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         dict *set = o->ptr;
 264         dictIterator *di = dictGetIterator(set);
 265         dictEntry *de;
 266
 267         if (rdbSaveLen(fp,dictSize(set)) == -1) return -1;
 268         while((de = dictNext(di)) != NULL) {
 269             robj *eleobj = dictGetEntryKey(de);
 270
 271             if (rdbSaveStringObject(fp,eleobj) == -1) return -1;
 272         }
 273         dictReleaseIterator(di);
 274     } else if (o->type == REDIS_ZSET) {
 275         /* Save a set value */
 276         zset *zs = o->ptr;
 277         dictIterator *di = dictGetIterator(zs->dict);
 278         dictEntry *de;
 279
 280         if (rdbSaveLen(fp,dictSize(zs->dict)) == -1) return -1;
 281         while((de = dictNext(di)) != NULL) {
 282             robj *eleobj = dictGetEntryKey(de);
 283             double *score = dictGetEntryVal(de);
 284
 285             if (rdbSaveStringObject(fp,eleobj) == -1) return -1;
 286             if (rdbSaveDoubleValue(fp,*score) == -1) return -1;
 287         }
 288         dictReleaseIterator(di);
 289     } else if (o->type == REDIS_HASH) {
 290         /* Save a hash value */
 291         if (o->encoding == REDIS_ENCODING_ZIPMAP) {
 292             unsigned char *p = zipmapRewind(o->ptr);
 293             unsigned int count = zipmapLen(o->ptr);
 294             unsigned char *key, *val;
 295             unsigned int klen, vlen;
 296
 297             if (rdbSaveLen(fp,count) == -1) return -1;
 298             while((p = zipmapNext(p,&key,&klen,&val,&vlen)) != NULL) {
 299                 if (rdbSaveRawString(fp,key,klen) == -1) return -1;
 300                 if (rdbSaveRawString(fp,val,vlen) == -1) return -1;
 301             }
 302         } else {
 303             dictIterator *di = dictGetIterator(o->ptr);
 304             dictEntry *de;
 305
 306             if (rdbSaveLen(fp,dictSize((dict*)o->ptr)) == -1) return -1;
 307             while((de = dictNext(di)) != NULL) {
 308                 robj *key = dictGetEntryKey(de);
 309                 robj *val = dictGetEntryVal(de);
 310
 311                 if (rdbSaveStringObject(fp,key) == -1) return -1;
 312                 if (rdbSaveStringObject(fp,val) == -1) return -1;
 313             }
 314             dictReleaseIterator(di);
 315         }
 316     } else {
 317         redisPanic("Unknown object type");
 318     }
 319     return 0;
 320 }
 321
 322 /* Return the length the object will have on disk if saved with
 323  * the rdbSaveObject() function. Currently we use a trick to get
 324  * this length with very little changes to the code. In the future
 325  * we could switch to a faster solution. */
 326 off_t rdbSavedObjectLen(robj *o, FILE *fp) {
 327     if (fp == NULL) fp = server.devnull;
 328     rewind(fp);
 329     redisAssert(rdbSaveObject(fp,o) != 1);
 330     return ftello(fp);
 331 }
 332
 333 /* Return the number of pages required to save this object in the swap file */
 334 off_t rdbSavedObjectPages(robj *o, FILE *fp) {
 335     off_t bytes = rdbSavedObjectLen(o,fp);
 336
 337     return (bytes+(server.vm_page_size-1))/server.vm_page_size;
 338 }
 339
 340 /* Save the DB on disk. Return REDIS_ERR on error, REDIS_OK on success */
 341 int rdbSave(char *filename) {
 342     dictIterator *di = NULL;
 343     dictEntry *de;
 344     FILE *fp;
 345     char tmpfile[256];
 346     int j;
 347     time_t now = time(NULL);
 348
