76 lines
1.7 KiB
C
76 lines
1.7 KiB
C
#include <unistd.h>
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#include <string.h>
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#include <stdio.h>
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#include <sys/wait.h>
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#include <time.h>
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#include <stdlib.h>
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#define BILLION 1000000000L
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#define MILLION 1000000L
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#define THOUSAND 1000L
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void get_time_ts(struct timespec *t0) {
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if (clock_gettime(CLOCK_REALTIME, t0) == -1) {
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perror("clock_gettime");
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exit(1);
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}
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}
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long long duration_ns(struct timespec t0, struct timespec t1) {
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return ((t1.tv_sec - t0.tv_sec)*BILLION) + (t1.tv_nsec - t0.tv_nsec);
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}
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void print_time_ns(long long time) {
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printf("%llds %lldms %lldµs %lldns\n"
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, time/BILLION
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, (time/MILLION)%THOUSAND
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, (time/THOUSAND)%THOUSAND
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, time%THOUSAND
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);
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}
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#define BUFSIZE 1024
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int main (int argc, char **argv) {
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struct timespec t0, t1;
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long long duration;
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long long max_duration = 0;
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int parent_to_child[2];
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int child_to_parent[2];
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if ( -1 == pipe(parent_to_child) ) return 1;
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if ( -1 == pipe(child_to_parent) ) return 1;
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char msg1[] = "ping";
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char bufchild[BUFSIZE] = {0} ;
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int nbytes;
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int pid = fork();
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switch ( pid ) {
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case -1: return 2;
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case 0: /*child*/
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close(child_to_parent[0]);
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close(parent_to_child[1]);
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while((nbytes = read(parent_to_child[0], bufchild, BUFSIZE)) > 0) {
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write(child_to_parent[1], bufchild, nbytes);
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}
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break;
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default: /*parent*/
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close(parent_to_child[0]);
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close(child_to_parent[1]);
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while (max_duration < BILLION) {
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get_time_ts(&t0);
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write(parent_to_child[1], msg1, strlen(msg1) + 1);
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nbytes = read(child_to_parent[0], bufchild, BUFSIZE);
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get_time_ts(&t1);
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duration = duration_ns(t0, t1);
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printf("read: %s\n", bufchild);
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print_time_ns(duration);
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max_duration += duration;
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}
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close(parent_to_child[0]);
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close(parent_to_child[1]);
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wait(NULL);
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}
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return 0;
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}
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