src/rdb.c

   1 #include "redis.h"
   2 #include "lzf.h"    /* LZF compression library */
   3
   4 #include <math.h>
   5 #include <sys/types.h>
   6 #include <sys/time.h>
   7 #include <sys/resource.h>
   8 #include <sys/wait.h>
   9 #include <arpa/inet.h>
  10 #include <sys/stat.h>
  11
  12 /* Convenience wrapper around fwrite, that returns the number of bytes written
  13  * to the file instead of the number of objects (see fwrite(3)) and -1 in the
  14  * case of an error. It also supports a NULL *fp to skip writing altogether
  15  * instead of writing to /dev/null. */
  16 static int rdbWriteRaw(FILE *fp, void *p, size_t len) {
  17     if (fp != NULL && fwrite(p,len,1,fp) == 0) return -1;
  18     return len;
  19 }
  20
  21 int rdbSaveType(FILE *fp, unsigned char type) {
  22     return rdbWriteRaw(fp,&type,1);
  23 }
  24
  25 int rdbSaveTime(FILE *fp, time_t t) {
  26     int32_t t32 = (int32_t) t;
  27     return rdbWriteRaw(fp,&t32,4);
  28 }
  29
  30 /* check rdbLoadLen() comments for more info */
  31 int rdbSaveLen(FILE *fp, uint32_t len) {
  32     unsigned char buf[2];
  33     int nwritten;
  34
  35     if (len < (1<<6)) {
  36         /* Save a 6 bit len */
  37         buf[0] = (len&0xFF)|(REDIS_RDB_6BITLEN<<6);
  38         if (rdbWriteRaw(fp,buf,1) == -1) return -1;
  39         nwritten = 1;
  40     } else if (len < (1<<14)) {
  41         /* Save a 14 bit len */
  42         buf[0] = ((len>>8)&0xFF)|(REDIS_RDB_14BITLEN<<6);
  43         buf[1] = len&0xFF;
  44         if (rdbWriteRaw(fp,buf,2) == -1) return -1;
  45         nwritten = 2;
  46     } else {
  47         /* Save a 32 bit len */
  48         buf[0] = (REDIS_RDB_32BITLEN<<6);
  49         if (rdbWriteRaw(fp,buf,1) == -1) return -1;
  50         len = htonl(len);
  51         if (rdbWriteRaw(fp,&len,4) == -1) return -1;
  52         nwritten = 1+4;
  53     }
  54     return nwritten;
  55 }
  56
  57 /* Encode 'value' as an integer if possible (if integer will fit the
  58  * supported range). If the function sucessful encoded the integer
  59  * then the (up to 5 bytes) encoded representation is written in the
  60  * string pointed by 'enc' and the length is returned. Otherwise
  61  * 0 is returned. */
  62 int rdbEncodeInteger(long long value, unsigned char *enc) {
  63     /* Finally check if it fits in our ranges */
  64     if (value >= -(1<<7) && value <= (1<<7)-1) {
  65         enc[0] = (REDIS_RDB_ENCVAL<<6)|REDIS_RDB_ENC_INT8;
  66         enc[1] = value&0xFF;
  67         return 2;
  68     } else if (value >= -(1<<15) && value <= (1<<15)-1) {
  69         enc[0] = (REDIS_RDB_ENCVAL<<6)|REDIS_RDB_ENC_INT16;
  70         enc[1] = value&0xFF;
  71         enc[2] = (value>>8)&0xFF;
  72         return 3;
  73     } else if (value >= -((long long)1<<31) && value <= ((long long)1<<31)-1) {
  74         enc[0] = (REDIS_RDB_ENCVAL<<6)|REDIS_RDB_ENC_INT32;
  75         enc[1] = value&0xFF;
  76         enc[2] = (value>>8)&0xFF;
  77         enc[3] = (value>>16)&0xFF;
  78         enc[4] = (value>>24)&0xFF;
  79         return 5;
  80     } else {
  81         return 0;
  82     }
  83 }
  84
  85 /* String objects in the form "2391" "-100" without any space and with a
  86  * range of values that can fit in an 8, 16 or 32 bit signed value can be
  87  * encoded as integers to save space */
  88 int rdbTryIntegerEncoding(char *s, size_t len, unsigned char *enc) {
  89     long long value;
  90     char *endptr, buf[32];
  91
  92     /* Check if it's possible to encode this value as a number */
  93     value = strtoll(s, &endptr, 10);
  94     if (endptr[0] != '\0') return 0;
  95     ll2string(buf,32,value);
  96
  97     /* If the number converted back into a string is not identical
  98      * then it's not possible to encode the string as integer */
  99     if (strlen(buf) != len || memcmp(buf,s,len)) return 0;
 100
 101     return rdbEncodeInteger(value,enc);
 102 }
 103
 104 int rdbSaveLzfStringObject(FILE *fp, unsigned char *s, size_t len) {
 105     size_t comprlen, outlen;
 106     unsigned char byte;
 107     int n, nwritten = 0;
 108     void *out;
 109
 110     /* We require at least four bytes compression for this to be worth it */
 111     if (len <= 4) return 0;
 112     outlen = len-4;
