客户端-服务器餐厅模拟

Question

我正在使用 C 中的 select() 制作一个模拟快餐或其他任何东西的客户端服务器。

我有客户随机点 1-5 种“食物”。服务器每 30 秒决定一次。所有客户最喜欢的食物是什么？他为那些客户提供服务，他们关闭连接，其余的，向他们发送消息等待。未服务的客户端再尝试2次，否则他们离开。

我的问题是，如何让服务器每 30 秒检查一次。他们的命令是什么？

我尝试制作一个数组，但我不知道如何让服务器每 30 秒连续“检查”一次。然后将数组设置为0。

伪代码如下:

**client**

patience=0;served=0;
do
{send random 1-5
receieve message. if 1->served=1; if 0, patience++;
}while patience !=3 and served!=1;

if served==1 send -1
else send -2
close connection

**Server**
while(1)
{
serves clients in a concurent manner
select
adds client in socket list
serves client


waits message
if 1-5 adds in vector
//here I don't know how to make it wait for 30 sec.
//If I put sleep(30), it's going to sleep for each client every time. I want it to permanently check every 30 sec and send messages to clients.
send respones(0 or 1, depending on if the max order is the same as the client's)

if -1, thanks for the food
if -2, going somewhere else

close client connection
}

Answer 1

您可能想在循环中尝试 sleep() 函数，它将做的是暂停您的程序那么长的时间，然后执行后面的语句。

sleep(30);

我想这就是你想要的。看看here了解更多关于 sleep 的信息。

你的代码应该是这样的:

for(i=0; i<=100; i++)//Checks 100 times
{
    sleep(30);
    checkserverforupdate();

}

更新代码:

while(1){//runs infinite times
    sleep(30);//pauses here for 30 seconds everytime before/after running the following code

    *client**

    patience=0;served=0;
    do
    {send random 1-5
    receieve message. if 1->served=1; if 0, patience++;
    }while patience !=3 and served!=1;

    if served==1 send -1
    else send -2
    close connection

    **Server**
    while(1)
    {
    serves clients in a concurent manner
    select
    adds client in socket list
    serves client


    waits message
    if 1-5 adds in vector
    //here I don't know how to make it wait for 30 sec.
    //If I put sleep(30), it's going to sleep for each client every time. I want it to permanently check every 30 sec and send messages to clients.
    send respones(0 or 1, depending on if the max order is the same as the client's)

    if -1, thanks for the food
    if -2, going somewhere else

    close client connection
    }
}

看看 sleep(30) 会发生什么，程序会暂停 30 秒，然后执行其后编写的代码，如果将其放在 while 循环中，它每次都会等待。

更新 2:

C 中获取当前时间的代码:

here

/* localtime example */
#include <stdio.h>
#include <time.h>

int main ()
{
  time_t rawtime;
  struct tm * timeinfo;

  time ( &rawtime );
  timeinfo = localtime ( &rawtime );
  printf ( "Current local time and date: %s", asctime (timeinfo) );

  return 0;
}

更新 3:所以你的代码应该是这样的:

  time_t rawtime;
  struct tm * timeinfo;
  time ( &rawtime );
  timeinfo = localtime ( &rawtime );
  printf ( "Current local time and date: %s", asctime (timeinfo) );


  All of your code here

  and then get the time again,
  time_t rawtime1;
  .....

  and then you may calculate the difference between them and put a sleep statement as you wish. If the time you want it to pause is in x then,

  sleep(x);

  return 0;