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redis/src/t_set.c

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/*
* Copyright (c) 2009-2012, Salvatore Sanfilippo <antirez at gmail dot com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of Redis nor the names of its contributors may be used
* to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include "server.h"
/*-----------------------------------------------------------------------------
* Set Commands
*----------------------------------------------------------------------------*/
void sunionDiffGenericCommand(redisClient *c, robj **setkeys, int setnum,
robj *dstkey, int op);
/* Factory method to return a set that *can* hold "value". When the object has
* an integer-encodable value, an intset will be returned. Otherwise a regular
* hash table. */
robj *setTypeCreate(robj *value) {
if (isObjectRepresentableAsLongLong(value,NULL) == REDIS_OK)
return createIntsetObject();
return createSetObject();
}
/* Add the specified value into a set. The function takes care of incrementing
* the reference count of the object if needed in order to retain a copy.
*
* If the value was already member of the set, nothing is done and 0 is
* returned, otherwise the new element is added and 1 is returned. */
int setTypeAdd(robj *subject, robj *value) {
long long llval;
if (subject->encoding == REDIS_ENCODING_HT) {
if (dictAdd(subject->ptr,value,NULL) == DICT_OK) {
incrRefCount(value);
return 1;
}
} else if (subject->encoding == REDIS_ENCODING_INTSET) {
if (isObjectRepresentableAsLongLong(value,&llval) == REDIS_OK) {
uint8_t success = 0;
subject->ptr = intsetAdd(subject->ptr,llval,&success);
if (success) {
/* Convert to regular set when the intset contains
* too many entries. */
if (intsetLen(subject->ptr) > server.set_max_intset_entries)
setTypeConvert(subject,REDIS_ENCODING_HT);
return 1;
}
} else {
/* Failed to get integer from object, convert to regular set. */
setTypeConvert(subject,REDIS_ENCODING_HT);
/* The set *was* an intset and this value is not integer
* encodable, so dictAdd should always work. */
redisAssertWithInfo(NULL,value,
dictAdd(subject->ptr,value,NULL) == DICT_OK);
incrRefCount(value);
return 1;
}
} else {
redisPanic("Unknown set encoding");
}
return 0;
}
int setTypeRemove(robj *setobj, robj *value) {
long long llval;
if (setobj->encoding == REDIS_ENCODING_HT) {
if (dictDelete(setobj->ptr,value) == DICT_OK) {
if (htNeedsResize(setobj->ptr)) dictResize(setobj->ptr);
return 1;
}
} else if (setobj->encoding == REDIS_ENCODING_INTSET) {
if (isObjectRepresentableAsLongLong(value,&llval) == REDIS_OK) {
int success;
setobj->ptr = intsetRemove(setobj->ptr,llval,&success);
if (success) return 1;
}
} else {
redisPanic("Unknown set encoding");
}
return 0;
}
int setTypeIsMember(robj *subject, robj *value) {
long long llval;
if (subject->encoding == REDIS_ENCODING_HT) {
return dictFind((dict*)subject->ptr,value) != NULL;
} else if (subject->encoding == REDIS_ENCODING_INTSET) {
if (isObjectRepresentableAsLongLong(value,&llval) == REDIS_OK) {
return intsetFind((intset*)subject->ptr,llval);
}
} else {
redisPanic("Unknown set encoding");
}
return 0;
}
setTypeIterator *setTypeInitIterator(robj *subject) {
setTypeIterator *si = zmalloc(sizeof(setTypeIterator));
si->subject = subject;
si->encoding = subject->encoding;
if (si->encoding == REDIS_ENCODING_HT) {
si->di = dictGetIterator(subject->ptr);
} else if (si->encoding == REDIS_ENCODING_INTSET) {
si->ii = 0;
} else {
redisPanic("Unknown set encoding");
}
return si;
}
void setTypeReleaseIterator(setTypeIterator *si) {
if (si->encoding == REDIS_ENCODING_HT)
dictReleaseIterator(si->di);
zfree(si);
}
/* Move to the next entry in the set. Returns the object at the current
* position.
*
* Since set elements can be internally be stored as redis objects or
* simple arrays of integers, setTypeNext returns the encoding of the
* set object you are iterating, and will populate the appropriate pointer
* (objele) or (llele) accordingly.
*
* Note that both the objele and llele pointers should be passed and cannot
* be NULL since the function will try to defensively populate the non
* used field with values which are easy to trap if misused.
*
* When there are no longer elements -1 is returned.