 113     if ((out = zmalloc(outlen+1)) == NULL) return 0;
 114     comprlen = lzf_compress(s, len, out, outlen);
 115     if (comprlen == 0) {
 116         zfree(out);
 117         return 0;
 118     }
 119     /* Data compressed! Let's save it on disk */
 120     byte = (REDIS_RDB_ENCVAL<<6)|REDIS_RDB_ENC_LZF;
 121     if ((n = rdbWriteRaw(fp,&byte,1)) == -1) goto writeerr;
 122     nwritten += n;
 123
 124     if ((n = rdbSaveLen(fp,comprlen)) == -1) goto writeerr;
 125     nwritten += n;
 126
 127     if ((n = rdbSaveLen(fp,len)) == -1) goto writeerr;
 128     nwritten += n;
 129
 130     if ((n = rdbWriteRaw(fp,out,comprlen)) == -1) goto writeerr;
 131     nwritten += n;
 132
 133     zfree(out);
 134     return nwritten;
 135
 136 writeerr:
 137     zfree(out);
 138     return -1;
 139 }
 140
 141 /* Save a string objet as [len][data] on disk. If the object is a string
 142  * representation of an integer value we try to save it in a special form */
 143 int rdbSaveRawString(FILE *fp, unsigned char *s, size_t len) {
 144     int enclen;
 145     int n, nwritten = 0;
 146
 147     /* Try integer encoding */
 148     if (len <= 11) {
 149         unsigned char buf[5];
 150         if ((enclen = rdbTryIntegerEncoding((char*)s,len,buf)) > 0) {
 151             if (rdbWriteRaw(fp,buf,enclen) == -1) return -1;
 152             return enclen;
 153         }
 154     }
 155
 156     /* Try LZF compression - under 20 bytes it's unable to compress even
 157      * aaaaaaaaaaaaaaaaaa so skip it */
 158     if (server.rdbcompression && len > 20) {
 159         n = rdbSaveLzfStringObject(fp,s,len);
 160         if (n == -1) return -1;
 161         if (n > 0) return n;
 162         /* Return value of 0 means data can't be compressed, save the old way */
 163     }
 164
 165     /* Store verbatim */
 166     if ((n = rdbSaveLen(fp,len)) == -1) return -1;
 167     nwritten += n;
 168     if (len > 0) {
 169         if (rdbWriteRaw(fp,s,len) == -1) return -1;
 170         nwritten += len;
 171     }
 172     return nwritten;
 173 }
 174
 175 /* Save a long long value as either an encoded string or a string. */
 176 int rdbSaveLongLongAsStringObject(FILE *fp, long long value) {
 177     unsigned char buf[32];
 178     int n, nwritten = 0;
 179     int enclen = rdbEncodeInteger(value,buf);
 180     if (enclen > 0) {
 181         return rdbWriteRaw(fp,buf,enclen);
 182     } else {
 183         /* Encode as string */
 184         enclen = ll2string((char*)buf,32,value);
 185         redisAssert(enclen < 32);
 186         if ((n = rdbSaveLen(fp,enclen)) == -1) return -1;
 187         nwritten += n;
 188         if ((n = rdbWriteRaw(fp,buf,enclen)) == -1) return -1;
 189         nwritten += n;
 190     }
 191     return nwritten;
 192 }
 193
 194 /* Like rdbSaveStringObjectRaw() but handle encoded objects */
 195 int rdbSaveStringObject(FILE *fp, robj *obj) {
 196     /* Avoid to decode the object, then encode it again, if the
 197      * object is alrady integer encoded. */
 198     if (obj->encoding == REDIS_ENCODING_INT) {
 199         return rdbSaveLongLongAsStringObject(fp,(long)obj->ptr);
 200     } else {
 201         redisAssert(obj->encoding == REDIS_ENCODING_RAW);
 202         return rdbSaveRawString(fp,obj->ptr,sdslen(obj->ptr));
 203     }
 204 }
 205
 206 /* Save a double value. Doubles are saved as strings prefixed by an unsigned
 207  * 8 bit integer specifing the length of the representation.
 208  * This 8 bit integer has special values in order to specify the following
 209  * conditions:
 210  * 253: not a number
 211  * 254: + inf
 212  * 255: - inf
 213  */
 214 int rdbSaveDoubleValue(FILE *fp, double val) {
 215     unsigned char buf[128];
 216     int len;
 217
 218     if (isnan(val)) {
 219         buf[0] = 253;
 220         len = 1;
 221     } else if (!isfinite(val)) {
 222         len = 1;
 223         buf[0] = (val < 0) ? 255 : 254;
 224     } else {
 225 #if (DBL_MANT_DIG >= 52) && (LLONG_MAX == 0x7fffffffffffffffLL)
 226         /* Check if the float is in a safe range to be casted into a
 227          * long long. We are assuming that long long is 64 bit here.
 228          * Also we are assuming that there are no implementations around where
 229          * double has precision < 52 bit.
