I am developing a multi-threaded network application focused on packet processing that involves sender and receiver threads. This application runs on a single-core CPU, which adds complexity to how threading is managed. To ensure that other threads do not access and send the same packet before the receiving thread signals completion (via a semaphore), I acquire a mutex lock in the sender thread. The process includes locking the mutex, setting packet->request = 1, calling the send(packet) function, waiting for the semaphore post, and finally unlocking the mutex to return packet->result.

In the receiver thread, after the packet is received with recv(packet), I set packet->result = 100 (for example) and signal the semaphore with sem_post.

Here is the simplified implementation:

#include <pthread.h>
#include <semaphore.h>

typedef struct {
    int request;
    int result;
} Packet;

pthread_mutex_t mutex;
sem_t sem;
Packet *packet;

void *sender(void *arg) {
    pthread_mutex_lock(&mutex);
    packet->request = 1;
    send(packet);
    sem_wait(&sem);
    int result = packet->result;
    pthread_mutex_unlock(&mutex);
    return (void*)(intptr_t)result;
}

void *receiver(void *arg) {
    recv(packet);
    packet->result = 100;
    sem_post(&sem);
    return NULL;
}

int main() {
    pthread_t t1, t2;
    pthread_mutex_init(&mutex, NULL);
    sem_init(&sem, 0, 0);
    packet = malloc(sizeof(Packet));

    pthread_create(&t1, NULL, sender, NULL);
    pthread_create(&t2, NULL, receiver, NULL);

    pthread_join(t1, NULL);
    pthread_join(t2, NULL);

    pthread_mutex_destroy(&mutex);
    sem_destroy(&sem);
    free(packet);

    return 0;
}

Given that this system operates on a single-core CPU, I am especially concerned about potential deadlocks and inefficiencies due to the nature of single-core context switching and thread management. Are there better approaches or optimizations that could be applied to this synchronization strategy to ensure safety and efficiency? I am looking forward to your expert advice and suggestions. Thank you!