【发布时间】：2016-07-13 01:27:25
【问题描述】：
我正在编写一个具有 3 个进程的系统，Judge、Player 1 和 player 2。
我使用信号kill(playerPid,SIGUSR1) 让judge 在轮到他时唤醒player，
以及一个信号kill(judge,SIGHUP)在转弯完成后唤醒裁判。
在每个kill signal 之后，我使用pause()，因此该过程不会继续。
有时问题出在kill signal 之后，例如从player 到judge，judge 在玩家执行他的pause() 之前唤醒。
下一次judge 将唤醒这个player 他将pause 和我的程序将堆栈因为所有3 processes 都处于pause 状态没有人唤醒他们。
所以我的问题是： kill 命令之后应该发生什么？
1。当前进程一直持续到 pause() 为止，然后转到他发出信号的进程。 例如：
kill(judge, SIGHUP);
//stops here and goes to the judge.
pause();
这是我的代码中有时会发生的情况，我在 pause() 上的所有进程都卡住了。
2。当前进程停止并转到他刚刚发出信号的进程。 例如：
kill(judge, SIGHUP);
pause();
//stops here and going to the judge.
**这是我的代码中大部分时间发生的事情。
在我的代码中，行为发生了变化，有时像数字 1，有时像数字 2。
我做错了什么？
进程是否有可能在收到信号的处理函数完成运行之前唤醒？
或者进程是否有可能在终止信号之后暂停，然后再到达暂停行？如果是这样，为什么以及如何处理？
这是我的代码：
///////////////////////signal handlers
void sigHandler(int signo)
{
printf("Received signal %d\n", signo);
if(signo == SIGHUP )//fatehr gets it from son
{
signal(SIGHUP ,sigHandler);
printf("son woke up father\n");
}
else if (signo == SIGUSR1)//son gets it from father
{
signal(SIGUSR1, sigHandler);
printf("Judge waking player B\n");
}
else if (signo == SIGUSR2)//father gets it from son
{
signal(SIGUSR2, sigHandler);
printf("Judge waking player A\n");
}
else if (signo == SIGTERM)//son get it when father kill them
{
signal(SIGTERM, sigHandler);
printf("%d im dead\n", getpid());
kill(getppid(), SIGUSR2);
exit(1);
}
else if (signo == SIGINT)//father get it to play round with ^C
{
signal(SIGINT, sigHandler);
printf("play round!!!!!!!!!!!!\n");
}
}
void sigHandler2(int signo)
{
if (signo == SIGINT)//son get it to play round with ^C
{
signal(SIGINT, sigHandler2);
}
}
void wakePlayer(int player,int turn, int* boardPtr)
{
boardPtr[27] = 0;
while (boardPtr[27] != 1)//while player didnt finish his turn
{
if (turn==1)
kill(player, SIGUSR1);
else
kill(player, SIGUSR2);
pause();
}
}
///////////////////////End of signal handlers
int main(){
int j = 1;;
int player1;
int player2;
int judge;
time_t t;
key_t key;
int shmid;
int *boardPtr;
judge = getpid();
srand(time(NULL) *(5));
shmid = createShm(&boardPtr);//creating shm
boardPtr[1] = 2;
player1 = fork();//create player 1
if (player1 == -1)
{
printf("error in fork");
exit(1);
}
if (player1>0)//not player 1
{
player2 = fork();//create player 2
if (player2 == -1)
{
printf("error in fork");
exit(1);
}
if (player2>0)//This is The Judge!********************************************************************************
{
signal(SIGHUP, sigHandler);//signal from player after he did his turn
signal(SIGINT, sigHandler);//catch the ^c to make the next turn
printf("father started\n");
while(boardPtr[1]!=0)//Players didnt set up their handlers
{
sleep(1);
}
printf("father initiating\n");
initiation(boardPtr, player1, player2);//create the board and choose a player to start
printBoard(boardPtr, 0);//print the current board.
while (checkWin(boardPtr) == 0)//while no one won.
{
if (boardPtr[26] == 1)//if it is player "b" turn.
wakePlayer(player1,1, boardPtr);
else //if it is player "a" turn.
wakePlayer(player2,2, boardPtr);
//pause();
printBoard(boardPtr, j);//print the current board.
boardPtr[26] = (boardPtr[26] * 2) % 3;//change turns
j++;
}
printf("game finished!\n");
killItWithFire(player1, player2, shmid, &boardPtr);//cleaning up after match.
printf("Judge is suiciding, goodbye!\n");
exit(1);
}
else if (player2 == 0)//this is player 2!******************************************************************************
{
signal(SIGUSR2, sigHandler);//signal from judge to make a turn
signal(SIGTERM, sigHandler);//signal from judge to terminate
signal(SIGINT, sigHandler2);//get the ^c and pause.
printf("%d player A started\n", getpid());
boardPtr[1]--;//mark player A handlers are set.
pause();
while (1)
{
int r = roll(1);
printf("%d player A threw a %d\n", getpid(), r);
if (boardPtr[22] == 0)//checking if it is an initation round
{
boardPtr[21] = r;
}
else
{
turn(2, r, boardPtr);//makes a turn
}
boardPtr[27] = 1;//mark that i finished my turn.
kill(judge, SIGHUP);//signal to judge after turn.
pause();
}
}
}
else//this is player 1!**********************************************************************************************
{
signal(SIGUSR1, sigHandler);//signal from judge to make a turn
signal(SIGTERM, sigHandler);//signal from judge to terminate
signal(SIGINT, sigHandler2);//signal to pause when player gets a ctrl C
printf("%d player B started\n", getpid());
boardPtr[1]--;//mark player A handlers are set.
pause();
while (1)
{
int r = roll(2);
printf("%d player B threw a %d\n", getpid(), r);
if (boardPtr[22] == 0)//flag to check if it is an initiation round.
{
boardPtr[20] = r;
}
else
{
turn(1, r, boardPtr);//player b makes a turn
}
boardPtr[27] = 1;//marks that player B finished his turn.
kill(judge, SIGHUP);//signal to judge after turn.
pause();
}
}
return 0;
}
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