順風車運營研發團隊 閆昌
一. smove
使用方式: smove source destination member
使用描述: 將member元素從source集合移動到destination集合
smove是原子性操作
如果 source 集合不存在或不包含指定的 member 元素，則 SMOVE 命令不執行任何操作，僅返回 0 。否則， member 元素從 source 集合中被移除，並新增到 destination 集合中去
當 destination 集合已經包含 member 元素時， SMOVE 命令只是簡單地將 source 集合中的 member 元素刪除。
當 source 或 destination 不是集合型別時，返回一個錯誤。
原始碼分析:
void smoveCommand(client *c) {
robj *srcset, *dstset, *ele;
srcset = lookupKeyWrite(c->db,c->argv[1]);
dstset = lookupKeyWrite(c->db,c->argv[2]);
ele = c->argv[3];
if (srcset == NULL) {//如果source不存在, 則直接返回
addReply(c,shared.czero);
return;
}
if (checkType(c,srcset,OBJ_SET) ||
(dstset && checkType(c,dstset,OBJ_SET))) return;//source和dest必須全部為set型別, 否則退出
if (srcset == dstset) {//如果source和dest相同, 則直接返回
addReply(c,setTypeIsMember(srcset,ele->ptr) ?
shared.cone : shared.czero);
return;
}
if (!setTypeRemove(srcset,ele->ptr)) {//如果source移除失敗, 則直接返回
addReply(c,shared.czero);
return;
}
notifyKeyspaceEvent(NOTIFY_SET,"srem",c->argv[1],c->db->id);
if (setTypeSize(srcset) == 0) {//如果移除一個元素之後, source已經為空, 則將source刪除
dbDelete(c->db,c->argv[1]);
notifyKeyspaceEvent(NOTIFY_GENERIC,"del",c->argv[1],c->db->id);
}
if (!dstset) {//如果dest為空, 需要先將dest建立出來
dstset = setTypeCreate(ele->ptr);
dbAdd(c->db,c->argv[2],dstset);
}
signalModifiedKey(c->db,c->argv[1]);
signalModifiedKey(c->db,c->argv[2]);
server.dirty++;
if (setTypeAdd(dstset,ele->ptr)) {//將元素新增到dest當中
server.dirty++;
notifyKeyspaceEvent(NOTIFY_SET,"sadd",c->argv[2],c->db->id);
}
addReply(c,shared.cone);
}二. spop
使用方式spop key [count]
從設定值儲存中移除並返回一個或多個隨機key
原始碼分析: count=0的情況
void spopCommand(client *c) {
robj *set, *ele, *aux;
sds sdsele;
int64_t llele;
int encoding;
if (c->argc == 3) {
spopWithCountCommand(c);
return;
} else if (c->argc > 3) {
addReply(c,shared.syntaxerr);
return;
}
if ((set = lookupKeyWriteOrReply(c,c->argv[1],shared.nullbulk)) == NULL ||
checkType(c,set,OBJ_SET)) return;
/**
獲取隨機元素演算法:
1. 如果是hash型別, 獲取hash key
1.1 正在rehash: 則獲取 rehashidx + random()%(ht[0]+ht[1]-rehashidx) //此時key可能在ht[0]也可能在ht[1]中, 但一但在rehashidx之後
1.2 沒有在rehash, 直接: random() % ht[0].length
2. 如果是整數集合型別: rand()%length
*/
encoding = setTypeRandomElement(set,&sdsele,&llele);//獲取隨機的一個元素
if (encoding == OBJ_ENCODING_INTSET) {
ele = createStringObjectFromLongLong(llele);
set->ptr = intsetRemove(set->ptr,llele,NULL);//刪除這個元素
} else {
ele = createStringObject(sdsele,sdslen(sdsele));
setTypeRemove(set,ele->ptr);//刪除這個元素
}
notifyKeyspaceEvent(NOTIFY_SET,"spop",c->argv[1],c->db->id);
aux = createStringObject("SREM",4);
rewriteClientCommandVector(c,3,aux,c->argv[1],ele);
decrRefCount(aux);
addReplyBulk(c,ele);
decrRefCount(ele);
if (setTypeSize(set) == 0) {//如果set已經為空, 則需要刪除set集合
