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 void freeStringObject(robj *o) {
 106     if (o->encoding == REDIS_ENCODING_RAW) {
 107         sdsfree(o->ptr);
 108     }
 109 }
 110
 111 void freeListObject(robj *o) {
 112     switch (o->encoding) {
 113     case REDIS_ENCODING_LINKEDLIST:
 114         listRelease((list*) o->ptr);
 115         break;
 116     case REDIS_ENCODING_ZIPLIST:
 117         zfree(o->ptr);
 118         break;
 119     default:
 120         redisPanic("Unknown list encoding type");
 121     }
 122 }
 123
 124 void freeSetObject(robj *o) {
 125     switch (o->encoding) {
 126     case REDIS_ENCODING_HT:
 127         dictRelease((dict*) o->ptr);
 128         break;
 129     case REDIS_ENCODING_INTSET:
 130         zfree(o->ptr);
 131         break;
 132     default:
 133         redisPanic("Unknown set encoding type");
 134     }
 135 }
 136
 137 void freeZsetObject(robj *o) {
 138     zset *zs = o->ptr;
 139
 140     dictRelease(zs->dict);
 141     zslFree(zs->zsl);
 142     zfree(zs);
 143 }
 144
 145 void freeHashObject(robj *o) {
 146     switch (o->encoding) {
 147     case REDIS_ENCODING_HT:
 148         dictRelease((dict*) o->ptr);
 149         break;
 150     case REDIS_ENCODING_ZIPMAP:
 151         zfree(o->ptr);
 152         break;
 153     default:
 154         redisPanic("Unknown hash encoding type");
 155         break;
 156     }
 157 }
 158
 159 void incrRefCount(robj *o) {
 160     o->refcount++;
 161 }
 162
 163 void decrRefCount(void *obj) {
 164     robj *o = obj;
 165
 166     if (o->refcount <= 0) redisPanic("decrRefCount against refcount <= 0");
 167     if (--(o->refcount) == 0) {
 168         switch(o->type) {
 169         case REDIS_STRING: freeStringObject(o); break;
 170         case REDIS_LIST: freeListObject(o); break;
 171         case REDIS_SET: freeSetObject(o); break;
 172         case REDIS_ZSET: freeZsetObject(o); break;
 173         case REDIS_HASH: freeHashObject(o); break;
 174         default: redisPanic("Unknown object type"); break;
 175         }
 176         o->ptr = NULL; /* defensive programming. We'll see NULL in traces. */
 177         zfree(o);
 178     }
 179 }
 180
 181 int checkType(redisClient *c, robj *o, int type) {
 182     if (o->type != type) {
 183         addReply(c,shared.wrongtypeerr);
 184         return 1;
 185     }
 186     return 0;
 187 }
 188
 189 /* Try to encode a string object in order to save space */
 190 robj *tryObjectEncoding(robj *o) {
 191     long value;
 192     sds s = o->ptr;
 193
 194     if (o->encoding != REDIS_ENCODING_RAW)
 195         return o; /* Already encoded */
 196
 197     /* It's not safe to encode shared objects: shared objects can be shared
 198      * everywhere in the "object space" of Redis. Encoded objects can only
 199      * appear as "values" (and not, for instance, as keys) */
 200      if (o->refcount > 1) return o;
 201
 202     /* Currently we try to encode only strings */
 203     redisAssert(o->type == REDIS_STRING);
 204
 205     /* Check if we can represent this string as a long integer */
 206     if (isStringRepresentableAsLong(s,&value) == REDIS_ERR) return o;
 207
 208     /* Ok, this object can be encoded...
 209      *
 210      * Can I use a shared object? Only if the object is inside a given
 211      * range and if the back end in use is in-memory. For disk store every
 212      * object in memory used as value should be independent.
 213      *
 214      * Note that we also avoid using shared integers when maxmemory is used
 215      * because every object needs to have a private LRU field for the LRU
 216      * algorithm to work well. */
 217     if (!server.ds_enabled &&
 218         server.maxmemory == 0 && value >= 0 && value < REDIS_SHARED_INTEGERS &&
 219         pthread_equal(pthread_self(),server.mainthread))
 220     {
 221         decrRefCount(o);
 222         incrRefCount(shared.integers[value]);
 223         return shared.integers[value];
 224     } else {
 225         o->encoding = REDIS_ENCODING_INT;
 226         sdsfree(o->ptr);
 227         o->ptr = (void*) value;
 228         return o;
 229     }
 230 }
 231
 232 /* Get a decoded version of an encoded object (returned as a new object).
