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 int isObjectRepresentableAsLongLong(robj *o, long long *llval) {
 206     redisAssert(o->type == REDIS_STRING);
 207     if (o->encoding == REDIS_ENCODING_INT) {
 208         if (llval) *llval = (long) o->ptr;
 209         return REDIS_OK;
 210     } else {
 211         return string2ll(o->ptr,sdslen(o->ptr),llval) ? REDIS_OK : REDIS_ERR;
 212     }
 213 }
 214
 215 /* Try to encode a string object in order to save space */
 216 robj *tryObjectEncoding(robj *o) {
 217     long value;
 218     sds s = o->ptr;
 219
 220     if (o->encoding != REDIS_ENCODING_RAW)
 221         return o; /* Already encoded */
 222
 223     /* It's not safe to encode shared objects: shared objects can be shared
 224      * everywhere in the "object space" of Redis. Encoded objects can only
 225      * appear as "values" (and not, for instance, as keys) */
 226      if (o->refcount > 1) return o;
 227
 228     /* Currently we try to encode only strings */
 229     redisAssert(o->type == REDIS_STRING);
 230
 231     /* Check if we can represent this string as a long integer */
 232     if (!string2l(s,sdslen(s),&value)) return o;
 233
 234     /* Ok, this object can be encoded...
 235      *
 236      * Can I use a shared object? Only if the object is inside a given
 237      * range and if the back end in use is in-memory. For disk store every
 238      * object in memory used as value should be independent.
 239      *
 240      * Note that we also avoid using shared integers when maxmemory is used
 241      * because every object needs to have a private LRU field for the LRU
 242      * algorithm to work well. */
 243     if (!server.ds_enabled &&
 244         server.maxmemory == 0 && value >= 0 && value < REDIS_SHARED_INTEGERS &&
 245         pthread_equal(pthread_self(),server.mainthread))
 246     {
 247         decrRefCount(o);
 248         incrRefCount(shared.integers[value]);
 249         return shared.integers[value];
 250     } else {
 251         o->encoding = REDIS_ENCODING_INT;
 252         sdsfree(o->ptr);
 253         o->ptr = (void*) value;
 254         return o;
 255     }
 256 }
 257
 258 /* Get a decoded version of an encoded object (returned as a new object).
 259  * If the object is already raw-encoded just increment the ref count. */
 260 robj *getDecodedObject(robj *o) {
 261     robj *dec;
 262
 263     if (o->encoding == REDIS_ENCODING_RAW) {
 264         incrRefCount(o);
 265         return o;
 266     }
 267     if (o->type == REDIS_STRING && o->encoding == REDIS_ENCODING_INT) {
 268         char buf[32];
 269
 270         ll2string(buf,32,(long)o->ptr);
 271         dec = createStringObject(buf,strlen(buf));
 272         return dec;
 273     } else {
 274         redisPanic("Unknown encoding type");
 275     }
 276 }
 277
 278 /* Compare two string objects via strcmp() or alike.
 279  * Note that the objects may be integer-encoded. In such a case we
 280  * use ll2string() to get a string representation of the numbers on the stack
 281  * and compare the strings, it's much faster than calling getDecodedObject().
