Updated Week7

OS/C/Week7/q1.c

@@ -0,0 +1,103 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include <semaphore.h>
+#include <unistd.h>
+
+#define BUFFER_SIZE 10
+#define NUM_ITEMS 20     // items to be produced/consumed
+
+int buffer[BUFFER_SIZE];
+int in = 0;
+int out = 0;
+
+sem_t empty;  // empty slots semaphore
+sem_t full;   // available items semaphore
+
+pthread_mutex_t mutex;  // mutex for shared vars
+
+void* producer(void* arg) {
+    int item;
+    for (int i = 0; i < NUM_ITEMS; i++) {
+        item = i;  // item is set to index
+
+        // waiting for empty slot
+        sem_wait(&empty);
+
+        // critical section
+        pthread_mutex_lock(&mutex);
+
+        // item placement into buffer
+        buffer[in] = item;
+        printf("Produced: %d at index %d\n", item, in);
+        in = (in + 1) % BUFFER_SIZE;
+
+        // critical section exit
+        pthread_mutex_unlock(&mutex);
+
+        // empty slot available
+        sem_post(&full);
+
+        // production time sim using sleep
+        sleep(1);
+    }
+    pthread_exit(NULL);
+}
+
+void* consumer(void* arg) {
+    int item;
+    for (int i = 0; i < NUM_ITEMS; i++) {
+        // waiting for at least one item in the buffer
+        sem_wait(&full);
+
+        // critical section
+        pthread_mutex_lock(&mutex);
+
+        // item removal from buffer
+        item = buffer[out];
+        printf("Consumed: %d from index %d\n", item, out);
+        out = (out + 1) % BUFFER_SIZE;
+
+        // critical section exit
+        pthread_mutex_unlock(&mutex);
+
+        // empty slot
+        sem_post(&empty);
+
+        // consumption time sim using sleep
+        sleep(2);
+    }
+    pthread_exit(NULL);
+}
+
+int main(void) {
+    pthread_t producer_tid, consumer_tid;
+
+    // semaphore init
+    sem_init(&empty, 0, BUFFER_SIZE);  // empty slots init
+    sem_init(&full, 0, 0);             // available items init
+
+    // mutex init
+    pthread_mutex_init(&mutex, NULL);
+
+    // thread creator
+    if (pthread_create(&producer_tid, NULL, producer, NULL) != 0) {
+        perror("Failed to create producer thread");
+        exit(EXIT_FAILURE);
+    }
+    if (pthread_create(&consumer_tid, NULL, consumer, NULL) != 0) {
+        perror("Failed to create consumer thread");
+        exit(EXIT_FAILURE);
+    }
+
+    // thread completion wait
+    pthread_join(producer_tid, NULL);
+    pthread_join(consumer_tid, NULL);
+
+    // cleanup of semaphores and mutex
+    sem_destroy(&empty);
+    sem_destroy(&full);
+    pthread_mutex_destroy(&mutex);
+
+    return 0;
+}