 230          *
 231          * Under this assumptions we test if a double is inside an interval
 232          * where casting to long long is safe. Then using two castings we
 233          * make sure the decimal part is zero. If all this is true we use
 234          * integer printing function that is much faster. */
 235         double min = -4503599627370495; /* (2^52)-1 */
 236         double max = 4503599627370496; /* -(2^52) */
 237         if (val > min && val < max && val == ((double)((long long)val)))
 238             ll2string((char*)buf+1,sizeof(buf),(long long)val);
 239         else
 240 #endif
 241             snprintf((char*)buf+1,sizeof(buf)-1,"%.17g",val);
 242         buf[0] = strlen((char*)buf+1);
 243         len = buf[0]+1;
 244     }
 245     return rdbWriteRaw(fp,buf,len);
 246 }
 247
 248 /* Save a Redis object. */
 249 int rdbSaveObject(FILE *fp, robj *o) {
 250     int n, nwritten = 0;
 251
 252     if (o->type == REDIS_STRING) {
 253         /* Save a string value */
 254         if ((n = rdbSaveStringObject(fp,o)) == -1) return -1;
 255         nwritten += n;
 256     } else if (o->type == REDIS_LIST) {
 257         /* Save a list value */
 258         if (o->encoding == REDIS_ENCODING_ZIPLIST) {
 259             size_t l = ziplistBlobLen((unsigned char*)o->ptr);
 260
 261             if ((n = rdbSaveRawString(fp,o->ptr,l)) == -1) return -1;
 262             nwritten += n;
 263         } else if (o->encoding == REDIS_ENCODING_LINKEDLIST) {
 264             list *list = o->ptr;
 265             listIter li;
 266             listNode *ln;
 267
 268             if ((n = rdbSaveLen(fp,listLength(list))) == -1) return -1;
 269             nwritten += n;
 270
 271             listRewind(list,&li);
 272             while((ln = listNext(&li))) {
 273                 robj *eleobj = listNodeValue(ln);
 274                 if ((n = rdbSaveStringObject(fp,eleobj)) == -1) return -1;
 275                 nwritten += n;
 276             }
 277         } else {
 278             redisPanic("Unknown list encoding");
 279         }
 280     } else if (o->type == REDIS_SET) {
 281         /* Save a set value */
 282         if (o->encoding == REDIS_ENCODING_HT) {
 283             dict *set = o->ptr;
 284             dictIterator *di = dictGetIterator(set);
 285             dictEntry *de;
 286
 287             if ((n = rdbSaveLen(fp,dictSize(set))) == -1) return -1;
 288             nwritten += n;
 289
 290             while((de = dictNext(di)) != NULL) {
 291                 robj *eleobj = dictGetEntryKey(de);
 292                 if ((n = rdbSaveStringObject(fp,eleobj)) == -1) return -1;
 293                 nwritten += n;
 294             }
 295             dictReleaseIterator(di);
 296         } else if (o->encoding == REDIS_ENCODING_INTSET) {
 297             size_t l = intsetBlobLen((intset*)o->ptr);
 298
 299             if ((n = rdbSaveRawString(fp,o->ptr,l)) == -1) return -1;
 300             nwritten += n;
 301         } else {
 302             redisPanic("Unknown set encoding");
 303         }
 304     } else if (o->type == REDIS_ZSET) {
 305         /* Save a sorted set value */
 306         if (o->encoding == REDIS_ENCODING_ZIPLIST) {
 307             size_t l = ziplistBlobLen((unsigned char*)o->ptr);
 308
 309             if ((n = rdbSaveRawString(fp,o->ptr,l)) == -1) return -1;
 310             nwritten += n;
 311         } else if (o->encoding == REDIS_ENCODING_RAW) {
 312             zset *zs = o->ptr;
 313             dictIterator *di = dictGetIterator(zs->dict);
 314             dictEntry *de;
 315
 316             if ((n = rdbSaveLen(fp,dictSize(zs->dict))) == -1) return -1;
 317             nwritten += n;
 318
 319             while((de = dictNext(di)) != NULL) {
 320                 robj *eleobj = dictGetEntryKey(de);
 321                 double *score = dictGetEntryVal(de);
 322
 323                 if ((n = rdbSaveStringObject(fp,eleobj)) == -1) return -1;
 324                 nwritten += n;
 325                 if ((n = rdbSaveDoubleValue(fp,*score)) == -1) return -1;
 326                 nwritten += n;
 327             }
 328             dictReleaseIterator(di);
 329         } else {
 330             redisPanic("Unknown sorted set enoding");
 331         }
 332     } else if (o->type == REDIS_HASH) {
 333         /* Save a hash value */
 334         if (o->encoding == REDIS_ENCODING_ZIPMAP) {
 335             size_t l = zipmapBlobLen((unsigned char*)o->ptr);
 336
 337             if ((n = rdbSaveRawString(fp,o->ptr,l)) == -1) return -1;
 338             nwritten += n;
 339         } else {
 340             dictIterator *di = dictGetIterator(o->ptr);
 341             dictEntry *de;
 342
 343             if ((n = rdbSaveLen(fp,dictSize((dict*)o->ptr))) == -1) return -1;
 344             nwritten += n;
 345
 346             while((de = dictNext(di)) != NULL) {
 347                 robj *key = dictGetEntryKey(de);
 348                 robj *val = dictGetEntryVal(de);
 349
 350                 if ((n = rdbSaveStringObject(fp,key)) == -1) return -1;
 351                 nwritten += n;
 352                 if ((n = rdbSaveStringObject(fp,val)) == -1) return -1;
 353                 nwritten += n;
 354             }
 355             dictReleaseIterator(di);
 356         }
 357     } else {
 358         redisPanic("Unknown object type");
 359     }
 360     return nwritten;
 361 }
 362
 363 /* Return the length the object will have on disk if saved with
 364  * the rdbSaveObject() function. Currently we use a trick to get
 365  * this length with very little changes to the code. In the future
 366  * we could switch to a faster solution. */
 367 off_t rdbSavedObjectLen(robj *o) {
 368     int len = rdbSaveObject(NULL,o);
 369     redisAssert(len != -1);
 370     return len;
 371 }
 372
 373 /* Save a key-value pair, with expire time, type, key, value.
 374  * On error -1 is returned.
