src/sort.c

   1 #include "redis.h"
   2 #include "pqsort.h" /* Partial qsort for SORT+LIMIT */
   3 #include <math.h> /* isnan() */
   4
   5 redisSortOperation *createSortOperation(int type, robj *pattern) {
   6     redisSortOperation *so = zmalloc(sizeof(*so));
   7     so->type = type;
   8     so->pattern = pattern;
   9     return so;
  10 }
  11
  12 /* Return the value associated to the key with a name obtained
  13  * substituting the first occurence of '*' in 'pattern' with 'subst'.
  14  * The returned object will always have its refcount increased by 1
  15  * when it is non-NULL. */
  16 robj *lookupKeyByPattern(redisDb *db, robj *pattern, robj *subst) {
  17     char *p, *f;
  18     sds spat, ssub;
  19     robj keyobj, fieldobj, *o;
  20     int prefixlen, sublen, postfixlen, fieldlen;
  21     /* Expoit the internal sds representation to create a sds string allocated on the stack in order to make this function faster */
  22     struct {
  23         int len;
  24         int free;
  25         char buf[REDIS_SORTKEY_MAX+1];
  26     } keyname, fieldname;
  27
  28     /* If the pattern is "#" return the substitution object itself in order
  29      * to implement the "SORT ... GET #" feature. */
  30     spat = pattern->ptr;
  31     if (spat[0] == '#' && spat[1] == '\0') {
  32         incrRefCount(subst);
  33         return subst;
  34     }
  35
  36     /* The substitution object may be specially encoded. If so we create
  37      * a decoded object on the fly. Otherwise getDecodedObject will just
  38      * increment the ref count, that we'll decrement later. */
  39     subst = getDecodedObject(subst);
  40
  41     ssub = subst->ptr;
  42     if (sdslen(spat)+sdslen(ssub)-1 > REDIS_SORTKEY_MAX) return NULL;
  43     p = strchr(spat,'*');
  44     if (!p) {
  45         decrRefCount(subst);
  46         return NULL;
  47     }
  48
  49     /* Find out if we're dealing with a hash dereference. */
  50     if ((f = strstr(p+1, "->")) != NULL) {
  51         fieldlen = sdslen(spat)-(f-spat);
  52         /* this also copies \0 character */
  53         memcpy(fieldname.buf,f+2,fieldlen-1);
  54         fieldname.len = fieldlen-2;
  55     } else {
  56         fieldlen = 0;
  57     }
  58
  59     prefixlen = p-spat;
  60     sublen = sdslen(ssub);
  61     postfixlen = sdslen(spat)-(prefixlen+1)-fieldlen;
  62     memcpy(keyname.buf,spat,prefixlen);
  63     memcpy(keyname.buf+prefixlen,ssub,sublen);
  64     memcpy(keyname.buf+prefixlen+sublen,p+1,postfixlen);
  65     keyname.buf[prefixlen+sublen+postfixlen] = '\0';
  66     keyname.len = prefixlen+sublen+postfixlen;
  67     decrRefCount(subst);
  68
  69     /* Lookup substituted key */
  70     initStaticStringObject(keyobj,((char*)&keyname)+(sizeof(struct sdshdr)));
  71     o = lookupKeyRead(db,&keyobj);
  72     if (o == NULL) return NULL;
  73
  74     if (fieldlen > 0) {
  75         if (o->type != REDIS_HASH || fieldname.len < 1) return NULL;
  76
  77         /* Retrieve value from hash by the field name. This operation
  78          * already increases the refcount of the returned object. */
  79         initStaticStringObject(fieldobj,((char*)&fieldname)+(sizeof(struct sdshdr)));
  80         o = hashTypeGetObject(o, &fieldobj);
  81     } else {
  82         if (o->type != REDIS_STRING) return NULL;
  83
  84         /* Every object that this function returns needs to have its refcount
  85          * increased. sortCommand decreases it again. */
  86         incrRefCount(o);
  87     }
  88
  89     return o;
  90 }
  91
  92 /* sortCompare() is used by qsort in sortCommand(). Given that qsort_r with
  93  * the additional parameter is not standard but a BSD-specific we have to
  94  * pass sorting parameters via the global 'server' structure */
  95 int sortCompare(const void *s1, const void *s2) {
  96     const redisSortObject *so1 = s1, *so2 = s2;
  97     int cmp;
  98
  99     if (!server.sort_alpha) {
 100         /* Numeric sorting. Here it's trivial as we precomputed scores */
 101         if (so1->u.score > so2->u.score) {
 102             cmp = 1;
 103         } else if (so1->u.score < so2->u.score) {
 104             cmp = -1;
 105         } else {
 106             /* Objects have the same score, but we don't want the comparison
 107              * to be undefined, so we compare objects lexicographycally.
