FIFO in While循环卡住并等待读取

时间：2017-04-16 20:01:47

标签： c unix fork ipc fifo

服务器将其PID发送到客户端，客户端获取并在循环中发送SIGUSR1信号，因此我在服务器代码中具有处理程序。从理论上讲，它需要获取信号并为客户端创建一些随机矩阵。客户端接收服务器PID，但由于某种原因它永远不会向客户端发送矩阵。它等待并插入永远闪烁。我假设他们不会彼此连接，但为什么？我试图发送一个矩阵，它做得很好。

client.c 

int main()
{
    int n=2;
      pid_t pid=1;
      int i,j;
      double matrix[20][20];
   char *myfifo2 = "/tmp/kek_fifo";
       int server_to_client;
   char *myfifo3 = "/tmp/fifor_fifo";
       int fifor;
       int forke=1;

   char str[BUFSIZ];
     fifor = open(myfifo3, O_RDONLY);
        read(fifor,&pid,sizeof(pid));
        printf("pid %d\n",pid);

   close(fifor);
    unlink(myfifo3);



 while(1){
      printf("no\n");
      server_to_client = open(myfifo2, O_RDONLY);
      read(server_to_client,matrix,sizeof(matrix));
      close(server_to_client);
      printf("yes\n");
    forke=fork();
    if(forke){

        printf("forke buyuktur >= parent olmali %d \n",forke);
     for(i = 0; i < 2*n; i++){
        for(j = 0; j < 2*n; j++){
            printf("%2f ",matrix[i][j]);
        }
        printf("\n");
    }
        wait(0); //parent child bekliyo 
    }

    else{
        printf("forke =0  yani child %d \n",forke);

        exit(0);
    }
        //sleep(5);
       kill(pid,SIGUSR1);


    }   


   return 0;
}

server.c 

void actionHandler(int signum);
void matrix_init(double m[20][20],int n);
void randome(double myPointer[20][20],int n);

static int signalcheck=0;
int main()
{
   int i,j;
      int n=2; //argv olacak
      pid_t pide=getpid();
      printf("pide is %d \n",pide);
       struct sigaction action;
       action.sa_handler=actionHandler; 
       action.sa_flags = 0;

   int client_to_server;
   char *myfifo = "/tmp/client_to_server_fifo";
   int forke;
   int server_to_client;
   char *myfifo2 = "/tmp/kek_fifo";
   char *myfifo3 = "/tmp/fifor_fifo";
   int fifor;
   char buf[BUFSIZ];
   double M[20][20];
    matrix_init(M,n);

   /* create the FIFO (named pipe) */
 //  mkfifo(myfifo, 0666);
  mkfifo(myfifo2, 0666);
   mkfifo(myfifo3,0666);

   fifor =open(myfifo3,O_WRONLY);
   write(fifor,&pide,sizeof(pide));
   close(fifor);
   unlink(myfifo3);

   if ((sigemptyset(&action.sa_mask) == -1) ||
      (sigaction(SIGUSR1, &action, NULL) == -1))
      perror("Failed to install SIGURS1 signal handler");

   /* open, read, and display the message from the FIFO */
  // client_to_server = open(myfifo, O_RDONLY);


   printf("Server ON.\n");

   while (1)
   {



   if(signalcheck==1){

   forke=fork();
   if(forke==0){
      while(1){
         randome(M,n);

         server_to_client = open(myfifo2, O_WRONLY);
         write(server_to_client,M,sizeof(M));
         close(server_to_client);
         unlink(myfifo2);
         printf("matrix yarat\n");
         //sleep(5);
         //create matrix send to fifo 
      }
   }
      /*
      read(client_to_server, buf, BUFSIZ);

      if (strcmp("exit",buf)==0)
      {
         printf("Server OFF.\n");
         break;
      }

      else if (strcmp("",buf)!=0)
      {
         printf("Received: %s\n", buf);
         printf("Sending back...\n");
         write(server_to_client,buf,BUFSIZ);
      }

       clean buf from any data 
      memset(buf, 0, sizeof(buf)); */
         //sleep(5);
   }
   signalcheck=0;
   }