 349     /* Wait for I/O therads to terminate, just in case this is a
 350      * foreground-saving, to avoid seeking the swap file descriptor at the
 351      * same time. */
 352     if (server.vm_enabled)
 353         waitEmptyIOJobsQueue();
 354
 355     snprintf(tmpfile,256,"temp-%d.rdb", (int) getpid());
 356     fp = fopen(tmpfile,"w");
 357     if (!fp) {
 358         redisLog(REDIS_WARNING, "Failed saving the DB: %s", strerror(errno));
 359         return REDIS_ERR;
 360     }
 361     if (fwrite("REDIS0001",9,1,fp) == 0) goto werr;
 362     for (j = 0; j < server.dbnum; j++) {
 363         redisDb *db = server.db+j;
 364         dict *d = db->dict;
 365         if (dictSize(d) == 0) continue;
 366         di = dictGetIterator(d);
 367         if (!di) {
 368             fclose(fp);
 369             return REDIS_ERR;
 370         }
 371
 372         /* Write the SELECT DB opcode */
 373         if (rdbSaveType(fp,REDIS_SELECTDB) == -1) goto werr;
 374         if (rdbSaveLen(fp,j) == -1) goto werr;
 375
 376         /* Iterate this DB writing every entry */
 377         while((de = dictNext(di)) != NULL) {
 378             sds keystr = dictGetEntryKey(de);
 379             robj key, *o = dictGetEntryVal(de);
 380             time_t expiretime;
 381
 382             initStaticStringObject(key,keystr);
 383             expiretime = getExpire(db,&key);
 384
 385             /* Save the expire time */
 386             if (expiretime != -1) {
 387                 /* If this key is already expired skip it */
 388                 if (expiretime < now) continue;
 389                 if (rdbSaveType(fp,REDIS_EXPIRETIME) == -1) goto werr;
 390                 if (rdbSaveTime(fp,expiretime) == -1) goto werr;
 391             }
 392             /* Save the key and associated value. This requires special
 393              * handling if the value is swapped out. */
 394             if (!server.vm_enabled || o->storage == REDIS_VM_MEMORY ||
 395                                       o->storage == REDIS_VM_SWAPPING) {
 396                 /* Save type, key, value */
 397                 if (rdbSaveType(fp,o->type) == -1) goto werr;
 398                 if (rdbSaveStringObject(fp,&key) == -1) goto werr;
 399                 if (rdbSaveObject(fp,o) == -1) goto werr;
 400             } else {
 401                 /* REDIS_VM_SWAPPED or REDIS_VM_LOADING */
 402                 robj *po;
 403                 /* Get a preview of the object in memory */
 404                 po = vmPreviewObject(o);
 405                 /* Save type, key, value */
 406                 if (rdbSaveType(fp,po->type) == -1) goto werr;
 407                 if (rdbSaveStringObject(fp,&key) == -1) goto werr;
 408                 if (rdbSaveObject(fp,po) == -1) goto werr;
 409                 /* Remove the loaded object from memory */
 410                 decrRefCount(po);
 411             }
 412         }
 413         dictReleaseIterator(di);
 414     }
 415     /* EOF opcode */
 416     if (rdbSaveType(fp,REDIS_EOF) == -1) goto werr;
 417
 418     /* Make sure data will not remain on the OS's output buffers */
 419     fflush(fp);
 420     fsync(fileno(fp));
 421     fclose(fp);
 422
 423     /* Use RENAME to make sure the DB file is changed atomically only
 424      * if the generate DB file is ok. */
 425     if (rename(tmpfile,filename) == -1) {
 426         redisLog(REDIS_WARNING,"Error moving temp DB file on the final destination: %s", strerror(errno));
