顺风车运营研发团队 张仕华
ZADD
ZADD key [NX|XX] [CH] [INCR]score member [score member …]
将元素及对应分值添加到一个有序集合中
NX:不更新已经存在的key,只增加新元素
XX:只更新已经存在的key,不增加新元素
CH:abbr:changed.不指定时只返回新增的元素个数,指定时返回新增的和更新的元素个数之和
INCR:参考zincrby
//通过第二个参数区分是zadd还是zincrby
void zaddCommand(client *c) {
zaddGenericCommand(c,ZADD_NONE);
}/* This generic command implements both ZADD and ZINCRBY. */
//zadd和zincrby两个命令都是调用这个函数
void zaddGenericCommand(client *c, int flags) {
static char *nanerr = "resulting score is not a number (NaN)";
robj *key = c->argv[1];
robj *zobj;
sds ele;
double score = 0, *scores = NULL;
int j, elements;
int scoreidx = 0;
/* The following vars are used in order to track what the command actually
* did during the execution, to reply to the client and to trigger the
* notification of keyspace change. */
int added = 0; /* Number of new elements added. */
int updated = 0; /* Number of elements with updated score. */
int processed = 0; /* Number of elements processed, may remain zero with
options like XX. */
/* Parse options. At the end 'scoreidx' is set to the argument position
* of the score of the first score-element pair. */
scoreidx = 2;//从第二个参数开始处理.先处理nx,xx,ch,incr参数
while(scoreidx < c->argc) {
char *opt = c->argv[scoreidx]->ptr;
if (!strcasecmp(opt,"nx")) flags |= ZADD_NX;
else if (!strcasecmp(opt,"xx")) flags |= ZADD_XX;
else if (!strcasecmp(opt,"ch")) flags |= ZADD_CH;
else if (!strcasecmp(opt,"incr")) flags |= ZADD_INCR;
else break;
scoreidx++;
}
/* Turn options into simple to check vars. */
//从flag中取出相应的标志赋给独立的变量
int incr = (flags & ZADD_INCR) != 0;
int nx = (flags & ZADD_NX) != 0;
int xx = (flags & ZADD_XX) != 0;
int ch = (flags & ZADD_CH) != 0;
/* After the options, we expect to have an even number of args, since
* we expect any number of score-element pairs. */
//member和score是一一对应的,所以肯定是2的倍数.所以如果不是2的倍数或者根本
//没有member和score,直接返回命令语法错误
elements = c->argc-scoreidx;
if (elements % 2 || !elements) {
addReply(c,shared.syntaxerr);
return;
}
//elements赋值为有多少对<element,score>
elements /= 2; /* Now this holds the number of score-element pairs. */
/* Check for incompatible options. */
//nx和xxflag互斥,二者不能同时出现
if (nx && xx) {
addReplyError(c,
"XX and NX options at the same time are not compatible");
return;
}
//若有incr标志,则只能有一对<element,score>
//为什么不能是多对?
