src/object.c

   1 #include "redis.h"
   2 #include <math.h>
   3
   4 robj *createObject(int type, void *ptr) {
   5     robj *o = zmalloc(sizeof(*o));
   6     o->type = type;
   7     o->encoding = REDIS_ENCODING_RAW;
   8     o->ptr = ptr;
   9     o->refcount = 1;
  10
  11     /* Set the LRU to the current lruclock (minutes resolution).
  12      * We do this regardless of the fact VM is active as LRU is also
  13      * used for the maxmemory directive when Redis is used as cache.
  14      *
  15      * Note that this code may run in the context of an I/O thread
  16      * and accessing server.lruclock in theory is an error
  17      * (no locks). But in practice this is safe, and even if we read
  18      * garbage Redis will not fail. */
  19     o->lru = server.lruclock;
  20     /* The following is only needed if VM is active, but since the conditional
  21      * is probably more costly than initializing the field it's better to
  22      * have every field properly initialized anyway. */
  23     return o;
  24 }
  25
  26 robj *createStringObject(char *ptr, size_t len) {
  27     return createObject(REDIS_STRING,sdsnewlen(ptr,len));
  28 }
  29
  30 robj *createStringObjectFromLongLong(long long value) {
  31     robj *o;
  32     if (value >= 0 && value < REDIS_SHARED_INTEGERS) {
  33         incrRefCount(shared.integers[value]);
  34         o = shared.integers[value];
  35     } else {
  36         if (value >= LONG_MIN && value <= LONG_MAX) {
  37             o = createObject(REDIS_STRING, NULL);
  38             o->encoding = REDIS_ENCODING_INT;
  39             o->ptr = (void*)((long)value);
  40         } else {
  41             o = createObject(REDIS_STRING,sdsfromlonglong(value));
  42         }
  43     }
  44     return o;
  45 }
  46
  47 robj *dupStringObject(robj *o) {
  48     redisAssertWithInfo(NULL,o,o->encoding == REDIS_ENCODING_RAW);
  49     return createStringObject(o->ptr,sdslen(o->ptr));
  50 }
  51
  52 robj *createListObject(void) {
  53     list *l = listCreate();
  54     robj *o = createObject(REDIS_LIST,l);
  55     listSetFreeMethod(l,decrRefCount);
  56     o->encoding = REDIS_ENCODING_LINKEDLIST;
  57     return o;
  58 }
  59
  60 robj *createZiplistObject(void) {
  61     unsigned char *zl = ziplistNew();
  62     robj *o = createObject(REDIS_LIST,zl);
  63     o->encoding = REDIS_ENCODING_ZIPLIST;
  64     return o;
  65 }
  66
  67 robj *createSetObject(void) {
  68     dict *d = dictCreate(&setDictType,NULL);
  69     robj *o = createObject(REDIS_SET,d);
  70     o->encoding = REDIS_ENCODING_HT;
  71     return o;
  72 }
  73
  74 robj *createIntsetObject(void) {
  75     intset *is = intsetNew();
  76     robj *o = createObject(REDIS_SET,is);
  77     o->encoding = REDIS_ENCODING_INTSET;
  78     return o;
  79 }
  80
  81 robj *createHashObject(void) {
  82     /* All the Hashes start as zipmaps. Will be automatically converted
  83      * into hash tables if there are enough elements or big elements
  84      * inside. */
  85     unsigned char *zm = zipmapNew();