 108              * This way the result of SORT is deterministic. */
 109             cmp = compareStringObjects(so1->obj,so2->obj);
 110         }
 111     } else {
 112         /* Alphanumeric sorting */
 113         if (server.sort_bypattern) {
 114             if (!so1->u.cmpobj || !so2->u.cmpobj) {
 115                 /* At least one compare object is NULL */
 116                 if (so1->u.cmpobj == so2->u.cmpobj)
 117                     cmp = 0;
 118                 else if (so1->u.cmpobj == NULL)
 119                     cmp = -1;
 120                 else
 121                     cmp = 1;
 122             } else {
 123                 /* We have both the objects, use strcoll */
 124                 cmp = strcoll(so1->u.cmpobj->ptr,so2->u.cmpobj->ptr);
 125             }
 126         } else {
 127             /* Compare elements directly. */
 128             cmp = compareStringObjects(so1->obj,so2->obj);
 129         }
 130     }
 131     return server.sort_desc ? -cmp : cmp;
 132 }
 133
 134 /* The SORT command is the most complex command in Redis. Warning: this code
 135  * is optimized for speed and a bit less for readability */
 136 void sortCommand(redisClient *c) {
 137     list *operations;
 138     unsigned int outputlen = 0;
 139     int desc = 0, alpha = 0;
 140     long limit_start = 0, limit_count = -1, start, end;
 141     int j, dontsort = 0, vectorlen;
 142     int getop = 0; /* GET operation counter */
 143     int int_convertion_error = 0;
 144     robj *sortval, *sortby = NULL, *storekey = NULL;
 145     redisSortObject *vector; /* Resulting vector to sort */
 146
 147     /* Lookup the key to sort. It must be of the right types */
 148     sortval = lookupKeyRead(c->db,c->argv[1]);
 149     if (sortval && sortval->type != REDIS_SET && sortval->type != REDIS_LIST &&
 150         sortval->type != REDIS_ZSET)
 151     {
 152         addReply(c,shared.wrongtypeerr);
 153         return;
 154     }
 155
 156     /* Create a list of operations to perform for every sorted element.
 157      * Operations can be GET/DEL/INCR/DECR */
 158     operations = listCreate();
 159     listSetFreeMethod(operations,zfree);
 160     j = 2;
 161
 162     /* Now we need to protect sortval incrementing its count, in the future
 163      * SORT may have options able to overwrite/delete keys during the sorting
 164      * and the sorted key itself may get destroied */
 165     if (sortval)
 166         incrRefCount(sortval);
 167     else
 168         sortval = createListObject();
 169
 170     /* The SORT command has an SQL-alike syntax, parse it */
 171     while(j < c->argc) {
 172         int leftargs = c->argc-j-1;
 173         if (!strcasecmp(c->argv[j]->ptr,"asc")) {
 174             desc = 0;
 175         } else if (!strcasecmp(c->argv[j]->ptr,"desc")) {
 176             desc = 1;
 177         } else if (!strcasecmp(c->argv[j]->ptr,"alpha")) {
 178             alpha = 1;
 179         } else if (!strcasecmp(c->argv[j]->ptr,"limit") && leftargs >= 2) {
 180             if ((getLongFromObjectOrReply(c, c->argv[j+1], &limit_start, NULL) != REDIS_OK) ||
 181                 (getLongFromObjectOrReply(c, c->argv[j+2], &limit_count, NULL) != REDIS_OK)) return;
 182             j+=2;
 183         } else if (!strcasecmp(c->argv[j]->ptr,"store") && leftargs >= 1) {
 184             storekey = c->argv[j+1];
 185             j++;
 186         } else if (!strcasecmp(c->argv[j]->ptr,"by") && leftargs >= 1) {
 187             sortby = c->argv[j+1];
 188             /* If the BY pattern does not contain '*', i.e. it is constant,
 189              * we don't need to sort nor to lookup the weight keys. */
 190             if (strchr(c->argv[j+1]->ptr,'*') == NULL) dontsort = 1;
 191             j++;
 192         } else if (!strcasecmp(c->argv[j]->ptr,"get") && leftargs >= 1) {
 193             listAddNodeTail(operations,createSortOperation(
 194                 REDIS_SORT_GET,c->argv[j+1]));
 195             getop++;
 196             j++;
 197         } else {
 198             decrRefCount(sortval);
 199             listRelease(operations);
 200             addReply(c,shared.syntaxerr);
 201             return;
 202         }
 203         j++;
 204     }
 205