 427         unlink(tmpfile);
 428         return REDIS_ERR;
 429     }
 430     redisLog(REDIS_NOTICE,"DB saved on disk");
 431     server.dirty = 0;
 432     server.lastsave = time(NULL);
 433     return REDIS_OK;
 434
 435 werr:
 436     fclose(fp);
 437     unlink(tmpfile);
 438     redisLog(REDIS_WARNING,"Write error saving DB on disk: %s", strerror(errno));
 439     if (di) dictReleaseIterator(di);
 440     return REDIS_ERR;
 441 }
 442
 443 int rdbSaveBackground(char *filename) {
 444     pid_t childpid;
 445
 446     if (server.bgsavechildpid != -1) return REDIS_ERR;
 447     if (server.vm_enabled) waitEmptyIOJobsQueue();
 448     if ((childpid = fork()) == 0) {
 449         /* Child */
 450         if (server.vm_enabled) vmReopenSwapFile();
 451         close(server.fd);
 452         if (rdbSave(filename) == REDIS_OK) {
 453             _exit(0);
 454         } else {
 455             _exit(1);
 456         }
 457     } else {
 458         /* Parent */
 459         if (childpid == -1) {
 460             redisLog(REDIS_WARNING,"Can't save in background: fork: %s",
 461                 strerror(errno));
 462             return REDIS_ERR;
 463         }
 464         redisLog(REDIS_NOTICE,"Background saving started by pid %d",childpid);
 465         server.bgsavechildpid = childpid;
 466         updateDictResizePolicy();
 467         return REDIS_OK;
 468     }
 469     return REDIS_OK; /* unreached */
 470 }
 471
 472 void rdbRemoveTempFile(pid_t childpid) {
 473     char tmpfile[256];
 474
 475     snprintf(tmpfile,256,"temp-%d.rdb", (int) childpid);
 476     unlink(tmpfile);
 477 }
 478
 479 int rdbLoadType(FILE *fp) {
 480     unsigned char type;
 481     if (fread(&type,1,1,fp) == 0) return -1;
 482     return type;
 483 }
 484
 485 time_t rdbLoadTime(FILE *fp) {
 486     int32_t t32;
 487     if (fread(&t32,4,1,fp) == 0) return -1;
 488     return (time_t) t32;
 489 }
 490
 491 /* Load an encoded length from the DB, see the REDIS_RDB_* defines on the top
 492  * of this file for a description of how this are stored on disk.
 493  *
 494  * isencoded is set to 1 if the readed length is not actually a length but
 495  * an "encoding type", check the above comments for more info */
 496 uint32_t rdbLoadLen(FILE *fp, int *isencoded) {
 497     unsigned char buf[2];
 498     uint32_t len;
 499     int type;
 500
 501     if (isencoded) *isencoded = 0;
 502     if (fread(buf,1,1,fp) == 0) return REDIS_RDB_LENERR;
 503     type = (buf[0]&0xC0)>>6;
 504     if (type == REDIS_RDB_6BITLEN) {
 505         /* Read a 6 bit len */
 506         return buf[0]&0x3F;
 507     } else if (type == REDIS_RDB_ENCVAL) {
 508         /* Read a 6 bit len encoding type */
 509         if (isencoded) *isencoded = 1;
 510         return buf[0]&0x3F;
 511     } else if (type == REDIS_RDB_14BITLEN) {
 512         /* Read a 14 bit len */
 513         if (fread(buf+1,1,1,fp) == 0) return REDIS_RDB_LENERR;
 514         return ((buf[0]&0x3F)<<8)|buf[1];
 515     } else {
 516         /* Read a 32 bit len */
 517         if (fread(&len,4,1,fp) == 0) return REDIS_RDB_LENERR;
 518         return ntohl(len);
 519     }
 520 }
 521
 522 /* Load an integer-encoded object from file 'fp', with the specified
 523  * encoding type 'enctype'. If encode is true the function may return
 524  * an integer-encoded object as reply, otherwise the returned object