dbDelete(c->db,c->argv[1]);
notifyKeyspaceEvent(NOTIFY_GENERIC,"del",c->argv[1],c->db->id);
}
signalModifiedKey(c->db,c->argv[1]);
server.dirty++;
}count不為0的情況:
當count數量大於set的個數時, 直接返回所有的值, 並刪除set
size-count=remining, 當remining*5>count時, 迴圈count次, 每次隨機彈出一個key
當remining<=5時, 迴圈remining次, 隨機彈出一個值並壓入到一個新的set中, 最後將這個新的set覆蓋原來的set
void spopWithCountCommand(client *c) {
long l;
unsigned long count, size;
robj *set;
if (getLongFromObjectOrReply(c,c->argv[2],&l,NULL) != C_OK) return;
if (l >= 0) {
count = (unsigned long) l;
} else {
addReply(c,shared.outofrangeerr);
return;
}
if ((set = lookupKeyReadOrReply(c,c->argv[1],shared.emptymultibulk))
== NULL || checkType(c,set,OBJ_SET)) return;
if (count == 0) {
addReply(c,shared.emptymultibulk);
return;
}
size = setTypeSize(set);
notifyKeyspaceEvent(NOTIFY_SET,"spop",c->argv[1],c->db->id);
server.dirty += count;
/* CASE 1:
* 當count數量大於set的數量, 則直接將set的所有元素都返回, 並刪除set */
if (count >= size) {
sunionDiffGenericCommand(c,c->argv+1,1,NULL,SET_OP_UNION);//獲取集合中的所有值
dbDelete(c->db,c->argv[1]);
notifyKeyspaceEvent(NOTIFY_GENERIC,"del",c->argv[1],c->db->id);
rewriteClientCommandVector(c,2,shared.del,c->argv[1]);
signalModifiedKey(c->db,c->argv[1]);
server.dirty++;
return;
}
robj *propargv[3];
propargv[0] = createStringObject("SREM",4);
propargv[1] = c->argv[1];
addReplyMultiBulkLen(c,count);
/* Common iteration vars. */
sds sdsele;
robj *objele;
int encoding;
int64_t llele;
unsigned long remaining = size-count; /* Elements left after SPOP. */
/*當刪除count個元素後, 剩下的元素個數*5大於count時, 需要迴圈count次, 每次隨機pop出一個元素*/
if (remaining*SPOP_MOVE_STRATEGY_MUL > count) {
while(count--) {
/* Emit and remove. */
encoding = setTypeRandomElement(set,&sdsele,&llele);//獲取隨機的一個元素
if (encoding == OBJ_ENCODING_INTSET) {
addReplyBulkLongLong(c,llele);
objele = createStringObjectFromLongLong(llele);
set->ptr = intsetRemove(set->ptr,llele,NULL);//刪除隨機出來的元素
} else {
addReplyBulkCBuffer(c,sdsele,sdslen(sdsele));
objele = createStringObject(sdsele,sdslen(sdsele));
setTypeRemove(set,sdsele);
}
/* Replicate/AOF this command as an SREM operation */
propargv[2] = objele;
alsoPropagate(server.sremCommand,c->db->id,propargv,3,
PROPAGATE_AOF|PROPAGATE_REPL);
decrRefCount(objele);
}
} else {
/* 否則迴圈remining次, 將pop出來的元素賦值給新的set, 最後將新的set覆蓋原來的set值 */
robj *newset = NULL;
/* Create a new set with just the remaining elements. */
while(remaining--) {
encoding = setTypeRandomElement(set,&sdsele,&llele);
if (encoding == OBJ_ENCODING_INTSET) {
sdsele = sdsfromlonglong(llele);
} else {
sdsele = sdsdup(sdsele);
}
if (!newset) newset = setTypeCreate(sdsele);
setTypeAdd(newset,sdsele);
setTypeRemove(set,sdsele);