* Returned objects ref count is not incremented, so this function is
* copy on write friendly. */
int setTypeNext(setTypeIterator *si, robj **objele, int64_t *llele) {
if (si->encoding == REDIS_ENCODING_HT) {
dictEntry *de = dictNext(si->di);
if (de == NULL) return -1;
*objele = dictGetKey(de);
*llele = -123456789; /* Not needed. Defensive. */
} else if (si->encoding == REDIS_ENCODING_INTSET) {
if (!intsetGet(si->subject->ptr,si->ii++,llele))
return -1;
*objele = NULL; /* Not needed. Defensive. */
} else {
redisPanic("Wrong set encoding in setTypeNext");
}
return si->encoding;
}
/* The not copy on write friendly version but easy to use version
* of setTypeNext() is setTypeNextObject(), returning new objects
* or incrementing the ref count of returned objects. So if you don't
* retain a pointer to this object you should call decrRefCount() against it.
*
* This function is the way to go for write operations where COW is not
* an issue as the result will be anyway of incrementing the ref count. */
robj *setTypeNextObject(setTypeIterator *si) {
int64_t intele;
robj *objele;
int encoding;
encoding = setTypeNext(si,&objele,&intele);
switch(encoding) {
case -1: return NULL;
case REDIS_ENCODING_INTSET:
return createStringObjectFromLongLong(intele);
case REDIS_ENCODING_HT:
incrRefCount(objele);
return objele;
default:
redisPanic("Unsupported encoding");
}
return NULL; /* just to suppress warnings */
}
/* Return random element from a non empty set.
* The returned element can be a int64_t value if the set is encoded
* as an "intset" blob of integers, or a redis object if the set
* is a regular set.
*
* The caller provides both pointers to be populated with the right
* object. The return value of the function is the object->encoding
* field of the object and is used by the caller to check if the
* int64_t pointer or the redis object pointer was populated.
*
* Note that both the objele and llele pointers should be passed and cannot
* be NULL since the function will try to defensively populate the non
* used field with values which are easy to trap if misused.
*
* When an object is returned (the set was a real set) the ref count
* of the object is not incremented so this function can be considered
* copy on write friendly. */
int setTypeRandomElement(robj *setobj, robj **objele, int64_t *llele) {
if (setobj->encoding == REDIS_ENCODING_HT) {
dictEntry *de = dictGetRandomKey(setobj->ptr);
*objele = dictGetKey(de);
*llele = -123456789; /* Not needed. Defensive. */
} else if (setobj->encoding == REDIS_ENCODING_INTSET) {
*llele = intsetRandom(setobj->ptr);
*objele = NULL; /* Not needed. Defensive. */
} else {
redisPanic("Unknown set encoding");
}
return setobj->encoding;
}
unsigned long setTypeSize(robj *subject) {
if (subject->encoding == REDIS_ENCODING_HT) {
return dictSize((dict*)subject->ptr);
} else if (subject->encoding == REDIS_ENCODING_INTSET) {
return intsetLen((intset*)subject->ptr);
} else {
redisPanic("Unknown set encoding");
}
}
/* Convert the set to specified encoding. The resulting dict (when converting
* to a hash table) is presized to hold the number of elements in the original
* set. */
void setTypeConvert(robj *setobj, int enc) {
setTypeIterator *si;
redisAssertWithInfo(NULL,setobj,setobj->type == REDIS_SET &&
setobj->encoding == REDIS_ENCODING_INTSET);
if (enc == REDIS_ENCODING_HT) {
int64_t intele;
dict *d = dictCreate(&setDictType,NULL);
robj *element;
/* Presize the dict to avoid rehashing */
dictExpand(d,intsetLen(setobj->ptr));
/* To add the elements we extract integers and create redis objects */
si = setTypeInitIterator(setobj);
while (setTypeNext(si,&element,&intele) != -1) {
element = createStringObjectFromLongLong(intele);
redisAssertWithInfo(NULL,element,
dictAdd(d,element,NULL) == DICT_OK);
}
setTypeReleaseIterator(si);
setobj->encoding = REDIS_ENCODING_HT;
zfree(setobj->ptr);
setobj->ptr = d;
} else {
redisPanic("Unsupported set conversion");
}
}
void saddCommand(redisClient *c) {
robj *set;
int j, added = 0;
set = lookupKeyWrite(c->db,c->argv[1]);
if (set == NULL) {
set = setTypeCreate(c->argv[2]);
dbAdd(c->db,c->argv[1],set);
} else {
if (set->type != REDIS_SET) {
addReply(c,shared.wrongtypeerr);
return;
}
}
for (j = 2; j < c->argc; j++) {
c->argv[j] = tryObjectEncoding(c->argv[j]);
if (setTypeAdd(set,c->argv[j])) added++;
}
if (added) {
signalModifiedKey(c->db,c->argv[1]);
notifyKeyspaceEvent(REDIS_NOTIFY_SET,"sadd",c->argv[1],c->db->id);
}
