1 /*
  2  * Copyright (c) 2009-2012, Salvatore Sanfilippo <antirez at gmail dot com>
  3  * All rights reserved.
  4  *
  5  * Redistribution and use in source and binary forms, with or without
  6  * modification, are permitted provided that the following conditions are met:
  7  *
  8  *   * Redistributions of source code must retain the above copyright notice,
 
  9  *     this list of conditions and the following disclaimer.
 10  *   * Redistributions in binary form must reproduce the above copyright
 11  *     notice, this list of conditions and the following disclaimer in the
 12  *     documentation and/or other materials provided with the distribution.
 13
 
  *   * Neither the name of Redis nor the names of its contributors may be used
 14  *     to endorse or promote products derived from this software without
 15  *     specific prior written permission.
 16  *
 17  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 18  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 
 19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 20  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 21  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 22  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 23  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 24  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 25  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 26  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 27  * POSSIBILITY OF SUCH DAMAGE.
 28  */
 29 
 30 #include "redis.h"
 31 
 32 /*-----------------------------------------------------------------------------
 33  * Set Commands
 34  *----------------------------------------------------------------------------*/
 35 
 36 void sunionDiffGenericCommand(redisClient *c, robj **setkeys, int setnum, robj *dstkey, int op);
 37 
 38 /* Factory method to return a set that *can* hold "value". When the object has
 39  * an integer-encodable value, an intset will be returned. Otherwise a regular
 40  * hash table. */
 41 robj *setTypeCreate(robj *value) {
 42     if (isObjectRepresentableAsLongLong(value,NULL) == REDIS_OK)
 43         return createIntsetObject();
 44     return createSetObject();
 45 }
 46 
 47 int setTypeAdd(robj *subject, robj *value) {
 48     long long llval;
 49     if (subject->encoding == REDIS_ENCODING_HT) {
 50         if (dictAdd(subject->ptr,value,NULL) == DICT_OK) {
 51             incrRefCount(value);
 52             return 1;
 53         }
 54     } else if (subject->encoding == REDIS_ENCODING_INTSET) {
 55         if (isObjectRepresentableAsLongLong(value,&llval) == REDIS_OK) {
 56             uint8_t success = 0;
 57             subject->ptr = intsetAdd(subject->ptr,llval,&success);
 58             if (success) {
 59                 /* Convert to regular set when the intset contains
 60                  * too many entries. */
 61                 if (intsetLen(subject->ptr) > server.set_max_intset_entries)
 62                     setTypeConvert(subject,REDIS_ENCODING_HT);
 63                 return 1;
 64             }
 65         } else {
 66             /* Failed to get integer from object, convert to regular set. */
 67             setTypeConvert(subject,REDIS_ENCODING_HT);
 68 
 69             /* The set *was* an intset and this value is not integer
 70              * encodable, so dictAdd should always work. */
 71             redisAssertWithInfo(NULL,value,dictAdd(subject->ptr,value,NULL) == DICT_OK);
 72             incrRefCount(value);
 73             return 1;
 74         }
 75     } else {
 76         redisPanic("Unknown set encoding");
 77     }
 78     return 0;
 79 }
 80 
 81 int setTypeRemove(robj *setobj, robj *value) {
 82     long long llval;
 83     if (setobj->encoding == REDIS_ENCODING_HT) {
 84         if (dictDelete(setobj->ptr,value) == DICT_OK) {
 85             if (htNeedsResize(setobj->ptr)) dictResize(setobj->ptr);
 86             return 1;
 87         }
 88     } else if (setobj->encoding == REDIS_ENCODING_INTSET) {
