mysql的udf编程之非阻塞超时重传

MySQL的UDF(User Defined Function)类似于一种API, 用户根据一定的规范用C/C++(或采用C调用规范的语言)编写一组函数(UDF)，然后编译成动态链接库，通过DROP FUNCTION语句来加载和卸载UDF。UDF被加载后可以像调用MySQL的内置函数一样来调用它，并且服务器在启动时会自动加载原来存在的UDF。

my_bool http_post_init(UDF_INIT *initid, UDF_ARGS *args, char *message);
void http_post_deinit(UDF_INIT *initid);
longlong http_post(UDF_INIT *initid, UDF_ARGS *args, char *is_null,char *error);
/*************************************************************************
** Example of init function
** Arguments:
** initid                        Points to a structure that the init function should fill.
**            char *ptr;            A pointer that the function can use.
** message                        Error message
**RETURN                        This function should return 1 if something goes wrong. In this case
**************************************************************************/
my_bool http_post_init(UDF_INIT *initid, UDF_ARGS *args, char *message)
{
if (args->arg_count < 3 )
{
    strcpy(message,"Wrong arguments to http_post; ");
    return 1;
}

if(args->arg_count == 4 && args->args[3]!=NULL)
{
      int flexibleLength = strlen(args->args[3]);
      if(flexibleLength > 160000)
      {
          int allocLength = 200 + flexibleLength;
          if (!(initid->ptr=(char*) malloc(allocLength) ) )
          {
                strcpy(message,"Couldn't allocate memory in http_post_init");
                return 1;
          }
        return 0;
      }
      else
      {
          initid->ptr=NULL;
    }

}
   return 0;

}

/****************************************************************************
** Deinit function. This should all resources allocated by
** this function.
** Arguments:
** initid    Return value from xxxx_init
****************************************************************************/
void http_post_deinit(UDF_INIT *initid)
{
     if (initid!=NULL && initid->ptr!=NULL)
          {
              free(initid->ptr);
              initid->ptr = NULL;
          }

}

/***************************************************************************
** UDF string function.
** Arguments:
** initid    Structure filled by xxx_init
** args        The same structure as to xxx_init. This structure
** This function should return a pointer to the result string.
** Normally this is 'result' but may also be an alloced string.
***************************************************************************/
longlong http_post(    UDF_INIT *initid, UDF_ARGS *args,
                char *is_null __attribute__((unused)),
                char *error __attribute__((unused)))
{
    int sockfd=0;
    int numbytes=0;
    int flags=0;
    int cycletimes=0;
    char* sendBuffer=NULL;

    fd_set wset;
    struct timeval tval;
    tval.tv_sec = 0;
    tval.tv_usec = 300000;

    if(initid->ptr == NULL)
    {
        char sendArray[160000] = "\0";
        sendBuffer=sendArray;
    }
    else
    {
        sendBuffer = initid->ptr;
    }

    struct sockaddr_in serv_addr;
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(atoi(args->args[1]));
    serv_addr.sin_addr.s_addr = inet_addr(args->args[0]);
    bzero(&(serv_addr.sin_zero),8);

    if(args->arg_count == 4 && (args->args[3]!=NULL) )
    {
        int argsNum = strlen(args->args[3]);
        sprintf(sendBuffer,"POST /?%s HTTP/1.1\r\nContent-Length:%d\r\n\r\n%s",args->args[2],argsNum,args->args[3]);
    }
    else
    {
        sprintf(sendBuffer,"POST /?%s HTTP/1.1\r\n",args->args[2]);
    }

    if((sockfd = socket(AF_INET,SOCK_STREAM,0)) == -1)
    {
        close(sockfd);
        return 2;
    }
    flags = fcntl(sockfd,F_GETFL,0);
    fcntl(sockfd,F_SETFL,flags|O_NONBLOCK);//设置为非阻塞