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
  97     zs->dict = dictCreate(&zsetDictType,NULL);
  98     zs->zsl = zslCreate();
  99     return createObject(REDIS_ZSET,zs);
 100 }
 101
 102 void freeStringObject(robj *o) {
 103     if (o->encoding == REDIS_ENCODING_RAW) {
 104         sdsfree(o->ptr);
 105     }
 106 }
 107
 108 void freeListObject(robj *o) {
 109     switch (o->encoding) {
 110     case REDIS_ENCODING_LINKEDLIST:
 111         listRelease((list*) o->ptr);
 112         break;
 113     case REDIS_ENCODING_ZIPLIST:
 114         zfree(o->ptr);
 115         break;
 116     default:
 117         redisPanic("Unknown list encoding type");
 118     }
 119 }
 120
 121 void freeSetObject(robj *o) {
 122     switch (o->encoding) {
 123     case REDIS_ENCODING_HT:
 124         dictRelease((dict*) o->ptr);
 125         break;
 126     case REDIS_ENCODING_INTSET:
 127         zfree(o->ptr);
 128         break;
 129     default:
 130         redisPanic("Unknown set encoding type");
 131     }
 132 }
 133
 134 void freeZsetObject(robj *o) {
 135     zset *zs = o->ptr;
 136
 137     dictRelease(zs->dict);
 138     zslFree(zs->zsl);
 139     zfree(zs);
 140 }
 141
 142 void freeHashObject(robj *o) {
 143     switch (o->encoding) {
 144     case REDIS_ENCODING_HT:
 145         dictRelease((dict*) o->ptr);
 146         break;
 147     case REDIS_ENCODING_ZIPMAP:
 148         zfree(o->ptr);
 149         break;
 150     default:
 151         redisPanic("Unknown hash encoding type");
 152         break;
 153     }
 154 }
 155
 156 void incrRefCount(robj *o) {
 157     o->refcount++;
 158 }
 159
 160 void decrRefCount(void *obj) {
 161     robj *o = obj;
 162
 163     if (o->refcount <= 0) redisPanic("decrRefCount against refcount <= 0");
 164     if (--(o->refcount) == 0) {
 165         switch(o->type) {
 166         case REDIS_STRING: freeStringObject(o); break;
 167         case REDIS_LIST: freeListObject(o); break;
 168         case REDIS_SET: freeSetObject(o); break;
 169         case REDIS_ZSET: freeZsetObject(o); break;
 170         case REDIS_HASH: freeHashObject(o); break;
 171         default: redisPanic("Unknown object type"); break;
 172         }
 173         o->ptr = NULL; /* defensive programming. We'll see NULL in traces. */
 174         zfree(o);
 175     }
 176 }
 177
 178 int checkType(redisClient *c, robj *o, int type) {
 179     if (o->type != type) {
 180         addReply(c,shared.wrongtypeerr);
 181         return 1;
 182     }
 183     return 0;
 184 }
 185
 186 /* Try to encode a string object in order to save space */
 187 robj *tryObjectEncoding(robj *o) {
 188     long value;
 189     sds s = o->ptr;
 190
 191     if (o->encoding != REDIS_ENCODING_RAW)
 192         return o; /* Already encoded */
 193
 194     /* It's not safe to encode shared objects: shared objects can be shared
 195      * everywhere in the "object space" of Redis. Encoded objects can only
 196      * appear as "values" (and not, for instance, as keys) */
 197      if (o->refcount > 1) return o;
 198
 199     /* Currently we try to encode only strings */
 200     redisAssert(o->type == REDIS_STRING);
 201
 202     /* Check if we can represent this string as a long integer */
 203     if (isStringRepresentableAsLong(s,&value) == REDIS_ERR) return o;
 204
 205     /* Ok, this object can be encoded...
 206      *
 207      * Can I use a shared object? Only if the object is inside a given
 208      * range and if the back end in use is in-memory. For disk store every
 209      * object in memory used as value should be independent.
 210      *
 211      * Note that we also avoid using shared integers when maxmemory is used
 212      * because every object needs to have a private LRU field for the LRU
 213      * algorithm to work well. */
 214     if (!server.ds_enabled &&
 215         server.maxmemory == 0 && value >= 0 && value < REDIS_SHARED_INTEGERS &&
 216         pthread_equal(pthread_self(),server.mainthread))
 217     {
 218         decrRefCount(o);
 219         incrRefCount(shared.integers[value]);
 220         return shared.integers[value];
 221     } else {
 222         o->encoding = REDIS_ENCODING_INT;
 223         sdsfree(o->ptr);
 224         o->ptr = (void*) value;
 225         return o;
 226     }
 227 }
 228
 229 /* Get a decoded version of an encoded object (returned as a new object).