 375  * On success if the key was actaully saved 1 is returned, otherwise 0
 376  * is returned (the key was already expired). */
 377 int rdbSaveKeyValuePair(FILE *fp, robj *key, robj *val,
 378                         time_t expiretime, time_t now)
 379 {
 380     int vtype;
 381
 382     /* Save the expire time */
 383     if (expiretime != -1) {
 384         /* If this key is already expired skip it */
 385         if (expiretime < now) return 0;
 386         if (rdbSaveType(fp,REDIS_EXPIRETIME) == -1) return -1;
 387         if (rdbSaveTime(fp,expiretime) == -1) return -1;
 388     }
 389     /* Fix the object type if needed, to support saving zipmaps, ziplists,
 390      * and intsets, directly as blobs of bytes: they are already serialized. */
 391     vtype = val->type;
 392     if (vtype == REDIS_HASH && val->encoding == REDIS_ENCODING_ZIPMAP)
 393         vtype = REDIS_HASH_ZIPMAP;
 394     else if (vtype == REDIS_LIST && val->encoding == REDIS_ENCODING_ZIPLIST)
 395         vtype = REDIS_LIST_ZIPLIST;
 396     else if (vtype == REDIS_SET && val->encoding == REDIS_ENCODING_INTSET)
 397         vtype = REDIS_SET_INTSET;
 398     else if (vtype == REDIS_ZSET && val->encoding == REDIS_ENCODING_ZIPLIST)
 399         vtype = REDIS_ZSET_ZIPLIST;
 400     /* Save type, key, value */
 401     if (rdbSaveType(fp,vtype) == -1) return -1;
 402     if (rdbSaveStringObject(fp,key) == -1) return -1;
 403     if (rdbSaveObject(fp,val) == -1) return -1;
 404     return 1;
 405 }
 406
 407 /* Save the DB on disk. Return REDIS_ERR on error, REDIS_OK on success */
 408 int rdbSave(char *filename) {
 409     dictIterator *di = NULL;
 410     dictEntry *de;
 411     FILE *fp;
 412     char tmpfile[256];
 413     int j;
 414     time_t now = time(NULL);
 415
 416     if (server.ds_enabled) {
 417         cacheForcePointInTime();
 418         return dsRdbSave(filename);
 419     }
 420
 421     snprintf(tmpfile,256,"temp-%d.rdb", (int) getpid());
 422     fp = fopen(tmpfile,"w");
 423     if (!fp) {
 424         redisLog(REDIS_WARNING, "Failed opening .rdb for saving: %s",
 425             strerror(errno));
 426         return REDIS_ERR;
 427     }
 428     if (fwrite("REDIS0001",9,1,fp) == 0) goto werr;
 429     for (j = 0; j < server.dbnum; j++) {
 430         redisDb *db = server.db+j;
 431         dict *d = db->dict;
 432         if (dictSize(d) == 0) continue;
 433         di = dictGetIterator(d);
 434         if (!di) {
 435             fclose(fp);
 436             return REDIS_ERR;
 437         }
 438
 439         /* Write the SELECT DB opcode */
 440         if (rdbSaveType(fp,REDIS_SELECTDB) == -1) goto werr;
 441         if (rdbSaveLen(fp,j) == -1) goto werr;
 442
 443         /* Iterate this DB writing every entry */
 444         while((de = dictNext(di)) != NULL) {
 445             sds keystr = dictGetEntryKey(de);
 446             robj key, *o = dictGetEntryVal(de);
 447             time_t expire;
 448
 449             initStaticStringObject(key,keystr);
 450             expire = getExpire(db,&key);
 451             if (rdbSaveKeyValuePair(fp,&key,o,expire,now) == -1) goto werr;
 452         }
 453         dictReleaseIterator(di);
 454     }
 455     /* EOF opcode */
 456     if (rdbSaveType(fp,REDIS_EOF) == -1) goto werr;
 457
 458     /* Make sure data will not remain on the OS's output buffers */
 459     fflush(fp);
 460     fsync(fileno(fp));
 461     fclose(fp);
 462
 463     /* Use RENAME to make sure the DB file is changed atomically only
 464      * if the generate DB file is ok. */
 465     if (rename(tmpfile,filename) == -1) {
 466         redisLog(REDIS_WARNING,"Error moving temp DB file on the final destination: %s", strerror(errno));
 467         unlink(tmpfile);
 468         return REDIS_ERR;
 469     }
 470     redisLog(REDIS_NOTICE,"DB saved on disk");
 471     server.dirty = 0;
 472     server.lastsave = time(NULL);
 473     return REDIS_OK;
 474
 475 werr:
 476     fclose(fp);
 477     unlink(tmpfile);
 478     redisLog(REDIS_WARNING,"Write error saving DB on disk: %s", strerror(errno));
 479     if (di) dictReleaseIterator(di);
 480     return REDIS_ERR;
 481 }
 482
 483 int rdbSaveBackground(char *filename) {
 484     pid_t childpid;
 485
 486     if (server.bgsavechildpid != -1 ||
 487         server.bgsavethread != (pthread_t) -1) return REDIS_ERR;
 488
 489     server.dirty_before_bgsave = server.dirty;
 490
 491     if (server.ds_enabled) {
 492         cacheForcePointInTime();
 493         return dsRdbSaveBackground(filename);
 494     }
 495
 496     if ((childpid = fork()) == 0) {
 497         int retval;
 498
 499         /* Child */
 500         if (server.ipfd > 0) close(server.ipfd);
 501         if (server.sofd > 0) close(server.sofd);
 502         retval = rdbSave(filename);
 503         _exit((retval == REDIS_OK) ? 0 : 1);
 504     } else {
 505         /* Parent */
 506         if (childpid == -1) {
 507             redisLog(REDIS_WARNING,"Can't save in background: fork: %s",
 508                 strerror(errno));
 509             return REDIS_ERR;
 510         }
 511         redisLog(REDIS_NOTICE,"Background saving started by pid %d",childpid);
 512         server.bgsavechildpid = childpid;
 513         updateDictResizePolicy();
 514         return REDIS_OK;
 515     }
 516     return REDIS_OK; /* unreached */
 517 }
 518
 519 void rdbRemoveTempFile(pid_t childpid) {
 520     char tmpfile[256];
 521
 522     snprintf(tmpfile,256,"temp-%d.rdb", (int) childpid);
 523     unlink(tmpfile);
 524 }
 525
 526 int rdbLoadType(FILE *fp) {
 527     unsigned char type;
 528     if (fread(&type,1,1,fp) == 0) return -1;
 529     return type;
 530 }
 531
 532 time_t rdbLoadTime(FILE *fp) {
 533     int32_t t32;
 534     if (fread(&t32,4,1,fp) == 0) return -1;
 535     return (time_t) t32;
 536 }
 537
 538 /* Load an encoded length from the DB, see the REDIS_RDB_* defines on the top
 539  * of this file for a description of how this are stored on disk.
