15天玩转redis —— 第五篇 集合对象类型

  这篇我们来看看Redis五大类型中的第四大类型:“集合类型”,集合类型还是蛮有意思的,第一个是因为它算是只使用key的Dictionary简易版,

这样说来的话,它就比Dictionary节省很多内存消耗,第二个是因为它和C#中的HashSet是一个等同类型,废话不多说,先看redis手册,如下:

上面就是redis中的set类型使用到的所有方法,还是老话,常用的方法也就那么四个(CURD)。。。

 

一: 常用方法

1. SAdd

  这个方法毫无疑问,就是向集合里面添加数据,比如下面这样,我往fruits集合里面添加喜爱的水果。

127.0.0.1:6379> sadd fruits apple
(integer) 1
127.0.0.1:6379> sadd fruits banana
(integer) 1
127.0.0.1:6379> smembers fruits
1) "banana"
2) "apple"
127.0.0.1:6379> 

 

上面这个sadd你也看到了,我往集合里面成功添加了两个元素,现在你可能不满足这么简单的添加,你或许想知道set这个集合在redis底层是使用

什么来实现的,你可以用object encoding查看一下便知:

127.0.0.1:6379> object encoding fruits
"hashtable"
127.0.0.1:6379> 

 

看到了吧,是hashtable这个吊毛,现在闭上眼睛都能想到,肯定就是只用key的dictionary啦,对不对,如果你还有疑问的话,我还可以找到底层

代码给你看,好不啦???

 

有没有看到dictAdd方法,而其中的第三个参数正好是Null。。。对应着*val形参,你看牛叉不牛叉。。。然后我再带你看看dictAdd方法的定义。

好了,关于hashtable的实现理论,我在上一篇文章中也已经说过了,这里就不再赘叙了。

 

2. SPOP,SMEMBERS

    既然元素进来了,总不能不出来吧,这里的第一个SPOP:移除并返回集合中的一个随机元素,有一点奇怪的是,这种奇怪的方法其实在我们

C#中的HashSet并没有好办法解决,就比如”这个随机“就有点烦人了,下面这是我能想到的方法。

 

刚才随便插了一句话,下面我们继续SAdd,再SPop出来。

127.0.0.1:6379> sadd fruits pear
(integer) 1
127.0.0.1:6379> sadd fruits grape
(integer) 1
127.0.0.1:6379> sadd fruits chestnut
(integer) 1
127.0.0.1:6379> smembers fruits
1) "grape"
2) "pear"
3) "banana"
4) "apple"
5) "chestnut"
127.0.0.1:6379> spop fruits
"apple"
127.0.0.1:6379> spop fruits
"chestnut"
127.0.0.1:6379> smembers fruits
1) "grape"
2) "pear"
3) "banana"
127.0.0.1:6379> 

这个方法确实还是蛮好的,起码它是原子性操作,如果要我自己实现的话,起码还是要10行左右代码的。

 

3. SREM

    既然说到了CURD,那怎么能少了D呢,它的功能定义就是:移除集合 key 中的一个或多个 member 元素,不存在的 member 元素会被忽略,

下面我随便举个例子,删除fruits中的pear。

127.0.0.1:6379> smembers fruits
1) "grape"
2) "pear"
3) "banana"
127.0.0.1:6379> srem fruits pear
(integer) 1
127.0.0.1:6379> smembers fruits
1) "grape"
2) "banana"
127.0.0.1:6379> 

 