if (incr && elements > 1) {
addReplyError(c,
"INCR option supports a single increment-element pair");
return;
}
/* Start parsing all the scores, we need to emit any syntax error
* before executing additions to the sorted set, as the command should
* either execute fully or nothing at all. */
//依次检查每一个分数值
scores = zmalloc(sizeof(double)*elements);
for (j = 0; j < elements; j++) {
//该函数中会检查score是否是合法的double类型的值
if (getDoubleFromObjectOrReply(c,c->argv[scoreidx+j*2],&scores[j],NULL)
!= C_OK) goto cleanup;
}
/* Lookup the key and create the sorted set if does not exist. */
//根据key查找对应的有序集合的value
zobj = lookupKeyWrite(c->db,key);
//key不存在
if (zobj == NULL) {
//如果设置了xx这个flag,直接返回错误
if (xx) goto reply_to_client; /* No key + XX option: nothing to do. */
//根据redis的配置,如果有序集合设置了不使用ziplist存储或者说第一个插入元素的长度大于
//设置的最大ziplist的元素长度值,则使用跳跃表存储否则使用ziplist
if (server.zset_max_ziplist_entries == 0 ||
server.zset_max_ziplist_value < sdslen(c->argv[scoreidx+1]->ptr))
{
zobj = createZsetObject();
} else {
zobj = createZsetZiplistObject();
}
//把key,zobj插入字典
dbAdd(c->db,key,zobj);
//key存在
} else {
//如果不是有序集合,直接返回错误
if (zobj->type != OBJ_ZSET) {
addReply(c,shared.wrongtypeerr);
goto cleanup;
}
}
//elements是<member,score>对数
for (j = 0; j < elements; j++) {
double newscore;
score = scores[j];
//retflags设置为前文中的flags变量
int retflags = flags;
ele = c->argv[scoreidx+1+j*2]->ptr;
//每次遍历,score是分数,ele是member.调用zsetadd插入zobj
int retval = zsetAdd(zobj, score, ele, &retflags, &newscore);
if (retval == 0) {
addReplyError(c,nanerr);
goto cleanup;
}
//根据retflags,即一个元素是更新还是新加入,还是未做处理(即member存在,并且
//score值与新设置的一致),更新相应的计数变量(这些变量最后会返回给客户端)
if (retflags & ZADD_ADDED) added++;
if (retflags & ZADD_UPDATED) updated++;
if (!(retflags & ZADD_NOP)) processed++;
score = newscore;
}
server.dirty += (added+updated);
//通过命令中的flag,返回给客户端不同的值
reply_to_client:
if (incr) { /* ZINCRBY or INCR option. */
if (processed)
addReplyDouble(c,score);
else
addReply(c,shared.nullbulk);
} else { /* ZADD. */
addReplyLongLong(c,ch ? added+updated : added);
}
//如果有更新或者新加,需要执行相应的watch key的通知及keyspace的通知
cleanup:
zfree(scores);
if (added || updated) {
signalModifiedKey(c->db,key);
notifyKeyspaceEvent(NOTIFY_ZSET,
incr ? "zincr" : "zadd", key, c->db->id);
}
}ZINCRBY
ZINCRBY key increment member
如果key存在,就给相应member的score增加increment
否则直接给key设置分数为increment
//与zadd调用同一个函数,相当于zadd key incr,把incr flag置位
void zincrbyCommand(client *c) {
zaddGenericCommand(c,ZADD_INCR);
}ZCARD
ZCARD key
返回有序集合的元素个数
void zcardCommand(client *c) {
robj *key = c->argv[1];
robj *zobj;
//查找key对应的value
if ((zobj = lookupKeyReadOrReply(c,key,shared.czero)) == NULL ||
checkType(c,zobj,OBJ_ZSET)) return;
//通过zsetLength获取zobj中的元素个数
addReplyLongLong(c,zsetLength(zobj));
}unsigned int zsetLength(const robj *zobj) {
int length = -1;
//如果是ziplist,通过zzlLength函数获取长度
//如果长度字段中的值小于UINT16_MAX，直接返回长度。否则需要遍历获取长度
if (zobj->encoding == OBJ_ENCODING_ZIPLIST) {
length = zzlLength(zobj->ptr);
//如果是skiplist,直接返回zsl->length
