mirror of https://github.com/t1meshift/os_labs.git
143 lines
2.5 KiB
C
143 lines
2.5 KiB
C
/* Example code for Think OS.
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Copyright 2015 Allen Downey
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License: Creative Commons Attribution-ShareAlike 3.0
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <assert.h>
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#include <pthread.h>
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#include "utils.h"
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#define NUM_CHILDREN 2
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#define QUEUE_LENGTH 1600000
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// QUEUE
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typedef struct {
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int *array;
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int length;
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int next_in;
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int next_out;
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} Queue;
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Queue *make_queue(int length)
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{
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Queue *queue = (Queue *) malloc(sizeof(Queue));
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queue->length = length;
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queue->array = (int *) malloc(length * sizeof(int));
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queue->next_in = 0;
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queue->next_out = 0;
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return queue;
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}
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int queue_incr(Queue *queue, int i)
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{
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return (i+1) % queue->length;
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}
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int queue_empty(Queue *queue)
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{
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// queue is empty if next_in and next_out are the same
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return (queue->next_in == queue->next_out);
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}
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int queue_full(Queue *queue)
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{
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// queue is full if incrementing next_in lands on next_out
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return (queue_incr(queue, queue->next_in) == queue->next_out);
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}
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void queue_push(Queue *queue, int item) {
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if (queue_full(queue)) {
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perror_exit("queue is full");
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}
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queue->array[queue->next_in] = item;
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queue->next_in = queue_incr(queue, queue->next_in);
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}
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int queue_pop(Queue *queue) {
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if (queue_empty(queue)) {
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perror_exit("queue is empty");
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}
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int item = queue->array[queue->next_out];
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queue->next_out = queue_incr(queue, queue->next_out);
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return item;
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}
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// SHARED
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typedef struct {
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Queue *queue;
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} Shared;
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Shared *make_shared()
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{
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Shared *shared = check_malloc(sizeof(Shared));
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shared->queue = make_queue(QUEUE_LENGTH);
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return shared;
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}
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// THREAD
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pthread_t make_thread(void *(*entry)(void *), Shared *shared)
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{
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int ret;
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pthread_t thread;
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ret = pthread_create(&thread, NULL, entry, (void *) shared);
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if (ret != 0) {
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perror_exit("pthread_create failed");
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}
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return thread;
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}
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void join_thread(pthread_t thread)
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{
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int ret = pthread_join(thread, NULL);
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if (ret == -1) {
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perror_exit("pthread_join failed");
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}
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}
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// PRODUCER-CONSUMER
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void *producer_entry(void *arg)
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{
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int i;
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Shared *shared = (Shared *) arg;
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for (i=0; i<QUEUE_LENGTH-1; i++) {
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printf("adding item %d\n", i);
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queue_push(shared->queue, i);
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}
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pthread_exit(NULL);
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}
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void *consumer_entry(void *arg)
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{
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int i;
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int item;
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Shared *shared = (Shared *) arg;
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for (i=0; i<QUEUE_LENGTH-1; i++) {
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item = queue_pop(shared->queue);
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printf("consuming item %d\n", item);
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}
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pthread_exit(NULL);
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}
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// TEST CODE
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#include "testing.ic"
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int main()
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{
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thread_safe_test();
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empty_queue_test();
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return 0;
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}
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