redis系列-redis的连接

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Redis 是完全开源免费的，遵守BSD协议，先进的key - value持久化产品。它通常被称为数据结构服务器，因为值（value）可以是字符串(String), 哈希(Map), 列表(list), 集合(sets) 和有序集合(sorted sets)等类型。

redis客户端连接比较简单，但日常中redis的使用和维护会有很多地方需要学习。本文只简单介绍下常用函数。

//hiredis/hiredis.h/* Context for a connection to Redis */typedef struct redisContext {    int err; /* Error flags, 0 when there is no error */    char errstr[128]; /* String representation of error when applicable */    int fd;     int flags;    char *obuf; /* Write buffer */    redisReader *reader; /* Protocol reader */} redisContext;/* This is the reply object returned by redisCommand() */#define REDIS_REPLY_STRING 1#define REDIS_REPLY_ARRAY 2#define REDIS_REPLY_INTEGER 3#define REDIS_REPLY_NIL 4#define REDIS_REPLY_STATUS 5#define REDIS_REPLY_ERROR 6typedef struct redisReply {    int type; /* REDIS_REPLY_* */    long long integer; /* The integer when type is REDIS_REPLY_INTEGER */    int len; /* Length of string */    char *str; /* Used for both REDIS_REPLY_ERROR and REDIS_REPLY_STRING */    size_t elements; /* number of elements, for REDIS_REPLY_ARRAY */    struct redisReply **element; /* elements vector for REDIS_REPLY_ARRAY */} redisReply;redisContext *redisConnectWithTimeout(const char *ip, int port, struct timeval tv);void redisFree(redisContext *c);//Issue a command to Redis, NULL if error, otherwise replyvoid *redisCommand(redisContext *c, const char *format, ...);/* Function to free the reply objects hiredis returns by default. */void freeReplyObject(void *reply);

应用实例：

#include "hiredis/hiredis.h"  redisContext* context = NULL;  redisReply* reply = NULL;  int retry = 0;  while (retry < 5)   {    reply != NULL ? freeReplyObject(reply):;    context != NULL ? redisFree(context):;    context = redisConnect("127.0.0.1", 8600);    if (NULL == context || context->err != 0)    {      cout << "connect err" << endl;      continue;    }    redisReply* reply = (redisReply*)redisCommand(context, "%s", "set name John");    if (NULL == reply || reply == REDIS_REPLY_ERROR)    {     cout << "exe command fail" << endl;     continue;    }    cout << "ok" << endl;    }  reply != NULL ? freeReplyObject(reply):;  context != NULL ? redisFree(context):;

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