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) == 0) {
 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         o->ptr = NULL; /* defensive programming. We'll see NULL in traces. */
 193         zfree(o);
 194     }
 195 }
 196
 197 int checkType(redisClient *c, robj *o, int type) {
 198     if (o->type != type) {
 199         addReply(c,shared.wrongtypeerr);
 200         return 1;
 201     }
 202     return 0;
 203 }
 204
 205 /* Try to encode a string object in order to save space */
 206 robj *tryObjectEncoding(robj *o) {
 207     long value;
 208     sds s = o->ptr;
 209
 210     if (o->encoding != REDIS_ENCODING_RAW)
 211         return o; /* Already encoded */
 212
 213     /* It's not safe to encode shared objects: shared objects can be shared
 214      * everywhere in the "object space" of Redis. Encoded objects can only
 215      * appear as "values" (and not, for instance, as keys) */
 216      if (o->refcount > 1) return o;
 217
 218     /* Currently we try to encode only strings */
 219     redisAssert(o->type == REDIS_STRING);
 220
 221     /* Check if we can represent this string as a long integer */
 222     if (isStringRepresentableAsLong(s,&value) == REDIS_ERR) return o;
 223
 224     /* Ok, this object can be encoded...
 225      *
 226      * Can I use a shared object? Only if the object is inside a given
 227      * range and if the back end in use is in-memory. For disk store every
 228      * object in memory used as value should be independent.
 229      *
 230      * Note that we also avoid using shared integers when maxmemory is used
 231      * because every object needs to have a private LRU field for the LRU
 232      * algorithm to work well. */
 233     if (!server.ds_enabled &&
 234         server.maxmemory == 0 && value >= 0 && value < REDIS_SHARED_INTEGERS &&
 235         pthread_equal(pthread_self(),server.mainthread))
 236     {
 237         decrRefCount(o);
 238         incrRefCount(shared.integers[value]);
 239         return shared.integers[value];
 240     } else {
 241         o->encoding = REDIS_ENCODING_INT;
 242         sdsfree(o->ptr);
 243         o->ptr = (void*) value;
 244         return o;
 245     }
 246 }
 247
 248 /* Get a decoded version of an encoded object (returned as a new object).
 249  * If the object is already raw-encoded just increment the ref count. */
 250 robj *getDecodedObject(robj *o) {
 251     robj *dec;
 252
 253     if (o->encoding == REDIS_ENCODING_RAW) {
 254         incrRefCount(o);
 255         return o;
 256     }
 257     if (o->type == REDIS_STRING && o->encoding == REDIS_ENCODING_INT) {
 258         char buf[32];
 259
 260         ll2string(buf,32,(long)o->ptr);
 261         dec = createStringObject(buf,strlen(buf));
 262         return dec;
 263     } else {
 264         redisPanic("Unknown encoding type");
 265     }
 266 }
 267
 268 /* Compare two string objects via strcmp() or alike.
 269  * Note that the objects may be integer-encoded. In such a case we
 270  * use ll2string() to get a string representation of the numbers on the stack
 271  * and compare the strings, it's much faster than calling getDecodedObject().