  86     robj *o = createObject(REDIS_HASH,zm);
  87     o->encoding = REDIS_ENCODING_ZIPMAP;
  88     return o;
  89 }
  90
  91 robj *createZsetObject(void) {
  92     zset *zs = zmalloc(sizeof(*zs));
  93     robj *o;
  94
  95     zs->dict = dictCreate(&zsetDictType,NULL);
  96     zs->zsl = zslCreate();
  97     o = createObject(REDIS_ZSET,zs);
  98     o->encoding = REDIS_ENCODING_SKIPLIST;
  99     return o;
 100 }
 101
 102 robj *createZsetZiplistObject(void) {
 103     unsigned char *zl = ziplistNew();
 104     robj *o = createObject(REDIS_ZSET,zl);
 105     o->encoding = REDIS_ENCODING_ZIPLIST;
 106     return o;
 107 }
 108
 109 void freeStringObject(robj *o) {
 110     if (o->encoding == REDIS_ENCODING_RAW) {
 111         sdsfree(o->ptr);
 112     }
 113 }
 114
 115 void freeListObject(robj *o) {
 116     switch (o->encoding) {
 117     case REDIS_ENCODING_LINKEDLIST:
 118         listRelease((list*) o->ptr);
 119         break;
 120     case REDIS_ENCODING_ZIPLIST:
 121         zfree(o->ptr);
 122         break;
 123     default:
 124         redisPanic("Unknown list encoding type");
 125     }
 126 }
 127
 128 void freeSetObject(robj *o) {
 129     switch (o->encoding) {
 130     case REDIS_ENCODING_HT:
 131         dictRelease((dict*) o->ptr);
 132         break;
 133     case REDIS_ENCODING_INTSET:
 134         zfree(o->ptr);
 135         break;
 136     default:
 137         redisPanic("Unknown set encoding type");
 138     }
 139 }
 140
 141 void freeZsetObject(robj *o) {
 142     zset *zs;
 143     switch (o->encoding) {
 144     case REDIS_ENCODING_SKIPLIST:
 145         zs = o->ptr;
 146         dictRelease(zs->dict);
 147         zslFree(zs->zsl);
 148         zfree(zs);
 149         break;
 150     case REDIS_ENCODING_ZIPLIST:
 151         zfree(o->ptr);
 152         break;
 153     default:
 154         redisPanic("Unknown sorted set encoding");
 155     }
 156 }
 157
 158 void freeHashObject(robj *o) {
 159     switch (o->encoding) {
 160     case REDIS_ENCODING_HT:
 161         dictRelease((dict*) o->ptr);
 162         break;
 163     case REDIS_ENCODING_ZIPMAP:
 164         zfree(o->ptr);
 165         break;
 166     default:
 167         redisPanic("Unknown hash encoding type");
 168         break;
 169     }
 170 }
 171
 172 void incrRefCount(robj *o) {
 173     o->refcount++;
 174 }
 175
 176 void decrRefCount(void *obj) {
 177     robj *o = obj;
 178
 179     if (o->refcount <= 0) redisPanic("decrRefCount against refcount <= 0");
 180     if (o->refcount == 1) {
 181         switch(o->type) {
 182         case REDIS_STRING: freeStringObject(o); break;
 183         case REDIS_LIST: freeListObject(o); break;
 184         case REDIS_SET: freeSetObject(o); break;
 185         case REDIS_ZSET: freeZsetObject(o); break;
 186         case REDIS_HASH: freeHashObject(o); break;
 187         default: redisPanic("Unknown object type"); break;
 188         }
 189         zfree(o);
 190     } else {
 191         o->refcount--;
 192     }
 193 }
 194
 195 /* This function set the ref count to zero without freeing the object.