 206     /* Destructively convert encoded sorted sets for SORT. */
 207     if (sortval->type == REDIS_ZSET)
 208         zsetConvert(sortval, REDIS_ENCODING_SKIPLIST);
 209
 210     /* Load the sorting vector with all the objects to sort */
 211     switch(sortval->type) {
 212     case REDIS_LIST: vectorlen = listTypeLength(sortval); break;
 213     case REDIS_SET: vectorlen =  setTypeSize(sortval); break;
 214     case REDIS_ZSET: vectorlen = dictSize(((zset*)sortval->ptr)->dict); break;
 215     default: vectorlen = 0; redisPanic("Bad SORT type"); /* Avoid GCC warning */
 216     }
 217     vector = zmalloc(sizeof(redisSortObject)*vectorlen);
 218     j = 0;
 219
 220     if (sortval->type == REDIS_LIST) {
 221         listTypeIterator *li = listTypeInitIterator(sortval,0,REDIS_TAIL);
 222         listTypeEntry entry;
 223         while(listTypeNext(li,&entry)) {
 224             vector[j].obj = listTypeGet(&entry);
 225             vector[j].u.score = 0;
 226             vector[j].u.cmpobj = NULL;
 227             j++;
 228         }
 229         listTypeReleaseIterator(li);
 230     } else if (sortval->type == REDIS_SET) {
 231         setTypeIterator *si = setTypeInitIterator(sortval);
 232         robj *ele;
 233         while((ele = setTypeNextObject(si)) != NULL) {
 234             vector[j].obj = ele;
 235             vector[j].u.score = 0;
 236             vector[j].u.cmpobj = NULL;
 237             j++;
 238         }
 239         setTypeReleaseIterator(si);
 240     } else if (sortval->type == REDIS_ZSET) {
 241         dict *set = ((zset*)sortval->ptr)->dict;
 242         dictIterator *di;
 243         dictEntry *setele;
 244         di = dictGetIterator(set);
 245         while((setele = dictNext(di)) != NULL) {
 246             vector[j].obj = dictGetKey(setele);
 247             vector[j].u.score = 0;
 248             vector[j].u.cmpobj = NULL;
 249             j++;
 250         }
 251         dictReleaseIterator(di);
 252     } else {
 253         redisPanic("Unknown type");
 254     }
 255     redisAssertWithInfo(c,sortval,j == vectorlen);
 256
 257     /* Now it's time to load the right scores in the sorting vector */
 258     if (dontsort == 0) {
 259         for (j = 0; j < vectorlen; j++) {
 260             robj *byval;
 261             if (sortby) {
 262                 /* lookup value to sort by */
 263                 byval = lookupKeyByPattern(c->db,sortby,vector[j].obj);
 264                 if (!byval) continue;
 265             } else {
 266                 /* use object itself to sort by */
 267                 byval = vector[j].obj;
 268             }
 269
 270             if (alpha) {
 271                 if (sortby) vector[j].u.cmpobj = getDecodedObject(byval);
 272             } else {
 273                 if (byval->encoding == REDIS_ENCODING_RAW) {
 274                     char *eptr;
 275
 276                     vector[j].u.score = strtod(byval->ptr,&eptr);
 277                     if (eptr[0] != '\0' || errno == ERANGE ||
 278                         isnan(vector[j].u.score))
 279                     {
 280                         int_convertion_error = 1;
 281                     }
 282                 } else if (byval->encoding == REDIS_ENCODING_INT) {
 283                     /* Don't need to decode the object if it's
 284                      * integer-encoded (the only encoding supported) so
 285                      * far. We can just cast it */
 286                     vector[j].u.score = (long)byval->ptr;
 287                 } else {
 288                     redisAssertWithInfo(c,sortval,1 != 1);
 289                 }
 290             }
 291
 292             /* when the object was retrieved using lookupKeyByPattern,
 293              * its refcount needs to be decreased. */
 294             if (sortby) {
 295                 decrRefCount(byval);
 296             }
 297         }
 298     }
 299
 300     /* We are ready to sort the vector... perform a bit of sanity check
 301      * on the LIMIT option too. We'll use a partial version of quicksort. */
 302     start = (limit_start < 0) ? 0 : limit_start;
 303     end = (limit_count < 0) ? vectorlen-1 : start+limit_count-1;
 304     if (start >= vectorlen) {
 305         start = vectorlen-1;