 //  close(client_to_server);
 //  close(server_to_client);
// unlink(myfifo);
  // unlink(myfifo2);
   return 0;
}
 void actionHandler(int signum)
{
    signalcheck=1;
      if(signum==SIGUSR1)
         printf("i catched signal code from client  i guess \n");
    /* Signal handler code goes here. */

}


void matrix_init(double m[20][20],int z){
    /* 
    this function purpose to create
    2Nx2N int matrix n being int z
    then initing this matrix to 0 before random numbers take in part
    it has error checks .
    blah!*/
    int i, j,n=z;
    double **k = (double **) malloc(n * sizeof(double*));

    if(m == NULL){
        printf("Error full matrix not created");
        exit(-1);
    }

    for(i = 0; i < n; i++){
        for(j = 0; j < n; j++){
            m[i][j] = 0;
        }
    }

}


 void randome(double  myPointer[20][20],int n){
    int i,j;
    int r;
    srand ( time(NULL) );
    for(i=0;i<n*2;i++)
        for(j=0;j<n*2;j++)
            myPointer[i][j]=rand()%10;
 }

1 个答案:

答案 0 :(得分：1)

我认为你的问题长期被忽略的一个原因是，代码是相当多的代码和相当数量的评论是无关的代码，并且布局不是。一切都很整洁。这些加起来＆＃34;阅读代码＆＃34;是一项艰苦的工作，它会让人们真正阅读它。

这个代码似乎可以在运行macOS Sierra 10.12.4的MacBook Pro上运行，使用GCC 6.3.0进行编译。

客户端代码

#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <unistd.h>

int main(void)
{
    int n = 2;
    pid_t pid = 1;
    int i, j;
    double matrix[20][20];
    char *myfifo2 = "/tmp/kek_fifo";
    int server_to_client;
    char *myfifo3 = "/tmp/fifor_fifo";
    int fifor;
    int forke = 1;

    fifor = open(myfifo3, O_RDONLY);
    read(fifor, &pid, sizeof(pid));
    printf("pid %d\n", pid);

    close(fifor);
    unlink(myfifo3);

    for (int loopnum = 0; loopnum < 20; loopnum++)
    {
        printf("begin loop %d\n", loopnum);
        kill(pid, SIGUSR1);
        printf("signal sent\n");
        server_to_client = open(myfifo2, O_RDONLY);
        printf("Open done\n");
        read(server_to_client, matrix, sizeof(matrix));
        printf("read done\n");
        close(server_to_client);
        printf("close done\n");
        forke = fork();
        if (forke)
        {
            printf("forke buyuktur >= parent olmali %d\n", forke);
            for (i = 0; i < 2 * n; i++)
            {
                for (j = 0; j < 2 * n; j++)
                {
                    printf("%2f ", matrix[i][j]);
                }
                printf("\n");
            }
            wait(0); // parent child bekliyo
        }
        else
        {
            printf("forke = 0  yani child %d\n", forke);
            exit(loopnum);
        }
    }

    return 0;
}

服务器代码

#include <assert.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

void actionHandler(int signum);
void matrix_init(double m[20][20], int n);
void randome(double myPointer[20][20], int n);

static volatile sig_atomic_t signalcheck = 0;

int main(void)
{
    int n = 2; // argv olacak
    pid_t pide = getpid();
    printf("pide is %d\n", pide);
    struct sigaction action;
    action.sa_handler = actionHandler;
    action.sa_flags = 0;

    int forke;
    int server_to_client;
    char *myfifo2 = "/tmp/kek_fifo";
    char *myfifo3 = "/tmp/fifor_fifo";
    int fifor;
    double M[20][20];
    matrix_init(M, n);
    srand(time(NULL));

    if ((sigemptyset(&action.sa_mask) == -1) ||
        (sigaction(SIGUSR1, &action, NULL) == -1))
    {
        perror("Failed to install SIGURS1 signal handler");
        return 1;
    }

