Promela的自旋建模

Question

我正在研究一个非常简单的promela模型。它使用两个不同的模块，充当人行横道/交通灯。第一个模块是输出当前信号的交通灯(绿色、红色、黄色、挂起)。该模块还接收一个称为“行人”的信号作为输入，该信号作为一个指示符，表示有行人想要过马路。第二个模块充当人行横道。它接收来自交通灯模块(绿色、黄色、绿色)的输出信号。它将行人信号输出到交通灯模块。这个模块简单地定义了行人是否在过路、等待或不存在。我的问题是，一旦计数值变为60，就会发生超时。我相信"SigG_out！1“是导致错误的原因，但我不知道原因。我已经附加了从命令行接收到的跟踪的图像。我对Spin和Promela完全陌生，所以我不知道如何使用跟踪中的信息在代码中找到我的问题。任何帮助都是非常感谢的。

以下是完整模型的代码：

mtype = {red, green, yellow, pending, none, crossing, waiting};
mtype traffic_mode;
mtype crosswalk_mode;
int count;
chan pedestrian_chan = [0] of {byte};

chan sigR_chan = [0] of {byte};

chan sigG_chan = [0] of {byte};

chan sigY_chan = [0] of {byte};

ltl l1 {!<> (pedestrian_chan[0] == 1) && (traffic_mode == green || traffic_mode == yellow || traffic_mode == pending)}
ltl l2 {[]<> (pedestrian_chan[0] == 1) -> crosswalk_mode == crossing }

proctype traffic_controller(chan pedestrian_in, sigR_out, sigG_out, sigY_out)

{

do
    ::if
      ::(traffic_mode == red) -> 
        count = count + 1;
        if
        ::(count >= 60) ->
            sigG_out ! 1;
            count = 0;
            traffic_mode = green;
        :: else -> skip;
        fi
      ::(traffic_mode == green) -> 
        if
        ::(count < 60) ->
            count = count + 1;
        ::(pedestrian_in == 1 & count < 60) ->
            count = count + 1;
            traffic_mode = pending;
        ::(pedestrian_in == 1 & count >= 60)
            count = 0;
            traffic_mode = yellow;
        fi
      ::(traffic_mode == pending) ->
        count = count + 1;
        if
        ::(count >= 60) ->
            sigY_out ! 1;
            count = 0;
            traffic_mode = yellow;
        ::else -> skip;
        fi  
      ::(traffic_mode == yellow) ->
        count = count + 1;
        if
        ::(count >= 5) ->
            sigR_out ! 1;
            count = 0;
            traffic_mode = red;
        :: else -> skip;
        fi
      fi
od  

}



proctype crosswalk(chan sigR_in, sigG_in, sigY_in, pedestrian_out)

{
do
    ::if
      ::(crosswalk_mode == crossing) ->
        if
        ::(sigG_in == 1) -> crosswalk_mode = none;
        fi
      ::(crosswalk_mode == none) ->
        if  
        :: (1 == 1) -> crosswalk_mode = none
        :: (1 == 1) -> 
            pedestrian_out ! 1
            crosswalk_mode = waiting
        fi
      ::(crosswalk_mode == waiting) ->
        if
        ::(sigR_in == 1) -> crosswalk_mode = crossing;
        fi
      fi
od   
}


init

{

    count = 0;

    traffic_mode = red;

    crosswalk_mode = crossing;


    atomic
    {
        run traffic_controller(pedestrian_chan, sigR_chan, sigG_chan, sigY_chan);
        run crosswalk(sigR_chan, sigG_chan, sigY_chan, pedestrian_chan);
    }

}

​

​

Answer 1

您使用channels是错误的，特别是这一行，我甚至不知道如何解释它：

:: (sigG_in == 1) ->

1. 您的通道是同步，这意味着每当一个进程在一边发送某些内容时，另一个进程必须在通道的另一端侦听以传递消息。否则，流程会阻塞，直到情况发生变化。您的通道是同步，因为您声明它们的大小为0。
2. 要从通道读取，需要使用正确的语法： int some_var；some_channel?some_var；//此处some_var包含通过some_channel接收的值

使用三个不同的通道发送不同的信号似乎有点毫无意义。使用三个不同的值怎么样？

mtype = { RED, GREEN, YELLOW };
chan c = [0] of { mtype };
...
c!RED
...
// (some other process)
...
mtype var;
c?var;
// here var contains RED
...