 540  *
 541  * isencoded is set to 1 if the readed length is not actually a length but
 542  * an "encoding type", check the above comments for more info */
 543 uint32_t rdbLoadLen(FILE *fp, int *isencoded) {
 544     unsigned char buf[2];
 545     uint32_t len;
 546     int type;
 547
 548     if (isencoded) *isencoded = 0;
 549     if (fread(buf,1,1,fp) == 0) return REDIS_RDB_LENERR;
 550     type = (buf[0]&0xC0)>>6;
 551     if (type == REDIS_RDB_6BITLEN) {
 552         /* Read a 6 bit len */
 553         return buf[0]&0x3F;
 554     } else if (type == REDIS_RDB_ENCVAL) {
 555         /* Read a 6 bit len encoding type */
 556         if (isencoded) *isencoded = 1;
 557         return buf[0]&0x3F;
 558     } else if (type == REDIS_RDB_14BITLEN) {
 559         /* Read a 14 bit len */
 560         if (fread(buf+1,1,1,fp) == 0) return REDIS_RDB_LENERR;
 561         return ((buf[0]&0x3F)<<8)|buf[1];
 562     } else {
 563         /* Read a 32 bit len */
 564         if (fread(&len,4,1,fp) == 0) return REDIS_RDB_LENERR;
 565         return ntohl(len);
 566     }
 567 }
 568
 569 /* Load an integer-encoded object from file 'fp', with the specified
 570  * encoding type 'enctype'. If encode is true the function may return
 571  * an integer-encoded object as reply, otherwise the returned object
 572  * will always be encoded as a raw string. */
 573 robj *rdbLoadIntegerObject(FILE *fp, int enctype, int encode) {
 574     unsigned char enc[4];
 575     long long val;
 576
 577     if (enctype == REDIS_RDB_ENC_INT8) {
 578         if (fread(enc,1,1,fp) == 0) return NULL;
 579         val = (signed char)enc[0];
 580     } else if (enctype == REDIS_RDB_ENC_INT16) {
 581         uint16_t v;
 582         if (fread(enc,2,1,fp) == 0) return NULL;
 583         v = enc[0]|(enc[1]<<8);
 584         val = (int16_t)v;
 585     } else if (enctype == REDIS_RDB_ENC_INT32) {
 586         uint32_t v;
 587         if (fread(enc,4,1,fp) == 0) return NULL;
 588         v = enc[0]|(enc[1]<<8)|(enc[2]<<16)|(enc[3]<<24);
 589         val = (int32_t)v;
 590     } else {
 591         val = 0; /* anti-warning */
 592         redisPanic("Unknown RDB integer encoding type");
 593     }
 594     if (encode)
 595         return createStringObjectFromLongLong(val);
 596     else
 597         return createObject(REDIS_STRING,sdsfromlonglong(val));
 598 }
 599
 600 robj *rdbLoadLzfStringObject(FILE*fp) {
 601     unsigned int len, clen;
 602     unsigned char *c = NULL;
 603     sds val = NULL;
 604
 605     if ((clen = rdbLoadLen(fp,NULL)) == REDIS_RDB_LENERR) return NULL;
 606     if ((len = rdbLoadLen(fp,NULL)) == REDIS_RDB_LENERR) return NULL;
 607     if ((c = zmalloc(clen)) == NULL) goto err;
 608     if ((val = sdsnewlen(NULL,len)) == NULL) goto err;
 609     if (fread(c,clen,1,fp) == 0) goto err;
 610     if (lzf_decompress(c,clen,val,len) == 0) goto err;
 611     zfree(c);
 612     return createObject(REDIS_STRING,val);
 613 err:
 614     zfree(c);
 615     sdsfree(val);
 616     return NULL;
 617 }
 618
 619 robj *rdbGenericLoadStringObject(FILE*fp, int encode) {
 620     int isencoded;
 621     uint32_t len;
 622     sds val;
 623
 624     len = rdbLoadLen(fp,&isencoded);
 625     if (isencoded) {
 626         switch(len) {
 627         case REDIS_RDB_ENC_INT8:
 628         case REDIS_RDB_ENC_INT16:
 629         case REDIS_RDB_ENC_INT32:
 630             return rdbLoadIntegerObject(fp,len,encode);
 631         case REDIS_RDB_ENC_LZF:
 632             return rdbLoadLzfStringObject(fp);
 633         default:
 634             redisPanic("Unknown RDB encoding type");
 635         }
 636     }
 637
 638     if (len == REDIS_RDB_LENERR) return NULL;
 639     val = sdsnewlen(NULL,len);
 640     if (len && fread(val,len,1,fp) == 0) {
 641         sdsfree(val);
 642         return NULL;
 643     }
 644     return createObject(REDIS_STRING,val);
 645 }
 646
 647 robj *rdbLoadStringObject(FILE *fp) {
 648     return rdbGenericLoadStringObject(fp,0);
 649 }
 650
 651 robj *rdbLoadEncodedStringObject(FILE *fp) {
 652     return rdbGenericLoadStringObject(fp,1);
 653 }
 654
 655 /* For information about double serialization check rdbSaveDoubleValue() */
 656 int rdbLoadDoubleValue(FILE *fp, double *val) {
 657     char buf[128];
 658     unsigned char len;
 659
 660     if (fread(&len,1,1,fp) == 0) return -1;
 661     switch(len) {
 662     case 255: *val = R_NegInf; return 0;
 663     case 254: *val = R_PosInf; return 0;
 664     case 253: *val = R_Nan; return 0;
 665     default:
 666         if (fread(buf,len,1,fp) == 0) return -1;
 667         buf[len] = '\0';
 668         sscanf(buf, "%lg", val);
 669         return 0;
 670     }
 671 }
 672
 673 /* Load a Redis object of the specified type from the specified file.
