在Linux上以相反顺序接收的实时信号

概述该程序向其自身发送实时信号并处理它们.一旦处理完毕,它就会按照收到的顺序输出收到的信号. $cat realtime.c#include <signal.h>#include <stdio.h>#include <unistd.h>#include <stdlib.h>int received_signals[10];int received_signals_value[10];i 该程序向其自身发送实时信号并处理它们.一旦处理完毕,它就会按照收到的顺序输出收到的信号.

$cat realtime.c#include <signal.h>#include <stdio.h>#include <unistd.h>#include <stdlib.h>int received_signals[10];int received_signals_value[10];int received_signals_count = 0;voID real_time_handler(int sig_number,siginfo_t * info,voID * arg __attribute__ ((unused))){    received_signals[received_signals_count] = sig_number - SIGRTMIN;    received_signals_value[received_signals_count] = info->si_value.sival_int;    ++received_signals_count;}voID send_real_time_signal(int sig_number,int value){    union sigval sig_value;    printf("Sending signal SIRTMIN+%d,value %d\n",sig_number,value);    sig_value.sival_int = value;    if (sigqueue(getpID(),sig_number + SIGRTMIN,sig_value) < 0) {        perror("sigqueue");        exit(EXIT_FAILURE);    }}int main(){    struct sigaction action;    sigset_t set;    int i;    // Handler setup    action.sa_sigaction = real_time_handler;    sigemptyset(&action.sa_mask);    action.sa_flags = SA_SIGINFO;    if ((sigaction(SIGRTMIN + 1,& action,NulL) < 0)     || (sigaction(SIGRTMIN + 2,NulL) < 0)     || (sigaction(SIGRTMIN + 3,NulL) < 0)) {        perror("sigaction");        exit(EXIT_FAILURE);    }    // Block all signals    sigfillset(&set);    sigprocmask(SIG_BLOCK,&set,NulL);    send_real_time_signal(1,0);    send_real_time_signal(2,1);    send_real_time_signal(3,2);    send_real_time_signal(1,3);    send_real_time_signal(2,4);    send_real_time_signal(3,5);    send_real_time_signal(3,6);    send_real_time_signal(2,7);    send_real_time_signal(1,8);    send_real_time_signal(3,9);    // Unblock all signals    sigfillset(&set);    sigprocmask(SIG_UNBLOCK,NulL);    // To make sure we're handling all signals before resuming    sleep(1);    // display results    for (i = 0; i < received_signals_count; ++i) {        printf("Received signal SIGRTMIN+%d,received_signals[i],received_signals_value[i]);    }    return EXIT_SUCCESS;}

我一直得到以下输出：

$gcc -Wall -Wextra -O2 -o realtime realtime.c$./realtimeSending signal SIRTMIN+1,value 0Sending signal SIRTMIN+2,value 1Sending signal SIRTMIN+3,value 2Sending signal SIRTMIN+1,value 3Sending signal SIRTMIN+2,value 4Sending signal SIRTMIN+3,value 5Sending signal SIRTMIN+3,value 6Sending signal SIRTMIN+2,value 7Sending signal SIRTMIN+1,value 8Sending signal SIRTMIN+3,value 9Received signal SIGRTMIN+3,value 2Received signal SIGRTMIN+3,value 5Received signal SIGRTMIN+3,value 6Received signal SIGRTMIN+3,value 9Received signal SIGRTMIN+2,value 1Received signal SIGRTMIN+2,value 4Received signal SIGRTMIN+2,value 7Received signal SIGRTMIN+1,value 0Received signal SIGRTMIN+1,value 3Received signal SIGRTMIN+1,value 8

这与signal(7)(http://man7.org/linux/man-pages/man7/signal.7.html)中的内容相矛盾：

Real-time signals are delivered in a guaranteed order. Multiple real-time signals of the same type are delivered in the order they were sent. If different real-time signals are sent to a process,they are delivered starting with the lowest-numbered signal. (I.e.,low-numbered signals have highest priority.) By contrast,if multiple standard signals are pending for a process,the order in which they are delivered is unspecifIEd.

据我了解,我应该得到：

$./realtimeSending signal SIRTMIN+1,value 9Received signal SIGRTMIN+1,value 8Received signal SIGRTMIN+2,value 7Received signal SIGRTMIN+3,value 9

我已经快速浏览了一下linux内核源代码,但却找不到处理实时信号的地方.

我做错了什么/遗失了什么或者手册页是不准确的？

解决方法 您的问题是您允许其他信号中断正在运行的信号处理程序：

sigemptyset(&action.sa_mask);

sa_mask字段指定不允许中断此处理程序执行的信号集.

这意味着您可以获得SIGRTMIN 1,在您可以执行任何 *** 作之前,您将获得另一个较低优先级的信号,然后您可以开始处理该信号.然后该信号又被另一个信号中断,依此类推.

要解决此问题,请禁止任何其他信号中断您的处理程序：

sigfillset(&action.sa_mask);

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