} else if (zobj->encoding == OBJ_ENCODING_SKIPLIST) {
length = ((const zset*)zobj->ptr)->zsl->length;
} else {
serverPanic("Unknown sorted set encoding");
}
return length;
}ZCOUNT
ZCOUNT key min max
返回key中score值在min和max之间的元素个数
其中min和max可以加(,如 zcount key (5 (10
加左括号表示不包含。不加表示包含
void zcountCommand(client *c) {
robj *key = c->argv[1];
robj *zobj;
zrangespec range;
int count = 0;
/* Parse the range arguments */
//判定范围.并将最大最小及是否包含写入range结构体中
if (zslParseRange(c->argv[2],c->argv[3],&range) != C_OK) {
addReplyError(c,"min or max is not a float");
return;
}
/* Lookup the sorted set */
if ((zobj = lookupKeyReadOrReply(c, key, shared.czero)) == NULL ||
checkType(c, zobj, OBJ_ZSET)) return;
//判断zobj底层编码是ziplist还是skiplist
if (zobj->encoding == OBJ_ENCODING_ZIPLIST) {
unsigned char *zl = zobj->ptr;
unsigned char *eptr, *sptr;
double score;
//找出第一个在范围之内的元素
/* Use the first element in range as the starting point */
eptr = zzlFirstInRange(zl,&range);
/* No "first" element */
if (eptr == NULL) {
addReply(c, shared.czero);
return;
}
/* First element is in range */
//ziplist中member和score是两个entry,并且member之后保存着score
//整体顺序是按score从小到大排列,score相同时,按member的字典序排列
sptr = ziplistNext(zl,eptr);
//所以此处从第一个元素的下一个entry处获取score
score = zzlGetScore(sptr);
serverAssertWithInfo(c,zobj,zslValueLteMax(score,&range));
/* Iterate over elements in range */
//迭代这个ziplist,如果score满足要求,则count++并且继续迭代,否则跳出
//最后会返回count
while (eptr) {
score = zzlGetScore(sptr);
/* Abort when the node is no longer in range. */
if (!zslValueLteMax(score,&range)) {
break;
} else {
count++;
zzlNext(zl,&eptr,&sptr);
}
}
} else if (zobj->encoding == OBJ_ENCODING_SKIPLIST) {
zset *zs = zobj->ptr;
zskiplist *zsl = zs->zsl;
zskiplistNode *zn;
unsigned long rank;
//如果是跳表,也是先取出第一个元素
/* Find first element in range */
zn = zslFirstInRange(zsl, &range);
/* Use rank of first element, if any, to determine preliminary count */
if (zn != NULL) {
//获取第一个元素的排名
rank = zslGetRank(zsl, zn->score, zn->ele);
count = (zsl->length - (rank - 1));
//如果最大值大于zsl中的最大值,则此count就是要找的个数
/* Find last element in range */
zn = zslLastInRange(zsl, &range);
/* Use rank of last element, if any, to determine the actual count */
if (zn != NULL) {
//如果最大值小于zsl中的最大值，则首先找到最后一个元素的rank
rank = zslGetRank(zsl, zn->score, zn->ele);
//重新计算count,与之前的计算公式合并之后为
//count = (zsl->length-(rankmin-1))-(zsl->length-rankmax))
// = rankmax-rankmin+1
count -= (zsl->length - rank);
}
}
} else {
serverPanic("Unknown sorted set encoding");
}
//返回count
addReplyLongLong(c, count);
}ZRANGEBYSCORE
ZRANGEBYSCORE key min max WITHSCORES
获取有序结合中分值位于 min和max之间的所有元素
withscores:将member 和 score一起返回
limit offset count:从偏移offset开始获取count个元素
min和max可以为 -inf,+inf,分别表示负无穷和正无穷
//入口函数
void zrangebyscoreCommand(client *c) {
genericZrangebyscoreCommand(c,0);
}/* This command implements ZRANGEBYSCORE, ZREVRANGEBYSCORE. */
void genericZrangebyscoreCommand(client *c, int reverse) {
zrangespec range;
robj *key = c->argv[1];
robj *zobj;
long offset = 0, limit = -1;
int withscores = 0;