    /* create the FIFO (named pipe) */
    mkfifo(myfifo2, 0666);
    mkfifo(myfifo3, 0666);

    fifor = open(myfifo3, O_WRONLY);
    write(fifor, &pide, sizeof(pide));
    close(fifor);
    unlink(myfifo3);

    printf("Server ON (%d).\n", signalcheck);

    while (1)
    {
        if (signalcheck == 1)
        {
            printf("Signal received:\n");
            signalcheck = 0;
            randome(M, n);
            forke = fork();
            if (forke == 0)
            {
                    server_to_client = open(myfifo2, O_WRONLY);
                    write(server_to_client, M, sizeof(M));
                    close(server_to_client);
                    printf("matrix yarat %d\n", (int)getpid());
                    exit(0);
            }
            else
            {
                int corpse;
                int status;
                while ((corpse = wait(&status)) != -1)
                    printf("PID %d exited with status 0x%.4x\n", corpse, status);
            }
        }
    }

    return 0;
}

void actionHandler(int signum)
{
    static char msg[] = "I caught a signal from the client\n";
    signalcheck = 1;
    if (signum == SIGUSR1)
    {
        int nb = write(1, msg, sizeof(msg)-1);
        assert(nb == sizeof(msg)-1);
    }
}

void matrix_init(double m[20][20], int z)
{
    for (int i = 0; i < z; i++)
    {
        for (int j = 0; j < z; j++)
            m[i][j] = 0;
    }
}

void randome(double myPointer[20][20], int n)
{
    int i, j;
    for (i = 0; i < n * 2; i++)
    {
        for (j = 0; j < n * 2; j++)
            myPointer[i][j] = rand() % 10;
    }
}

服务器输出

pide is 474
Server ON (0).
I caught a signal from the client
Signal received:
matrix yarat 476
PID 476 exited with status 0x0000
I caught a signal from the client
Signal received:
matrix yarat 478
PID 478 exited with status 0x0000
I caught a signal from the client
Signal received:
matrix yarat 481
PID 481 exited with status 0x0000
I caught a signal from the client
Signal received:
matrix yarat 483
PID 483 exited with status 0x0000
I caught a signal from the client
Signal received:
matrix yarat 485
PID 485 exited with status 0x0000
I caught a signal from the client
Signal received:
matrix yarat 488
PID 488 exited with status 0x0000
I caught a signal from the client
Signal received:
matrix yarat 491
PID 491 exited with status 0x0000
I caught a signal from the client
Signal received:
matrix yarat 493
PID 493 exited with status 0x0000
I caught a signal from the client
Signal received:
matrix yarat 496
PID 496 exited with status 0x0000
I caught a signal from the client
Signal received:
matrix yarat 499
PID 499 exited with status 0x0000
I caught a signal from the client
Signal received:
matrix yarat 501
PID 501 exited with status 0x0000
I caught a signal from the client
Signal received:
matrix yarat 503
PID 503 exited with status 0x0000
I caught a signal from the client
Signal received:
matrix yarat 506
PID 506 exited with status 0x0000
I caught a signal from the client
Signal received:
matrix yarat 512
PID 512 exited with status 0x0000
I caught a signal from the client
Signal received:
matrix yarat 514
PID 514 exited with status 0x0000
I caught a signal from the client
Signal received:
matrix yarat 516
PID 516 exited with status 0x0000
I caught a signal from the client
Signal received:
matrix yarat 518
PID 518 exited with status 0x0000
I caught a signal from the client
Signal received:
matrix yarat 521
PID 521 exited with status 0x0000
I caught a signal from the client
Signal received:
matrix yarat 523
PID 523 exited with status 0x0000
I caught a signal from the client
Signal received:
matrix yarat 525
PID 525 exited with status 0x0000
^C