server.dirty += added;
addReplyLongLong(c,added);
}
void sremCommand(redisClient *c) {
robj *set;
int j, deleted = 0, keyremoved = 0;
if ((set = lookupKeyWriteOrReply(c,c->argv[1],shared.czero)) == NULL ||
checkType(c,set,REDIS_SET)) return;
for (j = 2; j < c->argc; j++) {
if (setTypeRemove(set,c->argv[j])) {
deleted++;
if (setTypeSize(set) == 0) {
dbDelete(c->db,c->argv[1]);
keyremoved = 1;
break;
}
}
}
if (deleted) {
signalModifiedKey(c->db,c->argv[1]);
notifyKeyspaceEvent(REDIS_NOTIFY_SET,"srem",c->argv[1],c->db->id);
if (keyremoved)
notifyKeyspaceEvent(REDIS_NOTIFY_GENERIC,"del",c->argv[1],
c->db->id);
server.dirty += deleted;
}
addReplyLongLong(c,deleted);
}
void smoveCommand(redisClient *c) {
robj *srcset, *dstset, *ele;
srcset = lookupKeyWrite(c->db,c->argv[1]);
dstset = lookupKeyWrite(c->db,c->argv[2]);
ele = c->argv[3] = tryObjectEncoding(c->argv[3]);
/* If the source key does not exist return 0 */
if (srcset == NULL) {
addReply(c,shared.czero);
return;
}
/* If the source key has the wrong type, or the destination key
* is set and has the wrong type, return with an error. */
if (checkType(c,srcset,REDIS_SET) ||
(dstset && checkType(c,dstset,REDIS_SET))) return;
/* If srcset and dstset are equal, SMOVE is a no-op */
if (srcset == dstset) {
addReply(c,setTypeIsMember(srcset,ele) ? shared.cone : shared.czero);
return;
}
/* If the element cannot be removed from the src set, return 0. */
if (!setTypeRemove(srcset,ele)) {
addReply(c,shared.czero);
return;
}
notifyKeyspaceEvent(REDIS_NOTIFY_SET,"srem",c->argv[1],c->db->id);
/* Remove the src set from the database when empty */
if (setTypeSize(srcset) == 0) {
dbDelete(c->db,c->argv[1]);
notifyKeyspaceEvent(REDIS_NOTIFY_GENERIC,"del",c->argv[1],c->db->id);
}
signalModifiedKey(c->db,c->argv[1]);
signalModifiedKey(c->db,c->argv[2]);
server.dirty++;
/* Create the destination set when it doesn't exist */
if (!dstset) {
dstset = setTypeCreate(ele);
dbAdd(c->db,c->argv[2],dstset);
}
/* An extra key has changed when ele was successfully added to dstset */
if (setTypeAdd(dstset,ele)) {
server.dirty++;
notifyKeyspaceEvent(REDIS_NOTIFY_SET,"sadd",c->argv[2],c->db->id);
}
addReply(c,shared.cone);
}
void sismemberCommand(redisClient *c) {
robj *set;
if ((set = lookupKeyReadOrReply(c,c->argv[1],shared.czero)) == NULL ||
checkType(c,set,REDIS_SET)) return;
c->argv[2] = tryObjectEncoding(c->argv[2]);
if (setTypeIsMember(set,c->argv[2]))
addReply(c,shared.cone);
else
addReply(c,shared.czero);
}
void scardCommand(redisClient *c) {
robj *o;
if ((o = lookupKeyReadOrReply(c,c->argv[1],shared.czero)) == NULL ||
checkType(c,o,REDIS_SET)) return;
addReplyLongLong(c,setTypeSize(o));
}
/* Handle the "SPOP key <count>" variant. The normal version of the
* command is handled by the spopCommand() function itself. */
/* How many times bigger should be the set compared to the remaining size
* for us to use the "create new set" strategy? Read later in the
* implementation for more info. */
#define SPOP_MOVE_STRATEGY_MUL 5
void spopWithCountCommand(redisClient *c) {
long l;
unsigned long count, size;
robj *set;
/* Get the count argument */
if (getLongFromObjectOrReply(c,c->argv[2],&l,NULL) != REDIS_OK) return;
if (l >= 0) {
count = (unsigned) l;
} else {
addReply(c,shared.outofrangeerr);
return;
}
/* Make sure a key with the name inputted exists, and that it's type is
* indeed a set. Otherwise, return nil */
if ((set = lookupKeyReadOrReply(c,c->argv[1],shared.emptymultibulk))
== NULL || checkType(c,set,REDIS_SET)) return;
/* If count is zero, serve an empty multibulk ASAP to avoid special
* cases later. */
if (count == 0) {
addReply(c,shared.emptymultibulk);
return;
}
size = setTypeSize(set);
/* Generate an SPOP keyspace notification */
notifyKeyspaceEvent(REDIS_NOTIFY_SET,"spop",c->argv[1],c->db->id);
server.dirty += count;
/* CASE 1:
* The number of requested elements is greater than or equal to
* the number of elements inside the set: simply return the whole set. */
if (count >= size) {
/* We just return the entire set */
sunionDiffGenericCommand(c,c->argv+1,1,NULL,REDIS_OP_UNION);
/* Delete the set as it is now empty */
dbDelete(c->db,c->argv[1]);
notifyKeyspaceEvent(REDIS_NOTIFY_GENERIC,"del",c->argv[1],c->db->id);
/* Propagate this command as an DEL operation */
rewriteClientCommandVector(c,2,shared.del,c->argv[1]);
signalModifiedKey(c->db,c->argv[1]);
server.dirty++;
return;
}
/* Case 2 and 3 require to replicate SPOP as a set of SERM commands.
