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     o->storage = REDIS_VM_MEMORY;
  25     return o;
  26 }
  27
  28 robj *createStringObject(char *ptr, size_t len) {
  29     return createObject(REDIS_STRING,sdsnewlen(ptr,len));
  30 }
  31
  32 robj *createStringObjectFromLongLong(long long value) {
  33     robj *o;
  34     if (value >= 0 && value < REDIS_SHARED_INTEGERS &&
  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     /* Object is a swapped out value, or in the process of being loaded. */
 164     if (server.vm_enabled &&
 165         (o->storage == REDIS_VM_SWAPPED || o->storage == REDIS_VM_LOADING))
 166     {
 167         vmpointer *vp = obj;
 168         if (o->storage == REDIS_VM_LOADING) vmCancelThreadedIOJob(o);
 169         vmMarkPagesFree(vp->page,vp->usedpages);
 170         server.vm_stats_swapped_objects--;
 171         zfree(vp);
 172         return;
 173     }
 174
 175     if (o->refcount <= 0) redisPanic("decrRefCount against refcount <= 0");
 176     /* Object is in memory, or in the process of being swapped out.
 177      *
 178      * If the object is being swapped out, abort the operation on
 179      * decrRefCount even if the refcount does not drop to 0: the object
 180      * is referenced at least two times, as value of the key AND as
 181      * job->val in the iojob. So if we don't invalidate the iojob, when it is
 182      * done but the relevant key was removed in the meantime, the
 183      * complete jobs handler will not find the key about the job and the
 184      * assert will fail. */
 185     if (server.vm_enabled && o->storage == REDIS_VM_SWAPPING)
 186         vmCancelThreadedIOJob(o);
 187     if (--(o->refcount) == 0) {
 188         switch(o->type) {
 189         case REDIS_STRING: freeStringObject(o); break;
 190         case REDIS_LIST: freeListObject(o); break;
 191         case REDIS_SET: freeSetObject(o); break;
 192         case REDIS_ZSET: freeZsetObject(o); break;
 193         case REDIS_HASH: freeHashObject(o); break;
 194         default: redisPanic("Unknown object type"); break;
 195         }
 196         o->ptr = NULL; /* defensive programming. We'll see NULL in traces. */
 197         zfree(o);
 198     }
 199 }
 200
 201 int checkType(redisClient *c, robj *o, int type) {
 202     if (o->type != type) {
 203         addReply(c,shared.wrongtypeerr);
 204         return 1;
 205     }
 206     return 0;
 207 }
 208
 209 /* Try to encode a string object in order to save space */
 210 robj *tryObjectEncoding(robj *o) {
 211     long value;
 212     sds s = o->ptr;
 213
 214     if (o->encoding != REDIS_ENCODING_RAW)
 215         return o; /* Already encoded */
 216
 217     /* It's not safe to encode shared objects: shared objects can be shared
 218      * everywhere in the "object space" of Redis. Encoded objects can only
 219      * appear as "values" (and not, for instance, as keys) */
 220      if (o->refcount > 1) return o;
 221
 222     /* Currently we try to encode only strings */
 223     redisAssert(o->type == REDIS_STRING);
 224
 225     /* Check if we can represent this string as a long integer */
 226     if (isStringRepresentableAsLong(s,&value) == REDIS_ERR) return o;
 227
 228     /* Ok, this object can be encoded...
 229      *
 230      * Can I use a shared object? Only if the object is inside a given
 231      * range and if this is the main thread, since when VM is enabled we
 232      * have the constraint that I/O thread should only handle non-shared
 233      * objects, in order to avoid race conditions (we don't have per-object
 234      * locking).