unsigned long rangelen = 0;
void *replylen = NULL;
int minidx, maxidx;
//该函数同时用于zrangbyscore和zrevrangebyscore
//二者通过函数中的reverse参数标识
//正序时第二个参数是min，第三个参数是max,逆序反之
/* Parse the range arguments. */
if (reverse) {
/* Range is given as [max,min] */
maxidx = 2; minidx = 3;
} else {
/* Range is given as [min,max] */
minidx = 2; maxidx = 3;
}
//将参数解析出来赋值到range变量
if (zslParseRange(c->argv[minidx],c->argv[maxidx],&range) != C_OK) {
addReplyError(c,"min or max is not a float");
return;
}
/* Parse optional extra arguments. Note that ZCOUNT will exactly have
* 4 arguments, so we'll never enter the following code path. */
if (c->argc > 4) {
int remaining = c->argc - 4;
int pos = 4;
//解析withscores和limit参数
while (remaining) {
if (remaining >= 1 && !strcasecmp(c->argv[pos]->ptr,"withscores")) {
pos++; remaining--;
withscores = 1;
} else if (remaining >= 3 && !strcasecmp(c->argv[pos]->ptr,"limit")) {
if ((getLongFromObjectOrReply(c, c->argv[pos+1], &offset, NULL)
!= C_OK) ||
(getLongFromObjectOrReply(c, c->argv[pos+2], &limit, NULL)
!= C_OK))
{
return;
}
pos += 3; remaining -= 3;
} else {
addReply(c,shared.syntaxerr);
return;
}
}
}
/* Ok, lookup the key and get the range */
if ((zobj = lookupKeyReadOrReply(c,key,shared.emptymultibulk)) == NULL ||
checkType(c,zobj,OBJ_ZSET)) return;
//按zset底层编码是ziplist还是skiplist分别处理
if (zobj->encoding == OBJ_ENCODING_ZIPLIST) {
unsigned char *zl = zobj->ptr;
unsigned char *eptr, *sptr;
unsigned char *vstr;
unsigned int vlen;
long long vlong;
double score;
/* If reversed, get the last node in range as starting point. */
//按正序还是逆序分别取最后一个值或者第一个值
if (reverse) {
eptr = zzlLastInRange(zl,&range);
} else {
eptr = zzlFirstInRange(zl,&range);
}
/* No "first" element in the specified interval. */
if (eptr == NULL) {
addReply(c, shared.emptymultibulk);
return;
}
/* Get score pointer for the first element. */
serverAssertWithInfo(c,zobj,eptr != NULL);
sptr = ziplistNext(zl,eptr);
/* We don't know in advance how many matching elements there are in the
* list, so we push this object that will represent the multi-bulk
* length in the output buffer, and will "fix" it later */
replylen = addDeferredMultiBulkLength(c);
/* If there is an offset, just traverse the number of elements without
* checking the score because that is done in the next loop. */
//如果有offset,先偏移相应的元素
//注意此处zzlNext传入了两个指针,会一次偏移一个<member,score>对
//注意此处offset初始值是0,如果没指定则不会进入此处循环
while (eptr && offset--) {
if (reverse) {
zzlPrev(zl,&eptr,&sptr);
} else {
zzlNext(zl,&eptr,&sptr);
}
}
//如果有limit,则进入循环.取limit次.limit的初始值为-1,即使没指定,也会进入循环
//直到eptr为null或者循环中break掉
while (eptr && limit--) {
score = zzlGetScore(sptr);
/* Abort when the node is no longer in range. */
//不在范围之内时break掉
if (reverse) {
if (!zslValueGteMin(score,&range)) break;
} else {
if (!zslValueLteMax(score,&range)) break;
}
/* We know the element exists, so ziplistGet should always succeed */
serverAssertWithInfo(c,zobj,ziplistGet(eptr,&vstr,&vlen,&vlong));
//取出相应的值.可能为str,赋值给vstr,长度为vlen,或者为整型,赋值给vlong