 233  * If the object is already raw-encoded just increment the ref count. */
 234 robj *getDecodedObject(robj *o) {
 235     robj *dec;
 236
 237     if (o->encoding == REDIS_ENCODING_RAW) {
 238         incrRefCount(o);
 239         return o;
 240     }
 241     if (o->type == REDIS_STRING && o->encoding == REDIS_ENCODING_INT) {
 242         char buf[32];
 243
 244         ll2string(buf,32,(long)o->ptr);
 245         dec = createStringObject(buf,strlen(buf));
 246         return dec;
 247     } else {
 248         redisPanic("Unknown encoding type");
 249     }
 250 }
 251
 252 /* Compare two string objects via strcmp() or alike.
 253  * Note that the objects may be integer-encoded. In such a case we
 254  * use ll2string() to get a string representation of the numbers on the stack
 255  * and compare the strings, it's much faster than calling getDecodedObject().
 256  *
 257  * Important note: if objects are not integer encoded, but binary-safe strings,
 258  * sdscmp() from sds.c will apply memcmp() so this function ca be considered
 259  * binary safe. */
 260 int compareStringObjects(robj *a, robj *b) {
 261     redisAssert(a->type == REDIS_STRING && b->type == REDIS_STRING);
 262     char bufa[128], bufb[128], *astr, *bstr;
 263     int bothsds = 1;
 264
 265     if (a == b) return 0;
 266     if (a->encoding != REDIS_ENCODING_RAW) {
 267         ll2string(bufa,sizeof(bufa),(long) a->ptr);
 268         astr = bufa;
 269         bothsds = 0;
 270     } else {
 271         astr = a->ptr;
 272     }
 273     if (b->encoding != REDIS_ENCODING_RAW) {
 274         ll2string(bufb,sizeof(bufb),(long) b->ptr);
 275         bstr = bufb;
 276         bothsds = 0;
 277     } else {
 278         bstr = b->ptr;
 279     }
 280     return bothsds ? sdscmp(astr,bstr) : strcmp(astr,bstr);
 281 }
 282
 283 /* Equal string objects return 1 if the two objects are the same from the
 284  * point of view of a string comparison, otherwise 0 is returned. Note that
 285  * this function is faster then checking for (compareStringObject(a,b) == 0)
 286  * because it can perform some more optimization. */
 287 int equalStringObjects(robj *a, robj *b) {
 288     if (a->encoding != REDIS_ENCODING_RAW && b->encoding != REDIS_ENCODING_RAW){
 289         return a->ptr == b->ptr;
 290     } else {
 291         return compareStringObjects(a,b) == 0;
 292     }
 293 }
 294
 295 size_t stringObjectLen(robj *o) {
 296     redisAssert(o->type == REDIS_STRING);
 297     if (o->encoding == REDIS_ENCODING_RAW) {
 298         return sdslen(o->ptr);
 299     } else {
 300         char buf[32];
 301
 302         return ll2string(buf,32,(long)o->ptr);
 303     }
 304 }
 305
 306 int getDoubleFromObject(robj *o, double *target) {
 307     double value;
 308     char *eptr;
 309
 310     if (o == NULL) {
 311         value = 0;
 312     } else {
 313         redisAssert(o->type == REDIS_STRING);
 314         if (o->encoding == REDIS_ENCODING_RAW) {
 315             value = strtod(o->ptr, &eptr);
 316             if (eptr[0] != '\0' || isnan(value)) return REDIS_ERR;
 317         } else if (o->encoding == REDIS_ENCODING_INT) {
 318             value = (long)o->ptr;
 319         } else {
 320             redisPanic("Unknown string encoding");
 321         }
 322     }
 323
 324     *target = value;
 325     return REDIS_OK;
 326 }
 327
 328 int getDoubleFromObjectOrReply(redisClient *c, robj *o, double *target, const char *msg) {
 329     double value;
 330     if (getDoubleFromObject(o, &value) != REDIS_OK) {
 331         if (msg != NULL) {
 332             addReplyError(c,(char*)msg);
 333         } else {
 334             addReplyError(c,"value is not a double");
 335         }
 336         return REDIS_ERR;
 337     }
 338
 339     *target = value;
 340     return REDIS_OK;
 341 }
 342
 343 int getLongLongFromObject(robj *o, long long *target) {
 344     long long value;
 345     char *eptr;
 346
 347     if (o == NULL) {
 348         value = 0;
 349     } else {
 350         redisAssert(o->type == REDIS_STRING);
 351         if (o->encoding == REDIS_ENCODING_RAW) {
 352             value = strtoll(o->ptr, &eptr, 10);
