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
  11 int rdbSaveType(FILE *fp, unsigned char type) {
  12     if (fwrite(&type,1,1,fp) == 0) return -1;
  13     return 0;
  14 }
  15
  16 int rdbSaveTime(FILE *fp, time_t t) {
  17     int32_t t32 = (int32_t) t;
  18     if (fwrite(&t32,4,1,fp) == 0) return -1;
  19     return 0;
  20 }
  21
  22 /* check rdbLoadLen() comments for more info */
  23 int rdbSaveLen(FILE *fp, uint32_t len) {
  24     unsigned char buf[2];
  25
  26     if (len < (1<<6)) {
  27         /* Save a 6 bit len */
  28         buf[0] = (len&0xFF)|(REDIS_RDB_6BITLEN<<6);
  29         if (fwrite(buf,1,1,fp) == 0) return -1;
  30     } else if (len < (1<<14)) {
  31         /* Save a 14 bit len */
  32         buf[0] = ((len>>8)&0xFF)|(REDIS_RDB_14BITLEN<<6);
  33         buf[1] = len&0xFF;
  34         if (fwrite(buf,2,1,fp) == 0) return -1;
  35     } else {
  36         /* Save a 32 bit len */
  37         buf[0] = (REDIS_RDB_32BITLEN<<6);
  38         if (fwrite(buf,1,1,fp) == 0) return -1;
  39         len = htonl(len);
  40         if (fwrite(&len,4,1,fp) == 0) return -1;
  41     }
  42     return 0;
  43 }
  44
  45 /* Encode 'value' as an integer if possible (if integer will fit the
  46  * supported range). If the function sucessful encoded the integer
  47  * then the (up to 5 bytes) encoded representation is written in the
  48  * string pointed by 'enc' and the length is returned. Otherwise
  49  * 0 is returned. */
  50 int rdbEncodeInteger(long long value, unsigned char *enc) {
  51     /* Finally check if it fits in our ranges */
  52     if (value >= -(1<<7) && value <= (1<<7)-1) {
  53         enc[0] = (REDIS_RDB_ENCVAL<<6)|REDIS_RDB_ENC_INT8;
  54         enc[1] = value&0xFF;
  55         return 2;
  56     } else if (value >= -(1<<15) && value <= (1<<15)-1) {
  57         enc[0] = (REDIS_RDB_ENCVAL<<6)|REDIS_RDB_ENC_INT16;
  58         enc[1] = value&0xFF;
  59         enc[2] = (value>>8)&0xFF;
  60         return 3;
  61     } else if (value >= -((long long)1<<31) && value <= ((long long)1<<31)-1) {
  62         enc[0] = (REDIS_RDB_ENCVAL<<6)|REDIS_RDB_ENC_INT32;
  63         enc[1] = value&0xFF;
  64         enc[2] = (value>>8)&0xFF;
  65         enc[3] = (value>>16)&0xFF;
  66         enc[4] = (value>>24)&0xFF;
  67         return 5;
  68     } else {
  69         return 0;
  70     }
  71 }
  72
  73 /* String objects in the form "2391" "-100" without any space and with a
  74  * range of values that can fit in an 8, 16 or 32 bit signed value can be
  75  * encoded as integers to save space */
  76 int rdbTryIntegerEncoding(char *s, size_t len, unsigned char *enc) {
  77     long long value;
  78     char *endptr, buf[32];
  79
  80     /* Check if it's possible to encode this value as a number */
  81     value = strtoll(s, &endptr, 10);
  82     if (endptr[0] != '\0') return 0;
  83     ll2string(buf,32,value);
  84
  85     /* If the number converted back into a string is not identical
  86      * then it's not possible to encode the string as integer */
  87     if (strlen(buf) != len || memcmp(buf,s,len)) return 0;
  88
  89     return rdbEncodeInteger(value,enc);
  90 }
  91
  92 int rdbSaveLzfStringObject(FILE *fp, unsigned char *s, size_t len) {
  93     size_t comprlen, outlen;
  94     unsigned char byte;
  95     void *out;
  96
  97     /* We require at least four bytes compression for this to be worth it */
  98     if (len <= 4) return 0;
  99     outlen = len-4;
 100     if ((out = zmalloc(outlen+1)) == NULL) return 0;
 101     comprlen = lzf_compress(s, len, out, outlen);
 102     if (comprlen == 0) {
 103         zfree(out);
 104         return 0;
 105     }