^C是我在终端窗口中断服务器的地方。程序在繁忙的循环中旋转，使用99.5％的CPU。

客户端输出

pid 474
begin loop 0
signal sent
Open done
read done
close done
forke buyuktur >= parent olmali 477
5.000000 6.000000 0.000000 9.000000 
2.000000 1.000000 4.000000 7.000000 
0.000000 8.000000 2.000000 5.000000 
7.000000 8.000000 3.000000 2.000000 
forke = 0  yani child 0
begin loop 1
signal sent
Open done
read done
close done
forke buyuktur >= parent olmali 480
0.000000 7.000000 0.000000 3.000000 
0.000000 7.000000 2.000000 9.000000 
2.000000 4.000000 5.000000 5.000000 
9.000000 7.000000 3.000000 4.000000 
forke = 0  yani child 0
begin loop 2
signal sent
Open done
read done
close done
forke buyuktur >= parent olmali 482
8.000000 6.000000 1.000000 4.000000 
9.000000 2.000000 3.000000 9.000000 
2.000000 3.000000 8.000000 0.000000 
7.000000 8.000000 9.000000 8.000000 
forke = 0  yani child 0
begin loop 3
signal sent
Open done
read done
close done
forke buyuktur >= parent olmali 484
1.000000 4.000000 2.000000 9.000000 
5.000000 3.000000 5.000000 0.000000 
5.000000 9.000000 7.000000 5.000000 
3.000000 1.000000 7.000000 3.000000 
forke = 0  yani child 0
begin loop 4
signal sent
Open done
read done
close done
forke buyuktur >= parent olmali 487
2.000000 3.000000 0.000000 4.000000 
0.000000 2.000000 6.000000 8.000000 
1.000000 8.000000 8.000000 7.000000 
7.000000 4.000000 1.000000 4.000000 
forke = 0  yani child 0
begin loop 5
signal sent
Open done
read done
close done
forke buyuktur >= parent olmali 489
6.000000 3.000000 4.000000 0.000000 
5.000000 9.000000 2.000000 3.000000 
9.000000 7.000000 5.000000 4.000000 
5.000000 9.000000 1.000000 8.000000 
forke = 0  yani child 0
begin loop 6
signal sent
Open done
read done
close done
forke buyuktur >= parent olmali 492
7.000000 1.000000 4.000000 6.000000 
7.000000 1.000000 2.000000 4.000000 
5.000000 1.000000 8.000000 6.000000 
1.000000 9.000000 8.000000 6.000000 
forke = 0  yani child 0
begin loop 7
signal sent
Open done
read done
close done
forke buyuktur >= parent olmali 495
0.000000 0.000000 5.000000 1.000000 
6.000000 8.000000 3.000000 1.000000 
8.000000 1.000000 6.000000 9.000000 
7.000000 3.000000 1.000000 5.000000 
forke = 0  yani child 0
begin loop 8
signal sent
Open done
read done
close done
forke buyuktur >= parent olmali 497
3.000000 0.000000 1.000000 8.000000 
4.000000 4.000000 2.000000 3.000000 
8.000000 9.000000 6.000000 3.000000 
1.000000 3.000000 6.000000 3.000000 
forke = 0  yani child 0
begin loop 9
signal sent
Open done
read done
close done
forke buyuktur >= parent olmali 500
4.000000 0.000000 9.000000 3.000000 
1.000000 5.000000 1.000000 2.000000 
3.000000 0.000000 5.000000 6.000000 
4.000000 5.000000 9.000000 7.000000 
forke = 0  yani child 0
begin loop 10
signal sent
Open done
read done
close done
forke buyuktur >= parent olmali 502
4.000000 9.000000 7.000000 6.000000 
6.000000 4.000000 7.000000 1.000000 
3.000000 5.000000 9.000000 0.000000 
7.000000 9.000000 7.000000 9.000000 
forke = 0  yani child 0
begin loop 11