 282  *
 283  * Important note: if objects are not integer encoded, but binary-safe strings,
 284  * sdscmp() from sds.c will apply memcmp() so this function ca be considered
 285  * binary safe. */
 286 int compareStringObjects(robj *a, robj *b) {
 287     redisAssert(a->type == REDIS_STRING && b->type == REDIS_STRING);
 288     char bufa[128], bufb[128], *astr, *bstr;
 289     int bothsds = 1;
 290
 291     if (a == b) return 0;
 292     if (a->encoding != REDIS_ENCODING_RAW) {
 293         ll2string(bufa,sizeof(bufa),(long) a->ptr);
 294         astr = bufa;
 295         bothsds = 0;
 296     } else {
 297         astr = a->ptr;
 298     }
 299     if (b->encoding != REDIS_ENCODING_RAW) {
 300         ll2string(bufb,sizeof(bufb),(long) b->ptr);
 301         bstr = bufb;
 302         bothsds = 0;
 303     } else {
 304         bstr = b->ptr;
 305     }
 306     return bothsds ? sdscmp(astr,bstr) : strcmp(astr,bstr);
 307 }
 308
 309 /* Equal string objects return 1 if the two objects are the same from the
 310  * point of view of a string comparison, otherwise 0 is returned. Note that
 311  * this function is faster then checking for (compareStringObject(a,b) == 0)
 312  * because it can perform some more optimization. */
 313 int equalStringObjects(robj *a, robj *b) {
 314     if (a->encoding != REDIS_ENCODING_RAW && b->encoding != REDIS_ENCODING_RAW){
 315         return a->ptr == b->ptr;
 316     } else {
 317         return compareStringObjects(a,b) == 0;
 318     }
 319 }
 320
 321 size_t stringObjectLen(robj *o) {
 322     redisAssert(o->type == REDIS_STRING);
 323     if (o->encoding == REDIS_ENCODING_RAW) {
 324         return sdslen(o->ptr);
 325     } else {
 326         char buf[32];
 327
 328         return ll2string(buf,32,(long)o->ptr);
 329     }
 330 }
 331
 332 int getDoubleFromObject(robj *o, double *target) {
 333     double value;
 334     char *eptr;
 335
 336     if (o == NULL) {
 337         value = 0;
 338     } else {
 339         redisAssert(o->type == REDIS_STRING);
 340         if (o->encoding == REDIS_ENCODING_RAW) {
 341             value = strtod(o->ptr, &eptr);
 342             if (eptr[0] != '\0' || isnan(value)) return REDIS_ERR;
 343         } else if (o->encoding == REDIS_ENCODING_INT) {
 344             value = (long)o->ptr;
 345         } else {
 346             redisPanic("Unknown string encoding");
 347         }
 348     }
 349
 350     *target = value;
 351     return REDIS_OK;
 352 }
 353
 354 int getDoubleFromObjectOrReply(redisClient *c, robj *o, double *target, const char *msg) {
 355     double value;
 356     if (getDoubleFromObject(o, &value) != REDIS_OK) {
 357         if (msg != NULL) {
 358             addReplyError(c,(char*)msg);
 359         } else {
 360             addReplyError(c,"value is not a double");
 361         }
 362         return REDIS_ERR;
 363     }
 364
 365     *target = value;
 366     return REDIS_OK;
 367 }
 368
 369 int getLongLongFromObject(robj *o, long long *target) {
 370     long long value;
 371     char *eptr;
 372
 373     if (o == NULL) {
 374         value = 0;
 375     } else {
 376         redisAssert(o->type == REDIS_STRING);
 377         if (o->encoding == REDIS_ENCODING_RAW) {
 378             value = strtoll(o->ptr, &eptr, 10);
 379             if (eptr[0] != '\0') return REDIS_ERR;
 380             if (errno == ERANGE && (value == LLONG_MIN || value == LLONG_MAX))
 381                 return REDIS_ERR;
 382         } else if (o->encoding == REDIS_ENCODING_INT) {
 383             value = (long)o->ptr;
 384         } else {
 385             redisPanic("Unknown string encoding");
 386         }
 387     }
 388
 389     if (target) *target = value;
 390     return REDIS_OK;