sdsfree(sdsele);
}
incrRefCount(set); /* Protect the old set value. */
dbOverwrite(c->db,c->argv[1],newset);//將舊的set用新的set來覆蓋
/* Tranfer the old set to the client and release it. */
setTypeIterator *si;
si = setTypeInitIterator(set);
while((encoding = setTypeNext(si,&sdsele,&llele)) != -1) {
if (encoding == OBJ_ENCODING_INTSET) {
addReplyBulkLongLong(c,llele);
objele = createStringObjectFromLongLong(llele);
} else {
addReplyBulkCBuffer(c,sdsele,sdslen(sdsele));
objele = createStringObject(sdsele,sdslen(sdsele));
}
/* Replicate/AOF this command as an SREM operation */
propargv[2] = objele;
alsoPropagate(server.sremCommand,c->db->id,propargv,3,
PROPAGATE_AOF|PROPAGATE_REPL);
decrRefCount(objele);
}
setTypeReleaseIterator(si);
decrRefCount(set);
}
decrRefCount(propargv[0]);
preventCommandPropagation(c);
signalModifiedKey(c->db,c->argv[1]);
server.dirty++;
}三. sismember
使用方式: sismember key member
判斷member元素是否是集合key的成員
原始碼分析:
int setTypeIsMember(robj *subject, sds value) {
long long llval;
if (subject->encoding == OBJ_ENCODING_HT) {
return dictFind((dict*)subject->ptr,value) != NULL;//從字典中查詢
} else if (subject->encoding == OBJ_ENCODING_INTSET) {
if (isSdsRepresentableAsLongLong(value,&llval) == C_OK) {
return intsetFind((intset*)subject->ptr,llval);//從整數集合中查詢
}
} else {
serverPanic("Unknown set encoding");
}
return 0;
}因為整數集合中的元素是按從小到大有序排列的, 所以用二分法查詢即可找出
static uint8_t intsetSearch(intset *is, int64_t value, uint32_t *pos) {
int min = 0, max = intrev32ifbe(is->length)-1, mid = -1;
int64_t cur = -1;
if (intrev32ifbe(is->length) == 0) {//如果集合長度為0, 則直接返回
if (pos) *pos = 0;
return 0;
} else {
if (value > _intsetGet(is,intrev32ifbe(is->length)-1)) {//如果value大於整數集合的最大值, 則直接返回
if (pos) *pos = intrev32ifbe(is->length);
return 0;
} else if (value < _intsetGet(is,0)) {//如果value小於整數集合的最小值, 則直接返回
if (pos) *pos = 0;
return 0;
}
}
while(max >= min) {//二分法查詢
mid = ((unsigned int)min + (unsigned int)max) >> 1;
cur = _intsetGet(is,mid);//整數集合中的陣列contents是以char來儲存的值, 但整數集合有int16, int32, int64三種值, 所以要找值時, 需要根據偏移量和長度來獲取正確的值
if (value > cur) {
min = mid+1;
} else if (value < cur) {
max = mid-1;
} else {
break;
}
}
if (value == cur) {
if (pos) *pos = mid;
return 1;
} else {
if (pos) *pos = min;
return 0;
}
}
static int64_t _intsetGet(intset *is, int pos) {
return _intsetGetEncoded(is,pos,intrev32ifbe(is->encoding));
}
static int64_t _intsetGetEncoded(intset *is, int pos, uint8_t enc) {
int64_t v64;
int32_t v32;
int16_t v16;
if (enc == INTSET_ENC_INT64) {
memcpy(&v64,((int64_t*)is->contents)+pos,sizeof(v64));//需要根據偏移量(pos), 和長度來獲取到正確的值
memrev64ifbe(&v64);
return v64;
} else if (enc == INTSET_ENC_INT32) {