 272  *
 273  * Important note: if objects are not integer encoded, but binary-safe strings,
 274  * sdscmp() from sds.c will apply memcmp() so this function ca be considered
 275  * binary safe. */
 276 int compareStringObjects(robj *a, robj *b) {
 277     redisAssert(a->type == REDIS_STRING && b->type == REDIS_STRING);
 278     char bufa[128], bufb[128], *astr, *bstr;
 279     int bothsds = 1;
 280
 281     if (a == b) return 0;
 282     if (a->encoding != REDIS_ENCODING_RAW) {
 283         ll2string(bufa,sizeof(bufa),(long) a->ptr);
 284         astr = bufa;
 285         bothsds = 0;
 286     } else {
 287         astr = a->ptr;
 288     }
 289     if (b->encoding != REDIS_ENCODING_RAW) {
 290         ll2string(bufb,sizeof(bufb),(long) b->ptr);
 291         bstr = bufb;
 292         bothsds = 0;
 293     } else {
 294         bstr = b->ptr;
 295     }
 296     return bothsds ? sdscmp(astr,bstr) : strcmp(astr,bstr);
 297 }
 298
 299 /* Equal string objects return 1 if the two objects are the same from the
 300  * point of view of a string comparison, otherwise 0 is returned. Note that
 301  * this function is faster then checking for (compareStringObject(a,b) == 0)
 302  * because it can perform some more optimization. */
 303 int equalStringObjects(robj *a, robj *b) {
 304     if (a->encoding != REDIS_ENCODING_RAW && b->encoding != REDIS_ENCODING_RAW){
 305         return a->ptr == b->ptr;
 306     } else {
 307         return compareStringObjects(a,b) == 0;
 308     }
 309 }
 310
 311 size_t stringObjectLen(robj *o) {
 312     redisAssert(o->type == REDIS_STRING);
 313     if (o->encoding == REDIS_ENCODING_RAW) {
 314         return sdslen(o->ptr);
 315     } else {
 316         char buf[32];
 317
 318         return ll2string(buf,32,(long)o->ptr);
 319     }
 320 }
 321
 322 int getDoubleFromObject(robj *o, double *target) {
 323     double value;
 324     char *eptr;
 325
 326     if (o == NULL) {
 327         value = 0;
 328     } else {
 329         redisAssert(o->type == REDIS_STRING);
 330         if (o->encoding == REDIS_ENCODING_RAW) {
 331             value = strtod(o->ptr, &eptr);
 332             if (eptr[0] != '\0' || isnan(value)) return REDIS_ERR;
 333         } else if (o->encoding == REDIS_ENCODING_INT) {
 334             value = (long)o->ptr;
 335         } else {
 336             redisPanic("Unknown string encoding");
 337         }
 338     }
 339
 340     *target = value;
 341     return REDIS_OK;
 342 }
 343
 344 int getDoubleFromObjectOrReply(redisClient *c, robj *o, double *target, const char *msg) {
 345     double value;
 346     if (getDoubleFromObject(o, &value) != REDIS_OK) {
 347         if (msg != NULL) {
 348             addReplyError(c,(char*)msg);
 349         } else {
 350             addReplyError(c,"value is not a double");
 351         }
 352         return REDIS_ERR;
 353     }
 354
 355     *target = value;
 356     return REDIS_OK;
 357 }
 358
 359 int getLongLongFromObject(robj *o, long long *target) {
 360     long long value;
 361     char *eptr;
 362
 363     if (o == NULL) {
 364         value = 0;
 365     } else {
 366         redisAssert(o->type == REDIS_STRING);
 367         if (o->encoding == REDIS_ENCODING_RAW) {
 368             value = strtoll(o->ptr, &eptr, 10);
 369             if (eptr[0] != '\0') return REDIS_ERR;
 370             if (errno == ERANGE && (value == LLONG_MIN || value == LLONG_MAX))
 371                 return REDIS_ERR;
 372         } else if (o->encoding == REDIS_ENCODING_INT) {
 373             value = (long)o->ptr;
 374         } else {
 375             redisPanic("Unknown string encoding");
 376         }
 377     }
 378
 379     if (target) *target = value;
 380     return REDIS_OK;
