擴展redis cluster addslots 命令

眾所周知，redis集群集群模式下必須將16384個指派完，也就是16384個槽點都在處理時，集群才處于上線上線狀態，在指派槽時用的命令是這樣的 “cluster addslots 1 2 3” 這樣，這里有個不好的地方就是每次添加只能一個槽點一個槽點這樣添加，著實不方便，我想擴展一下redis的這個命令,令他支持""cluster addslots {1…5000} "這樣的語法
我們先看一下redis中 處理“ cluster addslots”命令的相關的代碼,在 cluster.c的clusterCommand方法中,
具體代碼如下(為了便于閱讀我會添加一些中文注釋以便于讀者理解):

else if ((!strcasecmp(c->argv[1]->ptr,"addslots") ||
               !strcasecmp(c->argv[1]->ptr,"delslots")) && c->argc >= 3)
    {	//如果是"cluster addslots或者 cluster "delslots命令
        /* CLUSTER ADDSLOTS <slot> [slot] ... */
        /* CLUSTER DELSLOTS <slot> [slot] ... */
        int j, slot;
        unsigned char *slots = zmalloc(CLUSTER_SLOTS);	//一個陣列，記錄所有要添加或者洗掉的槽 slots[519] == 1 代表 519槽位置要洗掉或者添加 
        int del = !strcasecmp(c->argv[1]->ptr,"delslots"); //是否是洗掉命令

        memset(slots,0,CLUSTER_SLOTS);	//常規操作
        /* Check that all the arguments are parseable and that all the
         * slots are not already busy. */
         /*遍歷引數串列 比如cluster addslots 1 2 3 4就是遍歷 1 2 3 4 */
        for (j = 2; j < c->argc; j++) {
            if ((slot = getSlotOrReply(c,c->argv[j])) == -1) {
                zfree(slots);
                return;
            }
            if (del && server.cluster->slots[slot] == NULL) {
                addReplyErrorFormat(c,"Slot %d is already unassigned", slot);
                zfree(slots);
                return;
            } else if (!del && server.cluster->slots[slot]) {
                addReplyErrorFormat(c,"Slot %d is already busy", slot);
                zfree(slots);
                return;
            }
            if (slots[slot]++ == 1) {
                addReplyErrorFormat(c,"Slot %d specified multiple times",
                    (int)slot);
                zfree(slots);
                return;
            }
        }
        //處理所有輸入 slot
        for (j = 0; j < CLUSTER_SLOTS; j++) {
            if (slots[j]) {
                int retval;

                /* If this slot was set as importing we can clear this
                 * state as now we are the real owner of the slot. */
                if (server.cluster->importing_slots_from[j])
                    server.cluster->importing_slots_from[j] = NULL;

                retval = del ? clusterDelSlot(j) :
                               clusterAddSlot(myself,j);
                serverAssertWithInfo(c,NULL,retval == C_OK);
            }
        }
        zfree(slots);
        clusterDoBeforeSleep(CLUSTER_TODO_UPDATE_STATE|CLUSTER_TODO_SAVE_CONFIG);
        addReply(c,shared.ok);
    }

然后改寫：

else if ((!strcasecmp(c->argv[1]->ptr,"addslots") ||
               !strcasecmp(c->argv[1]->ptr,"delslots")) && c->argc >= 3)
    {
        int j;
        int del = !strcasecmp(c->argv[1]->ptr,"delslots");
        for (j = 2; j < c->argc; j++) {
           addOrDelSlots(c,c->argv[j],del);
        }

