Day48 - epoll and timerfd Idle Timeout

Goal

Implement idle timeout handling in an epoll-based TCP server.

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Step 1 - Create timerfd

• Use timerfd_create()
• Set periodic timer (1 second)

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Step 2 - Add timerfd to epoll

epoll_ctl(epfd, EPOLL_CTL_ADD, timer_fd, &ev);

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Step 3 - Handle timer event

read(timer_fd, &expirations, sizeof(expirations));

Update server time:

server.timer_ms = get_current_ticks_ms();

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Step 4 - Add client list

• linked list
• add on accept
• remove on destroy

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Step 5 - Track last activity

client->last_active_ms = now;

Update on:

• accept
• recv > 0

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Step 6 - Scan timeout

while (client) {
    next = client->next;

    if (timeout)
        client_destroy();

    client = next;
}

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Step 7 - Testing

Run test script:

bash test_timeout.sh

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Expected Result

• idle client is disconnected
• active client remains connected
• multiple clients handled correctly