 391 }
 392
 393 int getLongLongFromObjectOrReply(redisClient *c, robj *o, long long *target, const char *msg) {
 394     long long value;
 395     if (getLongLongFromObject(o, &value) != REDIS_OK) {
 396         if (msg != NULL) {
 397             addReplyError(c,(char*)msg);
 398         } else {
 399             addReplyError(c,"value is not an integer or out of range");
 400         }
 401         return REDIS_ERR;
 402     }
 403
 404     *target = value;
 405     return REDIS_OK;
 406 }
 407
 408 int getLongFromObjectOrReply(redisClient *c, robj *o, long *target, const char *msg) {
 409     long long value;
 410
 411     if (getLongLongFromObjectOrReply(c, o, &value, msg) != REDIS_OK) return REDIS_ERR;
 412     if (value < LONG_MIN || value > LONG_MAX) {
 413         if (msg != NULL) {
 414             addReplyError(c,(char*)msg);
 415         } else {
 416             addReplyError(c,"value is out of range");
 417         }
 418         return REDIS_ERR;
 419     }
 420
 421     *target = value;
 422     return REDIS_OK;
 423 }
 424
 425 char *strEncoding(int encoding) {
 426     switch(encoding) {
 427     case REDIS_ENCODING_RAW: return "raw";
 428     case REDIS_ENCODING_INT: return "int";
 429     case REDIS_ENCODING_HT: return "hashtable";
 430     case REDIS_ENCODING_ZIPMAP: return "zipmap";
 431     case REDIS_ENCODING_LINKEDLIST: return "linkedlist";
 432     case REDIS_ENCODING_ZIPLIST: return "ziplist";
 433     case REDIS_ENCODING_INTSET: return "intset";
 434     case REDIS_ENCODING_SKIPLIST: return "skiplist";
 435     default: return "unknown";
 436     }
 437 }
 438
 439 /* Given an object returns the min number of seconds the object was never
 440  * requested, using an approximated LRU algorithm. */
 441 unsigned long estimateObjectIdleTime(robj *o) {
 442     if (server.lruclock >= o->lru) {
 443         return (server.lruclock - o->lru) * REDIS_LRU_CLOCK_RESOLUTION;
 444     } else {
 445         return ((REDIS_LRU_CLOCK_MAX - o->lru) + server.lruclock) *
 446                     REDIS_LRU_CLOCK_RESOLUTION;
 447     }
 448 }
 449
 450 /* This is an helper function for the DEBUG command. We need to lookup keys
 451  * without any modification of LRU or other parameters. */
 452 robj *objectCommandLookup(redisClient *c, robj *key) {
 453     dictEntry *de;
 454
 455     if ((de = dictFind(c->db->dict,key->ptr)) == NULL) return NULL;
 456     return (robj*) dictGetEntryVal(de);
 457 }
 458
 459 robj *objectCommandLookupOrReply(redisClient *c, robj *key, robj *reply) {
 460     robj *o = objectCommandLookup(c,key);
 461
 462     if (!o) addReply(c, reply);
 463     return o;
 464 }
 465
 466 /* Object command allows to inspect the internals of an Redis Object.
 467  * Usage: OBJECT <verb> ... arguments ... */
 468 void objectCommand(redisClient *c) {
 469     robj *o;
 470
 471     if (!strcasecmp(c->argv[1]->ptr,"refcount") && c->argc == 3) {
 472         if ((o = objectCommandLookupOrReply(c,c->argv[2],shared.nullbulk))
 473                 == NULL) return;
 474         addReplyLongLong(c,o->refcount);
 475     } else if (!strcasecmp(c->argv[1]->ptr,"encoding") && c->argc == 3) {
 476         if ((o = objectCommandLookupOrReply(c,c->argv[2],shared.nullbulk))
 477                 == NULL) return;
 478         addReplyBulkCString(c,strEncoding(o->encoding));
 479     } else if (!strcasecmp(c->argv[1]->ptr,"idletime") && c->argc == 3) {
 480         if ((o = objectCommandLookupOrReply(c,c->argv[2],shared.nullbulk))
 481                 == NULL) return;
 482         addReplyLongLong(c,estimateObjectIdleTime(o));
 483     } else {
 484         addReplyError(c,"Syntax error. Try OBJECT (refcount|encoding|idletime)");
 485     }
 486 }
 487