* Prepare our replication argument vector. Also send the array length
* which is common to both the code paths. */
robj *propargv[3];
propargv[0] = createStringObject("SREM",4);
propargv[1] = c->argv[1];
addReplyMultiBulkLen(c,count);
/* Common iteration vars. */
robj *objele;
int encoding;
int64_t llele;
unsigned long remaining = size-count; /* Elements left after SPOP. */
/* If we are here, the number of requested elements is less than the
* number of elements inside the set. Also we are sure that count < size.
* Use two different strategies.
*
* CASE 2: The number of elements to return is small compared to the
* set size. We can just extract random elements and return them to
* the set. */
if (remaining*SPOP_MOVE_STRATEGY_MUL > count) {
while(count--) {
encoding = setTypeRandomElement(set,&objele,&llele);
if (encoding == REDIS_ENCODING_INTSET) {
objele = createStringObjectFromLongLong(llele);
} else {
incrRefCount(objele);
}
/* Return the element to the client and remove from the set. */
addReplyBulk(c,objele);
setTypeRemove(set,objele);
/* Replicate/AOF this command as an SREM operation */
propargv[2] = objele;
alsoPropagate(server.sremCommand,c->db->id,propargv,3,
REDIS_PROPAGATE_AOF|REDIS_PROPAGATE_REPL);
decrRefCount(objele);
}
} else {
/* CASE 3: The number of elements to return is very big, approaching
* the size of the set itself. After some time extracting random elements
* from such a set becomes computationally expensive, so we use
* a different strategy, we extract random elements that we don't
* want to return (the elements that will remain part of the set),
* creating a new set as we do this (that will be stored as the original
* set). Then we return the elements left in the original set and
* release it. */
robj *newset = NULL;
/* Create a new set with just the remaining elements. */
while(remaining--) {
encoding = setTypeRandomElement(set,&objele,&llele);
if (encoding == REDIS_ENCODING_INTSET) {
objele = createStringObjectFromLongLong(llele);
} else {
incrRefCount(objele);
}
if (!newset) newset = setTypeCreate(objele);
setTypeAdd(newset,objele);
setTypeRemove(set,objele);
decrRefCount(objele);
}
/* Assign the new set as the key value. */
incrRefCount(set); /* Protect the old set value. */
dbOverwrite(c->db,c->argv[1],newset);
/* Tranfer the old set to the client and release it. */
setTypeIterator *si;
si = setTypeInitIterator(set);
while((encoding = setTypeNext(si,&objele,&llele)) != -1) {
if (encoding == REDIS_ENCODING_INTSET) {
objele = createStringObjectFromLongLong(llele);
} else {
incrRefCount(objele);
}
addReplyBulk(c,objele);
/* Replicate/AOF this command as an SREM operation */
propargv[2] = objele;
alsoPropagate(server.sremCommand,c->db->id,propargv,3,
REDIS_PROPAGATE_AOF|REDIS_PROPAGATE_REPL);
decrRefCount(objele);
}
setTypeReleaseIterator(si);
decrRefCount(set);
}
/* Don't propagate the command itself even if we incremented the
* dirty counter. We don't want to propagate an SPOP command since
* we propagated the command as a set of SREMs operations using
* the alsoPropagate() API. */
decrRefCount(propargv[0]);
preventCommandPropagation(c);
}
void spopCommand(redisClient *c) {
robj *set, *ele, *aux;
int64_t llele;
int encoding;
if (c->argc == 3) {
spopWithCountCommand(c);
return;
} else if (c->argc > 3) {
addReply(c,shared.syntaxerr);
return;
}
/* Make sure a key with the name inputted exists, and that it's type is
* indeed a set */
if ((set = lookupKeyWriteOrReply(c,c->argv[1],shared.nullbulk)) == NULL ||
checkType(c,set,REDIS_SET)) return;
/* Get a random element from the set */
encoding = setTypeRandomElement(set,&ele,&llele);
/* Remove the element from the set */
if (encoding == REDIS_ENCODING_INTSET) {
