src/object.c

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