 525  * will always be encoded as a raw string. */
 526 robj *rdbLoadIntegerObject(FILE *fp, int enctype, int encode) {
 527     unsigned char enc[4];
 528     long long val;
 529
 530     if (enctype == REDIS_RDB_ENC_INT8) {
 531         if (fread(enc,1,1,fp) == 0) return NULL;
 532         val = (signed char)enc[0];
 533     } else if (enctype == REDIS_RDB_ENC_INT16) {
 534         uint16_t v;
 535         if (fread(enc,2,1,fp) == 0) return NULL;
 536         v = enc[0]|(enc[1]<<8);
 537         val = (int16_t)v;
 538     } else if (enctype == REDIS_RDB_ENC_INT32) {
 539         uint32_t v;
 540         if (fread(enc,4,1,fp) == 0) return NULL;
 541         v = enc[0]|(enc[1]<<8)|(enc[2]<<16)|(enc[3]<<24);
 542         val = (int32_t)v;
 543     } else {
 544         val = 0; /* anti-warning */
 545         redisPanic("Unknown RDB integer encoding type");
 546     }
 547     if (encode)
 548         return createStringObjectFromLongLong(val);
 549     else
 550         return createObject(REDIS_STRING,sdsfromlonglong(val));
 551 }
 552
 553 robj *rdbLoadLzfStringObject(FILE*fp) {
 554     unsigned int len, clen;
 555     unsigned char *c = NULL;
 556     sds val = NULL;
 557
 558     if ((clen = rdbLoadLen(fp,NULL)) == REDIS_RDB_LENERR) return NULL;
 559     if ((len = rdbLoadLen(fp,NULL)) == REDIS_RDB_LENERR) return NULL;
 560     if ((c = zmalloc(clen)) == NULL) goto err;
 561     if ((val = sdsnewlen(NULL,len)) == NULL) goto err;
 562     if (fread(c,clen,1,fp) == 0) goto err;
 563     if (lzf_decompress(c,clen,val,len) == 0) goto err;
 564     zfree(c);
 565     return createObject(REDIS_STRING,val);
 566 err:
 567     zfree(c);
 568     sdsfree(val);
 569     return NULL;
 570 }
 571
 572 robj *rdbGenericLoadStringObject(FILE*fp, int encode) {
 573     int isencoded;
 574     uint32_t len;
 575     sds val;
 576
 577     len = rdbLoadLen(fp,&isencoded);
 578     if (isencoded) {
 579         switch(len) {
 580         case REDIS_RDB_ENC_INT8:
 581         case REDIS_RDB_ENC_INT16:
 582         case REDIS_RDB_ENC_INT32:
 583             return rdbLoadIntegerObject(fp,len,encode);
 584         case REDIS_RDB_ENC_LZF:
 585             return rdbLoadLzfStringObject(fp);
 586         default:
 587             redisPanic("Unknown RDB encoding type");
 588         }
 589     }
 590
 591     if (len == REDIS_RDB_LENERR) return NULL;
 592     val = sdsnewlen(NULL,len);
 593     if (len && fread(val,len,1,fp) == 0) {
 594         sdsfree(val);
 595         return NULL;
 596     }
 597     return createObject(REDIS_STRING,val);
 598 }
 599
 600 robj *rdbLoadStringObject(FILE *fp) {
 601     return rdbGenericLoadStringObject(fp,0);
 602 }
 603
 604 robj *rdbLoadEncodedStringObject(FILE *fp) {
 605     return rdbGenericLoadStringObject(fp,1);
 606 }
 607
 608 /* For information about double serialization check rdbSaveDoubleValue() */
 609 int rdbLoadDoubleValue(FILE *fp, double *val) {
 610     char buf[128];
 611     unsigned char len;
 612
 613     if (fread(&len,1,1,fp) == 0) return -1;
 614     switch(len) {
 615     case 255: *val = R_NegInf; return 0;
 616     case 254: *val = R_PosInf; return 0;
 617     case 253: *val = R_Nan; return 0;
 618     default:
 619         if (fread(buf,len,1,fp) == 0) return -1;
 620         buf[len] = '\0';
 621         sscanf(buf, "%lg", val);
 622         return 0;
 623     }
 624 }
 625
 626 /* Load a Redis object of the specified type from the specified file.