ele = createStringObjectFromLongLong(llele);
set->ptr = intsetRemove(set->ptr,llele,NULL);
} else {
incrRefCount(ele);
setTypeRemove(set,ele);
}
notifyKeyspaceEvent(REDIS_NOTIFY_SET,"spop",c->argv[1],c->db->id);
/* Replicate/AOF this command as an SREM operation */
aux = createStringObject("SREM",4);
rewriteClientCommandVector(c,3,aux,c->argv[1],ele);
decrRefCount(ele);
decrRefCount(aux);
/* Add the element to the reply */
addReplyBulk(c,ele);
/* Delete the set if it's empty */
if (setTypeSize(set) == 0) {
dbDelete(c->db,c->argv[1]);
notifyKeyspaceEvent(REDIS_NOTIFY_GENERIC,"del",c->argv[1],c->db->id);
}
/* Set has been modified */
signalModifiedKey(c->db,c->argv[1]);
server.dirty++;
}
/* handle the "SRANDMEMBER key <count>" variant. The normal version of the
* command is handled by the srandmemberCommand() function itself. */
/* How many times bigger should be the set compared to the requested size
* for us to don't use the "remove elements" strategy? Read later in the
* implementation for more info. */
#define SRANDMEMBER_SUB_STRATEGY_MUL 3
void srandmemberWithCountCommand(redisClient *c) {
long l;
unsigned long count, size;
int uniq = 1;
robj *set, *ele;
int64_t llele;
int encoding;
dict *d;
if (getLongFromObjectOrReply(c,c->argv[2],&l,NULL) != REDIS_OK) return;
if (l >= 0) {
count = (unsigned) l;
} else {
/* A negative count means: return the same elements multiple times
* (i.e. don't remove the extracted element after every extraction). */
count = -l;
uniq = 0;
}
if ((set = lookupKeyReadOrReply(c,c->argv[1],shared.emptymultibulk))
== NULL || checkType(c,set,REDIS_SET)) return;
size = setTypeSize(set);
/* If count is zero, serve it ASAP to avoid special cases later. */
if (count == 0) {
addReply(c,shared.emptymultibulk);
return;
}
/* CASE 1: The count was negative, so the extraction method is just:
* "return N random elements" sampling the whole set every time.
* This case is trivial and can be served without auxiliary data
* structures. */
if (!uniq) {
addReplyMultiBulkLen(c,count);
while(count--) {
encoding = setTypeRandomElement(set,&ele,&llele);
if (encoding == REDIS_ENCODING_INTSET) {
addReplyBulkLongLong(c,llele);
} else {
addReplyBulk(c,ele);
}
}
return;
}
/* CASE 2:
* The number of requested elements is greater than the number of
* elements inside the set: simply return the whole set. */
if (count >= size) {
sunionDiffGenericCommand(c,c->argv+1,1,NULL,REDIS_OP_UNION);
return;
}
/* For CASE 3 and CASE 4 we need an auxiliary dictionary. */
d = dictCreate(&setDictType,NULL);
/* CASE 3:
* The number of elements inside the set is not greater than
* SRANDMEMBER_SUB_STRATEGY_MUL times the number of requested elements.
* In this case we create a set from scratch with all the elements, and
* subtract random elements to reach the requested number of elements.
*
* This is done because if the number of requsted elements is just
* a bit less than the number of elements in the set, the natural approach
* used into CASE 3 is highly inefficient. */
if (count*SRANDMEMBER_SUB_STRATEGY_MUL > size) {
setTypeIterator *si;
/* Add all the elements into the temporary dictionary. */
si = setTypeInitIterator(set);
while((encoding = setTypeNext(si,&ele,&llele)) != -1) {
int retval = DICT_ERR;
if (encoding == REDIS_ENCODING_INTSET) {
retval = dictAdd(d,createStringObjectFromLongLong(llele),NULL);
} else {
retval = dictAdd(d,dupStringObject(ele),NULL);
}
redisAssert(retval == DICT_OK);
}
setTypeReleaseIterator(si);
redisAssert(dictSize(d) == size);
/* Remove random elements to reach the right count. */
while(size > count) {
dictEntry *de;
de = dictGetRandomKey(d);
dictDelete(d,dictGetKey(de));
size--;
}
}
/* CASE 4: We have a big set compared to the requested number of elements.
