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xixu-mexixu-me
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‎.vscode/settings.json‎

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{
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"files.associations": {
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"unistd.h": "c",
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"errno.h": "c"
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}
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}

‎5_Multithreaded-Programming/consumer.c‎

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// consumer.c
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <semaphore.h>
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#include <time.h>
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#include <string.h>
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#include <float.h> // For FLT_MAX, FLT_MIN (or DBL_MAX etc.)
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#include <signal.h> // For signal handling
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#include "data_structures.h" // Common header
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SharedData *shared_data_ptr = NULL;
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int shm_fd = -1;
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sem_t *mutex_sem = SEM_FAILED;
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volatile sig_atomic_t keep_running = 1;
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void cleanup_ipc_consumer() {
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printf("\nConsumer cleaning up...\n");
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if (shared_data_ptr != MAP_FAILED && shared_data_ptr != NULL) {
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if (munmap(shared_data_ptr, sizeof(SharedData)) == -1) {
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perror("munmap");
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}
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}
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if (shm_fd != -1) {
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close(shm_fd);
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// Consumer does NOT unlink shared memory, producer owns it
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}
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if (mutex_sem != SEM_FAILED) {
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sem_close(mutex_sem);
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// Consumer does NOT unlink semaphore, producer owns it
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}
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printf("Consumer cleanup complete.\n");
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}
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void sigint_handler_consumer(int sig) {
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printf("\nConsumer received SIGINT. Shutting down...\n");
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keep_running = 0;
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}
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int main() {
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struct sigaction sa;
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sa.sa_handler = sigint_handler_consumer;
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sigemptyset(&sa.sa_mask);
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sa.sa_flags = 0;
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if (sigaction(SIGINT, &sa, NULL) == -1) {
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perror("sigaction");
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return EXIT_FAILURE;
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}
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if (sigaction(SIGTERM, &sa, NULL) == -1) {
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perror("sigaction for SIGTERM");
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return EXIT_FAILURE;
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}
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// 1. Open existing POSIX shared memory object (DO NOT CREATE)
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shm_fd = shm_open(SHM_NAME, O_RDWR, 0666); // O_RDONLY if only reading
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if (shm_fd == -1) {
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perror("shm_open (Is the producer.c program running?)");
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return EXIT_FAILURE;
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}
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// 2. Map the shared memory object into the process's address space
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// Note: Size is known from SharedData struct. ftruncate is not needed here.
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shared_data_ptr = mmap(0, sizeof(SharedData), PROT_READ | PROT_WRITE, MAP_SHARED, shm_fd, 0); // PROT_READ if only reading
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if (shared_data_ptr == MAP_FAILED) {
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perror("mmap");
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close(shm_fd);
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return EXIT_FAILURE;
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}
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printf("Shared memory opened and mapped successfully.\n");
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// 3. Open existing POSIX named semaphore (DO NOT CREATE)
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mutex_sem = sem_open(SEM_MUTEX_NAME, 0); // Flags argument is 0 when opening existing
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if (mutex_sem == SEM_FAILED) {
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perror("sem_open (Is the producer.c program running and semaphore created?)");
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munmap(shared_data_ptr, sizeof(SharedData));
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close(shm_fd);
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return EXIT_FAILURE;
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}
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printf("Mutex semaphore opened successfully.\n");
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printf("Monitoring room display started. Press Ctrl+C to exit.\n");
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printf("Will display data every %d seconds.\n\n", MONITOR_DISPLAY_INTERVAL);
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// 4. Monitoring loop
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while (keep_running) {
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// Wait for semaphore
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if (sem_wait(mutex_sem) == -1) {
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if (keep_running)
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perror("sem_wait in consumer"); // Don't print error if shutting down
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break; // Exit loop on error or interruption
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}
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float max_temp = -FLT_MAX;
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float min_temp = FLT_MAX;
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int hottest_workshop_idx = -1;
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int coldest_workshop_idx = -1;
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int valid_data_found = 0;
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for (int i = 0; i < NUM_WORKSHOPS; ++i) {
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// Check if the workshop data looks initialized (not default 0.0 or some other sentinel)
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// For this example, any non-zero temp can be considered, or rely on producer to fill.
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// A more robust way would be a 'valid' flag per workshop or timestamp.
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if (shared_data_ptr->workshops[i].temperature != 0.0f || shared_data_ptr->workshops[i].humidity != 0.0f) {
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valid_data_found = 1; // At least one workshop has some data
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}
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float current_temp = shared_data_ptr->workshops[i].temperature;
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if (current_temp > max_temp) {
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max_temp = current_temp;
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hottest_workshop_idx = i;
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}
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if (current_temp < min_temp) {
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min_temp = current_temp;
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coldest_workshop_idx = i;
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}
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}
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// Release semaphore
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if (sem_post(mutex_sem) == -1) {
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perror("sem_post in consumer");
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break; // Exit loop on error
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}
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// Display data
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if (hottest_workshop_idx != -1 && coldest_workshop_idx != -1 && valid_data_found) {
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printf("--- Monitoring Update (%s", ctime(&(time_t){ time(NULL) })); // ctime adds newline
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printf(" Highest Temp: Workshop %d (%.2f C, %.2f %% Humidity)\n",
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shared_data_ptr->workshops[hottest_workshop_idx].workshop_id,
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max_temp,
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shared_data_ptr->workshops[hottest_workshop_idx].humidity);
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printf(" Lowest Temp: Workshop %d (%.2f C, %.2f %% Humidity)\n",
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shared_data_ptr->workshops[coldest_workshop_idx].workshop_id,
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min_temp,
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shared_data_ptr->workshops[coldest_workshop_idx].humidity);
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printf("---\n\n");
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}
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else if (!valid_data_found) {
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printf("[%s] Waiting for initial data from workshops...\n\n", ctime(&(time_t){ time(NULL) }));
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}
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else {
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printf("[%s] No valid temperature extremes found yet (all workshops might have same temp or no data).\n\n", ctime(&(time_t){ time(NULL) }));
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}
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fflush(stdout);
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// Sleep for the display interval
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for (int i = 0; i < MONITOR_DISPLAY_INTERVAL && keep_running; ++i) {
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sleep(1);
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}
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}
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// 5. Cleanup: Unmap shared memory, close file descriptor, close semaphore
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cleanup_ipc_consumer();
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return EXIT_SUCCESS;
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}