 627  * On success a newly allocated object is returned, otherwise NULL. */
 628 robj *rdbLoadObject(int type, FILE *fp) {
 629     robj *o, *ele, *dec;
 630     size_t len;
 631
 632     redisLog(REDIS_DEBUG,"LOADING OBJECT %d (at %d)\n",type,ftell(fp));
 633     if (type == REDIS_STRING) {
 634         /* Read string value */
 635         if ((o = rdbLoadEncodedStringObject(fp)) == NULL) return NULL;
 636         o = tryObjectEncoding(o);
 637     } else if (type == REDIS_LIST) {
 638         /* Read list value */
 639         if ((len = rdbLoadLen(fp,NULL)) == REDIS_RDB_LENERR) return NULL;
 640
 641         /* Use a real list when there are too many entries */
 642         if (len > server.list_max_ziplist_entries) {
 643             o = createListObject();
 644         } else {
 645             o = createZiplistObject();
 646         }
 647
 648         /* Load every single element of the list */
 649         while(len--) {
 650             if ((ele = rdbLoadEncodedStringObject(fp)) == NULL) return NULL;
 651
 652             /* If we are using a ziplist and the value is too big, convert
 653              * the object to a real list. */
 654             if (o->encoding == REDIS_ENCODING_ZIPLIST &&
 655                 ele->encoding == REDIS_ENCODING_RAW &&
 656                 sdslen(ele->ptr) > server.list_max_ziplist_value)
 657                     listTypeConvert(o,REDIS_ENCODING_LINKEDLIST);
 658
 659             if (o->encoding == REDIS_ENCODING_ZIPLIST) {
 660                 dec = getDecodedObject(ele);
 661                 o->ptr = ziplistPush(o->ptr,dec->ptr,sdslen(dec->ptr),REDIS_TAIL);
 662                 decrRefCount(dec);
 663                 decrRefCount(ele);
 664             } else {
 665                 ele = tryObjectEncoding(ele);
 666                 listAddNodeTail(o->ptr,ele);
 667             }
 668         }
 669     } else if (type == REDIS_SET) {
 670         /* Read list/set value */
 671         if ((len = rdbLoadLen(fp,NULL)) == REDIS_RDB_LENERR) return NULL;
 672         o = createSetObject();
 673         /* It's faster to expand the dict to the right size asap in order
 674          * to avoid rehashing */
 675         if (len > DICT_HT_INITIAL_SIZE)
 676             dictExpand(o->ptr,len);
 677         /* Load every single element of the list/set */
 678         while(len--) {
 679             if ((ele = rdbLoadEncodedStringObject(fp)) == NULL) return NULL;
 680             ele = tryObjectEncoding(ele);
 681             dictAdd((dict*)o->ptr,ele,NULL);
 682         }
 683     } else if (type == REDIS_ZSET) {
 684         /* Read list/set value */
 685         size_t zsetlen;
 686         zset *zs;
 687
 688         if ((zsetlen = rdbLoadLen(fp,NULL)) == REDIS_RDB_LENERR) return NULL;
 689         o = createZsetObject();
 690         zs = o->ptr;
 691         /* Load every single element of the list/set */
 692         while(zsetlen--) {
 693             robj *ele;
 694             double *score = zmalloc(sizeof(double));
 695
 696             if ((ele = rdbLoadEncodedStringObject(fp)) == NULL) return NULL;
 697             ele = tryObjectEncoding(ele);
 698             if (rdbLoadDoubleValue(fp,score) == -1) return NULL;
 699             dictAdd(zs->dict,ele,score);
 700             zslInsert(zs->zsl,*score,ele);
 701             incrRefCount(ele); /* added to skiplist */
 702         }
 703     } else if (type == REDIS_HASH) {
 704         size_t hashlen;
 705
 706         if ((hashlen = rdbLoadLen(fp,NULL)) == REDIS_RDB_LENERR) return NULL;
 707         o = createHashObject();
 708         /* Too many entries? Use an hash table. */
 709         if (hashlen > server.hash_max_zipmap_entries)
 710             convertToRealHash(o);
 711         /* Load every key/value, then set it into the zipmap or hash
 712          * table, as needed. */
 713         while(hashlen--) {
 714             robj *key, *val;
 715
 716             if ((key = rdbLoadEncodedStringObject(fp)) == NULL) return NULL;
 717             if ((val = rdbLoadEncodedStringObject(fp)) == NULL) return NULL;
 718             /* If we are using a zipmap and there are too big values
 719              * the object is converted to real hash table encoding. */
 720             if (o->encoding != REDIS_ENCODING_HT &&
