工作需要对Hiredis进行了简单封装，实现功能：
1、API进行统一，对外只提供一个接口；
2、屏蔽上层应用对连接的细节处理；
3、底层采用队列的方式保持连接池，保存连接会话；
4、重连时采用时间戳进行控制，每隔一定时间(3s)重连一次，，防止频繁重试造成的不必要浪费。
先看一下Hiredis的常用数据结构与API：
//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);
下面直接上封装后的代码：
class KGRedisClient{public:KGRedisClient(string ip, int port, int timeout = 2000);virtual ~KGRedisClient();bool ExecuteCmd(const char *cmd, size_t len, string &response);redisReply* ExecuteCmd(const char *cmd, size_t len);private:int m_timeout;int m_serverPort;string m_setverIp;CCriticalSection m_lock;std::queue<redisContext *> m_clients;time_t m_beginInvalidTime;static const int m_maxReconnectInterval = 3;redisContext* CreateContext();void ReleaseContext(redisContext *ctx, bool active);bool CheckStatus(redisContext *ctx);};KGRedisClient::KGRedisClient(string ip, int port, int timeout){m_timeout = timeout;m_serverPort = port;m_setverIp = ip;m_beginInvalidTime = 0;}KGRedisClient::~KGRedisClient(){CAutoLock autolock(m_lock);while(!m_clients.empty()){redisContext *ctx = m_clients.front();redisFree(ctx);m_clients.pop();}}bool KGRedisClient::ExecuteCmd(const char *cmd, size_t len,string &response){redisReply *reply = ExecuteCmd(cmd, len);if(reply == NULL) return false;boost::shared_ptr<redisReply> autoFree(reply, freeReplyObject);if(reply->type == REDIS_REPLY_INTEGER){response = _IntToStrA(reply->integer);return true;}else if(reply->type == REDIS_REPLY_STRING){response.assign(reply->str, reply->len);return true;}else if(reply->type == REDIS_REPLY_STATUS){response.assign(reply->str, reply->len);return true;}else if(reply->type == REDIS_REPLY_NIL){response = "";return true;}else if(reply->type == REDIS_REPLY_ERROR){response.assign(reply->str, reply->len);return false;}else if(reply->type == REDIS_REPLY_ARRAY){response = "Not Support Array Result!!!";return false;}else{response = "Undefine Reply Type";return false;}}redisReply* KGRedisClient::ExecuteCmd(const char *cmd, size_t len){redisContext *ctx = CreateContext();if(ctx == NULL) return NULL;redisReply *reply = (redisReply*)redisCommand(ctx, "%b", cmd, len);ReleaseContext(ctx, reply != NULL);return reply;}redisContext* KGRedisClient::CreateContext(){{CAutoLock autolock(m_lock);if(!m_clients.empty()){redisContext *ctx = m_clients.front();m_clients.pop();return ctx;}}time_t now = time(NULL);if(now < m_beginInvalidTime + m_maxReconnectInterval) return NULL;struct timeval tv;tv.tv_sec = m_timeout / 1000;tv.tv_usec = (m_timeout % 1000) * 1000;;redisContext *ctx = redisConnectWithTimeout(m_setverIp.c_str(), m_serverPort, tv);if(ctx == NULL || ctx->err != 0){if(ctx != NULL) redisFree(ctx);m_beginInvalidTime = time(NULL);return NULL;}return ctx;}void KGRedisClient::ReleaseContext(redisContext *ctx, bool active){if(ctx == NULL) return;if(!active) {redisFree(ctx); return;}CAutoLock autolock(m_lock);m_clients.push(ctx);}bool KGRedisClient::CheckStatus(redisContext *ctx){redisReply *reply = (redisReply*)redisCommand(ctx, "ping");if(reply == NULL) return false;boost::shared_ptr<redisReply> autoFree(reply, freeReplyObject);if(reply->type != REDIS_REPLY_STATUS) return false;if(strcasecmp(reply->str,"PONG") != 0) return false;return true;}
稍加解释：
成员变量：m_clients用于保存连接池。
成员变量：m_beginInvalidTime、m_maxReconnectInterval 用于控制断掉时的频繁连接。
对外API：ExecuteCmd(const char *cmd, string &response);
始终调整好自己观风景的心态，