 106     /* Data compressed! Let's save it on disk */
 107     byte = (REDIS_RDB_ENCVAL<<6)|REDIS_RDB_ENC_LZF;
 108     if (fwrite(&byte,1,1,fp) == 0) goto writeerr;
 109     if (rdbSaveLen(fp,comprlen) == -1) goto writeerr;
 110     if (rdbSaveLen(fp,len) == -1) goto writeerr;
 111     if (fwrite(out,comprlen,1,fp) == 0) goto writeerr;
 112     zfree(out);
 113     return comprlen;
 114
 115 writeerr:
 116     zfree(out);
 117     return -1;
 118 }
 119
 120 /* Save a string objet as [len][data] on disk. If the object is a string
 121  * representation of an integer value we try to safe it in a special form */
 122 int rdbSaveRawString(FILE *fp, unsigned char *s, size_t len) {
 123     int enclen;
 124
 125     /* Try integer encoding */
 126     if (len <= 11) {
 127         unsigned char buf[5];
 128         if ((enclen = rdbTryIntegerEncoding((char*)s,len,buf)) > 0) {
 129             if (fwrite(buf,enclen,1,fp) == 0) return -1;
 130             return 0;
 131         }
 132     }
 133
 134     /* Try LZF compression - under 20 bytes it's unable to compress even
 135      * aaaaaaaaaaaaaaaaaa so skip it */
 136     if (server.rdbcompression && len > 20) {
 137         int retval;
 138
 139         retval = rdbSaveLzfStringObject(fp,s,len);
 140         if (retval == -1) return -1;
 141         if (retval > 0) return 0;
 142         /* retval == 0 means data can't be compressed, save the old way */
 143     }
 144
 145     /* Store verbatim */
 146     if (rdbSaveLen(fp,len) == -1) return -1;
 147     if (len && fwrite(s,len,1,fp) == 0) return -1;
 148     return 0;
 149 }
 150
 151 /* Save a long long value as either an encoded string or a string. */
 152 int rdbSaveLongLongAsStringObject(FILE *fp, long long value) {
 153     unsigned char buf[32];
 154     int enclen = rdbEncodeInteger(value,buf);
 155     if (enclen > 0) {
 156         if (fwrite(buf,enclen,1,fp) == 0) return -1;
 157     } else {
 158         /* Encode as string */
 159         enclen = ll2string((char*)buf,32,value);
 160         redisAssert(enclen < 32);
 161         if (rdbSaveLen(fp,enclen) == -1) return -1;
 162         if (fwrite(buf,enclen,1,fp) == 0) return -1;
 163     }
 164     return 0;
 165 }
 166
 167 /* Like rdbSaveStringObjectRaw() but handle encoded objects */
 168 int rdbSaveStringObject(FILE *fp, robj *obj) {
 169     /* Avoid to decode the object, then encode it again, if the
 170      * object is alrady integer encoded. */
 171     if (obj->encoding == REDIS_ENCODING_INT) {
 172         return rdbSaveLongLongAsStringObject(fp,(long)obj->ptr);
 173     } else {
 174         redisAssert(obj->encoding == REDIS_ENCODING_RAW);
 175         return rdbSaveRawString(fp,obj->ptr,sdslen(obj->ptr));
 176     }
 177 }
 178
 179 /* Save a double value. Doubles are saved as strings prefixed by an unsigned
 180  * 8 bit integer specifing the length of the representation.
 181  * This 8 bit integer has special values in order to specify the following
 182  * conditions:
 183  * 253: not a number
 184  * 254: + inf
 185  * 255: - inf
 186  */
 187 int rdbSaveDoubleValue(FILE *fp, double val) {
 188     unsigned char buf[128];
 189     int len;
 190
 191     if (isnan(val)) {
 192         buf[0] = 253;
 193         len = 1;
 194     } else if (!isfinite(val)) {
 195         len = 1;
 196         buf[0] = (val < 0) ? 255 : 254;
 197     } else {
 198 #if (DBL_MANT_DIG >= 52) && (LLONG_MAX == 0x7fffffffffffffffLL)
 199         /* Check if the float is in a safe range to be casted into a
 200          * long long. We are assuming that long long is 64 bit here.
 201          * Also we are assuming that there are no implementations around where
 202          * double has precision < 52 bit.