 89         if (isObjectRepresentableAsLongLong(value,&llval) == REDIS_OK) {
 90             int success;
 91             setobj->ptr = intsetRemove(setobj->ptr,llval,&success);
 92             if (success) return 1;
 93         }
 94     } else {
 95         redisPanic("Unknown set encoding");
 96     }
 97     return 0;
 98 }
 99 
100 int setTypeIsMember(robj *subject, robj *value) {
101     long long llval;
102     if (subject->encoding == REDIS_ENCODING_HT) {
103         return dictFind((dict*)subject->ptr,value) != NULL;
104     } else if (subject->encoding == REDIS_ENCODING_INTSET) {
105         if (isObjectRepresentableAsLongLong(value,&llval) == REDIS_OK) {
106             return intsetFind((intset*)subject->ptr,llval);
107         }
108     } else {
109         redisPanic("Unknown set encoding");
110     }
111     return 0;
112 }
113 
114 setTypeIterator *setTypeInitIterator(robj *subject) {
115     setTypeIterator *si = zmalloc(sizeof(setTypeIterator));
116     si->subject = subject;
117     si->encoding = subject->encoding;
118     if (si->encoding == REDIS_ENCODING_HT) {
119         si->di = dictGetIterator(subject->ptr);
120     } else if (si->encoding == REDIS_ENCODING_INTSET) {
121         si->ii = 0;
122     } else {
123         redisPanic("Unknown set encoding");
124     }
125     return si;
126 }
127 
128 void setTypeReleaseIterator(setTypeIterator *si) {
129     if (si->encoding == REDIS_ENCODING_HT)
130         dictReleaseIterator(si->di);
131     zfree(si);
132 }
133 
134 /* Move to the next entry in the set. Returns the object at the current
135  * position.
136  *
137  * Since set elements can be internally be stored as redis objects or
138  * simple arrays of integers, setTypeNext returns the encoding of the
139  * set object you are iterating, and will populate the appropriate pointer
140  * (eobj) or (llobj) accordingly.
141  *
142  * When there are no longer elements -1 is returned.
143  * Returned objects ref count is not incremented, so this function is
144  * copy on write friendly. */
145 int setTypeNext(setTypeIterator *si, robj **objele, int64_t *llele) {
146     if (si->encoding == REDIS_ENCODING_HT) {
147         dictEntry *de = dictNext(si->di);
148         if (de == NULL) return -1;
149         *objele = dictGetKey(de);
150     } else if (si->encoding == REDIS_ENCODING_INTSET) {
151         if (!intsetGet(si->subject->ptr,si->ii++,llele))
152             return -1;
153     }
154     return si->encoding;
155 }
156 
157 /* The not copy on write friendly version but easy to use version
158  * of setTypeNext() is setTypeNextObject(), returning new objects
159  * or incrementing the ref count of returned objects. So if you don't
160  * retain a pointer to this object you should call decrRefCount() against it.
161  *
162  * This function is the way to go for write operations where COW is not
163  * an issue as the result will be anyway of incrementing the ref count. */
164 robj *setTypeNextObject(setTypeIterator *si) {
165     int64_t intele;
166     robj *objele;
167     int encoding;
168 
169     encoding = setTypeNext(si,&objele,&intele);
170     switch(encoding) {
171         case -1:    return NULL;
172         case REDIS_ENCODING_INTSET:
173             return createStringObjectFromLongLong(intele);
174         case REDIS_ENCODING_HT:
175             incrRefCount(objele);
176             return objele;
177         default:
178             redisPanic("Unsupported encoding");
179     }
180     return NULL; /* just to suppress warnings */
181 }
182 
183 /* Return random element from a non empty set.
184  * The returned element can be a int64_t value if the set is encoded
185  * as an "intset" blob of integers, or a redis object if the set
186  * is a regular set.
187  *
188  * The caller provides both pointers to be populated with the right
189  * object. The return value of the function is the object->encoding
190  * field of the object and is used by the caller to check if the
191  * int64_t pointer or the redis object pointer was populated.