   好了,常用的操作就那么几个,是不是觉得好傻瓜哦。。。傻瓜就对了,方法是简单的,关键你需要了解这个方法底层是如何实现的,这样才能做到

心里有数,就比如Set函数,它的源代码全部都在 “t.set.c” 中。

  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*SRANDMEMBER_SUB_STRATEGY_MUL > size) {
489         setTypeIterator *si;
490 
491         /* Add all the elements into the temporary dictionary. */
492         si = setTypeInitIterator(set);
493         while((encoding = setTypeNext(si,&ele,&llele)) != -1) {
494             int retval = DICT_ERR;
495 
496             if (encoding == REDIS_ENCODING_INTSET) {
497                 retval = dictAdd(d,createStringObjectFromLongLong(llele),NULL);
498             } else {
499                 retval = dictAdd(d,dupStringObject(ele),NULL);
500             }
501             redisAssert(retval == DICT_OK);
502         }
503         setTypeReleaseIterator(si);
504         redisAssert(dictSize(d) == size);
505 
506         /* Remove random elements to reach the right count. */
507         while(size > count) {
508             dictEntry *de;
509 
510             de = dictGetRandomKey(d);
511             dictDelete(d,dictGetKey(de));
512             size--;
513         }
514     }
515 
516     /* CASE 4: We have a big set compared to the requested number of elements.
517      * In this case we can simply get random elements from the set and add
518      * to the temporary set, trying to eventually get enough unique elements
519      * to reach the specified count. */
520     else {
521         unsigned long added = 0;
522 
523         while(added < count) {
524             encoding = setTypeRandomElement(set,&ele,&llele);
525             if (encoding == REDIS_ENCODING_INTSET) {
526                 ele = createStringObjectFromLongLong(llele);
527             } else {
528                 ele = dupStringObject(ele);
529             }
530             /* Try to add the object to the dictionary. If it already exists
531              * free it, otherwise increment the number of objects we have
532              * in the result dictionary. */
533             if (dictAdd(d,ele,NULL) == DICT_OK)
534                 added++;
535             else
536                 decrRefCount(ele);
537         }
538     }
539 
540     /* CASE 3 & 4: send the result to the user. */
541     {
542         dictIterator *di;
543         dictEntry *de;
544 
545         addReplyMultiBulkLen(c,count);
546         di = dictGetIterator(d);
547         while((de = dictNext(di)) != NULL)
548             addReplyBulk(c,dictGetKey(de));
549         dictReleaseIterator(di);
550         dictRelease(d);
551     }
552 }
553 
554 void srandmemberCommand(redisClient *c) {
555     robj *set, *ele;
556     int64_t llele;
557     int encoding;
558 
559     if (c->argc == 3) {
560         srandmemberWithCountCommand(c);
561         return;
562     } else if (c->argc > 3) {
563         addReply(c,shared.syntaxerr);
564         return;
565     }
566 
567     if ((set = lookupKeyReadOrReply(c,c->argv[1],shared.nullbulk)) == NULL ||
568         checkType(c,set,REDIS_SET)) return;
569 
570     encoding = setTypeRandomElement(set,&ele,&llele);
571     if (encoding == REDIS_ENCODING_INTSET) {
572         addReplyBulkLongLong(c,llele);
573     } else {
574         addReplyBulk(c,ele);
575     }
576 }
577 
578 int qsortCompareSetsByCardinality(const void *s1, const void *s2) {
579     return setTypeSize(*(robj**)s1)-setTypeSize(*(robj**)s2);
580 }
581 
582 /* This is used by SDIFF and in this case we can receive NULL that should
583  * be handled as empty sets. */
584 int qsortCompareSetsByRevCardinality(const void *s1, const void *s2) {
585     robj *o1 = *(robj**)s1, *o2 = *(robj**)s2;
586 
587     return  (o2 ? setTypeSize(o2) : 0) - (o1 ? setTypeSize(o1) : 0);
588 }
589 
590 void sinterGenericCommand(redisClient *c, robj **setkeys, unsigned long setnum, robj *dstkey) {
591     robj **sets = zmalloc(sizeof(robj*)*setnum);
592     setTypeIterator *si;
593     robj *eleobj, *dstset = NULL;
594     int64_t intobj;
595     void *replylen = NULL;
596     unsigned long j, cardinality = 0;
597     int encoding;
598 
599     for (j = 0; j < setnum; j++) {
600         robj *setobj = dstkey ?
601             lookupKeyWrite(c->db,setkeys[j]) :
602             lookupKeyRead(c->db,setkeys[j]);
603         if (!setobj) {
604             zfree(sets);