 203          *
 204          * Under this assumptions we test if a double is inside an interval
 205          * where casting to long long is safe. Then using two castings we
 206          * make sure the decimal part is zero. If all this is true we use
 207          * integer printing function that is much faster. */
 208         double min = -4503599627370495; /* (2^52)-1 */
 209         double max = 4503599627370496; /* -(2^52) */
 210         if (val > min && val < max && val == ((double)((long long)val)))
 211             ll2string((char*)buf+1,sizeof(buf),(long long)val);
 212         else
 213 #endif
 214             snprintf((char*)buf+1,sizeof(buf)-1,"%.17g",val);
 215         buf[0] = strlen((char*)buf+1);
 216         len = buf[0]+1;
 217     }
 218     if (fwrite(buf,len,1,fp) == 0) return -1;
 219     return 0;
 220 }
 221
 222 /* Save a Redis object. */
 223 int rdbSaveObject(FILE *fp, robj *o) {
 224     if (o->type == REDIS_STRING) {
 225         /* Save a string value */
 226         if (rdbSaveStringObject(fp,o) == -1) return -1;
 227     } else if (o->type == REDIS_LIST) {
 228         /* Save a list value */
 229         if (o->encoding == REDIS_ENCODING_ZIPLIST) {
 230             unsigned char *p;
 231             unsigned char *vstr;
 232             unsigned int vlen;
 233             long long vlong;
 234
 235             if (rdbSaveLen(fp,ziplistLen(o->ptr)) == -1) return -1;
 236             p = ziplistIndex(o->ptr,0);
 237             while(ziplistGet(p,&vstr,&vlen,&vlong)) {
 238                 if (vstr) {
 239                     if (rdbSaveRawString(fp,vstr,vlen) == -1)
 240                         return -1;
 241                 } else {
 242                     if (rdbSaveLongLongAsStringObject(fp,vlong) == -1)
 243                         return -1;
 244                 }
 245                 p = ziplistNext(o->ptr,p);
 246             }
 247         } else if (o->encoding == REDIS_ENCODING_LINKEDLIST) {
 248             list *list = o->ptr;
 249             listIter li;
 250             listNode *ln;
 251
 252             if (rdbSaveLen(fp,listLength(list)) == -1) return -1;
 253             listRewind(list,&li);
 254             while((ln = listNext(&li))) {
 255                 robj *eleobj = listNodeValue(ln);
 256                 if (rdbSaveStringObject(fp,eleobj) == -1) return -1;
 257             }
 258         } else {
 259             redisPanic("Unknown list encoding");
 260         }
 261     } else if (o->type == REDIS_SET) {
 262         /* Save a set value */
 263         if (o->encoding == REDIS_ENCODING_HT) {
 264             dict *set = o->ptr;
 265             dictIterator *di = dictGetIterator(set);
 266             dictEntry *de;
 267
 268             if (rdbSaveLen(fp,dictSize(set)) == -1) return -1;
 269             while((de = dictNext(di)) != NULL) {
 270                 robj *eleobj = dictGetEntryKey(de);
 271                 if (rdbSaveStringObject(fp,eleobj) == -1) return -1;
 272             }
 273             dictReleaseIterator(di);
 274         } else if (o->encoding == REDIS_ENCODING_INTSET) {
 275             intset *is = o->ptr;
 276             int64_t llval;
 277             int i = 0;
 278
 279             if (rdbSaveLen(fp,intsetLen(is)) == -1) return -1;
 280             while(intsetGet(is,i++,&llval)) {
 281                 if (rdbSaveLongLongAsStringObject(fp,llval) == -1) return -1;
 282             }
 283         } else {
 284             redisPanic("Unknown set encoding");
 285         }
 286     } else if (o->type == REDIS_ZSET) {
 287         /* Save a set value */
 288         zset *zs = o->ptr;
 289         dictIterator *di = dictGetIterator(zs->dict);
 290         dictEntry *de;
 291
 292         if (rdbSaveLen(fp,dictSize(zs->dict)) == -1) return -1;
 293         while((de = dictNext(di)) != NULL) {
 294             robj *eleobj = dictGetEntryKey(de);
 295             double *score = dictGetEntryVal(de);
 296
 297             if (rdbSaveStringObject(fp,eleobj) == -1) return -1;
 298             if (rdbSaveDoubleValue(fp,*score) == -1) return -1;
 299         }
 300         dictReleaseIterator(di);
 301     } else if (o->type == REDIS_HASH) {
 302         /* Save a hash value */
 303         if (o->encoding == REDIS_ENCODING_ZIPMAP) {
 304             unsigned char *p = zipmapRewind(o->ptr);
 305             unsigned int count = zipmapLen(o->ptr);
 306             unsigned char *key, *val;
 307             unsigned int klen, vlen;
 308
 309             if (rdbSaveLen(fp,count) == -1) return -1;
 310             while((p = zipmapNext(p,&key,&klen,&val,&vlen)) != NULL) {
 311                 if (rdbSaveRawString(fp,key,klen) == -1) return -1;
 312                 if (rdbSaveRawString(fp,val,vlen) == -1) return -1;
 313             }
 314         } else {
 315             dictIterator *di = dictGetIterator(o->ptr);
 316             dictEntry *de;
 317
 318             if (rdbSaveLen(fp,dictSize((dict*)o->ptr)) == -1) return -1;
 319             while((de = dictNext(di)) != NULL) {
 320                 robj *key = dictGetEntryKey(de);
 321                 robj *val = dictGetEntryVal(de);
 322
 323                 if (rdbSaveStringObject(fp,key) == -1) return -1;
 324                 if (rdbSaveStringObject(fp,val) == -1) return -1;
 325             }
 326             dictReleaseIterator(di);
 327         }
 328     } else {
 329         redisPanic("Unknown object type");
 330     }
 331     return 0;
 332 }
 333
 334 /* Return the length the object will have on disk if saved with
 335  * the rdbSaveObject() function. Currently we use a trick to get
 336  * this length with very little changes to the code. In the future
 337  * we could switch to a faster solution. */
 338 off_t rdbSavedObjectLen(robj *o, FILE *fp) {
 339     if (fp == NULL) fp = server.devnull;
 340     rewind(fp);
 341     redisAssert(rdbSaveObject(fp,o) != 1);
 342     return ftello(fp);
 343 }
 344
 345 /* Return the number of pages required to save this object in the swap file */