192  *
193  * When an object is returned (the set was a real set) the ref count
194  * of the object is not incremented so this function can be considered
195  * copy on write friendly. */
196 int setTypeRandomElement(robj *setobj, robj **objele, int64_t *llele) {
197     if (setobj->encoding == REDIS_ENCODING_HT) {
198         dictEntry *de = dictGetRandomKey(setobj->ptr);
199         *objele = dictGetKey(de);
200     } else if (setobj->encoding == REDIS_ENCODING_INTSET) {
201         *llele = intsetRandom(setobj->ptr);
202     } else {
203         redisPanic("Unknown set encoding");
204     }
205     return setobj->encoding;
206 }
207 
208 unsigned long setTypeSize(robj *subject) {
209     if (subject->encoding == REDIS_ENCODING_HT) {
210         return dictSize((dict*)subject->ptr);
211     } else if (subject->encoding == REDIS_ENCODING_INTSET) {
212         return intsetLen((intset*)subject->ptr);
213     } else {
214         redisPanic("Unknown set encoding");
215     }
216 }
217 
218 /* Convert the set to specified encoding. The resulting dict (when converting
219  * to a hash table) is presized to hold the number of elements in the original
220  * set. */
221 void setTypeConvert(robj *setobj, int enc) {
222     setTypeIterator *si;
223     redisAssertWithInfo(NULL,setobj,setobj->type == REDIS_SET &&
224                              setobj->encoding == REDIS_ENCODING_INTSET);
225 
226     if (enc == REDIS_ENCODING_HT) {
227         int64_t intele;
228         dict *d = dictCreate(&setDictType,NULL);
229         robj *element;
230 
231         /* Presize the dict to avoid rehashing */
232         dictExpand(d,intsetLen(setobj->ptr));
233 
234         /* To add the elements we extract integers and create redis objects */
235         si = setTypeInitIterator(setobj);
236         while (setTypeNext(si,NULL,&intele) != -1) {
237             element = createStringObjectFromLongLong(intele);
238             redisAssertWithInfo(NULL,element,dictAdd(d,element,NULL) == DICT_OK);
239         }
240         setTypeReleaseIterator(si);
241 
242         setobj->encoding = REDIS_ENCODING_HT;
243         zfree(setobj->ptr);
244         setobj->ptr = d;
245     } else {
246         redisPanic("Unsupported set conversion");
247     }
248 }
249 
250 void saddCommand(redisClient *c) {
251     robj *set;
252     int j, added = 0;
253 
254     set = lookupKeyWrite(c->db,c->argv[1]);
255     if (set == NULL) {
256         set = setTypeCreate(c->argv[2]);
257         dbAdd(c->db,c->argv[1],set);
258     } else {
259         if (set->type != REDIS_SET) {
260             addReply(c,shared.wrongtypeerr);
261             return;
262         }
263     }
264 
265     for (j = 2; j < c->argc; j++) {
266         c->argv[j] = tryObjectEncoding(c->argv[j]);
267         if (setTypeAdd(set,c->argv[j])) added++;
268     }
269     if (added) {
270         signalModifiedKey(c->db,c->argv[1]);
271         notifyKeyspaceEvent(REDIS_NOTIFY_SET,"sadd",c->argv[1],c->db->id);
272     }
273     server.dirty += added;
274     addReplyLongLong(c,added);
275 }
276 
277 void sremCommand(redisClient *c) {
278     robj *set;
279     int j, deleted = 0, keyremoved = 0;
280 
281     if ((set = lookupKeyWriteOrReply(c,c->argv[1],shared.czero)) == NULL ||
282         checkType(c,set,REDIS_SET)) return;
283 
284     for (j = 2; j < c->argc; j++) {
285         if (setTypeRemove(set,c->argv[j])) {
286             deleted++;
287             if (setTypeSize(set) == 0) {
288                 dbDelete(c->db,c->argv[1]);
289                 keyremoved = 1;
290                 break;
