88 lines
1.8 KiB
C
88 lines
1.8 KiB
C
#include <errno.h>
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#include <fcntl.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/eventfd.h>
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#include <sys/select.h>
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#include <sys/wait.h>
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#include <time.h>
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#include <unistd.h>
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// 创建 eventfd 并返回 fd
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int create_eventfd() {
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int fd = eventfd(0, EFD_NONBLOCK);
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if (fd == -1) {
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perror("eventfd");
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exit(EXIT_FAILURE);
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}
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return fd;
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}
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// 子线程或子进程模拟事件发生
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void trigger_event(int efd, unsigned int delay_sec) {
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printf("[trigger] Writing eventfd after %u seconds...\n", delay_sec);
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sleep(delay_sec);
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uint64_t val = 1;
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if (write(efd, &val, sizeof(val)) != sizeof(val)) {
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perror("write eventfd");
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exit(EXIT_FAILURE);
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}
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printf("[trigger] Event written to eventfd.\n");
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}
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int main() {
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int efd = create_eventfd();
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pid_t pid = fork();
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if (pid < 0) {
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perror("fork");
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exit(1);
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}
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if (pid == 0) {
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// 子进程：触发事件
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trigger_event(efd, 3);
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close(efd);
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exit(0);
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}
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// 父进程：使用 select 等待事件发生
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printf("[select_test] Waiting for event...\n");
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fd_set rfds;
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FD_ZERO(&rfds);
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FD_SET(efd, &rfds);
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int maxfd = efd + 1;
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struct timeval timeout;
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timeout.tv_sec = 5;
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timeout.tv_usec = 0;
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int ret = select(maxfd, &rfds, NULL, NULL, &timeout);
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if (ret < 0) {
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perror("select");
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exit(1);
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}
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printf("[select_test] select returned: %d\n", ret);
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if (FD_ISSET(efd, &rfds)) {
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printf("[select_test] Event occurred on eventfd.\n");
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uint64_t val;
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if (read(efd, &val, sizeof(val)) != sizeof(val)) {
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perror("read");
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exit(1);
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}
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printf("[select_test] Received eventfd value: %lu\n", val);
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}
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// wait for child process to finish
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int status;
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waitpid(pid, &status, 0);
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printf("[parent] Child exited with status: %d\n", WEXITSTATUS(status));
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close(efd);
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return 0;
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}
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