 235      *
 236      * Note that we also avoid using shared integers when maxmemory is used
 237      * because very object needs to have a private LRU field for the LRU
 238      * algorithm to work well. */
 239     if (server.maxmemory == 0 && value >= 0 && value < REDIS_SHARED_INTEGERS &&
 240         pthread_equal(pthread_self(),server.mainthread)) {
 241         decrRefCount(o);
 242         incrRefCount(shared.integers[value]);
 243         return shared.integers[value];
 244     } else {
 245         o->encoding = REDIS_ENCODING_INT;
 246         sdsfree(o->ptr);
 247         o->ptr = (void*) value;
 248         return o;
 249     }
 250 }
 251
 252 /* Get a decoded version of an encoded object (returned as a new object).
 253  * If the object is already raw-encoded just increment the ref count. */
 254 robj *getDecodedObject(robj *o) {
 255     robj *dec;
 256
 257     if (o->encoding == REDIS_ENCODING_RAW) {
 258         incrRefCount(o);
 259         return o;
 260     }
 261     if (o->type == REDIS_STRING && o->encoding == REDIS_ENCODING_INT) {
 262         char buf[32];
 263
 264         ll2string(buf,32,(long)o->ptr);
 265         dec = createStringObject(buf,strlen(buf));
 266         return dec;
 267     } else {
 268         redisPanic("Unknown encoding type");
 269     }
 270 }
 271
 272 /* Compare two string objects via strcmp() or alike.
 273  * Note that the objects may be integer-encoded. In such a case we
 274  * use ll2string() to get a string representation of the numbers on the stack
 275  * and compare the strings, it's much faster than calling getDecodedObject().
 276  *
 277  * Important note: if objects are not integer encoded, but binary-safe strings,
 278  * sdscmp() from sds.c will apply memcmp() so this function ca be considered
 279  * binary safe. */
 280 int compareStringObjects(robj *a, robj *b) {
 281     redisAssert(a->type == REDIS_STRING && b->type == REDIS_STRING);
 282     char bufa[128], bufb[128], *astr, *bstr;
 283     int bothsds = 1;
 284
 285     if (a == b) return 0;
 286     if (a->encoding != REDIS_ENCODING_RAW) {
 287         ll2string(bufa,sizeof(bufa),(long) a->ptr);
 288         astr = bufa;
 289         bothsds = 0;
 290     } else {
 291         astr = a->ptr;
 292     }
 293     if (b->encoding != REDIS_ENCODING_RAW) {
 294         ll2string(bufb,sizeof(bufb),(long) b->ptr);
 295         bstr = bufb;
 296         bothsds = 0;
 297     } else {
 298         bstr = b->ptr;
 299     }
 300     return bothsds ? sdscmp(astr,bstr) : strcmp(astr,bstr);
 301 }
 302
 303 /* Equal string objects return 1 if the two objects are the same from the
 304  * point of view of a string comparison, otherwise 0 is returned. Note that
 305  * this function is faster then checking for (compareStringObject(a,b) == 0)
 306  * because it can perform some more optimization. */
 307 int equalStringObjects(robj *a, robj *b) {
 308     if (a->encoding != REDIS_ENCODING_RAW && b->encoding != REDIS_ENCODING_RAW){
 309         return a->ptr == b->ptr;
 310     } else {
 311         return compareStringObjects(a,b) == 0;
 312     }
 313 }
 314
 315 size_t stringObjectLen(robj *o) {
 316     redisAssert(o->type == REDIS_STRING);
 317     if (o->encoding == REDIS_ENCODING_RAW) {
 318         return sdslen(o->ptr);
 319     } else {
 320         char buf[32];
 321
 322         return ll2string(buf,32,(long)o->ptr);
 323     }
 324 }
 325
 326 int getDoubleFromObject(robj *o, double *target) {
 327     double value;
 328     char *eptr;
 329
 330     if (o == NULL) {
 331         value = 0;
 332     } else {
 333         redisAssert(o->type == REDIS_STRING);
 334         if (o->encoding == REDIS_ENCODING_RAW) {