‎5_Multithreaded-Programming/data_structures.h‎

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// data_structures.h
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#ifndef DATA_STRUCTURES_H
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#define DATA_STRUCTURES_H
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#include <pthread.h> // For pthread_t, though not strictly needed in Program 2 if monitor is in main
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#include <semaphore.h> // For sem_t
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#include <time.h> // For time_t (optional)
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#define NUM_WORKSHOPS 10
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#define SHM_NAME "/workshop_monitoring_shm"
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#define SEM_MUTEX_NAME "/workshop_monitoring_mutex_sem"
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// Min/Max values for simulation
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#define MIN_TEMP 10.0f
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#define MAX_TEMP 40.0f
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#define MIN_HUMIDITY 20.0f
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#define MAX_HUMIDITY 80.0f
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// Interval for workshop data generation (seconds)
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#define WORKSHOP_UPDATE_INTERVAL 2
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// Interval for monitoring display (seconds)
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#define MONITOR_DISPLAY_INTERVAL 5
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typedef struct {
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int workshop_id;
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float temperature;
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float humidity;
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// time_t last_updated; // Optional: timestamp of last update
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} WorkshopData;
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typedef struct {
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WorkshopData workshops[NUM_WORKSHOPS];
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// Could add a generation counter or other metadata if needed
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// int data_ready_count; // Could be used with condition variables if within one process
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} SharedData;
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#endif // DATA_STRUCTURES_H

‎5_Multithreaded-Programming/parity_checker.c‎

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#include <stdio.h>
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#include <pthread.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <stdbool.h>
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// Shared variables
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int total_count = 0;
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int even_count = 0;
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pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
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bool running = true;
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// Thread to report total count every 3 seconds
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void* report_total(void* arg) {
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while(running) {
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sleep(3);
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pthread_mutex_lock(&mutex);
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printf("Total numbers entered so far: %d\n", total_count);
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pthread_mutex_unlock(&mutex);
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}
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return NULL;
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}
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// Thread to report even count every 5 seconds
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void* report_even(void* arg) {
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while(running) {
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sleep(5);
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pthread_mutex_lock(&mutex);
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printf("Total even numbers entered so far: %d\n", even_count);
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pthread_mutex_unlock(&mutex);
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}
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return NULL;
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}
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int main() {
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pthread_t total_thread, even_thread;
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int num;
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// Create the reporting threads
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pthread_create(&total_thread, NULL, report_total, NULL);
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pthread_create(&even_thread, NULL, report_even, NULL);
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printf("Enter integers (enter a negative number to exit):\n");
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while(1) {
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scanf("%d", &num);
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if(num < 0) {
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printf("Negative number entered. Exiting program.\n");
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break;
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}
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pthread_mutex_lock(&mutex);
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total_count++;
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if(num % 2 == 0) {
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even_count++;
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printf("%d is an even number.\n", num);
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} else {
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printf("%d is an odd number.\n", num);
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}
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pthread_mutex_unlock(&mutex);
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}
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// Signal threads to terminate and wait for them
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running = false;
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pthread_join(total_thread, NULL);
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pthread_join(even_thread, NULL);
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pthread_mutex_destroy(&mutex);
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return 0;
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}

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