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#include <stdio.h> #include <pthread.h> #include <semaphore.h> #include <unistd.h> #include <stdlib.h> #include <time.h> #define NUM_RUNWAYS 3 #define NUM_AIRPLANES 5 sem_t runways[NUM_RUNWAYS]; pthread_mutex_t log_mutex = PTHREAD_MUTEX_INITIALIZER; void log_message(const char *message) { pthread_mutex_lock(&log_mutex); printf("%s\n", message); pthread_mutex_unlock(&log_mutex); } void *airplane_thread(void *arg) { int airplane_id = *(int *)arg; srand((unsigned int)time(NULL) + airplane_id); // Simulate random decision to land or take off int decision = rand() % 2; // 0 for landing, 1 for taking off if (decision == 0) { log_message("Airplane %d is requesting permission to land."); } else { log_message("Airplane %d is requesting permission to take off."); } for (int i = 0; i < NUM_RUNWAYS; ++i) { if (sem_trywait(&runways[i]) == 0) { if (decision == 0) { log_message("Airplane %d has landed on Runway %d.", airplane_id, i); sleep(2); // Simulating the landing process log_message("Airplane %d has taken off from Runway %d.", airplane_id, i); } else { log_message("Airplane %d has taken off from Runway %d.", airplane_id, i); } sem_post(&runways[i]); // Release the runway after landing/taking off break; } } pthread_exit(NULL); } int main() { pthread_t airplanes[NUM_AIRPLANES]; int airplane_ids[NUM_AIRPLANES]; // Initialize semaphores for (int i = 0; i < NUM_RUNWAYS; ++i) { sem_init(&runways[i], 0, 1); // Initial value of 1 (available) } // Create airplane threads for (int i = 0; i < NUM_AIRPLANES; ++i) { airplane_ids[i] = i + 1; pthread_create(&airplanes[i], NULL, airplane_thread, &airplane_ids[i]); } // Join threads for (int i = 0; i < NUM_AIRPLANES; ++i) { pthread_join(airplanes[i], NULL); } // Destroy semaphores for (int i = 0; i < NUM_RUNWAYS; ++i) { sem_destroy(&runways[i]); } return 0; }
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