 674  * On success a newly allocated object is returned, otherwise NULL. */
 675 robj *rdbLoadObject(int type, FILE *fp) {
 676     robj *o, *ele, *dec;
 677     size_t len;
 678     unsigned int i;
 679
 680     redisLog(REDIS_DEBUG,"LOADING OBJECT %d (at %d)\n",type,ftell(fp));
 681     if (type == REDIS_STRING) {
 682         /* Read string value */
 683         if ((o = rdbLoadEncodedStringObject(fp)) == NULL) return NULL;
 684         o = tryObjectEncoding(o);
 685     } else if (type == REDIS_LIST) {
 686         /* Read list value */
 687         if ((len = rdbLoadLen(fp,NULL)) == REDIS_RDB_LENERR) return NULL;
 688
 689         /* Use a real list when there are too many entries */
 690         if (len > server.list_max_ziplist_entries) {
 691             o = createListObject();
 692         } else {
 693             o = createZiplistObject();
 694         }
 695
 696         /* Load every single element of the list */
 697         while(len--) {
 698             if ((ele = rdbLoadEncodedStringObject(fp)) == NULL) return NULL;
 699
 700             /* If we are using a ziplist and the value is too big, convert
 701              * the object to a real list. */
 702             if (o->encoding == REDIS_ENCODING_ZIPLIST &&
 703                 ele->encoding == REDIS_ENCODING_RAW &&
 704                 sdslen(ele->ptr) > server.list_max_ziplist_value)
 705                     listTypeConvert(o,REDIS_ENCODING_LINKEDLIST);
 706
 707             if (o->encoding == REDIS_ENCODING_ZIPLIST) {
 708                 dec = getDecodedObject(ele);
 709                 o->ptr = ziplistPush(o->ptr,dec->ptr,sdslen(dec->ptr),REDIS_TAIL);
 710                 decrRefCount(dec);
 711                 decrRefCount(ele);
 712             } else {
 713                 ele = tryObjectEncoding(ele);
 714                 listAddNodeTail(o->ptr,ele);
 715             }
 716         }
 717     } else if (type == REDIS_SET) {
 718         /* Read list/set value */
 719         if ((len = rdbLoadLen(fp,NULL)) == REDIS_RDB_LENERR) return NULL;
 720
 721         /* Use a regular set when there are too many entries. */
 722         if (len > server.set_max_intset_entries) {
 723             o = createSetObject();
 724             /* It's faster to expand the dict to the right size asap in order
 725              * to avoid rehashing */
 726             if (len > DICT_HT_INITIAL_SIZE)
 727                 dictExpand(o->ptr,len);
 728         } else {
 729             o = createIntsetObject();
 730         }
 731
 732         /* Load every single element of the list/set */
 733         for (i = 0; i < len; i++) {
 734             long long llval;
 735             if ((ele = rdbLoadEncodedStringObject(fp)) == NULL) return NULL;
 736             ele = tryObjectEncoding(ele);
 737
 738             if (o->encoding == REDIS_ENCODING_INTSET) {
 739                 /* Fetch integer value from element */
 740                 if (isObjectRepresentableAsLongLong(ele,&llval) == REDIS_OK) {
 741                     o->ptr = intsetAdd(o->ptr,llval,NULL);
 742                 } else {
 743                     setTypeConvert(o,REDIS_ENCODING_HT);
 744                     dictExpand(o->ptr,len);
 745                 }
 746             }
 747
 748             /* This will also be called when the set was just converted
 749              * to regular hashtable encoded set */
 750             if (o->encoding == REDIS_ENCODING_HT) {
 751                 dictAdd((dict*)o->ptr,ele,NULL);
 752             } else {
 753                 decrRefCount(ele);
 754             }
 755         }
 756     } else if (type == REDIS_ZSET) {
 757         /* Read list/set value */
 758         size_t zsetlen;
 759         size_t maxelelen = 0;
 760         zset *zs;
 761
 762         if ((zsetlen = rdbLoadLen(fp,NULL)) == REDIS_RDB_LENERR) return NULL;
 763         o = createZsetObject();
 764         zs = o->ptr;
 765
 766         /* Load every single element of the list/set */
 767         while(zsetlen--) {
 768             robj *ele;
 769             double score;
 770             zskiplistNode *znode;
 771
 772             if ((ele = rdbLoadEncodedStringObject(fp)) == NULL) return NULL;
 773             ele = tryObjectEncoding(ele);
 774             if (rdbLoadDoubleValue(fp,&score) == -1) return NULL;
 775
 776             /* Don't care about integer-encoded strings. */
 777             if (ele->encoding == REDIS_ENCODING_RAW &&
 778                 sdslen(ele->ptr) > maxelelen)
 779                     maxelelen = sdslen(ele->ptr);
 780
 781             znode = zslInsert(zs->zsl,score,ele);
 782             dictAdd(zs->dict,ele,&znode->score);
 783             incrRefCount(ele); /* added to skiplist */
 784         }
 785
 786         /* Convert *after* loading, since sorted sets are not stored ordered. */
 787         if (zsetLength(o) <= server.zset_max_ziplist_entries &&
 788             maxelelen <= server.zset_max_ziplist_value)
 789                 zsetConvert(o,REDIS_ENCODING_ZIPLIST);
 790     } else if (type == REDIS_HASH) {
 791         size_t hashlen;
 792
 793         if ((hashlen = rdbLoadLen(fp,NULL)) == REDIS_RDB_LENERR) return NULL;
 794         o = createHashObject();