 346 off_t rdbSavedObjectPages(robj *o, FILE *fp) {
 347     off_t bytes = rdbSavedObjectLen(o,fp);
 348
 349     return (bytes+(server.vm_page_size-1))/server.vm_page_size;
 350 }
 351
 352 /* Save the DB on disk. Return REDIS_ERR on error, REDIS_OK on success */
 353 int rdbSave(char *filename) {
 354     dictIterator *di = NULL;
 355     dictEntry *de;
 356     FILE *fp;
 357     char tmpfile[256];
 358     int j;
 359     time_t now = time(NULL);
 360
 361     /* Wait for I/O therads to terminate, just in case this is a
 362      * foreground-saving, to avoid seeking the swap file descriptor at the
 363      * same time. */
 364     if (server.vm_enabled)
 365         waitEmptyIOJobsQueue();
 366
 367     snprintf(tmpfile,256,"temp-%d.rdb", (int) getpid());
 368     fp = fopen(tmpfile,"w");
 369     if (!fp) {
 370         redisLog(REDIS_WARNING, "Failed saving the DB: %s", strerror(errno));
 371         return REDIS_ERR;
 372     }
 373     if (fwrite("REDIS0001",9,1,fp) == 0) goto werr;
 374     for (j = 0; j < server.dbnum; j++) {
 375         redisDb *db = server.db+j;
 376         dict *d = db->dict;
 377         if (dictSize(d) == 0) continue;
 378         di = dictGetIterator(d);
 379         if (!di) {
 380             fclose(fp);
 381             return REDIS_ERR;
 382         }
 383
 384         /* Write the SELECT DB opcode */
 385         if (rdbSaveType(fp,REDIS_SELECTDB) == -1) goto werr;
 386         if (rdbSaveLen(fp,j) == -1) goto werr;
 387
 388         /* Iterate this DB writing every entry */
 389         while((de = dictNext(di)) != NULL) {
 390             sds keystr = dictGetEntryKey(de);
 391             robj key, *o = dictGetEntryVal(de);
 392             time_t expiretime;
 393
 394             initStaticStringObject(key,keystr);
 395             expiretime = getExpire(db,&key);
 396
 397             /* Save the expire time */
 398             if (expiretime != -1) {
 399                 /* If this key is already expired skip it */
 400                 if (expiretime < now) continue;
 401                 if (rdbSaveType(fp,REDIS_EXPIRETIME) == -1) goto werr;
 402                 if (rdbSaveTime(fp,expiretime) == -1) goto werr;
 403             }
 404             /* Save the key and associated value. This requires special
 405              * handling if the value is swapped out. */
 406             if (!server.vm_enabled || o->storage == REDIS_VM_MEMORY ||
 407                                       o->storage == REDIS_VM_SWAPPING) {
 408                 /* Save type, key, value */
 409                 if (rdbSaveType(fp,o->type) == -1) goto werr;
 410                 if (rdbSaveStringObject(fp,&key) == -1) goto werr;
 411                 if (rdbSaveObject(fp,o) == -1) goto werr;
 412             } else {
 413                 /* REDIS_VM_SWAPPED or REDIS_VM_LOADING */
 414                 robj *po;
 415                 /* Get a preview of the object in memory */
 416                 po = vmPreviewObject(o);
 417                 /* Save type, key, value */
 418                 if (rdbSaveType(fp,po->type) == -1) goto werr;
 419                 if (rdbSaveStringObject(fp,&key) == -1) goto werr;
 420                 if (rdbSaveObject(fp,po) == -1) goto werr;
 421                 /* Remove the loaded object from memory */
 422                 decrRefCount(po);
 423             }
 424         }
 425         dictReleaseIterator(di);
 426     }
 427     /* EOF opcode */
 428     if (rdbSaveType(fp,REDIS_EOF) == -1) goto werr;
 429
 430     /* Make sure data will not remain on the OS's output buffers */
 431     fflush(fp);
 432     fsync(fileno(fp));
 433     fclose(fp);
 434
 435     /* Use RENAME to make sure the DB file is changed atomically only
 436      * if the generate DB file is ok. */
 437     if (rename(tmpfile,filename) == -1) {
 438         redisLog(REDIS_WARNING,"Error moving temp DB file on the final destination: %s", strerror(errno));
 439         unlink(tmpfile);
 440         return REDIS_ERR;
 441     }
 442     redisLog(REDIS_NOTICE,"DB saved on disk");
 443     server.dirty = 0;
 444     server.lastsave = time(NULL);
 445     return REDIS_OK;
 446
 447 werr:
 448     fclose(fp);
 449     unlink(tmpfile);
 450     redisLog(REDIS_WARNING,"Write error saving DB on disk: %s", strerror(errno));
 451     if (di) dictReleaseIterator(di);
 452     return REDIS_ERR;
 453 }
 454
 455 int rdbSaveBackground(char *filename) {
 456     pid_t childpid;
 457
 458     if (server.bgsavechildpid != -1) return REDIS_ERR;
 459     if (server.vm_enabled) waitEmptyIOJobsQueue();
 460     server.dirty_before_bgsave = server.dirty;
 461     if ((childpid = fork()) == 0) {
 462         /* Child */
 463         if (server.vm_enabled) vmReopenSwapFile();
 464         close(server.fd);
 465         if (rdbSave(filename) == REDIS_OK) {
 466             _exit(0);
 467         } else {
 468             _exit(1);
 469         }
 470     } else {
 471         /* Parent */
 472         if (childpid == -1) {
 473             redisLog(REDIS_WARNING,"Can't save in background: fork: %s",
 474                 strerror(errno));
 475             return REDIS_ERR;
 476         }
 477         redisLog(REDIS_NOTICE,"Background saving started by pid %d",childpid);
 478         server.bgsavechildpid = childpid;
 479         updateDictResizePolicy();
 480         return REDIS_OK;
 481     }
 482     return REDIS_OK; /* unreached */
 483 }
 484
 485 void rdbRemoveTempFile(pid_t childpid) {
 486     char tmpfile[256];
 487
 488     snprintf(tmpfile,256,"temp-%d.rdb", (int) childpid);
 489     unlink(tmpfile);
 490 }
 491
 492 int rdbLoadType(FILE *fp) {
 493     unsigned char type;
 494     if (fread(&type,1,1,fp) == 0) return -1;
 495     return type;
 496 }
 497
 498 time_t rdbLoadTime(FILE *fp) {
 499     int32_t t32;
 500     if (fread(&t32,4,1,fp) == 0) return -1;
 501     return (time_t) t32;
 502 }
 503
 504 /* Load an encoded length from the DB, see the REDIS_RDB_* defines on the top
 505  * of this file for a description of how this are stored on disk.