 196  * It is useful in order to pass a new object to functions incrementing
 197  * the ref count of the received object. Example:
 198  *
 199  *    functionThatWillIncrementRefCount(resetRefCount(CreateObject(...)));
 200  *
 201  * Otherwise you need to resort to the less elegant pattern:
 202  *
 203  *    *obj = createObject(...);
 204  *    functionThatWillIncrementRefCount(obj);
 205  *    decrRefCount(obj);
 206  */
 207 robj *resetRefCount(robj *obj) {
 208     obj->refcount = 0;
 209     return obj;
 210 }
 211
 212 int checkType(redisClient *c, robj *o, int type) {
 213     if (o->type != type) {
 214         addReply(c,shared.wrongtypeerr);
 215         return 1;
 216     }
 217     return 0;
 218 }
 219
 220 int isObjectRepresentableAsLongLong(robj *o, long long *llval) {
 221     redisAssertWithInfo(NULL,o,o->type == REDIS_STRING);
 222     if (o->encoding == REDIS_ENCODING_INT) {
 223         if (llval) *llval = (long) o->ptr;
 224         return REDIS_OK;
 225     } else {
 226         return string2ll(o->ptr,sdslen(o->ptr),llval) ? REDIS_OK : REDIS_ERR;
 227     }
 228 }
 229
 230 /* Try to encode a string object in order to save space */
 231 robj *tryObjectEncoding(robj *o) {
 232     long value;
 233     sds s = o->ptr;
 234
 235     if (o->encoding != REDIS_ENCODING_RAW)
 236         return o; /* Already encoded */
 237
 238     /* It's not safe to encode shared objects: shared objects can be shared
 239      * everywhere in the "object space" of Redis. Encoded objects can only
 240      * appear as "values" (and not, for instance, as keys) */
 241      if (o->refcount > 1) return o;
 242
 243     /* Currently we try to encode only strings */
 244     redisAssertWithInfo(NULL,o,o->type == REDIS_STRING);
 245
 246     /* Check if we can represent this string as a long integer */
 247     if (!string2l(s,sdslen(s),&value)) return o;
 248
 249     /* Ok, this object can be encoded...
 250      *
 251      * Can I use a shared object? Only if the object is inside a given
 252      * range and if the back end in use is in-memory. For disk store every
 253      * object in memory used as value should be independent.
 254      *
 255      * Note that we also avoid using shared integers when maxmemory is used
 256      * because every object needs to have a private LRU field for the LRU
 257      * algorithm to work well. */
 258     if (server.maxmemory == 0 && value >= 0 && value < REDIS_SHARED_INTEGERS) {
 259         decrRefCount(o);
 260         incrRefCount(shared.integers[value]);
 261         return shared.integers[value];
 262     } else {
 263         o->encoding = REDIS_ENCODING_INT;
 264         sdsfree(o->ptr);
 265         o->ptr = (void*) value;
 266         return o;
 267     }
 268 }
 269
 270 /* Get a decoded version of an encoded object (returned as a new object).
 271  * If the object is already raw-encoded just increment the ref count. */
 272 robj *getDecodedObject(robj *o) {
 273     robj *dec;
 274
 275     if (o->encoding == REDIS_ENCODING_RAW) {
 276         incrRefCount(o);
 277         return o;
 278     }
 279     if (o->type == REDIS_STRING && o->encoding == REDIS_ENCODING_INT) {
 280         char buf[32];
 281
 282         ll2string(buf,32,(long)o->ptr);
 283         dec = createStringObject(buf,strlen(buf));
 284         return dec;
 285     } else {
 286         redisPanic("Unknown encoding type");
 287     }
 288 }
 289
 290 /* Compare two string objects via strcmp() or alike.
 291  * Note that the objects may be integer-encoded. In such a case we
 292  * use ll2string() to get a string representation of the numbers on the stack
 293  * and compare the strings, it's much faster than calling getDecodedObject().