 721                ((key->encoding == REDIS_ENCODING_RAW &&
 722                 sdslen(key->ptr) > server.hash_max_zipmap_value) ||
 723                 (val->encoding == REDIS_ENCODING_RAW &&
 724                 sdslen(val->ptr) > server.hash_max_zipmap_value)))
 725             {
 726                     convertToRealHash(o);
 727             }
 728
 729             if (o->encoding == REDIS_ENCODING_ZIPMAP) {
 730                 unsigned char *zm = o->ptr;
 731                 robj *deckey, *decval;
 732
 733                 /* We need raw string objects to add them to the zipmap */
 734                 deckey = getDecodedObject(key);
 735                 decval = getDecodedObject(val);
 736                 zm = zipmapSet(zm,deckey->ptr,sdslen(deckey->ptr),
 737                                   decval->ptr,sdslen(decval->ptr),NULL);
 738                 o->ptr = zm;
 739                 decrRefCount(deckey);
 740                 decrRefCount(decval);
 741                 decrRefCount(key);
 742                 decrRefCount(val);
 743             } else {
 744                 key = tryObjectEncoding(key);
 745                 val = tryObjectEncoding(val);
 746                 dictAdd((dict*)o->ptr,key,val);
 747             }
 748         }
 749     } else {
 750         redisPanic("Unknown object type");
 751     }
 752     return o;
 753 }
 754
 755 int rdbLoad(char *filename) {
 756     FILE *fp;
 757     uint32_t dbid;
 758     int type, retval, rdbver;
 759     int swap_all_values = 0;
 760     redisDb *db = server.db+0;
 761     char buf[1024];
 762     time_t expiretime, now = time(NULL);
 763
 764     fp = fopen(filename,"r");
 765     if (!fp) return REDIS_ERR;
 766     if (fread(buf,9,1,fp) == 0) goto eoferr;
 767     buf[9] = '\0';
 768     if (memcmp(buf,"REDIS",5) != 0) {
 769         fclose(fp);
 770         redisLog(REDIS_WARNING,"Wrong signature trying to load DB from file");
 771         return REDIS_ERR;
 772     }
 773     rdbver = atoi(buf+5);
 774     if (rdbver != 1) {
 775         fclose(fp);
 776         redisLog(REDIS_WARNING,"Can't handle RDB format version %d",rdbver);
 777         return REDIS_ERR;
 778     }
 779     while(1) {
 780         robj *key, *val;
 781         int force_swapout;
 782
 783         expiretime = -1;
 784         /* Read type. */
 785         if ((type = rdbLoadType(fp)) == -1) goto eoferr;
 786         if (type == REDIS_EXPIRETIME) {
 787             if ((expiretime = rdbLoadTime(fp)) == -1) goto eoferr;
 788             /* We read the time so we need to read the object type again */
 789             if ((type = rdbLoadType(fp)) == -1) goto eoferr;
 790         }
 791         if (type == REDIS_EOF) break;
 792         /* Handle SELECT DB opcode as a special case */
 793         if (type == REDIS_SELECTDB) {
 794             if ((dbid = rdbLoadLen(fp,NULL)) == REDIS_RDB_LENERR)
 795                 goto eoferr;
 796             if (dbid >= (unsigned)server.dbnum) {
 797                 redisLog(REDIS_WARNING,"FATAL: Data file was created with a Redis server configured to handle more than %d databases. Exiting\n", server.dbnum);
 798                 exit(1);
 799             }
 800             db = server.db+dbid;
 801             continue;
 802         }
 803         /* Read key */
 804         if ((key = rdbLoadStringObject(fp)) == NULL) goto eoferr;
 805         /* Read value */
 806         if ((val = rdbLoadObject(type,fp)) == NULL) goto eoferr;
 807         /* Check if the key already expired */
 808         if (expiretime != -1 && expiretime < now) {
 809             decrRefCount(key);
 810             decrRefCount(val);
 811             continue;
 812         }
 813         /* Add the new object in the hash table */
 814         retval = dbAdd(db,key,val);
 815         if (retval == REDIS_ERR) {
 816             redisLog(REDIS_WARNING,"Loading DB, duplicated key (%s) found! Unrecoverable error, exiting now.", key->ptr);
 817             exit(1);
 818         }
 819         /* Set the expire time if needed */
 820         if (expiretime != -1) setExpire(db,key,expiretime);
 821
 822         /* Handle swapping while loading big datasets when VM is on */
 823
 824         /* If we detecter we are hopeless about fitting something in memory
 825          * we just swap every new key on disk. Directly...