 353             if (eptr[0] != '\0') return REDIS_ERR;
 354             if (errno == ERANGE && (value == LLONG_MIN || value == LLONG_MAX))
 355                 return REDIS_ERR;
 356         } else if (o->encoding == REDIS_ENCODING_INT) {
 357             value = (long)o->ptr;
 358         } else {
 359             redisPanic("Unknown string encoding");
 360         }
 361     }
 362
 363     if (target) *target = value;
 364     return REDIS_OK;
 365 }
 366
 367 int getLongLongFromObjectOrReply(redisClient *c, robj *o, long long *target, const char *msg) {
 368     long long value;
 369     if (getLongLongFromObject(o, &value) != REDIS_OK) {
 370         if (msg != NULL) {
 371             addReplyError(c,(char*)msg);
 372         } else {
 373             addReplyError(c,"value is not an integer or out of range");
 374         }
 375         return REDIS_ERR;
 376     }
 377
 378     *target = value;
 379     return REDIS_OK;
 380 }
 381
 382 int getLongFromObjectOrReply(redisClient *c, robj *o, long *target, const char *msg) {
 383     long long value;
 384
 385     if (getLongLongFromObjectOrReply(c, o, &value, msg) != REDIS_OK) return REDIS_ERR;
 386     if (value < LONG_MIN || value > LONG_MAX) {
 387         if (msg != NULL) {
 388             addReplyError(c,(char*)msg);
 389         } else {
 390             addReplyError(c,"value is out of range");
 391         }
 392         return REDIS_ERR;
 393     }
 394
 395     *target = value;
 396     return REDIS_OK;
 397 }
 398
 399 char *strEncoding(int encoding) {
 400     switch(encoding) {
 401     case REDIS_ENCODING_RAW: return "raw";
 402     case REDIS_ENCODING_INT: return "int";
 403     case REDIS_ENCODING_HT: return "hashtable";
 404     case REDIS_ENCODING_ZIPMAP: return "zipmap";
 405     case REDIS_ENCODING_LINKEDLIST: return "linkedlist";
 406     case REDIS_ENCODING_ZIPLIST: return "ziplist";
 407     case REDIS_ENCODING_INTSET: return "intset";
 408     case REDIS_ENCODING_SKIPLIST: return "skiplist";
 409     default: return "unknown";
 410     }
 411 }
 412
 413 /* Given an object returns the min number of seconds the object was never
 414  * requested, using an approximated LRU algorithm. */
 415 unsigned long estimateObjectIdleTime(robj *o) {
 416     if (server.lruclock >= o->lru) {
 417         return (server.lruclock - o->lru) * REDIS_LRU_CLOCK_RESOLUTION;
 418     } else {
 419         return ((REDIS_LRU_CLOCK_MAX - o->lru) + server.lruclock) *
 420                     REDIS_LRU_CLOCK_RESOLUTION;
 421     }
 422 }
 423
 424 /* This is an helper function for the DEBUG command. We need to lookup keys
 425  * without any modification of LRU or other parameters. */
 426 robj *objectCommandLookup(redisClient *c, robj *key) {
 427     dictEntry *de;
 428
 429     if ((de = dictFind(c->db->dict,key->ptr)) == NULL) return NULL;
 430     return (robj*) dictGetEntryVal(de);
 431 }
 432
 433 robj *objectCommandLookupOrReply(redisClient *c, robj *key, robj *reply) {
 434     robj *o = objectCommandLookup(c,key);
 435
 436     if (!o) addReply(c, reply);
 437     return o;
 438 }
 439
 440 /* Object command allows to inspect the internals of an Redis Object.
 441  * Usage: OBJECT <verb> ... arguments ... */
 442 void objectCommand(redisClient *c) {
 443     robj *o;
 444
 445     if (!strcasecmp(c->argv[1]->ptr,"refcount") && c->argc == 3) {
 446         if ((o = objectCommandLookupOrReply(c,c->argv[2],shared.nullbulk))
 447                 == NULL) return;
 448         addReplyLongLong(c,o->refcount);
 449     } else if (!strcasecmp(c->argv[1]->ptr,"encoding") && c->argc == 3) {
 450         if ((o = objectCommandLookupOrReply(c,c->argv[2],shared.nullbulk))
 451                 == NULL) return;
 452         addReplyBulkCString(c,strEncoding(o->encoding));
 453     } else if (!strcasecmp(c->argv[1]->ptr,"idletime") && c->argc == 3) {
 454         if ((o = objectCommandLookupOrReply(c,c->argv[2],shared.nullbulk))
 455                 == NULL) return;
 456         addReplyLongLong(c,estimateObjectIdleTime(o));
 457     } else {
 458         addReplyError(c,"Syntax error. Try OBJECT (refcount|encoding|idletime)");
 459     }
 460 }
 461