 506  *
 507  * isencoded is set to 1 if the readed length is not actually a length but
 508  * an "encoding type", check the above comments for more info */
 509 uint32_t rdbLoadLen(FILE *fp, int *isencoded) {
 510     unsigned char buf[2];
 511     uint32_t len;
 512     int type;
 513
 514     if (isencoded) *isencoded = 0;
 515     if (fread(buf,1,1,fp) == 0) return REDIS_RDB_LENERR;
 516     type = (buf[0]&0xC0)>>6;
 517     if (type == REDIS_RDB_6BITLEN) {
 518         /* Read a 6 bit len */
 519         return buf[0]&0x3F;
 520     } else if (type == REDIS_RDB_ENCVAL) {
 521         /* Read a 6 bit len encoding type */
 522         if (isencoded) *isencoded = 1;
 523         return buf[0]&0x3F;
 524     } else if (type == REDIS_RDB_14BITLEN) {
 525         /* Read a 14 bit len */
 526         if (fread(buf+1,1,1,fp) == 0) return REDIS_RDB_LENERR;
 527         return ((buf[0]&0x3F)<<8)|buf[1];
 528     } else {
 529         /* Read a 32 bit len */
 530         if (fread(&len,4,1,fp) == 0) return REDIS_RDB_LENERR;
 531         return ntohl(len);
 532     }
 533 }
 534
 535 /* Load an integer-encoded object from file 'fp', with the specified
 536  * encoding type 'enctype'. If encode is true the function may return
 537  * an integer-encoded object as reply, otherwise the returned object
 538  * will always be encoded as a raw string. */
 539 robj *rdbLoadIntegerObject(FILE *fp, int enctype, int encode) {
 540     unsigned char enc[4];
 541     long long val;
 542
 543     if (enctype == REDIS_RDB_ENC_INT8) {
 544         if (fread(enc,1,1,fp) == 0) return NULL;
 545         val = (signed char)enc[0];
 546     } else if (enctype == REDIS_RDB_ENC_INT16) {
 547         uint16_t v;
 548         if (fread(enc,2,1,fp) == 0) return NULL;
 549         v = enc[0]|(enc[1]<<8);
 550         val = (int16_t)v;
 551     } else if (enctype == REDIS_RDB_ENC_INT32) {
 552         uint32_t v;
 553         if (fread(enc,4,1,fp) == 0) return NULL;
 554         v = enc[0]|(enc[1]<<8)|(enc[2]<<16)|(enc[3]<<24);
 555         val = (int32_t)v;
 556     } else {
 557         val = 0; /* anti-warning */
 558         redisPanic("Unknown RDB integer encoding type");
 559     }
 560     if (encode)
 561         return createStringObjectFromLongLong(val);
 562     else
 563         return createObject(REDIS_STRING,sdsfromlonglong(val));
 564 }
 565
 566 robj *rdbLoadLzfStringObject(FILE*fp) {
 567     unsigned int len, clen;
 568     unsigned char *c = NULL;
 569     sds val = NULL;
 570
 571     if ((clen = rdbLoadLen(fp,NULL)) == REDIS_RDB_LENERR) return NULL;
 572     if ((len = rdbLoadLen(fp,NULL)) == REDIS_RDB_LENERR) return NULL;
 573     if ((c = zmalloc(clen)) == NULL) goto err;
 574     if ((val = sdsnewlen(NULL,len)) == NULL) goto err;
 575     if (fread(c,clen,1,fp) == 0) goto err;
 576     if (lzf_decompress(c,clen,val,len) == 0) goto err;
 577     zfree(c);
 578     return createObject(REDIS_STRING,val);
 579 err:
 580     zfree(c);
 581     sdsfree(val);
 582     return NULL;
 583 }
 584
 585 robj *rdbGenericLoadStringObject(FILE*fp, int encode) {
 586     int isencoded;
 587     uint32_t len;
 588     sds val;
 589
 590     len = rdbLoadLen(fp,&isencoded);
 591     if (isencoded) {
 592         switch(len) {
 593         case REDIS_RDB_ENC_INT8:
 594         case REDIS_RDB_ENC_INT16:
 595         case REDIS_RDB_ENC_INT32:
 596             return rdbLoadIntegerObject(fp,len,encode);
 597         case REDIS_RDB_ENC_LZF:
 598             return rdbLoadLzfStringObject(fp);
 599         default:
 600             redisPanic("Unknown RDB encoding type");
 601         }
 602     }
 603
 604     if (len == REDIS_RDB_LENERR) return NULL;
 605     val = sdsnewlen(NULL,len);
 606     if (len && fread(val,len,1,fp) == 0) {
 607         sdsfree(val);
 608         return NULL;
 609     }
 610     return createObject(REDIS_STRING,val);
 611 }
 612
 613 robj *rdbLoadStringObject(FILE *fp) {
 614     return rdbGenericLoadStringObject(fp,0);
 615 }
 616
 617 robj *rdbLoadEncodedStringObject(FILE *fp) {
 618     return rdbGenericLoadStringObject(fp,1);
 619 }
 620
 621 /* For information about double serialization check rdbSaveDoubleValue() */
 622 int rdbLoadDoubleValue(FILE *fp, double *val) {
 623     char buf[128];
 624     unsigned char len;
 625
 626     if (fread(&len,1,1,fp) == 0) return -1;