* In this case we can simply get random elements from the set and add
* to the temporary set, trying to eventually get enough unique elements
* to reach the specified count. */
else {
unsigned long added = 0;
while(added < count) {
encoding = setTypeRandomElement(set,&ele,&llele);
if (encoding == REDIS_ENCODING_INTSET) {
ele = createStringObjectFromLongLong(llele);
} else {
ele = dupStringObject(ele);
}
/* Try to add the object to the dictionary. If it already exists
* free it, otherwise increment the number of objects we have
* in the result dictionary. */
if (dictAdd(d,ele,NULL) == DICT_OK)
added++;
else
decrRefCount(ele);
}
}
/* CASE 3 & 4: send the result to the user. */
{
dictIterator *di;
dictEntry *de;
addReplyMultiBulkLen(c,count);
di = dictGetIterator(d);
while((de = dictNext(di)) != NULL)
addReplyBulk(c,dictGetKey(de));
dictReleaseIterator(di);
dictRelease(d);
}
}
void srandmemberCommand(redisClient *c) {
robj *set, *ele;
int64_t llele;
int encoding;
if (c->argc == 3) {
srandmemberWithCountCommand(c);
return;
} else if (c->argc > 3) {
addReply(c,shared.syntaxerr);
return;
}
if ((set = lookupKeyReadOrReply(c,c->argv[1],shared.nullbulk)) == NULL ||
checkType(c,set,REDIS_SET)) return;
encoding = setTypeRandomElement(set,&ele,&llele);
if (encoding == REDIS_ENCODING_INTSET) {
addReplyBulkLongLong(c,llele);
} else {
addReplyBulk(c,ele);
}
}
int qsortCompareSetsByCardinality(const void *s1, const void *s2) {
return setTypeSize(*(robj**)s1)-setTypeSize(*(robj**)s2);
}
/* This is used by SDIFF and in this case we can receive NULL that should
* be handled as empty sets. */
int qsortCompareSetsByRevCardinality(const void *s1, const void *s2) {
robj *o1 = *(robj**)s1, *o2 = *(robj**)s2;
return (o2 ? setTypeSize(o2) : 0) - (o1 ? setTypeSize(o1) : 0);
}
void sinterGenericCommand(redisClient *c, robj **setkeys,
unsigned long setnum, robj *dstkey) {
robj **sets = zmalloc(sizeof(robj*)*setnum);
setTypeIterator *si;
robj *eleobj, *dstset = NULL;
int64_t intobj;
void *replylen = NULL;
unsigned long j, cardinality = 0;
int encoding;
for (j = 0; j < setnum; j++) {
robj *setobj = dstkey ?
lookupKeyWrite(c->db,setkeys[j]) :
lookupKeyRead(c->db,setkeys[j]);
if (!setobj) {
zfree(sets);
if (dstkey) {
if (dbDelete(c->db,dstkey)) {
signalModifiedKey(c->db,dstkey);
server.dirty++;
}
addReply(c,shared.czero);
} else {
addReply(c,shared.emptymultibulk);
}
return;
}
if (checkType(c,setobj,REDIS_SET)) {
zfree(sets);
return;
}
sets[j] = setobj;
}
/* Sort sets from the smallest to largest, this will improve our
* algorithm's performance */
qsort(sets,setnum,sizeof(robj*),qsortCompareSetsByCardinality);
/* The first thing we should output is the total number of elements...