 230  * If the object is already raw-encoded just increment the ref count. */
 231 robj *getDecodedObject(robj *o) {
 232     robj *dec;
 233
 234     if (o->encoding == REDIS_ENCODING_RAW) {
 235         incrRefCount(o);
 236         return o;
 237     }
 238     if (o->type == REDIS_STRING && o->encoding == REDIS_ENCODING_INT) {
 239         char buf[32];
 240
 241         ll2string(buf,32,(long)o->ptr);
 242         dec = createStringObject(buf,strlen(buf));
 243         return dec;
 244     } else {
 245         redisPanic("Unknown encoding type");
 246     }
 247 }
 248
 249 /* Compare two string objects via strcmp() or alike.
 250  * Note that the objects may be integer-encoded. In such a case we
 251  * use ll2string() to get a string representation of the numbers on the stack
 252  * and compare the strings, it's much faster than calling getDecodedObject().
 253  *
 254  * Important note: if objects are not integer encoded, but binary-safe strings,
 255  * sdscmp() from sds.c will apply memcmp() so this function ca be considered
 256  * binary safe. */
 257 int compareStringObjects(robj *a, robj *b) {
 258     redisAssert(a->type == REDIS_STRING && b->type == REDIS_STRING);
 259     char bufa[128], bufb[128], *astr, *bstr;
 260     int bothsds = 1;
 261
 262     if (a == b) return 0;
 263     if (a->encoding != REDIS_ENCODING_RAW) {
 264         ll2string(bufa,sizeof(bufa),(long) a->ptr);
 265         astr = bufa;
 266         bothsds = 0;
 267     } else {
 268         astr = a->ptr;
 269     }
 270     if (b->encoding != REDIS_ENCODING_RAW) {
 271         ll2string(bufb,sizeof(bufb),(long) b->ptr);
 272         bstr = bufb;
 273         bothsds = 0;
 274     } else {
 275         bstr = b->ptr;
 276     }
 277     return bothsds ? sdscmp(astr,bstr) : strcmp(astr,bstr);
 278 }
 279
 280 /* Equal string objects return 1 if the two objects are the same from the
 281  * point of view of a string comparison, otherwise 0 is returned. Note that
 282  * this function is faster then checking for (compareStringObject(a,b) == 0)
 283  * because it can perform some more optimization. */
 284 int equalStringObjects(robj *a, robj *b) {
 285     if (a->encoding != REDIS_ENCODING_RAW && b->encoding != REDIS_ENCODING_RAW){
 286         return a->ptr == b->ptr;
 287     } else {
 288         return compareStringObjects(a,b) == 0;
 289     }
 290 }
 291
 292 size_t stringObjectLen(robj *o) {
 293     redisAssert(o->type == REDIS_STRING);
 294     if (o->encoding == REDIS_ENCODING_RAW) {
 295         return sdslen(o->ptr);
 296     } else {
 297         char buf[32];
 298
 299         return ll2string(buf,32,(long)o->ptr);
 300     }
 301 }
 302
 303 int getDoubleFromObject(robj *o, double *target) {
 304     double value;
 305     char *eptr;
 306
 307     if (o == NULL) {
 308         value = 0;
 309     } else {
 310         redisAssert(o->type == REDIS_STRING);
 311         if (o->encoding == REDIS_ENCODING_RAW) {
 312             value = strtod(o->ptr, &eptr);
 313             if (eptr[0] != '\0' || isnan(value)) return REDIS_ERR;
 314         } else if (o->encoding == REDIS_ENCODING_INT) {
 315             value = (long)o->ptr;
 316         } else {
 317             redisPanic("Unknown string encoding");
 318         }
 319     }
 320
 321     *target = value;
 322     return REDIS_OK;
 323 }
 324
 325 int getDoubleFromObjectOrReply(redisClient *c, robj *o, double *target, const char *msg) {
 326     double value;
 327     if (getDoubleFromObject(o, &value) != REDIS_OK) {
 328         if (msg != NULL) {
 329             addReplyError(c,(char*)msg);
 330         } else {
 331             addReplyError(c,"value is not a double");
 332         }
 333         return REDIS_ERR;
 334     }
 335
 336     *target = value;
 337     return REDIS_OK;
 338 }
 339
 340 int getLongLongFromObject(robj *o, long long *target) {
 341     long long value;
 342     char *eptr;
 343
 344     if (o == NULL) {
 345         value = 0;
 346     } else {
 347         redisAssert(o->type == REDIS_STRING);
 348         if (o->encoding == REDIS_ENCODING_RAW) {
 349             value = strtoll(o->ptr, &eptr, 10);