 294  *
 295  * Important note: if objects are not integer encoded, but binary-safe strings,
 296  * sdscmp() from sds.c will apply memcmp() so this function ca be considered
 297  * binary safe. */
 298 int compareStringObjects(robj *a, robj *b) {
 299     redisAssertWithInfo(NULL,a,a->type == REDIS_STRING && b->type == REDIS_STRING);
 300     char bufa[128], bufb[128], *astr, *bstr;
 301     int bothsds = 1;
 302
 303     if (a == b) return 0;
 304     if (a->encoding != REDIS_ENCODING_RAW) {
 305         ll2string(bufa,sizeof(bufa),(long) a->ptr);
 306         astr = bufa;
 307         bothsds = 0;
 308     } else {
 309         astr = a->ptr;
 310     }
 311     if (b->encoding != REDIS_ENCODING_RAW) {
 312         ll2string(bufb,sizeof(bufb),(long) b->ptr);
 313         bstr = bufb;
 314         bothsds = 0;
 315     } else {
 316         bstr = b->ptr;
 317     }
 318     return bothsds ? sdscmp(astr,bstr) : strcmp(astr,bstr);
 319 }
 320
 321 /* Equal string objects return 1 if the two objects are the same from the
 322  * point of view of a string comparison, otherwise 0 is returned. Note that
 323  * this function is faster then checking for (compareStringObject(a,b) == 0)
 324  * because it can perform some more optimization. */
 325 int equalStringObjects(robj *a, robj *b) {
 326     if (a->encoding != REDIS_ENCODING_RAW && b->encoding != REDIS_ENCODING_RAW){
 327         return a->ptr == b->ptr;
 328     } else {
 329         return compareStringObjects(a,b) == 0;
 330     }
 331 }
 332
 333 size_t stringObjectLen(robj *o) {
 334     redisAssertWithInfo(NULL,o,o->type == REDIS_STRING);
 335     if (o->encoding == REDIS_ENCODING_RAW) {
 336         return sdslen(o->ptr);
 337     } else {
 338         char buf[32];
 339
 340         return ll2string(buf,32,(long)o->ptr);
 341     }
 342 }
 343
 344 int getDoubleFromObject(robj *o, double *target) {
 345     double value;
 346     char *eptr;
 347
 348     if (o == NULL) {
 349         value = 0;
 350     } else {
 351         redisAssertWithInfo(NULL,o,o->type == REDIS_STRING);
 352         if (o->encoding == REDIS_ENCODING_RAW) {
 353             value = strtod(o->ptr, &eptr);
 354             if (eptr[0] != '\0' || isnan(value)) return REDIS_ERR;
 355         } else if (o->encoding == REDIS_ENCODING_INT) {
 356             value = (long)o->ptr;
 357         } else {
 358             redisPanic("Unknown string encoding");
 359         }
 360     }
 361
 362     *target = value;
 363     return REDIS_OK;
 364 }
 365
 366 int getDoubleFromObjectOrReply(redisClient *c, robj *o, double *target, const char *msg) {
 367     double value;
 368     if (getDoubleFromObject(o, &value) != REDIS_OK) {
 369         if (msg != NULL) {
 370             addReplyError(c,(char*)msg);
 371         } else {
 372             addReplyError(c,"value is not a double");
 373         }
 374         return REDIS_ERR;
 375     }
 376
 377     *target = value;
 378     return REDIS_OK;
 379 }
 380
 381 int getLongLongFromObject(robj *o, long long *target) {
 382     long long value;
 383     char *eptr;
 384
 385     if (o == NULL) {
 386         value = 0;
 387     } else {
 388         redisAssertWithInfo(NULL,o,o->type == REDIS_STRING);
 389         if (o->encoding == REDIS_ENCODING_RAW) {
 390             value = strtoll(o->ptr, &eptr, 10);
 391             if (eptr[0] != '\0') return REDIS_ERR;
 392             if (errno == ERANGE && (value == LLONG_MIN || value == LLONG_MAX))
 393                 return REDIS_ERR;
 394         } else if (o->encoding == REDIS_ENCODING_INT) {
 395             value = (long)o->ptr;
 396         } else {
 397             redisPanic("Unknown string encoding");
 398         }
 399     }
 400
 401     if (target) *target = value;