 627     switch(len) {
 628     case 255: *val = R_NegInf; return 0;
 629     case 254: *val = R_PosInf; return 0;
 630     case 253: *val = R_Nan; return 0;
 631     default:
 632         if (fread(buf,len,1,fp) == 0) return -1;
 633         buf[len] = '\0';
 634         sscanf(buf, "%lg", val);
 635         return 0;
 636     }
 637 }
 638
 639 /* Load a Redis object of the specified type from the specified file.
 640  * On success a newly allocated object is returned, otherwise NULL. */
 641 robj *rdbLoadObject(int type, FILE *fp) {
 642     robj *o, *ele, *dec;
 643     size_t len;
 644     unsigned int i;
 645
 646     redisLog(REDIS_DEBUG,"LOADING OBJECT %d (at %d)\n",type,ftell(fp));
 647     if (type == REDIS_STRING) {
 648         /* Read string value */
 649         if ((o = rdbLoadEncodedStringObject(fp)) == NULL) return NULL;
 650         o = tryObjectEncoding(o);
 651     } else if (type == REDIS_LIST) {
 652         /* Read list value */
 653         if ((len = rdbLoadLen(fp,NULL)) == REDIS_RDB_LENERR) return NULL;
 654
 655         /* Use a real list when there are too many entries */
 656         if (len > server.list_max_ziplist_entries) {
 657             o = createListObject();
 658         } else {
 659             o = createZiplistObject();
 660         }
 661
 662         /* Load every single element of the list */
 663         while(len--) {
 664             if ((ele = rdbLoadEncodedStringObject(fp)) == NULL) return NULL;
 665
 666             /* If we are using a ziplist and the value is too big, convert
 667              * the object to a real list. */
 668             if (o->encoding == REDIS_ENCODING_ZIPLIST &&
 669                 ele->encoding == REDIS_ENCODING_RAW &&
 670                 sdslen(ele->ptr) > server.list_max_ziplist_value)
 671                     listTypeConvert(o,REDIS_ENCODING_LINKEDLIST);
 672
 673             if (o->encoding == REDIS_ENCODING_ZIPLIST) {
 674                 dec = getDecodedObject(ele);
 675                 o->ptr = ziplistPush(o->ptr,dec->ptr,sdslen(dec->ptr),REDIS_TAIL);
 676                 decrRefCount(dec);
 677                 decrRefCount(ele);
 678             } else {
 679                 ele = tryObjectEncoding(ele);
 680                 listAddNodeTail(o->ptr,ele);
 681             }
 682         }
 683     } else if (type == REDIS_SET) {
 684         /* Read list/set value */
 685         if ((len = rdbLoadLen(fp,NULL)) == REDIS_RDB_LENERR) return NULL;
 686
 687         /* Use a regular set when there are too many entries. */
 688         if (len > server.set_max_intset_entries) {
 689             o = createSetObject();
 690             /* It's faster to expand the dict to the right size asap in order
 691              * to avoid rehashing */
 692             if (len > DICT_HT_INITIAL_SIZE)
 693                 dictExpand(o->ptr,len);
 694         } else {
 695             o = createIntsetObject();
 696         }
 697
 698         /* Load every single element of the list/set */
 699         for (i = 0; i < len; i++) {
 700             long long llval;
 701             if ((ele = rdbLoadEncodedStringObject(fp)) == NULL) return NULL;
 702             ele = tryObjectEncoding(ele);
 703
 704             if (o->encoding == REDIS_ENCODING_INTSET) {
 705                 /* Fetch integer value from element */
 706                 if (isObjectRepresentableAsLongLong(ele,&llval) == REDIS_OK) {
 707                     o->ptr = intsetAdd(o->ptr,llval,NULL);
 708                 } else {
 709                     setTypeConvert(o,REDIS_ENCODING_HT);
 710                     dictExpand(o->ptr,len);
 711                 }
 712             }
 713
 714             /* This will also be called when the set was just converted
 715              * to regular hashtable encoded set */
 716             if (o->encoding == REDIS_ENCODING_HT) {
 717                 dictAdd((dict*)o->ptr,ele,NULL);
 718             } else {
 719                 decrRefCount(ele);
 720             }
 721         }
 722     } else if (type == REDIS_ZSET) {
 723         /* Read list/set value */
 724         size_t zsetlen;
 725         zset *zs;
 726
 727         if ((zsetlen = rdbLoadLen(fp,NULL)) == REDIS_RDB_LENERR) return NULL;
 728         o = createZsetObject();
 729         zs = o->ptr;
 730         /* Load every single element of the list/set */