signal sent
Open done
read done
close done
forke buyuktur >= parent olmali 504
3.000000 3.000000 0.000000 3.000000 
7.000000 5.000000 8.000000 5.000000 
6.000000 1.000000 3.000000 6.000000 
8.000000 3.000000 3.000000 0.000000 
forke = 0  yani child 0
begin loop 12
signal sent
Open done
read done
close done
forke buyuktur >= parent olmali 507
6.000000 5.000000 1.000000 8.000000 
7.000000 3.000000 9.000000 7.000000 
9.000000 4.000000 0.000000 5.000000 
1.000000 6.000000 9.000000 3.000000 
forke = 0  yani child 0
begin loop 13
signal sent
Open done
read done
close done
forke buyuktur >= parent olmali 513
6.000000 4.000000 6.000000 3.000000 
5.000000 6.000000 6.000000 0.000000 
2.000000 1.000000 5.000000 2.000000 
7.000000 3.000000 9.000000 8.000000 
forke = 0  yani child 0
begin loop 14
signal sent
Open done
read done
close done
forke buyuktur >= parent olmali 515
0.000000 3.000000 7.000000 8.000000 
9.000000 1.000000 2.000000 4.000000 
5.000000 7.000000 4.000000 8.000000 
3.000000 1.000000 1.000000 6.000000 
forke = 0  yani child 0
begin loop 15
signal sent
Open done
read done
close done
forke buyuktur >= parent olmali 517
0.000000 8.000000 9.000000 7.000000 
7.000000 3.000000 3.000000 0.000000 
4.000000 0.000000 8.000000 1.000000 
5.000000 8.000000 4.000000 4.000000 
forke = 0  yani child 0
begin loop 16
signal sent
Open done
read done
close done
forke buyuktur >= parent olmali 520
8.000000 3.000000 8.000000 8.000000 
1.000000 7.000000 0.000000 3.000000 
4.000000 2.000000 0.000000 3.000000 
8.000000 4.000000 4.000000 8.000000 
forke = 0  yani child 0
begin loop 17
signal sent
Open done
read done
close done
forke buyuktur >= parent olmali 522
9.000000 3.000000 9.000000 3.000000 
3.000000 3.000000 2.000000 9.000000 
9.000000 3.000000 6.000000 0.000000 
8.000000 0.000000 8.000000 1.000000 
forke = 0  yani child 0
begin loop 18
signal sent
Open done
read done
close done
forke buyuktur >= parent olmali 524
9.000000 1.000000 4.000000 3.000000 
4.000000 8.000000 9.000000 2.000000 
2.000000 5.000000 0.000000 6.000000 
9.000000 0.000000 5.000000 7.000000 
forke = 0  yani child 0
begin loop 19
signal sent
Open done
read done
close done
forke buyuktur >= parent olmali 526
2.000000 0.000000 5.000000 3.000000 
1.000000 2.000000 1.000000 3.000000 
3.000000 6.000000 5.000000 8.000000 
7.000000 3.000000 2.000000 5.000000 
forke = 0  yani child 0

请注意，客户端在20次循环后整齐退出;它可能应该更小。

一些变化

  • 代码only calls srand() once
  • 代码在弄乱FIFO之前设置服务器信号处理程序。
  • 代码不再在循环中删除FIFO。
  • 代码不再将signalcheck设置为零，除非它是一个。似乎有一个问题是，每当检查时，＆＃39; signalcheck`变量为零。
  • 代码使用static volatile sig_atomic_t signalcheck。
  • 随机矩阵在fork()之前生成，以便看到不同的结果。
  • 服务器清理死去的孩子（僵尸）。
  • 目前还不清楚为什么服务器或孩子分叉，但是或多或少都没有找到。
  • signal handler doesn't use printf()。

仍需要改进

代码远非完美。有许多事情需要解决，包括：

  • 正确处理错误（例如，在服务器中fork()之后）。
  • 终止服务器而非中断的机制。
  • 检测客户端何时停止。
  • 不使用信号告诉服务器有工作。
  • 删除客户端分叉。
  • 决定服务器是否真的需要分叉。
  • 使用可配置的FIFO名称。
  • 更好地整理矩阵初始化。
  • 等
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