今天讲的这个是用来给redis数据库做性能测试的，说到性能测试，感觉这必然是高大上的操作了，redis性能测试，测的到底是哪方面的性能，如何测试，通过什么指标反映此次测试的性能好坏呢，下面我通过源码给大家做一一解答。

redis做的性能测试时对立面的基本操作做的检测，比如Client客户端执行set，get，lpush等数据操作的性能，可以从他的测试程序可以看出：

 if (test_is_selected("get")) {
            len = redisFormatCommand(&cmd,"GET key:__rand_int__");
            benchmark("GET",cmd,len);
            free(cmd);
        }

        if (test_is_selected("incr")) {
            len = redisFormatCommand(&cmd,"INCR counter:__rand_int__");
            benchmark("INCR",cmd,len);
            free(cmd);
        }

        if (test_is_selected("lpush")) {
            len = redisFormatCommand(&cmd,"LPUSH mylist %s",data);
            benchmark("LPUSH",cmd,len);
            free(cmd);
        }

        if (test_is_selected("lpop")) {
            len = redisFormatCommand(&cmd,"LPOP mylist");
            benchmark("LPOP",cmd,len);
            free(cmd);
        }

/* 对指定的CMD命令做性能测试 */
static void benchmark(char *title, char *cmd, int len) {
    client c;

    config.title = title;
    config.requests_issued = 0;
    config.requests_finished = 0;

    c = createClient(cmd,len,NULL);
    createMissingClients(c);

    config.start = mstime();
    aeMain(config.el);
    //最后通过计算总延时，显示延时报告，体现性能测试的结果
    config.totlatency = mstime()-config.start;

    showLatencyReport();
    freeAllClients();
}

/* 介绍一下struct timeva l结构体
struct timeva l结构体在time.h中的定义为：
struct timeva l
{
  __time_t tv_sec;        // Seconds. 
  __suseconds_t tv_usec;    // Microseconds. (微秒)
}; */

/* config配置信息结构体，static静态变量，使得全局只有一个 */
static struct config {
	//消息事件
    aeEventLoop *el;
    const char *hostip;
    int hostport;
    //据此判断是否是本地测试
    const char *hostsocket;
    //Client总数量
    int numclients;
    int liveclients;
    //请求的总数
    int requests;
    int requests_issued;
    //请求完成的总数
    int requests_finished;
    int keysize;
    int datasize;
    int randomkeys;
    int randomkeys_keyspacelen;
    int keepalive;
    int pipeline;
    long long start;
    long long totlatency;
    long long *latency;
    const char *title;
    //Client列表，这个在下面会经常提起
    list *clients;
    int quiet;
    int csv;
    //判断是否loop循环处理
    int loop;
    int idlemode;
    int dbnum;
    sds dbnumstr;
    char *tests;
    char *auth;
} config;

typedef struct _client {
	//redis上下文
    redisContext *context;
    //此缓冲区将用于后面的读写handler
    sds obuf;
    //rand指针数组
    char **randptr;         /* Pointers to :rand: strings inside the command buf */
    //randptr中指针个数
    size_t randlen;         /* Number of pointers in client->randptr */
    //randptr中没有被使用的指针个数
    size_t randfree;        /* Number of unused pointers in client->randptr */
    unsigned int written;   /* Bytes of 'obuf' already written */
    //请求的发起时间
    long long start;        /* Start time of a request */
    //请求的延时
    long long latency;      /* Request latency */
    //请求的等待个数
    int pending;            /* Number of pending requests (replies to consume) */
    int selectlen;  /* If non-zero, a SELECT of 'selectlen' bytes is currently
                       used as a prefix of the pipline of commands. This gets
                       discarded the first time it's sent. */
} *client;