 731         while(zsetlen--) {
 732             robj *ele;
 733             double score;
 734             zskiplistNode *znode;
 735
 736             if ((ele = rdbLoadEncodedStringObject(fp)) == NULL) return NULL;
 737             ele = tryObjectEncoding(ele);
 738             if (rdbLoadDoubleValue(fp,&score) == -1) return NULL;
 739             znode = zslInsert(zs->zsl,score,ele);
 740             dictAdd(zs->dict,ele,&znode->score);
 741             incrRefCount(ele); /* added to skiplist */
 742         }
 743     } else if (type == REDIS_HASH) {
 744         size_t hashlen;
 745
 746         if ((hashlen = rdbLoadLen(fp,NULL)) == REDIS_RDB_LENERR) return NULL;
 747         o = createHashObject();
 748         /* Too many entries? Use an hash table. */
 749         if (hashlen > server.hash_max_zipmap_entries)
 750             convertToRealHash(o);
 751         /* Load every key/value, then set it into the zipmap or hash
 752          * table, as needed. */
 753         while(hashlen--) {
 754             robj *key, *val;
 755
 756             if ((key = rdbLoadEncodedStringObject(fp)) == NULL) return NULL;
 757             if ((val = rdbLoadEncodedStringObject(fp)) == NULL) return NULL;
 758             /* If we are using a zipmap and there are too big values
 759              * the object is converted to real hash table encoding. */
 760             if (o->encoding != REDIS_ENCODING_HT &&
 761                ((key->encoding == REDIS_ENCODING_RAW &&
 762                 sdslen(key->ptr) > server.hash_max_zipmap_value) ||
 763                 (val->encoding == REDIS_ENCODING_RAW &&
 764                 sdslen(val->ptr) > server.hash_max_zipmap_value)))
 765             {
 766                     convertToRealHash(o);
 767             }
 768
 769             if (o->encoding == REDIS_ENCODING_ZIPMAP) {
 770                 unsigned char *zm = o->ptr;
 771                 robj *deckey, *decval;
 772
 773                 /* We need raw string objects to add them to the zipmap */
 774                 deckey = getDecodedObject(key);
 775                 decval = getDecodedObject(val);
 776                 zm = zipmapSet(zm,deckey->ptr,sdslen(deckey->ptr),
 777                                   decval->ptr,sdslen(decval->ptr),NULL);
 778                 o->ptr = zm;
 779                 decrRefCount(deckey);
 780                 decrRefCount(decval);
 781                 decrRefCount(key);
 782                 decrRefCount(val);
 783             } else {
 784                 key = tryObjectEncoding(key);
 785                 val = tryObjectEncoding(val);
 786                 dictAdd((dict*)o->ptr,key,val);
 787             }
 788         }
 789     } else {
 790         redisPanic("Unknown object type");
 791     }
 792     return o;
 793 }
 794
 795 int rdbLoad(char *filename) {
 796     FILE *fp;
 797     uint32_t dbid;
 798     int type, retval, rdbver;
 799     int swap_all_values = 0;
 800     redisDb *db = server.db+0;
 801     char buf[1024];
 802     time_t expiretime, now = time(NULL);
 803
 804     fp = fopen(filename,"r");
 805     if (!fp) return REDIS_ERR;
 806     if (fread(buf,9,1,fp) == 0) goto eoferr;
 807     buf[9] = '\0';
 808     if (memcmp(buf,"REDIS",5) != 0) {
 809         fclose(fp);
 810         redisLog(REDIS_WARNING,"Wrong signature trying to load DB from file");
 811         return REDIS_ERR;
 812     }
 813     rdbver = atoi(buf+5);
 814     if (rdbver != 1) {
 815         fclose(fp);
 816         redisLog(REDIS_WARNING,"Can't handle RDB format version %d",rdbver);
 817         return REDIS_ERR;
 818     }
 819     while(1) {
 820         robj *key, *val;
 821         int force_swapout;
 822
 823         expiretime = -1;
 824         /* Read type. */
 825         if ((type = rdbLoadType(fp)) == -1) goto eoferr;
 826         if (type == REDIS_EXPIRETIME) {
 827             if ((expiretime = rdbLoadTime(fp)) == -1) goto eoferr;
 828             /* We read the time so we need to read the object type again */
 829             if ((type = rdbLoadType(fp)) == -1) goto eoferr;
 830         }
 831         if (type == REDIS_EOF) break;
 832         /* Handle SELECT DB opcode as a special case */
 833         if (type == REDIS_SELECTDB) {
 834             if ((dbid = rdbLoadLen(fp,NULL)) == REDIS_RDB_LENERR)
 835                 goto eoferr;