 795         /* Too many entries? Use an hash table. */
 796         if (hashlen > server.hash_max_zipmap_entries)
 797             convertToRealHash(o);
 798         /* Load every key/value, then set it into the zipmap or hash
 799          * table, as needed. */
 800         while(hashlen--) {
 801             robj *key, *val;
 802
 803             if ((key = rdbLoadEncodedStringObject(fp)) == NULL) return NULL;
 804             if ((val = rdbLoadEncodedStringObject(fp)) == NULL) return NULL;
 805             /* If we are using a zipmap and there are too big values
 806              * the object is converted to real hash table encoding. */
 807             if (o->encoding != REDIS_ENCODING_HT &&
 808                ((key->encoding == REDIS_ENCODING_RAW &&
 809                 sdslen(key->ptr) > server.hash_max_zipmap_value) ||
 810                 (val->encoding == REDIS_ENCODING_RAW &&
 811                 sdslen(val->ptr) > server.hash_max_zipmap_value)))
 812             {
 813                     convertToRealHash(o);
 814             }
 815
 816             if (o->encoding == REDIS_ENCODING_ZIPMAP) {
 817                 unsigned char *zm = o->ptr;
 818                 robj *deckey, *decval;
 819
 820                 /* We need raw string objects to add them to the zipmap */
 821                 deckey = getDecodedObject(key);
 822                 decval = getDecodedObject(val);
 823                 zm = zipmapSet(zm,deckey->ptr,sdslen(deckey->ptr),
 824                                   decval->ptr,sdslen(decval->ptr),NULL);
 825                 o->ptr = zm;
 826                 decrRefCount(deckey);
 827                 decrRefCount(decval);
 828                 decrRefCount(key);
 829                 decrRefCount(val);
 830             } else {
 831                 key = tryObjectEncoding(key);
 832                 val = tryObjectEncoding(val);
 833                 dictAdd((dict*)o->ptr,key,val);
 834             }
 835         }
 836     } else if (type == REDIS_HASH_ZIPMAP ||
 837                type == REDIS_LIST_ZIPLIST ||
 838                type == REDIS_SET_INTSET ||
 839                type == REDIS_ZSET_ZIPLIST)
 840     {
 841         robj *aux = rdbLoadStringObject(fp);
 842
 843         if (aux == NULL) return NULL;
 844         o = createObject(REDIS_STRING,NULL); /* string is just placeholder */
 845         o->ptr = zmalloc(sdslen(aux->ptr));
 846         memcpy(o->ptr,aux->ptr,sdslen(aux->ptr));
 847         decrRefCount(aux);
 848
 849         /* Fix the object encoding, and make sure to convert the encoded
 850          * data type into the base type if accordingly to the current
 851          * configuration there are too many elements in the encoded data
 852          * type. Note that we only check the length and not max element
 853          * size as this is an O(N) scan. Eventually everything will get
 854          * converted. */
 855         switch(type) {
 856             case REDIS_HASH_ZIPMAP:
 857                 o->type = REDIS_HASH;
 858                 o->encoding = REDIS_ENCODING_ZIPMAP;
 859                 if (zipmapLen(o->ptr) > server.hash_max_zipmap_entries)
 860                     convertToRealHash(o);
 861                 break;
 862             case REDIS_LIST_ZIPLIST:
 863                 o->type = REDIS_LIST;
 864                 o->encoding = REDIS_ENCODING_ZIPLIST;
 865                 if (ziplistLen(o->ptr) > server.list_max_ziplist_entries)
 866                     listTypeConvert(o,REDIS_ENCODING_LINKEDLIST);
 867                 break;
 868             case REDIS_SET_INTSET:
 869                 o->type = REDIS_SET;
 870                 o->encoding = REDIS_ENCODING_INTSET;
 871                 if (intsetLen(o->ptr) > server.set_max_intset_entries)
 872                     setTypeConvert(o,REDIS_ENCODING_HT);
 873                 break;
 874             case REDIS_ZSET_ZIPLIST:
 875                 o->type = REDIS_ZSET;
 876                 o->encoding = REDIS_ENCODING_ZIPLIST;
 877                 if (zsetLength(o) > server.zset_max_ziplist_entries)
 878                     zsetConvert(o,REDIS_ENCODING_RAW);
 879                 break;
 880             default:
 881                 redisPanic("Unknown enoding");
 882                 break;
 883         }
 884     } else {
 885         redisPanic("Unknown object type");
 886     }
 887     return o;
 888 }
 889
 890 /* Mark that we are loading in the global state and setup the fields
 891  * needed to provide loading stats. */
 892 void startLoading(FILE *fp) {
 893     struct stat sb;
 894
 895     /* Load the DB */
 896     server.loading = 1;
 897     server.loading_start_time = time(NULL);
 898     if (fstat(fileno(fp), &sb) == -1) {
 899         server.loading_total_bytes = 1; /* just to avoid division by zero */
 900     } else {
 901         server.loading_total_bytes = sb.st_size;
 902     }
 903 }
 904
 905 /* Refresh the loading progress info */
 906 void loadingProgress(off_t pos) {
 907     server.loading_loaded_bytes = pos;
 908 }
 909
 910 /* Loading finished */
 911 void stopLoading(void) {
 912     server.loading = 0;
 913 }
 914
 915 int rdbLoad(char *filename) {
 916     FILE *fp;