 306         end = vectorlen-2;
 307     }
 308     if (end >= vectorlen) end = vectorlen-1;
 309
 310     server.sort_dontsort = dontsort;
 311     if (dontsort == 0) {
 312         server.sort_desc = desc;
 313         server.sort_alpha = alpha;
 314         server.sort_bypattern = sortby ? 1 : 0;
 315         if (sortby && (start != 0 || end != vectorlen-1))
 316             pqsort(vector,vectorlen,sizeof(redisSortObject),sortCompare, start,end);
 317         else
 318             qsort(vector,vectorlen,sizeof(redisSortObject),sortCompare);
 319     }
 320
 321     /* Send command output to the output buffer, performing the specified
 322      * GET/DEL/INCR/DECR operations if any. */
 323     outputlen = getop ? getop*(end-start+1) : end-start+1;
 324     if (int_convertion_error) {
 325         addReplyError(c,"One or more scores can't be converted into double");
 326     } else if (storekey == NULL) {
 327         /* STORE option not specified, sent the sorting result to client */
 328         addReplyMultiBulkLen(c,outputlen);
 329         for (j = start; j <= end; j++) {
 330             listNode *ln;
 331             listIter li;
 332
 333             if (!getop) addReplyBulk(c,vector[j].obj);
 334             listRewind(operations,&li);
 335             while((ln = listNext(&li))) {
 336                 redisSortOperation *sop = ln->value;
 337                 robj *val = lookupKeyByPattern(c->db,sop->pattern,
 338                     vector[j].obj);
 339
 340                 if (sop->type == REDIS_SORT_GET) {
 341                     if (!val) {
 342                         addReply(c,shared.nullbulk);
 343                     } else {
 344                         addReplyBulk(c,val);
 345                         decrRefCount(val);
 346                     }
 347                 } else {
 348                     /* Always fails */
 349                     redisAssertWithInfo(c,sortval,sop->type == REDIS_SORT_GET);
 350                 }
 351             }
 352         }
 353     } else {
 354         robj *sobj = createZiplistObject();
 355
 356         /* STORE option specified, set the sorting result as a List object */
 357         for (j = start; j <= end; j++) {
 358             listNode *ln;
 359             listIter li;
 360
 361             if (!getop) {
 362                 listTypePush(sobj,vector[j].obj,REDIS_TAIL);
 363             } else {
 364                 listRewind(operations,&li);
 365                 while((ln = listNext(&li))) {
 366                     redisSortOperation *sop = ln->value;
 367                     robj *val = lookupKeyByPattern(c->db,sop->pattern,
 368                         vector[j].obj);
 369
 370                     if (sop->type == REDIS_SORT_GET) {
 371                         if (!val) val = createStringObject("",0);
 372
 373                         /* listTypePush does an incrRefCount, so we should take care
 374                          * care of the incremented refcount caused by either
 375                          * lookupKeyByPattern or createStringObject("",0) */
 376                         listTypePush(sobj,val,REDIS_TAIL);
 377                         decrRefCount(val);
 378                     } else {
 379                         /* Always fails */
 380                         redisAssertWithInfo(c,sortval,sop->type == REDIS_SORT_GET);
 381                     }
 382                 }
 383             }
 384         }
 385         if (outputlen) {
 386             setKey(c->db,storekey,sobj);
 387             server.dirty += outputlen;
 388         } else if (dbDelete(c->db,storekey)) {
 389             signalModifiedKey(c->db,storekey);
 390             server.dirty++;
 391         }
 392         decrRefCount(sobj);
 393         addReplyLongLong(c,outputlen);
 394     }
 395
 396     /* Cleanup */
 397     if (sortval->type == REDIS_LIST || sortval->type == REDIS_SET)
 398         for (j = 0; j < vectorlen; j++)
 399             decrRefCount(vector[j].obj);
 400     decrRefCount(sortval);
 401     listRelease(operations);
 402     for (j = 0; j < vectorlen; j++) {
 403         if (alpha && vector[j].u.cmpobj)
 404             decrRefCount(vector[j].u.cmpobj);
 405     }
 406     zfree(vector);
 407 }
 408
 409