291             }
292         }
293     }
294     if (deleted) {
295         signalModifiedKey(c->db,c->argv[1]);
296         notifyKeyspaceEvent(REDIS_NOTIFY_SET,"srem",c->argv[1],c->db->id);
297         if (keyremoved)
298             notifyKeyspaceEvent(REDIS_NOTIFY_GENERIC,"del",c->argv[1],
299                                 c->db->id);
300         server.dirty += deleted;
301     }
302     addReplyLongLong(c,deleted);
303 }
304 
305 void smoveCommand(redisClient *c) {
306     robj *srcset, *dstset, *ele;
307     srcset = lookupKeyWrite(c->db,c->argv[1]);
308     dstset = lookupKeyWrite(c->db,c->argv[2]);
309     ele = c->argv[3] = tryObjectEncoding(c->argv[3]);
310 
311     /* If the source key does not exist return 0 */
312     if (srcset == NULL) {
313         addReply(c,shared.czero);
314         return;
315     }
316 
317     /* If the source key has the wrong type, or the destination key
318      * is set and has the wrong type, return with an error. */
319     if (checkType(c,srcset,REDIS_SET) ||
320         (dstset && checkType(c,dstset,REDIS_SET))) return;
321 
322     /* If srcset and dstset are equal, SMOVE is a no-op */
323     if (srcset == dstset) {
324         addReply(c,setTypeIsMember(srcset,ele) ? shared.cone : shared.czero);
325         return;
326     }
327 
328     /* If the element cannot be removed from the src set, return 0. */
329     if (!setTypeRemove(srcset,ele)) {
330         addReply(c,shared.czero);
331         return;
332     }
333     notifyKeyspaceEvent(REDIS_NOTIFY_SET,"srem",c->argv[1],c->db->id);
334 
335     /* Remove the src set from the database when empty */
336     if (setTypeSize(srcset) == 0) {
337         dbDelete(c->db,c->argv[1]);
338         notifyKeyspaceEvent(REDIS_NOTIFY_GENERIC,"del",c->argv[1],c->db->id);
339     }
340     signalModifiedKey(c->db,c->argv[1]);
341     signalModifiedKey(c->db,c->argv[2]);
342     server.dirty++;
343 
344     /* Create the destination set when it doesn't exist */
345     if (!dstset) {
346         dstset = setTypeCreate(ele);
347         dbAdd(c->db,c->argv[2],dstset);
348     }
349 
350     /* An extra key has changed when ele was successfully added to dstset */
351     if (setTypeAdd(dstset,ele)) {
352         server.dirty++;
353         notifyKeyspaceEvent(REDIS_NOTIFY_SET,"sadd",c->argv[2],c->db->id);
354     }
355     addReply(c,shared.cone);
356 }
357 
358 void sismemberCommand(redisClient *c) {
359     robj *set;
360 
361     if ((set = lookupKeyReadOrReply(c,c->argv[1],shared.czero)) == NULL ||
362         checkType(c,set,REDIS_SET)) return;
363 
364     c->argv[2] = tryObjectEncoding(c->argv[2]);
365     if (setTypeIsMember(set,c->argv[2]))
366         addReply(c,shared.cone);
367     else
368         addReply(c,shared.czero);
369 }
370 
371 void scardCommand(redisClient *c) {
372     robj *o;
373 
374     if ((o = lookupKeyReadOrReply(c,c->argv[1],shared.czero)) == NULL ||
375         checkType(c,o,REDIS_SET)) return;
376 
377     addReplyLongLong(c,setTypeSize(o));
378 }
379 
380 void spopCommand(redisClient *c) {
381     robj *set, *ele, *aux;
382     int64_t llele;
383     int encoding;
384 
385     if ((set = lookupKeyWriteOrReply(c,c->argv[1],shared.nullbulk)) == NULL ||
386         checkType(c,set,REDIS_SET)) return;
387 
388     encoding = setTypeRandomElement(set,&ele,&llele);
389     if (encoding == REDIS_ENCODING_INTSET) {
390         ele = createStringObjectFromLongLong(llele);
391         set->ptr = intsetRemove(set->ptr,llele,NULL);
392     } else {
393         incrRefCount(ele);
394         setTypeRemove(set,ele);