 826          * Note that's important to check for this condition before resorting
 827          * to random sampling, otherwise we may try to swap already
 828          * swapped keys. */
 829         if (swap_all_values) {
 830             dictEntry *de = dictFind(db->dict,key->ptr);
 831
 832             /* de may be NULL since the key already expired */
 833             if (de) {
 834                 vmpointer *vp;
 835                 val = dictGetEntryVal(de);
 836
 837                 if (val->refcount == 1 &&
 838                     (vp = vmSwapObjectBlocking(val)) != NULL)
 839                     dictGetEntryVal(de) = vp;
 840             }
 841             decrRefCount(key);
 842             continue;
 843         }
 844         decrRefCount(key);
 845
 846         /* Flush data on disk once 32 MB of additional RAM are used... */
 847         force_swapout = 0;
 848         if ((zmalloc_used_memory() - server.vm_max_memory) > 1024*1024*32)
 849             force_swapout = 1;
 850
 851         /* If we have still some hope of having some value fitting memory
 852          * then we try random sampling. */
 853         if (!swap_all_values && server.vm_enabled && force_swapout) {
 854             while (zmalloc_used_memory() > server.vm_max_memory) {
 855                 if (vmSwapOneObjectBlocking() == REDIS_ERR) break;
 856             }
 857             if (zmalloc_used_memory() > server.vm_max_memory)
 858                 swap_all_values = 1; /* We are already using too much mem */
 859         }
 860     }
 861     fclose(fp);
 862     return REDIS_OK;
 863
 864 eoferr: /* unexpected end of file is handled here with a fatal exit */
 865     redisLog(REDIS_WARNING,"Short read or OOM loading DB. Unrecoverable error, aborting now.");
 866     exit(1);
 867     return REDIS_ERR; /* Just to avoid warning */
 868 }
 869
 870 /* A background saving child (BGSAVE) terminated its work. Handle this. */
 871 void backgroundSaveDoneHandler(int statloc) {
 872     int exitcode = WEXITSTATUS(statloc);
 873     int bysignal = WIFSIGNALED(statloc);
 874
 875     if (!bysignal && exitcode == 0) {
 876         redisLog(REDIS_NOTICE,
 877             "Background saving terminated with success");
 878         server.dirty = 0;
 879         server.lastsave = time(NULL);
 880     } else if (!bysignal && exitcode != 0) {
 881         redisLog(REDIS_WARNING, "Background saving error");
 882     } else {
 883         redisLog(REDIS_WARNING,
 884             "Background saving terminated by signal %d", WTERMSIG(statloc));
 885         rdbRemoveTempFile(server.bgsavechildpid);
 886     }
 887     server.bgsavechildpid = -1;
 888     /* Possibly there are slaves waiting for a BGSAVE in order to be served
 889      * (the first stage of SYNC is a bulk transfer of dump.rdb) */
 890     updateSlavesWaitingBgsave(exitcode == 0 ? REDIS_OK : REDIS_ERR);
 891 }