 335             value = strtod(o->ptr, &eptr);
 336             if (eptr[0] != '\0' || isnan(value)) return REDIS_ERR;
 337         } else if (o->encoding == REDIS_ENCODING_INT) {
 338             value = (long)o->ptr;
 339         } else {
 340             redisPanic("Unknown string encoding");
 341         }
 342     }
 343
 344     *target = value;
 345     return REDIS_OK;
 346 }
 347
 348 int getDoubleFromObjectOrReply(redisClient *c, robj *o, double *target, const char *msg) {
 349     double value;
 350     if (getDoubleFromObject(o, &value) != REDIS_OK) {
 351         if (msg != NULL) {
 352             addReplyError(c,(char*)msg);
 353         } else {
 354             addReplyError(c,"value is not a double");
 355         }
 356         return REDIS_ERR;
 357     }
 358
 359     *target = value;
 360     return REDIS_OK;
 361 }
 362
 363 int getLongLongFromObject(robj *o, long long *target) {
 364     long long value;
 365     char *eptr;
 366
 367     if (o == NULL) {
 368         value = 0;
 369     } else {
 370         redisAssert(o->type == REDIS_STRING);
 371         if (o->encoding == REDIS_ENCODING_RAW) {
 372             value = strtoll(o->ptr, &eptr, 10);
 373             if (eptr[0] != '\0') return REDIS_ERR;
 374             if (errno == ERANGE && (value == LLONG_MIN || value == LLONG_MAX))
 375                 return REDIS_ERR;
 376         } else if (o->encoding == REDIS_ENCODING_INT) {
 377             value = (long)o->ptr;
 378         } else {
 379             redisPanic("Unknown string encoding");
 380         }
 381     }
 382
 383     if (target) *target = value;
 384     return REDIS_OK;
 385 }
 386
 387 int getLongLongFromObjectOrReply(redisClient *c, robj *o, long long *target, const char *msg) {
 388     long long value;
 389     if (getLongLongFromObject(o, &value) != REDIS_OK) {
 390         if (msg != NULL) {
 391             addReplyError(c,(char*)msg);
 392         } else {
 393             addReplyError(c,"value is not an integer or out of range");
 394         }
 395         return REDIS_ERR;
 396     }
 397
 398     *target = value;
 399     return REDIS_OK;
 400 }
 401
 402 int getLongFromObjectOrReply(redisClient *c, robj *o, long *target, const char *msg) {
 403     long long value;
 404
 405     if (getLongLongFromObjectOrReply(c, o, &value, msg) != REDIS_OK) return REDIS_ERR;
 406     if (value < LONG_MIN || value > LONG_MAX) {
 407         if (msg != NULL) {
 408             addReplyError(c,(char*)msg);
 409         } else {
 410             addReplyError(c,"value is out of range");
 411         }
 412         return REDIS_ERR;
 413     }
 414
 415     *target = value;
 416     return REDIS_OK;
 417 }
 418
 419 char *strEncoding(int encoding) {
 420     switch(encoding) {
 421     case REDIS_ENCODING_RAW: return "raw";
 422     case REDIS_ENCODING_INT: return "int";
 423     case REDIS_ENCODING_HT: return "hashtable";
 424     case REDIS_ENCODING_ZIPMAP: return "zipmap";
 425     case REDIS_ENCODING_LINKEDLIST: return "linkedlist";
 426     case REDIS_ENCODING_ZIPLIST: return "ziplist";
 427     case REDIS_ENCODING_INTSET: return "intset";
 428     default: return "unknown";
 429     }
 430 }
 431
 432 /* Given an object returns the min number of seconds the object was never
 433  * requested, using an approximated LRU algorithm. */
 434 unsigned long estimateObjectIdleTime(robj *o) {
 435     if (server.lruclock >= o->lru) {
 436         return (server.lruclock - o->lru) * REDIS_LRU_CLOCK_RESOLUTION;
 437     } else {
 438         return ((REDIS_LRU_CLOCK_MAX - o->lru) + server.lruclock) *
 439                     REDIS_LRU_CLOCK_RESOLUTION;
 440     }
 441 }