* since this is a multi-bulk write, but at this stage we don't know
* the intersection set size, so we use a trick, append an empty object
* to the output list and save the pointer to later modify it with the
* right length */
if (!dstkey) {
replylen = addDeferredMultiBulkLength(c);
} else {
/* If we have a target key where to store the resulting set
* create this key with an empty set inside */
dstset = createIntsetObject();
}
/* Iterate all the elements of the first (smallest) set, and test
* the element against all the other sets, if at least one set does
* not include the element it is discarded */
si = setTypeInitIterator(sets[0]);
while((encoding = setTypeNext(si,&eleobj,&intobj)) != -1) {
for (j = 1; j < setnum; j++) {
if (sets[j] == sets[0]) continue;
if (encoding == REDIS_ENCODING_INTSET) {
/* intset with intset is simple... and fast */
if (sets[j]->encoding == REDIS_ENCODING_INTSET &&
!intsetFind((intset*)sets[j]->ptr,intobj))
{
break;
/* in order to compare an integer with an object we
* have to use the generic function, creating an object
* for this */
} else if (sets[j]->encoding == REDIS_ENCODING_HT) {
eleobj = createStringObjectFromLongLong(intobj);
if (!setTypeIsMember(sets[j],eleobj)) {
decrRefCount(eleobj);
break;
}
decrRefCount(eleobj);
}
} else if (encoding == REDIS_ENCODING_HT) {
/* Optimization... if the source object is integer
* encoded AND the target set is an intset, we can get
* a much faster path. */
if (eleobj->encoding == REDIS_ENCODING_INT &&
sets[j]->encoding == REDIS_ENCODING_INTSET &&
!intsetFind((intset*)sets[j]->ptr,(long)eleobj->ptr))
{
break;
/* else... object to object check is easy as we use the
* type agnostic API here. */
} else if (!setTypeIsMember(sets[j],eleobj)) {
break;
}
}
}
/* Only take action when all sets contain the member */
if (j == setnum) {
if (!dstkey) {
if (encoding == REDIS_ENCODING_HT)
addReplyBulk(c,eleobj);
else
addReplyBulkLongLong(c,intobj);
cardinality++;
} else {
if (encoding == REDIS_ENCODING_INTSET) {
eleobj = createStringObjectFromLongLong(intobj);
setTypeAdd(dstset,eleobj);
decrRefCount(eleobj);
} else {
setTypeAdd(dstset,eleobj);
}
}
}
}
setTypeReleaseIterator(si);
if (dstkey) {
/* Store the resulting set into the target, if the intersection
* is not an empty set. */
int deleted = dbDelete(c->db,dstkey);
if (setTypeSize(dstset) > 0) {
dbAdd(c->db,dstkey,dstset);
addReplyLongLong(c,setTypeSize(dstset));
notifyKeyspaceEvent(REDIS_NOTIFY_SET,"sinterstore",
dstkey,c->db->id);
} else {
decrRefCount(dstset);
addReply(c,shared.czero);
if (deleted)
notifyKeyspaceEvent(REDIS_NOTIFY_GENERIC,"del",
dstkey,c->db->id);
}
signalModifiedKey(c->db,dstkey);
server.dirty++;
} else {
setDeferredMultiBulkLength(c,replylen,cardinality);
}
zfree(sets);
}
void sinterCommand(redisClient *c) {
sinterGenericCommand(c,c->argv+1,c->argc-1,NULL);
}
void sinterstoreCommand(redisClient *c) {
sinterGenericCommand(c,c->argv+2,c->argc-2,c->argv[1]);
}
#define REDIS_OP_UNION 0
#define REDIS_OP_DIFF 1
#define REDIS_OP_INTER 2
void sunionDiffGenericCommand(redisClient *c, robj **setkeys, int setnum,
robj *dstkey, int op) {
robj **sets = zmalloc(sizeof(robj*)*setnum);
setTypeIterator *si;
robj *ele, *dstset = NULL;
int j, cardinality = 0;
int diff_algo = 1;
for (j = 0; j < setnum; j++) {
robj *setobj = dstkey ?
lookupKeyWrite(c->db,setkeys[j]) :
lookupKeyRead(c->db,setkeys[j]);
if (!setobj) {
sets[j] = NULL;
continue;
}
if (checkType(c,setobj,REDIS_SET)) {
zfree(sets);
return;
}
sets[j] = setobj;
}
/* Select what DIFF algorithm to use.
*
* Algorithm 1 is O(N*M) where N is the size of the element first set
* and M the total number of sets.
*
* Algorithm 2 is O(N) where N is the total number of elements in all
* the sets.
*
* We compute what is the best bet with the current input here. */
if (op == REDIS_OP_DIFF && sets[0]) {
long long algo_one_work = 0, algo_two_work = 0;
for (j = 0; j < setnum; j++) {
if (sets[j] == NULL) continue;
algo_one_work += setTypeSize(sets[0]);
algo_two_work += setTypeSize(sets[j]);
}
/* Algorithm 1 has better constant times and performs less operations
* if there are elements in common. Give it some advantage. */
algo_one_work /= 2;
diff_algo = (algo_one_work <= algo_two_work) ? 1 : 2;
if (diff_algo == 1 && setnum > 1) {
/* With algorithm 1 it is better to order the sets to subtract
* by decreasing size, so that we are more likely to find
* duplicated elements ASAP. */
qsort(sets+1,setnum-1,sizeof(robj*),
qsortCompareSetsByRevCardinality);
}
}
/* We need a temp set object to store our union. If the dstkey
* is not NULL (that is, we are inside an SUNIONSTORE operation) then
* this set object will be the resulting object to set into the target key*/
dstset = createIntsetObject();
if (op == REDIS_OP_UNION) {
/* Union is trivial, just add every element of every set to the
* temporary set. */
for (j = 0; j < setnum; j++) {
if (!sets[j]) continue; /* non existing keys are like empty sets */
si = setTypeInitIterator(sets[j]);
while((ele = setTypeNextObject(si)) != NULL) {
if (setTypeAdd(dstset,ele)) cardinality++;
decrRefCount(ele);
}
setTypeReleaseIterator(si);
}
} else if (op == REDIS_OP_DIFF && sets[0] && diff_algo == 1) {
/* DIFF Algorithm 1:
*
* We perform the diff by iterating all the elements of the first set,
* and only adding it to the target set if the element does not exist
* into all the other sets.