 402     return REDIS_OK;
 403 }
 404
 405 int getLongLongFromObjectOrReply(redisClient *c, robj *o, long long *target, const char *msg) {
 406     long long value;
 407     if (getLongLongFromObject(o, &value) != REDIS_OK) {
 408         if (msg != NULL) {
 409             addReplyError(c,(char*)msg);
 410         } else {
 411             addReplyError(c,"value is not an integer or out of range");
 412         }
 413         return REDIS_ERR;
 414     }
 415
 416     *target = value;
 417     return REDIS_OK;
 418 }
 419
 420 int getLongFromObjectOrReply(redisClient *c, robj *o, long *target, const char *msg) {
 421     long long value;
 422
 423     if (getLongLongFromObjectOrReply(c, o, &value, msg) != REDIS_OK) return REDIS_ERR;
 424     if (value < LONG_MIN || value > LONG_MAX) {
 425         if (msg != NULL) {
 426             addReplyError(c,(char*)msg);
 427         } else {
 428             addReplyError(c,"value is out of range");
 429         }
 430         return REDIS_ERR;
 431     }
 432
 433     *target = value;
 434     return REDIS_OK;
 435 }
 436
 437 char *strEncoding(int encoding) {
 438     switch(encoding) {
 439     case REDIS_ENCODING_RAW: return "raw";
 440     case REDIS_ENCODING_INT: return "int";
 441     case REDIS_ENCODING_HT: return "hashtable";
 442     case REDIS_ENCODING_ZIPMAP: return "zipmap";
 443     case REDIS_ENCODING_LINKEDLIST: return "linkedlist";
 444     case REDIS_ENCODING_ZIPLIST: return "ziplist";
 445     case REDIS_ENCODING_INTSET: return "intset";
 446     case REDIS_ENCODING_SKIPLIST: return "skiplist";
 447     default: return "unknown";
 448     }
 449 }
 450
 451 /* Given an object returns the min number of seconds the object was never
 452  * requested, using an approximated LRU algorithm. */
 453 unsigned long estimateObjectIdleTime(robj *o) {
 454     if (server.lruclock >= o->lru) {
 455         return (server.lruclock - o->lru) * REDIS_LRU_CLOCK_RESOLUTION;
 456     } else {
 457         return ((REDIS_LRU_CLOCK_MAX - o->lru) + server.lruclock) *
 458                     REDIS_LRU_CLOCK_RESOLUTION;
 459     }
 460 }
 461
 462 /* This is an helper function for the DEBUG command. We need to lookup keys
 463  * without any modification of LRU or other parameters. */
 464 robj *objectCommandLookup(redisClient *c, robj *key) {
 465     dictEntry *de;
 466
 467     if ((de = dictFind(c->db->dict,key->ptr)) == NULL) return NULL;
 468     return (robj*) dictGetEntryVal(de);
 469 }
 470
 471 robj *objectCommandLookupOrReply(redisClient *c, robj *key, robj *reply) {
 472     robj *o = objectCommandLookup(c,key);
 473
 474     if (!o) addReply(c, reply);
 475     return o;
 476 }
 477
 478 /* Object command allows to inspect the internals of an Redis Object.
 479  * Usage: OBJECT <verb> ... arguments ... */
 480 void objectCommand(redisClient *c) {
 481     robj *o;
 482
 483     if (!strcasecmp(c->argv[1]->ptr,"refcount") && c->argc == 3) {
 484         if ((o = objectCommandLookupOrReply(c,c->argv[2],shared.nullbulk))
 485                 == NULL) return;
 486         addReplyLongLong(c,o->refcount);
 487     } else if (!strcasecmp(c->argv[1]->ptr,"encoding") && c->argc == 3) {
 488         if ((o = objectCommandLookupOrReply(c,c->argv[2],shared.nullbulk))
 489                 == NULL) return;
 490         addReplyBulkCString(c,strEncoding(o->encoding));
 491     } else if (!strcasecmp(c->argv[1]->ptr,"idletime") && c->argc == 3) {
 492         if ((o = objectCommandLookupOrReply(c,c->argv[2],shared.nullbulk))
 493                 == NULL) return;
 494         addReplyLongLong(c,estimateObjectIdleTime(o));
 495     } else {
 496         addReplyError(c,"Syntax error. Try OBJECT (refcount|encoding|idletime)");
 497     }
 498 }
 499