605             if (dstkey) {
606                 if (dbDelete(c->db,dstkey)) {
607                     signalModifiedKey(c->db,dstkey);
608                     server.dirty++;
609                 }
610                 addReply(c,shared.czero);
611             } else {
612                 addReply(c,shared.emptymultibulk);
613             }
614             return;
615         }
616         if (checkType(c,setobj,REDIS_SET)) {
617             zfree(sets);
618             return;
619         }
620         sets[j] = setobj;
621     }
622     /* Sort sets from the smallest to largest, this will improve our
623      * algorithm's performance */
624     qsort(sets,setnum,sizeof(robj*),qsortCompareSetsByCardinality);
625 
626     /* The first thing we should output is the total number of elements...
627      * since this is a multi-bulk write, but at this stage we don't know
628      * the intersection set size, so we use a trick, append an empty object
629      * to the output list and save the pointer to later modify it with the
630      * right length */
631     if (!dstkey) {
632         replylen = addDeferredMultiBulkLength(c);
633     } else {
634         /* If we have a target key where to store the resulting set
635          * create this key with an empty set inside */
636         dstset = createIntsetObject();
637     }
638 
639     /* Iterate all the elements of the first (smallest) set, and test
640      * the element against all the other sets, if at least one set does
641      * not include the element it is discarded */
642     si = setTypeInitIterator(sets[0]);
643     while((encoding = setTypeNext(si,&eleobj,&intobj)) != -1) {
644         for (j = 1; j < setnum; j++) {
645             if (sets[j] == sets[0]) continue;
646             if (encoding == REDIS_ENCODING_INTSET) {
647                 /* intset with intset is simple... and fast */
648                 if (sets[j]->encoding == REDIS_ENCODING_INTSET &&
649                     !intsetFind((intset*)sets[j]->ptr,intobj))
650                 {
651                     break;
652                 /* in order to compare an integer with an object we
653                  * have to use the generic function, creating an object
654                  * for this */
655                 } else if (sets[j]->encoding == REDIS_ENCODING_HT) {
656                     eleobj = createStringObjectFromLongLong(intobj);
657                     if (!setTypeIsMember(sets[j],eleobj)) {
658                         decrRefCount(eleobj);
659                         break;
660                     }
661                     decrRefCount(eleobj);
662                 }
663             } else if (encoding == REDIS_ENCODING_HT) {
664                 /* Optimization... if the source object is integer
665                  * encoded AND the target set is an intset, we can get
666                  * a much faster path. */
667                 if (eleobj->encoding == REDIS_ENCODING_INT &&
668                     sets[j]->encoding == REDIS_ENCODING_INTSET &&
669                     !intsetFind((intset*)sets[j]->ptr,(long)eleobj->ptr))
670                 {
671                     break;
672                 /* else... object to object check is easy as we use the
673                  * type agnostic API here. */
674                 } else if (!setTypeIsMember(sets[j],eleobj)) {
675                     break;
676                 }
677             }
678         }
679 
680         /* Only take action when all sets contain the member */
681         if (j == setnum) {
682             if (!dstkey) {
683                 if (encoding == REDIS_ENCODING_HT)
684                     addReplyBulk(c,eleobj);
685                 else
686                     addReplyBulkLongLong(c,intobj);
687                 cardinality++;
688             } else {
689                 if (encoding == REDIS_ENCODING_INTSET) {
690                     eleobj = createStringObjectFromLongLong(intobj);
691                     setTypeAdd(dstset,eleobj);
692                     decrRefCount(eleobj);
693                 } else {
694                     setTypeAdd(dstset,eleobj);
695                 }
696             }
697         }
698     }
699     setTypeReleaseIterator(si);
700 
701     if (dstkey) {
702         /* Store the resulting set into the target, if the intersection