 917     uint32_t dbid;
 918     int type, retval, rdbver;
 919     redisDb *db = server.db+0;
 920     char buf[1024];
 921     time_t expiretime, now = time(NULL);
 922     long loops = 0;
 923
 924     fp = fopen(filename,"r");
 925     if (!fp) return REDIS_ERR;
 926     if (fread(buf,9,1,fp) == 0) goto eoferr;
 927     buf[9] = '\0';
 928     if (memcmp(buf,"REDIS",5) != 0) {
 929         fclose(fp);
 930         redisLog(REDIS_WARNING,"Wrong signature trying to load DB from file");
 931         return REDIS_ERR;
 932     }
 933     rdbver = atoi(buf+5);
 934     if (rdbver != 1) {
 935         fclose(fp);
 936         redisLog(REDIS_WARNING,"Can't handle RDB format version %d",rdbver);
 937         return REDIS_ERR;
 938     }
 939
 940     startLoading(fp);
 941     while(1) {
 942         robj *key, *val;
 943         expiretime = -1;
 944
 945         /* Serve the clients from time to time */
 946         if (!(loops++ % 1000)) {
 947             loadingProgress(ftello(fp));
 948             aeProcessEvents(server.el, AE_FILE_EVENTS|AE_DONT_WAIT);
 949         }
 950
 951         /* Read type. */
 952         if ((type = rdbLoadType(fp)) == -1) goto eoferr;
 953         if (type == REDIS_EXPIRETIME) {
 954             if ((expiretime = rdbLoadTime(fp)) == -1) goto eoferr;
 955             /* We read the time so we need to read the object type again */
 956             if ((type = rdbLoadType(fp)) == -1) goto eoferr;
 957         }
 958         if (type == REDIS_EOF) break;
 959         /* Handle SELECT DB opcode as a special case */
 960         if (type == REDIS_SELECTDB) {
 961             if ((dbid = rdbLoadLen(fp,NULL)) == REDIS_RDB_LENERR)
 962                 goto eoferr;
 963             if (dbid >= (unsigned)server.dbnum) {
 964                 redisLog(REDIS_WARNING,"FATAL: Data file was created with a Redis server configured to handle more than %d databases. Exiting\n", server.dbnum);
 965                 exit(1);
 966             }
 967             db = server.db+dbid;
 968             continue;
 969         }
 970         /* Read key */
 971         if ((key = rdbLoadStringObject(fp)) == NULL) goto eoferr;
 972         /* Read value */
 973         if ((val = rdbLoadObject(type,fp)) == NULL) goto eoferr;
 974         /* Check if the key already expired */
 975         if (expiretime != -1 && expiretime < now) {
 976             decrRefCount(key);
 977             decrRefCount(val);
 978             continue;
 979         }
 980         /* Add the new object in the hash table */
 981         retval = dbAdd(db,key,val);
 982         if (retval == REDIS_ERR) {
 983             redisLog(REDIS_WARNING,"Loading DB, duplicated key (%s) found! Unrecoverable error, exiting now.", key->ptr);
 984             exit(1);
 985         }
 986         /* Set the expire time if needed */
 987         if (expiretime != -1) setExpire(db,key,expiretime);
 988
 989         decrRefCount(key);
 990     }
 991     fclose(fp);
 992     stopLoading();
 993     return REDIS_OK;
 994
 995 eoferr: /* unexpected end of file is handled here with a fatal exit */
 996     redisLog(REDIS_WARNING,"Short read or OOM loading DB. Unrecoverable error, aborting now.");
 997     exit(1);
 998     return REDIS_ERR; /* Just to avoid warning */
 999 }
1000
1001 /* A background saving child (BGSAVE) terminated its work. Handle this. */
1002 void backgroundSaveDoneHandler(int exitcode, int bysignal) {
1003     if (!bysignal && exitcode == 0) {
1004         redisLog(REDIS_NOTICE,
1005             "Background saving terminated with success");
1006         server.dirty = server.dirty - server.dirty_before_bgsave;
1007         server.lastsave = time(NULL);
1008     } else if (!bysignal && exitcode != 0) {
1009         redisLog(REDIS_WARNING, "Background saving error");
1010     } else {
1011         redisLog(REDIS_WARNING,
1012             "Background saving terminated by signal %d", bysignal);
1013         rdbRemoveTempFile(server.bgsavechildpid);
1014     }
1015     server.bgsavechildpid = -1;
1016     server.bgsavethread = (pthread_t) -1;
1017     server.bgsavethread_state = REDIS_BGSAVE_THREAD_UNACTIVE;
1018     /* Possibly there are slaves waiting for a BGSAVE in order to be served
1019      * (the first stage of SYNC is a bulk transfer of dump.rdb) */
1020     updateSlavesWaitingBgsave(exitcode == 0 ? REDIS_OK : REDIS_ERR);
1021 }
1022
1023 void saveCommand(redisClient *c) {
1024     if (server.bgsavechildpid != -1 || server.bgsavethread != (pthread_t)-1) {
1025         addReplyError(c,"Background save already in progress");
1026         return;
1027     }
1028     if (rdbSave(server.dbfilename) == REDIS_OK) {
1029         addReply(c,shared.ok);
1030     } else {
1031         addReply(c,shared.err);
1032     }
1033 }
1034
1035 void bgsaveCommand(redisClient *c) {
1036     if (server.bgsavechildpid != -1 || server.bgsavethread != (pthread_t)-1) {
1037         addReplyError(c,"Background save already in progress");
1038         return;
1039     }
1040     if (rdbSaveBackground(server.dbfilename) == REDIS_OK) {
1041         addReplyStatus(c,"Background saving started");
1042     } else {
1043         addReply(c,shared.err);
1044     }
1045 }