
 323     }
 324
 325     if ((o = lookupKeyWriteOrReply(c,c->argv[1],shared.nokeyerr)) == NULL)
 326         return;
 327
 328     incrRefCount(o);
 329     if (dbAdd(c->db,c->argv[2],o) == REDIS_ERR) {
 330         if (nx) {
 331             decrRefCount(o);
 332             addReply(c,shared.czero);
 333             return;
 334         }
 335         dbReplace(c->db,c->argv[2],o);
 336     }
 337     dbDelete(c->db,c->argv[1]);
 338     touchWatchedKey(c->db,c->argv[1]);
 339     touchWatchedKey(c->db,c->argv[2]);
 340     server.dirty++;
 341     addReply(c,nx ? shared.cone : shared.ok);
 342 }
 343
 344 void renameCommand(redisClient *c) {
 345     renameGenericCommand(c,0);
 346 }
 347
 348 void renamenxCommand(redisClient *c) {
 349     renameGenericCommand(c,1);
 350 }
 351
 352 void moveCommand(redisClient *c) {
 353     robj *o;
 354     redisDb *src, *dst;
 355     int srcid;
 356
 357     /* Obtain source and target DB pointers */
 358     src = c->db;
 359     srcid = c->db->id;
 360     if (selectDb(c,atoi(c->argv[2]->ptr)) == REDIS_ERR) {
 361         addReply(c,shared.outofrangeerr);
 362         return;
 363     }
 364     dst = c->db;
 365     selectDb(c,srcid); /* Back to the source DB */
 366
 367     /* If the user is moving using as target the same
 368      * DB as the source DB it is probably an error. */
 369     if (src == dst) {
 370         addReply(c,shared.sameobjecterr);
 371         return;
 372     }
 373
 374     /* Check if the element exists and get a reference */
 375     o = lookupKeyWrite(c->db,c->argv[1]);
 376     if (!o) {
 377         addReply(c,shared.czero);
 378         return;
 379     }
 380
 381     /* Try to add the element to the target DB */
 382     if (dbAdd(dst,c->argv[1],o) == REDIS_ERR) {
 383         addReply(c,shared.czero);
 384         return;
 385     }
 386     incrRefCount(o);
 387
 388     /* OK! key moved, free the entry in the source DB */
 389     dbDelete(src,c->argv[1]);
 390     server.dirty++;
 391     addReply(c,shared.cone);
 392 }
 393
 394 /*-----------------------------------------------------------------------------
 395  * Expires API
 396  *----------------------------------------------------------------------------*/
 397
 398 int removeExpire(redisDb *db, robj *key) {
 399     /* An expire may only be removed if there is a corresponding entry in the
 400      * main dict. Otherwise, the key will never be freed. */
 401     redisAssert(dictFind(db->dict,key->ptr) != NULL);
 402     return dictDelete(db->expires,key->ptr) == DICT_OK;
 403 }
 404
 405 void setExpire(redisDb *db, robj *key, time_t when) {
 406     dictEntry *de;
 407
 408     /* Reuse the sds from the main dict in the expire dict */
 409     de = dictFind(db->dict,key->ptr);
 410     redisAssert(de != NULL);
 411     dictReplace(db->expires,dictGetEntryKey(de),(void*)when);
 412 }
 413
 414 /* Return the expire time of the specified key, or -1 if no expire
 415  * is associated with this key (i.e. the key is non volatile) */
 416 time_t getExpire(redisDb *db, robj *key) {
 417     dictEntry *de;
 418
 419     /* No expire? return ASAP */
 420     if (dictSize(db->expires) == 0 ||
 421        (de = dictFind(db->expires,key->ptr)) == NULL) return -1;
 422
 423     /* The entry was found in the expire dict, this means it should also
 424      * be present in the main dict (safety check). */
 425     redisAssert(dictFind(db->dict,key->ptr) != NULL);
 426     return (time_t) dictGetEntryVal(de);
 427 }
 428
 429 /* Propagate expires into slaves and the AOF file.
 430  * When a key expires in the master, a DEL operation for this key is sent
 431  * to all the slaves and the AOF file if enabled.