 350             if (eptr[0] != '\0') return REDIS_ERR;
 351             if (errno == ERANGE && (value == LLONG_MIN || value == LLONG_MAX))
 352                 return REDIS_ERR;
 353         } else if (o->encoding == REDIS_ENCODING_INT) {
 354             value = (long)o->ptr;
 355         } else {
 356             redisPanic("Unknown string encoding");
 357         }
 358     }
 359
 360     if (target) *target = value;
 361     return REDIS_OK;
 362 }
 363
 364 int getLongLongFromObjectOrReply(redisClient *c, robj *o, long long *target, const char *msg) {
 365     long long value;
 366     if (getLongLongFromObject(o, &value) != REDIS_OK) {
 367         if (msg != NULL) {
 368             addReplyError(c,(char*)msg);
 369         } else {
 370             addReplyError(c,"value is not an integer or out of range");
 371         }
 372         return REDIS_ERR;
 373     }
 374
 375     *target = value;
 376     return REDIS_OK;
 377 }
 378
 379 int getLongFromObjectOrReply(redisClient *c, robj *o, long *target, const char *msg) {
 380     long long value;
 381
 382     if (getLongLongFromObjectOrReply(c, o, &value, msg) != REDIS_OK) return REDIS_ERR;
 383     if (value < LONG_MIN || value > LONG_MAX) {
 384         if (msg != NULL) {
 385             addReplyError(c,(char*)msg);
 386         } else {
 387             addReplyError(c,"value is out of range");
 388         }
 389         return REDIS_ERR;
 390     }
 391
 392     *target = value;
 393     return REDIS_OK;
 394 }
 395
 396 char *strEncoding(int encoding) {
 397     switch(encoding) {
 398     case REDIS_ENCODING_RAW: return "raw";
 399     case REDIS_ENCODING_INT: return "int";
 400     case REDIS_ENCODING_HT: return "hashtable";
 401     case REDIS_ENCODING_ZIPMAP: return "zipmap";
 402     case REDIS_ENCODING_LINKEDLIST: return "linkedlist";
 403     case REDIS_ENCODING_ZIPLIST: return "ziplist";
 404     case REDIS_ENCODING_INTSET: return "intset";
 405     default: return "unknown";
 406     }
 407 }
 408
 409 /* Given an object returns the min number of seconds the object was never
 410  * requested, using an approximated LRU algorithm. */
 411 unsigned long estimateObjectIdleTime(robj *o) {
 412     if (server.lruclock >= o->lru) {
 413         return (server.lruclock - o->lru) * REDIS_LRU_CLOCK_RESOLUTION;
 414     } else {
 415         return ((REDIS_LRU_CLOCK_MAX - o->lru) + server.lruclock) *
 416                     REDIS_LRU_CLOCK_RESOLUTION;
 417     }
 418 }
 419
 420 /* This is an helper function for the DEBUG command. We need to lookup keys
 421  * without any modification of LRU or other parameters. */
 422 robj *objectCommandLookup(redisClient *c, robj *key) {
 423     dictEntry *de;
 424
 425     if ((de = dictFind(c->db->dict,key->ptr)) == NULL) return NULL;
 426     return (robj*) dictGetEntryVal(de);
 427 }
 428
 429 robj *objectCommandLookupOrReply(redisClient *c, robj *key, robj *reply) {
 430     robj *o = objectCommandLookup(c,key);
 431
 432     if (!o) addReply(c, reply);
 433     return o;
 434 }
 435
 436 /* Object command allows to inspect the internals of an Redis Object.
 437  * Usage: OBJECT <verb> ... arguments ... */
 438 void objectCommand(redisClient *c) {
 439     robj *o;
 440
 441     if (!strcasecmp(c->argv[1]->ptr,"refcount") && c->argc == 3) {
 442         if ((o = objectCommandLookupOrReply(c,c->argv[2],shared.nullbulk))
 443                 == NULL) return;
 444         addReplyLongLong(c,o->refcount);
 445     } else if (!strcasecmp(c->argv[1]->ptr,"encoding") && c->argc == 3) {
 446         if ((o = objectCommandLookupOrReply(c,c->argv[2],shared.nullbulk))
 447                 == NULL) return;
 448         addReplyBulkCString(c,strEncoding(o->encoding));
 449     } else if (!strcasecmp(c->argv[1]->ptr,"idletime") && c->argc == 3) {
 450         if ((o = objectCommandLookupOrReply(c,c->argv[2],shared.nullbulk))
 451                 == NULL) return;
 452         addReplyLongLong(c,estimateObjectIdleTime(o));
 453     } else {
 454         addReplyError(c,"Syntax error. Try OBJECT (refcount|encoding|idletime)");
 455     }
 456 }
 457