395     }
396     notifyKeyspaceEvent(REDIS_NOTIFY_SET,"spop",c->argv[1],c->db->id);
397 
398     /* Replicate/AOF this command as an SREM operation */
399     aux = createStringObject("SREM",4);
400     rewriteClientCommandVector(c,3,aux,c->argv[1],ele);
401     decrRefCount(ele);
402     decrRefCount(aux);
403 
404     addReplyBulk(c,ele);
405     if (setTypeSize(set) == 0) {
406         dbDelete(c->db,c->argv[1]);
407         notifyKeyspaceEvent(REDIS_NOTIFY_GENERIC,"del",c->argv[1],c->db->id);
408     }
409     signalModifiedKey(c->db,c->argv[1]);
410     server.dirty++;
411 }
412 
413 /* handle the "SRANDMEMBER key <count>" variant. The normal version of the
414  * command is handled by the srandmemberCommand() function itself. */
415 
416 /* How many times bigger should be the set compared to the requested size
417  * for us to don't use the "remove elements" strategy? Read later in the
418  * implementation for more info. */
419 #define SRANDMEMBER_SUB_STRATEGY_MUL 3
420 
421 void srandmemberWithCountCommand(redisClient *c) {
422     long l;
423     unsigned long count, size;
424     int uniq = 1;
425     robj *set, *ele;
426     int64_t llele;
427     int encoding;
428 
429     dict *d;
430 
431     if (getLongFromObjectOrReply(c,c->argv[2],&l,NULL) != REDIS_OK) return;
432     if (l >= 0) {
433         count = (unsigned) l;
434     } else {
435         /* A negative count means: return the same elements multiple times
436          * (i.e. don't remove the extracted element after every extraction). */
437         count = -l;
438         uniq = 0;
439     }
440 
441     if ((set = lookupKeyReadOrReply(c,c->argv[1],shared.emptymultibulk))
442         == NULL || checkType(c,set,REDIS_SET)) return;
443     size = setTypeSize(set);
444 
445     /* If count is zero, serve it ASAP to avoid special cases later. */
446     if (count == 0) {
447         addReply(c,shared.emptymultibulk);
448         return;
449     }
450 
451     /* CASE 1: The count was negative, so the extraction method is just:
452      * "return N random elements" sampling the whole set every time.
453      * This case is trivial and can be served without auxiliary data
454      * structures. */
455     if (!uniq) {
456         addReplyMultiBulkLen(c,count);
457         while(count--) {
458             encoding = setTypeRandomElement(set,&ele,&llele);
459             if (encoding == REDIS_ENCODING_INTSET) {
460                 addReplyBulkLongLong(c,llele);
461             } else {
462                 addReplyBulk(c,ele);
463             }
464         }
465         return;
466     }
467 
468     /* CASE 2:
469      * The number of requested elements is greater than the number of
470      * elements inside the set: simply return the whole set. */
471     if (count >= size) {
472         sunionDiffGenericCommand(c,c->argv+1,1,NULL,REDIS_OP_UNION);
473         return;
474     }
475 
476     /* For CASE 3 and CASE 4 we need an auxiliary dictionary. */
477     d = dictCreate(&setDictType,NULL);
478 
479     /* CASE 3:
480      * The number of elements inside the set is not greater than
481      * SRANDMEMBER_SUB_STRATEGY_MUL times the number of requested elements.
482      * In this case we create a set from scratch with all the elements, and
483      * subtract random elements to reach the requested number of elements.
484      *
485      * This is done because if the number of requsted elements is just
486      * a bit less than the number of elements in the set, the natural approach
487      * used into CASE 3 is highly inefficient. */
488     if (count*SRAN