 381 }
 382
 383 int getLongLongFromObjectOrReply(redisClient *c, robj *o, long long *target, const char *msg) {
 384     long long value;
 385     if (getLongLongFromObject(o, &value) != REDIS_OK) {
 386         if (msg != NULL) {
 387             addReplyError(c,(char*)msg);
 388         } else {
 389             addReplyError(c,"value is not an integer or out of range");
 390         }
 391         return REDIS_ERR;
 392     }
 393
 394     *target = value;
 395     return REDIS_OK;
 396 }
 397
 398 int getLongFromObjectOrReply(redisClient *c, robj *o, long *target, const char *msg) {
 399     long long value;
 400
 401     if (getLongLongFromObjectOrReply(c, o, &value, msg) != REDIS_OK) return REDIS_ERR;
 402     if (value < LONG_MIN || value > LONG_MAX) {
 403         if (msg != NULL) {
 404             addReplyError(c,(char*)msg);
 405         } else {
 406             addReplyError(c,"value is out of range");
 407         }
 408         return REDIS_ERR;
 409     }
 410
 411     *target = value;
 412     return REDIS_OK;
 413 }
 414
 415 char *strEncoding(int encoding) {
 416     switch(encoding) {
 417     case REDIS_ENCODING_RAW: return "raw";
 418     case REDIS_ENCODING_INT: return "int";
 419     case REDIS_ENCODING_HT: return "hashtable";
 420     case REDIS_ENCODING_ZIPMAP: return "zipmap";
 421     case REDIS_ENCODING_LINKEDLIST: return "linkedlist";
 422     case REDIS_ENCODING_ZIPLIST: return "ziplist";
 423     case REDIS_ENCODING_INTSET: return "intset";
 424     case REDIS_ENCODING_SKIPLIST: return "skiplist";
 425     default: return "unknown";
 426     }
 427 }
 428
 429 /* Given an object returns the min number of seconds the object was never
 430  * requested, using an approximated LRU algorithm. */
 431 unsigned long estimateObjectIdleTime(robj *o) {
 432     if (server.lruclock >= o->lru) {
 433         return (server.lruclock - o->lru) * REDIS_LRU_CLOCK_RESOLUTION;
 434     } else {
 435         return ((REDIS_LRU_CLOCK_MAX - o->lru) + server.lruclock) *
 436                     REDIS_LRU_CLOCK_RESOLUTION;
 437     }
 438 }
 439
 440 /* This is an helper function for the DEBUG command. We need to lookup keys
 441  * without any modification of LRU or other parameters. */
 442 robj *objectCommandLookup(redisClient *c, robj *key) {
 443     dictEntry *de;
 444
 445     if ((de = dictFind(c->db->dict,key->ptr)) == NULL) return NULL;
 446     return (robj*) dictGetEntryVal(de);
 447 }
 448
 449 robj *objectCommandLookupOrReply(redisClient *c, robj *key, robj *reply) {
 450     robj *o = objectCommandLookup(c,key);
 451
 452     if (!o) addReply(c, reply);
 453     return o;
 454 }
 455
 456 /* Object command allows to inspect the internals of an Redis Object.
 457  * Usage: OBJECT <verb> ... arguments ... */
 458 void objectCommand(redisClient *c) {
 459     robj *o;
 460
 461     if (!strcasecmp(c->argv[1]->ptr,"refcount") && c->argc == 3) {
 462         if ((o = objectCommandLookupOrReply(c,c->argv[2],shared.nullbulk))
 463                 == NULL) return;
 464         addReplyLongLong(c,o->refcount);
 465     } else if (!strcasecmp(c->argv[1]->ptr,"encoding") && c->argc == 3) {
 466         if ((o = objectCommandLookupOrReply(c,c->argv[2],shared.nullbulk))
 467                 == NULL) return;
 468         addReplyBulkCString(c,strEncoding(o->encoding));
 469     } else if (!strcasecmp(c->argv[1]->ptr,"idletime") && c->argc == 3) {
 470         if ((o = objectCommandLookupOrReply(c,c->argv[2],shared.nullbulk))
 471                 == NULL) return;
 472         addReplyLongLong(c,estimateObjectIdleTime(o));
 473     } else {
 474         addReplyError(c,"Syntax error. Try OBJECT (refcount|encoding|idletime)");
 475     }
 476 }
 477