703          * is not an empty set. */
704         int deleted = dbDelete(c->db,dstkey);
705         if (setTypeSize(dstset) > 0) {
706             dbAdd(c->db,dstkey,dstset);
707             addReplyLongLong(c,setTypeSize(dstset));
708             notifyKeyspaceEvent(REDIS_NOTIFY_SET,"sinterstore",
709                 dstkey,c->db->id);
710         } else {
711             decrRefCount(dstset);
712             addReply(c,shared.czero);
713             if (deleted)
714                 notifyKeyspaceEvent(REDIS_NOTIFY_GENERIC,"del",
715                     dstkey,c->db->id);
716         }
717         signalModifiedKey(c->db,dstkey);
718         server.dirty++;
719     } else {
720         setDeferredMultiBulkLength(c,replylen,cardinality);
721     }
722     zfree(sets);
723 }
724 
725 void sinterCommand(redisClient *c) {
726     sinterGenericCommand(c,c->argv+1,c->argc-1,NULL);
727 }
728 
729 void sinterstoreCommand(redisClient *c) {
730     sinterGenericCommand(c,c->argv+2,c->argc-2,c->argv[1]);
731 }
732 
733 #define REDIS_OP_UNION 0
734 #define REDIS_OP_DIFF 1
735 #define REDIS_OP_INTER 2
736 
737 void sunionDiffGenericCommand(redisClient *c, robj **setkeys, int setnum, robj *dstkey, int op) {
738     robj **sets = zmalloc(sizeof(robj*)*setnum);
739     setTypeIterator *si;
740     robj *ele, *dstset = NULL;
741     int j, cardinality = 0;
742     int diff_algo = 1;
743 
744     for (j = 0; j < setnum; j++) {
745         robj *setobj = dstkey ?
746             lookupKeyWrite(c->db,setkeys[j]) :
747             lookupKeyRead(c->db,setkeys[j]);
748         if (!setobj) {
749             sets[j] = NULL;
750             continue;
751         }
752         if (checkType(c,setobj,REDIS_SET)) {
753             zfree(sets);
754             return;
755         }
756         sets[j] = setobj;
757     }
758 
759     /* Select what DIFF algorithm to use.
760      *
761      * Algorithm 1 is O(N*M) where N is the size of the element first set
762      * and M the total number of sets.
763      *
764      * Algorithm 2 is O(N) where N is the total number of elements in all
765      * the sets.
766      *
767      * We compute what is the best bet with the current input here. */
768     if (op == REDIS_OP_DIFF && sets[0]) {
769         long long algo_one_work = 0, algo_two_work = 0;
770 
771         for (j = 0; j < setnum; j++) {
772             if (sets[j] == NULL) continue;
773 
774             algo_one_work += setTypeSize(sets[0]);
775             algo_two_work += setTypeSize(sets[j]);
776         }
777 
778         /* Algorithm 1 has better constant times and performs less operations
779          * if there are elements in common. Give it some advantage. */
780         algo_one_work /= 2;
781         diff_algo = (algo_one_work <= algo_two_work) ? 1 : 2;
782 
783         if (diff_algo == 1 && setnum > 1) {
784             /* With algorithm 1 it is better to order the sets to subtract
785              * by decreasing size, so that we are more likely to find
786              * duplicated elements ASAP. */
787             qsort(sets+1,setnum-1,sizeof(robj*),
788                 qsortCompareSetsByRevCardinality);
789         }
790     }
791 
792     /* We need a temp set object to store our union. If the dstkey
793      * is not NULL (that is, we are inside an SUNIONSTORE operation) then
794      * this set object will be the resulting object to set into the target key*/
795     dstset = createIntsetObject();
796 
797     if (op == REDIS_OP_UNION) {
798         /* Union is trivial, just add every element of every set to the
799          * temporary set. */
800         for (j = 0; j < setnum; j++) {
801             if (!sets[j]) continue; /* non existing keys are like empty sets */
802 
803             si = setTypeInitIterator(sets[j]);
804             while((ele = setTypeNextObject(si)) != NULL) {
805                 if (setTypeAdd(dstset,ele)) cardinality++;
806                 decrRefCount(ele);
807             }
808             setTypeReleaseIterator(si);
809         }
810     } else if (op == REDIS_OP_DIFF && sets[0] && diff_algo == 1) {
811         /* DIFF Algorithm 1:
812          *
813          * We perform the diff by iterating all the elements of the first set,
814          * and only adding it to the target set if the element does not exist
