79 lines
1.8 KiB
C
79 lines
1.8 KiB
C
//
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// Written for Computer Networks and Systems lab classes
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// AUTHOR : Sergiusz Warga
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/stat.h>
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#include <sys/types.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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#define N_OF_ELEMENTS 1e6
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#define N_OF_CHILDREN 10
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#define SPAN (int)(N_OF_ELEMENTS/N_OF_CHILDREN)
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int child_task(double * array, int start, int pipe) {
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double sum;
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for (int i = start; i < start + SPAN; ++i ) {
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sum += array[i];
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}
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write(pipe, &sum, sizeof(sum));
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close(pipe);
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return 0;
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}
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double avg(double * array) {
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double sum = 0;
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for (int i = 0; i < N_OF_CHILDREN; ++i) {
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sum += array[i];
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}
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return sum/N_OF_ELEMENTS;
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}
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int main() {
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int children_pids[N_OF_CHILDREN];
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pid_t pid;
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double sums[N_OF_CHILDREN] = {0};
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double * array = malloc(N_OF_ELEMENTS * sizeof(double));
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srandom(time(NULL));
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for (int i = 0; i < N_OF_ELEMENTS; ++i) {
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array[i] = 2*(double)random()/RAND_MAX - 1; // Nasty
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}
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int child_to_parent[N_OF_CHILDREN][2];
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for (int i = 0; i < N_OF_CHILDREN; ++i) {
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if (pipe(child_to_parent[i]) < 0 ){
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fprintf(stderr,"Something went wrong!\n");
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return -1;
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}
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pid = fork();
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if (pid == -1) { // If something went wrong.
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perror("Fork: ");
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exit(EXIT_FAILURE);
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}
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if (pid == 0){ // If this is a child process.
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child_task(array, (int)(i*SPAN), child_to_parent[i][1]);
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exit(EXIT_SUCCESS);
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}
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children_pids[i] = pid;
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}
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for (int i = 0; i < N_OF_CHILDREN; ++i) {
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read(child_to_parent[i][0], &sums[i], sizeof(double));
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close(child_to_parent[i][0]);
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}
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printf("avg = %f\n", avg(sums));
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return 0;
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} |