rangelen++;
if (vstr == NULL) {
addReplyBulkLongLong(c,vlong);
} else {
addReplyBulkCBuffer(c,vstr,vlen);
}
//如果设置了withscores标志,则返回分数
if (withscores) {
addReplyDouble(c,score);
}
//开始迭代下一个节点
/* Move to next node */
if (reverse) {
zzlPrev(zl,&eptr,&sptr);
} else {
zzlNext(zl,&eptr,&sptr);
}
}
} else if (zobj->encoding == OBJ_ENCODING_SKIPLIST) {
zset *zs = zobj->ptr;
zskiplist *zsl = zs->zsl;
zskiplistNode *ln;
//同ziplist,先查找起始或最终节点
/* If reversed, get the last node in range as starting point. */
if (reverse) {
ln = zslLastInRange(zsl,&range);
} else {
ln = zslFirstInRange(zsl,&range);
}
/* No "first" element in the specified interval. */
if (ln == NULL) {
addReply(c, shared.emptymultibulk);
return;
}
/* We don't know in advance how many matching elements there are in the
* list, so we push this object that will represent the multi-bulk
* length in the output buffer, and will "fix" it later */
//返回客户端时先返回元素个数,但此处并不知道需要返回多少个元素,所以先占个位置
//replylen是存储len字段的指针
replylen = addDeferredMultiBulkLength(c);
/* If there is an offset, just traverse the number of elements without
* checking the score because that is done in the next loop. */
//处理offset.向前或向后skip
while (ln && offset--) {
if (reverse) {
ln = ln->backward;
} else {
ln = ln->level[0].forward;
}
}
//处理limit
while (ln && limit--) {
/* Abort when the node is no longer in range. */
if (reverse) {
if (!zslValueGteMin(ln->score,&range)) break;
} else {
if (!zslValueLteMax(ln->score,&range)) break;
}
rangelen++;
addReplyBulkCBuffer(c,ln->ele,sdslen(ln->ele));
if (withscores) {
addReplyDouble(c,ln->score);
}
/* Move to next node */
if (reverse) {
ln = ln->backward;
} else {
ln = ln->level[0].forward;
}
}
} else {
serverPanic("Unknown sorted set encoding");
}
//如果有withscores参数,返回给客户端的字符串数量是2倍
if (withscores) {
rangelen *= 2;
}
//将rangelen放入replylen指向的位置,返回给客户端
setDeferredMultiBulkLength(c, replylen, rangelen);
}ZRANK
ZRANK key member
返回有序集合中元素member的rank
以0为起始rank,元素分数从低到高
zrevrank,元素分数从高到低
void zrankGenericCommand(client *c, int reverse) {
robj *key = c->argv[1];
robj *ele = c->argv[2];
robj *zobj;
long rank;
//通过key找出有序集合的value zobj
if ((zobj = lookupKeyReadOrReply(c,key,shared.nullbulk)) == NULL ||
checkType(c,zobj,OBJ_ZSET)) return;
serverAssertWithInfo(c,ele,sdsEncodedObject(ele));
//在zobj中查找ele(第二个参数member)
rank = zsetRank(zobj,ele->ptr,reverse);
if (rank >= 0) {
addReplyLongLong(c,rank);
} else {
addReply(c,shared.nullbulk);
}
}
void zrankCommand(client *c) {
zrankGenericCommand(c, 0);
}long zsetRank(robj *zobj, sds ele, int reverse) {
unsigned long llen;
unsigned long rank;
llen = zsetLength(zobj);
//ziplist从前往后遍历,比较entry中的元素与ele,每次将rank++
if (zobj->encoding == OBJ_ENCODING_ZIPLIST) {
unsigned char *zl = zobj->ptr;
unsigned char *eptr, *sptr;
eptr = ziplistIndex(zl,0);
serverAssert(eptr != NULL);
sptr = ziplistNext(zl,eptr);
serverAssert(sptr != NULL);
rank = 1;
while(eptr != NULL) {
if (ziplistCompare(eptr,(unsigned char*)ele,sdslen(ele)))
break;
rank++;
zzlNext(zl,&eptr,&sptr);
