linux 非可靠信号(31之前的信号)

1 当程序正在执行一个信号函数时,在函数执行期间,再次触发多个同样的信号,系统会保留一个

2 当程序正在执行一个信号函数时,在函数执行期间,再次触发一个不一样的信号,系统会暂停当前函数执行,跳转到新的信号

对应的函数去执行,执行完成后,才回到跳回之前所执行的函数中继续执行.

可以测试下面的程序

#include <stdio.h>
#include <string.h>

#include <unistd.h>

#include <signal.h>

#include <sys/time.h>

int g_iSeq=0;

void SignHandlerNew(int iSignNo,siginfo_t *pInfo,void *pReserved)

{
struct timeval tv;
gettimeofday( &tv, NULL );

int iSeq=g_iSeq++;

printf("%d Enter SignHandlerNew,signo:%d. time=%ld\n",iSeq,iSignNo,tv.tv_sec);

sleep(10);      /*睡眠3秒钟*/
gettimeofday( &tv, NULL );

printf("%d Leave SignHandlerNew,signo:%d  time=%ld\n",iSeq,iSignNo,tv.tv_sec);

}

int main(void)

{
timeval tv;
gettimeofday( &tv, NULL );
printf("process ID is %d,time is %ld\n",getpid(),tv.tv_sec);

char szBuf[20];                                     /*输入缓冲区，长度为20*/

int iRet;

struct sigaction act;                               /*包含信号处理动作的结构体*/

act.sa_sigaction=SignHandlerNew;                    /*指定信号处理函数*/

act.sa_flags=SA_SIGINFO;                            /*表明信号处理函数由sa_sigaction指定*/

sigemptyset(&act.sa_mask);

/*信号集处理函数（稍后进行介绍），将act.sa_mask所指向的信号集清空，*/

/*即不包含任何信号*/

sigaction(SIGINT,&act,NULL);                        /* 注册SIGINT信号*/

sigaction(SIGQUIT,&act,NULL);                       /* 注册SIGQUIT信号*/

sleep(150);
gettimeofday( &tv, NULL );
printf("process is over,time is %ld\n",tv.tv_sec);

return 0;

}

发送信号:

[d5000@localhost testcode]$ kill -SIGINT 6624

[d5000@localhost testcode]$ kill -SIGINT 6624

[d5000@localhost testcode]$ kill -SIGINT 6624

[d5000@localhost testcode]$ kill -SIGINT 6624

[d5000@localhost testcode]$ kill -SIGINT 6624

[d5000@localhost testcode]$ kill -SIGQUIT 6624

[d5000@localhost testcode]$ kill -SIGQUIT 6624

[d5000@localhost testcode]$ kill -SIGQUIT 6624

[d5000@localhost testcode]$ kill -SIGQUIT 6624

[d5000@localhost testcode]$ kill -SIGQUIT 6624

[d5000@localhost testcode]$ kill -SIGINT 6624

[d5000@localhost testcode]$ kill -SIGINT 6624

[d5000@localhost testcode]$ kill -SIGINT 6624

接受:

[d5000@localhost testcode]$ ./sigaction

process ID is 6624,time is 1414548809

0 Enter SignHandlerNew,signo:2. time=1414548819

1 Enter SignHandlerNew,signo:3. time=1414548833

1 Leave SignHandlerNew,signo:3 time=1414548863

2 Enter SignHandlerNew,signo:3. time=1414548863

2 Leave SignHandlerNew,signo:3 time=1414548893

0 Leave SignHandlerNew,signo:2 time=1414548893

3 Enter SignHandlerNew,signo:2. time=1414548893

3 Leave SignHandlerNew,signo:2 time=1414548923

process is over,time is 1414548923

可以看到2,3信号各接受2个,也就是各自等待一个!