 432  *
 433  * This way the key expiry is centralized in one place, and since both
 434  * AOF and the master->slave link guarantee operation ordering, everything
 435  * will be consistent even if we allow write operations against expiring
 436  * keys. */
 437 void propagateExpire(redisDb *db, robj *key) {
 438     struct redisCommand *cmd;
 439     robj *argv[2];
 440
 441     cmd = lookupCommand("del");
 442     argv[0] = createStringObject("DEL",3);
 443     argv[1] = key;
 444     incrRefCount(key);
 445
 446     if (server.appendonly)
 447         feedAppendOnlyFile(cmd,db->id,argv,2);
 448     if (listLength(server.slaves))
 449         replicationFeedSlaves(server.slaves,db->id,argv,2);
 450
 451     decrRefCount(argv[0]);
 452     decrRefCount(argv[1]);
 453 }
 454
 455 int expireIfNeeded(redisDb *db, robj *key) {
 456     time_t when = getExpire(db,key);
 457
 458     /* If we are running in the context of a slave, return ASAP:
 459      * the slave key expiration is controlled by the master that will
 460      * send us synthesized DEL operations for expired keys.
 461      *
 462      * Still we try to return the right information to the caller,
 463      * that is, 0 if we think the key should be still valid, 1 if
 464      * we think the key is expired at this time. */
 465     if (server.masterhost != NULL) {
 466         return time(NULL) > when;
 467     }
 468
 469     if (when < 0) return 0;
 470
 471     /* Return when this key has not expired */
 472     if (time(NULL) <= when) return 0;
 473
 474     /* Delete the key */
 475     server.stat_expiredkeys++;
 476     server.dirty++;
 477     propagateExpire(db,key);
 478     return dbDelete(db,key);
 479 }
 480
 481 /*-----------------------------------------------------------------------------
 482  * Expires Commands
 483  *----------------------------------------------------------------------------*/
 484
 485 void expireGenericCommand(redisClient *c, robj *key, robj *param, long offset) {
 486     dictEntry *de;
 487     time_t seconds;
 488
 489     if (getLongFromObjectOrReply(c, param, &seconds, NULL) != REDIS_OK) return;
 490
 491     seconds -= offset;
 492
 493     de = dictFind(c->db->dict,key->ptr);
 494     if (de == NULL) {
 495         addReply(c,shared.czero);
 496         return;
 497     }
 498     if (seconds <= 0) {
 499         if (dbDelete(c->db,key)) server.dirty++;
 500         addReply(c, shared.cone);
 501         touchWatchedKey(c->db,key);
 502         return;
 503     } else {
 504         time_t when = time(NULL)+seconds;
 505         setExpire(c->db,key,when);
 506         addReply(c,shared.cone);
 507         touchWatchedKey(c->db,key);
 508         server.dirty++;
 509         return;
 510     }
 511 }
 512
 513 void expireCommand(redisClient *c) {
 514     expireGenericCommand(c,c->argv[1],c->argv[2],0);
 515 }
 516
 517 void expireatCommand(redisClient *c) {
 518     expireGenericCommand(c,c->argv[1],c->argv[2],time(NULL));
 519 }
 520
 521 void ttlCommand(redisClient *c) {
 522     time_t expire, ttl = -1;
 523
 524     expire = getExpire(c->db,c->argv[1]);
 525     if (expire != -1) {
 526         ttl = (expire-time(NULL));
 527         if (ttl < 0) ttl = -1;
 528     }
 529     addReplyLongLong(c,(long long)ttl);
 530 }
 531
 532 void persistCommand(redisClient *c) {
 533     dictEntry *de;
 534
 535     de = dictFind(c->db->dict,c->argv[1]->ptr);
 536     if (de == NULL) {
 537         addReply(c,shared.czero);
 538     } else {
 539         if (removeExpire(c->db,c->argv[1])) {
 540             addReply(c,shared.cone);
 541             server.dirty++;
 542         } else {
 543             addReply(c,shared.czero);
 544         }
 545     }
 546 }