memcpy(&v32,((int32_t*)is->contents)+pos,sizeof(v32));
memrev32ifbe(&v32);
return v32;
} else {
memcpy(&v16,((int16_t*)is->contents)+pos,sizeof(v16));
memrev16ifbe(&v16);
return v16;
}
}四. smembers
執行方式: smembers key
返回集合key中的所有成員
不存在的key被視為空集合
smembers底層呼叫sinterGenericCommand函式, 即將所有集合(現在只有一個)取交集
void sinterGenericCommand(client *c, robj **setkeys,
unsigned long setnum, robj *dstkey) {
robj **sets = zmalloc(sizeof(robj*)*setnum);
setTypeIterator *si;
robj *dstset = NULL;
sds elesds;
int64_t intobj;
void *replylen = NULL;
unsigned long j, cardinality = 0;
int encoding;
for (j = 0; j < setnum; j++) {//setnum的值為1, 這個for迴圈只會執行一次
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,OBJ_SET)) {
zfree(sets);
return;
}
sets[j] = setobj;//將集合賦值給新的集合sets[0]
}
qsort(sets,setnum,sizeof(robj*),qsortCompareSetsByCardinality);
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();
}
si = setTypeInitIterator(sets[0]);
while((encoding = setTypeNext(si,&elesds,&intobj)) != -1) {
...
...
/* Only take action when all sets contain the member */
if (j == setnum) {
if (!dstkey) {//while迴圈set, 將每次遍歷取出的值返回給客戶端
if (encoding == OBJ_ENCODING_HT)
addReplyBulkCBuffer(c,elesds,sdslen(elesds));
else
addReplyBulkLongLong(c,intobj);
cardinality++;
} else {
...
}
}
}
setTypeReleaseIterator(si);
if (dstkey) {
......
} else {
setDeferredMultiBulkLength(c,replylen,cardinality);
}
zfree(sets);
}五. srandmember
同spop命令, 同樣可以接受多個count, 它與spop的區別為srandmember不會刪除元素值, spop會刪除元素值
六. srem
使用方式 srem key member [member ….]
移除集合中的一個或多個member元素, 不存在的member元素會被忽略
原始碼分析:
void sremCommand(client *c) {
robj *set;
int j, deleted = 0, keyremoved = 0;
if ((set = lookupKeyWriteOrReply(c,c->argv[1],shared.czero)) == NULL ||
checkType(c,set,OBJ_SET)) return;
for (j = 2; j < c->argc; j++) {//可以刪除多個元素
if (setTypeRemove(set,c->argv[j]->ptr)) {
deleted++;
if (setTypeSize(set) == 0) {
dbDelete(c->db,c->argv[1]);
keyremoved = 1;
break;
}
}
}
if (deleted) {
signalModifiedKey(c->db,c->argv[1]);
notifyKeyspaceEvent(NOTIFY_SET,"srem",c->argv[1],c->db->id);
if (keyremoved)
notifyKeyspaceEvent(NOTIFY_GENERIC,"del",c->argv[1],
c->db->id);
server.dirty += deleted;
}
addReplyLongLong(c,deleted);
}
int setTypeRemove(robj *setobj, sds value) {
long long llval;
if (setobj->encoding == OBJ_ENCODING_HT) {
if (dictDelete(setobj->ptr,value) == DICT_OK) {//從字典中刪除
if (htNeedsResize(setobj->ptr)) dictResize(setobj->ptr);
return 1;
}
} else if (setobj->encoding == OBJ_ENCODING_INTSET) {
if (isSdsRepresentableAsLongLong(value,&llval) == C_OK) {
int success;
setobj->ptr = intsetRemove(setobj->ptr,llval,&success);//從整數集合中刪除
if (success) return 1;
}
} else {
serverPanic("Unknown set encoding");
}
return 0;
}