*
* This way we perform at max N*M operations, where N is the size of
* the first set, and M the number of sets. */
si = setTypeInitIterator(sets[0]);
while((ele = setTypeNextObject(si)) != NULL) {
for (j = 1; j < setnum; j++) {
if (!sets[j]) continue; /* no key is an empty set. */
if (sets[j] == sets[0]) break; /* same set! */
if (setTypeIsMember(sets[j],ele)) break;
}
if (j == setnum) {
/* There is no other set with this element. Add it. */
setTypeAdd(dstset,ele);
cardinality++;
}
decrRefCount(ele);
}
setTypeReleaseIterator(si);
} else if (op == REDIS_OP_DIFF && sets[0] && diff_algo == 2) {
/* DIFF Algorithm 2:
*
* Add all the elements of the first set to the auxiliary set.
* Then remove all the elements of all the next sets from it.
*
* This is O(N) where N is the sum of all the elements in every
* set. */
for (j = 0; j < setnum; j++) {
if (!sets[j]) continue; /* non existing keys are like empty sets */
si = setTypeInitIterator(sets[j]);
while((ele = setTypeNextObject(si)) != NULL) {
if (j == 0) {
if (setTypeAdd(dstset,ele)) cardinality++;
} else {
if (setTypeRemove(dstset,ele)) cardinality--;
}
decrRefCount(ele);
}
setTypeReleaseIterator(si);
/* Exit if result set is empty as any additional removal
* of elements will have no effect. */
if (cardinality == 0) break;
}
}
/* Output the content of the resulting set, if not in STORE mode */
if (!dstkey) {
addReplyMultiBulkLen(c,cardinality);
si = setTypeInitIterator(dstset);
while((ele = setTypeNextObject(si)) != NULL) {
addReplyBulk(c,ele);
decrRefCount(ele);
}
setTypeReleaseIterator(si);
decrRefCount(dstset);
} else {
/* If we have a target key where to store the resulting set
* create this key with the result set inside */
int deleted = dbDelete(c->db,dstkey);
if (setTypeSize(dstset) > 0) {
dbAdd(c->db,dstkey,dstset);
addReplyLongLong(c,setTypeSize(dstset));
notifyKeyspaceEvent(REDIS_NOTIFY_SET,
op == REDIS_OP_UNION ? "sunionstore" : "sdiffstore",
dstkey,c->db->id);
} else {
decrRefCount(dstset);
addReply(c,shared.czero);
if (deleted)
notifyKeyspaceEvent(REDIS_NOTIFY_GENERIC,"del",
dstkey,c->db->id);
}
signalModifiedKey(c->db,dstkey);
server.dirty++;
}
zfree(sets);
}
void sunionCommand(redisClient *c) {
sunionDiffGenericCommand(c,c->argv+1,c->argc-1,NULL,REDIS_OP_UNION);
}
void sunionstoreCommand(redisClient *c) {
sunionDiffGenericCommand(c,c->argv+2,c->argc-2,c->argv[1],REDIS_OP_UNION);
}
void sdiffCommand(redisClient *c) {
sunionDiffGenericCommand(c,c->argv+1,c->argc-1,NULL,REDIS_OP_DIFF);
}
void sdiffstoreCommand(redisClient *c) {
sunionDiffGenericCommand(c,c->argv+2,c->argc-2,c->argv[1],REDIS_OP_DIFF);
}
void sscanCommand(redisClient *c) {
robj *set;
unsigned long cursor;
if (parseScanCursorOrReply(c,c->argv[2],&cursor) == REDIS_ERR) return;
if ((set = lookupKeyReadOrReply(c,c->argv[1],shared.emptyscan)) == NULL ||
checkType(c,set,REDIS_SET)) return;
scanGenericCommand(c,set,cursor);
}
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