815          * into all the other sets.
816          *
817          * This way we perform at max N*M operations, where N is the size of
818          * the first set, and M the number of sets. */
819         si = setTypeInitIterator(sets[0]);
820         while((ele = setTypeNextObject(si)) != NULL) {
821             for (j = 1; j < setnum; j++) {
822                 if (!sets[j]) continue; /* no key is an empty set. */
823                 if (sets[j] == sets[0]) break; /* same set! */
824                 if (setTypeIsMember(sets[j],ele)) break;
825             }
826             if (j == setnum) {
827                 /* There is no other set with this element. Add it. */
828                 setTypeAdd(dstset,ele);
829                 cardinality++;
830             }
831             decrRefCount(ele);
832         }
833         setTypeReleaseIterator(si);
834     } else if (op == REDIS_OP_DIFF && sets[0] && diff_algo == 2) {
835         /* DIFF Algorithm 2:
836          *
837          * Add all the elements of the first set to the auxiliary set.
838          * Then remove all the elements of all the next sets from it.
839          *
840          * This is O(N) where N is the sum of all the elements in every
841          * set. */
842         for (j = 0; j < setnum; j++) {
843             if (!sets[j]) continue; /* non existing keys are like empty sets */
844 
845             si = setTypeInitIterator(sets[j]);
846             while((ele = setTypeNextObject(si)) != NULL) {
847                 if (j == 0) {
848                     if (setTypeAdd(dstset,ele)) cardinality++;
849                 } else {
850                     if (setTypeRemove(dstset,ele)) cardinality--;
851                 }
852                 decrRefCount(ele);
853             }
854             setTypeReleaseIterator(si);
855 
856             /* Exit if result set is empty as any additional removal
857              * of elements will have no effect. */
858             if (cardinality == 0) break;
859         }
860     }
861 
862     /* Output the content of the resulting set, if not in STORE mode */
863     if (!dstkey) {
864         addReplyMultiBulkLen(c,cardinality);
865         si = setTypeInitIterator(dstset);
866         while((ele = setTypeNextObject(si)) != NULL) {
867             addReplyBulk(c,ele);
868             decrRefCount(ele);
869         }
870         setTypeReleaseIterator(si);
871         decrRefCount(dstset);
872     } else {
873         /* If we have a target key where to store the resulting set
874          * create this key with the result set inside */
875         int deleted = dbDelete(c->db,dstkey);
876         if (setTypeSize(dstset) > 0) {
877             dbAdd(c->db,dstkey,dstset);
878             addReplyLongLong(c,setTypeSize(dstset));
879             notifyKeyspaceEvent(REDIS_NOTIFY_SET,
880                 op == REDIS_OP_UNION ? "sunionstore" : "sdiffstore",
881                 dstkey,c->db->id);
882         } else {
883             decrRefCount(dstset);
884             addReply(c,shared.czero);
885             if (deleted)
886                 notifyKeyspaceEvent(REDIS_NOTIFY_GENERIC,"del",
887                     dstkey,c->db->id);
888         }
889         signalModifiedKey(c->db,dstkey);
890         server.dirty++;
891     }
892     zfree(sets);
893 }
894 
895 void sunionCommand(redisClient *c) {
896     sunionDiffGenericCommand(c,c->argv+1,c->argc-1,NULL,REDIS_OP_UNION);
897 }
898 
899 void sunionstoreCommand(redisClient *c) {
900     sunionDiffGenericCommand(c,c->argv+2,c->argc-2,c->argv[1],REDIS_OP_UNION);
901 }
902 
903 void sdiffCommand(redisClient *c) {
904     sunionDiffGenericCommand(c,c->argv+1,c->argc-1,NULL,REDIS_OP_DIFF);
905 }
906 
907 void sdiffstoreCommand(redisClient *c) {
908     sunionDiffGenericCommand(c,c->argv+2,c->argc-2,c->argv[1],REDIS_OP_DIFF);
909 }
910 
911 void sscanCommand(redisClient *c) {
912     robj *set;
913     unsigned long cursor;
914 
915     if (parseScanCursorOrReply(c,c->argv[2],&cursor) == REDIS_ERR) return;
916     if ((set = lookupKeyReadOrReply(c,c->argv[1],shared.emptyscan)) == NULL ||
917         checkType(c,set,REDIS_SET)) return;
918     scanGenericCommand(c,set,cursor);
919 }
View Code

 

posted @ 2015-11-19 16:52 一线码农 阅读(...) 评论(...) 编辑 收藏