 836             if (dbid >= (unsigned)server.dbnum) {
 837                 redisLog(REDIS_WARNING,"FATAL: Data file was created with a Redis server configured to handle more than %d databases. Exiting\n", server.dbnum);
 838                 exit(1);
 839             }
 840             db = server.db+dbid;
 841             continue;
 842         }
 843         /* Read key */
 844         if ((key = rdbLoadStringObject(fp)) == NULL) goto eoferr;
 845         /* Read value */
 846         if ((val = rdbLoadObject(type,fp)) == NULL) goto eoferr;
 847         /* Check if the key already expired */
 848         if (expiretime != -1 && expiretime < now) {
 849             decrRefCount(key);
 850             decrRefCount(val);
 851             continue;
 852         }
 853         /* Add the new object in the hash table */
 854         retval = dbAdd(db,key,val);
 855         if (retval == REDIS_ERR) {
 856             redisLog(REDIS_WARNING,"Loading DB, duplicated key (%s) found! Unrecoverable error, exiting now.", key->ptr);
 857             exit(1);
 858         }
 859         /* Set the expire time if needed */
 860         if (expiretime != -1) setExpire(db,key,expiretime);
 861
 862         /* Handle swapping while loading big datasets when VM is on */
 863
 864         /* If we detecter we are hopeless about fitting something in memory
 865          * we just swap every new key on disk. Directly...
 866          * Note that's important to check for this condition before resorting
 867          * to random sampling, otherwise we may try to swap already
 868          * swapped keys. */
 869         if (swap_all_values) {
 870             dictEntry *de = dictFind(db->dict,key->ptr);
 871
 872             /* de may be NULL since the key already expired */
 873             if (de) {
 874                 vmpointer *vp;
 875                 val = dictGetEntryVal(de);
 876
 877                 if (val->refcount == 1 &&
 878                     (vp = vmSwapObjectBlocking(val)) != NULL)
 879                     dictGetEntryVal(de) = vp;
 880             }
 881             decrRefCount(key);
 882             continue;
 883         }
 884         decrRefCount(key);
 885
 886         /* Flush data on disk once 32 MB of additional RAM are used... */
 887         force_swapout = 0;
 888         if ((zmalloc_used_memory() - server.vm_max_memory) > 1024*1024*32)
 889             force_swapout = 1;
 890
 891         /* If we have still some hope of having some value fitting memory
 892          * then we try random sampling. */
 893         if (!swap_all_values && server.vm_enabled && force_swapout) {
 894             while (zmalloc_used_memory() > server.vm_max_memory) {
 895                 if (vmSwapOneObjectBlocking() == REDIS_ERR) break;
 896             }
 897             if (zmalloc_used_memory() > server.vm_max_memory)
 898                 swap_all_values = 1; /* We are already using too much mem */
 899         }
 900     }
 901     fclose(fp);
 902     return REDIS_OK;
 903
 904 eoferr: /* unexpected end of file is handled here with a fatal exit */
 905     redisLog(REDIS_WARNING,"Short read or OOM loading DB. Unrecoverable error, aborting now.");
 906     exit(1);
 907     return REDIS_ERR; /* Just to avoid warning */
 908 }
 909
 910 /* A background saving child (BGSAVE) terminated its work. Handle this. */
 911 void backgroundSaveDoneHandler(int statloc) {
 912     int exitcode = WEXITSTATUS(statloc);
 913     int bysignal = WIFSIGNALED(statloc);
 914
 915     if (!bysignal && exitcode == 0) {
 916         redisLog(REDIS_NOTICE,
 917             "Background saving terminated with success");
 918         server.dirty = server.dirty - server.dirty_before_bgsave;
 919         server.lastsave = time(NULL);
 920     } else if (!bysignal && exitcode != 0) {
 921         redisLog(REDIS_WARNING, "Background saving error");
 922     } else {
 923         redisLog(REDIS_WARNING,
 924             "Background saving terminated by signal %d", WTERMSIG(statloc));
 925         rdbRemoveTempFile(server.bgsavechildpid);
 926     }
 927     server.bgsavechildpid = -1;
 928     /* Possibly there are slaves waiting for a BGSAVE in order to be served
 929      * (the first stage of SYNC is a bulk transfer of dump.rdb) */
 930     updateSlavesWaitingBgsave(exitcode == 0 ? REDIS_OK : REDIS_ERR);
 931 }