    } 

void addOrDelSlots(redisClient *c,robj *o,int del){ 
    int j;   
    char *arg = o->ptr;
    // 一個陣列，記錄所有要添加或者洗掉的槽
    unsigned char *slots = zmalloc(REDIS_CLUSTER_SLOTS);
    // 將 slots 陣列的所有值設定為 0
    memset(slots,0,REDIS_CLUSTER_SLOTS);
    if (strstr(arg,"{") == arg && strrchr(arg,'}') == (arg + strlen(arg) - 1))   //是否以"{"開頭"}"結尾 這是區間添加引數如"{0...1000}"
    {
        char *ellipsisIndex; //省略號下標即"..."
        char startNum[6], endNum[6],startNumTemp[6],endNumTemp[6];    //because of slotNums  maximum is "16384"
        int start, end;
        memset(startNum,0,6);
        memset(endNum,0,6);
        memset(startNumTemp,0,6);
        memset(endNumTemp,0,6);

        if( (ellipsisIndex = strstr(arg,"...")) == NULL){  //客戶端格式輸入錯誤
            addReplyErrorFormat(c,"cluster addslots format error %d", ellipsisIndex);
            return;
        }
        memcpy(startNum,arg + 1,ellipsisIndex - arg - 1);  //填充startNum
        memcpy(endNum,ellipsisIndex + 3,strlen(ellipsisIndex + 3) - 1);  //填充endNum
        start = atoi(startNum);
        end = atoi(endNum);
        sprintf(startNumTemp,"%d",start);
        sprintf(endNumTemp,"%d",end);
        if (strcmp(startNum,startNumTemp) || strcmp(endNum,endNumTemp))
        {
           addReplyErrorFormat(c,"cluster addslots format error");
            return;
        }       
        if(start <= -1 || end >= REDIS_CLUSTER_SLOTS || start > end){
            addReplyErrorFormat(c,"cluster addslots out of the");
            return;
        }

        for(;start <= end; start++)
            slots[start] = 1;
    }else{
            int slot;
             // 獲取 slot 數字
            if ( (slot = getSlotOrReply(c,o)) == - 1) {
                zfree(slots);
                return;
            }
            slots[slot] = 1;
    }

     // 處理所有輸入 slot
        for (j = 0; j < REDIS_CLUSTER_SLOTS; j++) {
            if (slots[j]) {
                int retval;
                if (del && server.cluster->slots[j] == NULL) {
                    addReplyErrorFormat(c,"Slot %d is already unassigned", j);
                    zfree(slots);
                    return;
                }else if (!del && server.cluster->slots[j]) {    // 如果這是 addslots 命令，并且槽已經有節點在負責，那么回傳一個錯誤
                    addReplyErrorFormat(c,"Slot %d is already busy", j);
                    zfree(slots);
                    return;
                }

                /* If this slot was set as importing we can clear this 
                 * state as now we are the real owner of the slot. */
                // 如果指定 slot 之前的狀態為載入狀態，那么現在可以清除這一狀態
                // 因為當前節點現在已經是 slot 的負責人了
                if (server.cluster->importing_slots_from[j])
                    server.cluster->importing_slots_from[j] = NULL;
                
                 // 添加或者洗掉指定 slot
                retval = del ? clusterDelSlot(j) :
                               clusterAddSlot(myself,j);
                redisAssertWithInfo(c,NULL,retval == REDIS_OK);
            }
        }
    
        zfree(slots);
        clusterDoBeforeSleep(CLUSTER_TODO_UPDATE_STATE|CLUSTER_TODO_SAVE_CONFIG);
        addReply(c,shared.ok);
}

這樣就可以支持范圍添加了像這樣:cluster addslots {0…100}了，這段代碼沒有太大的把握保證沒有bug(保不準可能各種出現段錯誤),我只用過一些測驗案例進行測驗過，貌似還行，這段代碼質量和風格其實不怎么樣，可能以后我會改寫優化這段代碼，或許吧，
之后的時間里我會寫一些關于redis,JDK，和一些開源框架的文章,全都是原始碼級別的,從原始碼層面搞懂原理，從原始碼中學習資料結構,設計模式，演算法，
不定期的佛性的更新，不過之后的文章中我肯定會用心寫，不會像這篇文章一樣任性，“行云流水”
~~
我曾踏月而來,只因你在山中