}
if (eptr != NULL) {
//如果是逆序取,直接将llen-rank就是逆向的rank
if (reverse)
return llen-rank;
else
return rank-1;
} else {
return -1;
}
//skiplist通过zslGetRank获取rank,具体过程为跳表查找,将相应路过节点的span相加
} else if (zobj->encoding == OBJ_ENCODING_SKIPLIST) {
zset *zs = zobj->ptr;
zskiplist *zsl = zs->zsl;
dictEntry *de;
double score;
de = dictFind(zs->dict,ele);
if (de != NULL) {
score = *(double*)dictGetVal(de);
rank = zslGetRank(zsl,score,ele);
/* Existing elements always have a rank. */
serverAssert(rank != 0);
//逆向取rank
if (reverse)
return llen-rank;
else
return rank-1;
} else {
return -1;
}
} else {
serverPanic("Unknown sorted set encoding");
}
}ZREM
ZREM key member [member …]
从有序集合中删除相应的member
void zremCommand(client *c) {
robj *key = c->argv[1];
robj *zobj;
int deleted = 0, keyremoved = 0, j;
//根据key找到对应的zobj
if ((zobj = lookupKeyWriteOrReply(c,key,shared.czero)) == NULL ||
checkType(c,zobj,OBJ_ZSET)) return;
//依次删除相应的元素,每次删除之后检查zset是否为空,如果为空,删掉该key,并且break
for (j = 2; j < c->argc; j++) {
if (zsetDel(zobj,c->argv[j]->ptr)) deleted++;
if (zsetLength(zobj) == 0) {
dbDelete(c->db,key);
keyremoved = 1;
break;
}
}
//如果确实有member被删除掉,通知keyspace zrem事件
//如果zset整个都被删除了,通知keyspace del事件
if (deleted) {
notifyKeyspaceEvent(NOTIFY_ZSET,"zrem",key,c->db->id);
if (keyremoved)
notifyKeyspaceEvent(NOTIFY_GENERIC,"del",key,c->db->id);
signalModifiedKey(c->db,key);
server.dirty += deleted;
}
//返回给客户端实际删除的member个数
addReplyLongLong(c,deleted);
}/* Delete the element 'ele' from the sorted set, returning 1 if the element
* existed and was deleted, 0 otherwise (the element was not there). */
int zsetDel(robj *zobj, sds ele) {
if (zobj->encoding == OBJ_ENCODING_ZIPLIST) {
unsigned char *eptr;
//ziplist先找到ele所在位置的指针eptr
if ((eptr = zzlFind(zobj->ptr,ele,NULL)) != NULL) {
//将该元素删除.ziplist删除时会resize,此处将删除之后ziplist的指针复值给zobj->ptr
zobj->ptr = zzlDelete(zobj->ptr,eptr);
return 1;
}
} else if (zobj->encoding == OBJ_ENCODING_SKIPLIST) {
zset *zs = zobj->ptr;
dictEntry *de;
double score;
//skiplist现将zobj->ptr->dict相应的ele删除掉。此处并未真实删除
//而是将ele所在的dictEntry返回
de = dictUnlink(zs->dict,ele);
if (de != NULL) {
/* Get the score in order to delete from the skiplist later. */
//通过dictEntry获取score
score = *(double*)dictGetVal(de);
/* Delete from the hash table and later from the skiplist.
* Note that the order is important: deleting from the skiplist
* actually releases the SDS string representing the element,
* which is shared between the skiplist and the hash table, so
* we need to delete from the skiplist as the final step. */
//此处将dict中的key和value实际free掉
dictFreeUnlinkedEntry(zs->dict,de);
/* Delete from skiplist. */
//从skiplist中删除元素.ele这个sds在hash和skiplist共享.从skiplist中删除时
//会释放此sds,所以必须先删除dict中的元素再删除skiplist中的元素
int retval = zslDelete(zs->zsl,score,ele,NULL);
serverAssert(retval);
//如果hash表中元素使用率小于10%,进行dict的resize
if (htNeedsResize(zs->dict)) dictResize(zs->dict);
return 1;
}
} else {
serverPanic("Unknown sorted set encoding");
}
return 0; /* No such element found. */
}