In event-driven programming, it is often necessary to execute certain actions based on time triggers. The C++ standard library provides the std::chrono library, which is a powerful tool for working with time in a portable and efficient way. In this blog post, we will explore how to use std::chrono to create time-based triggers for event-driven programming.

Table of Contents

• Introduction to std::chrono
• Using std::chrono to create timers
• Handling timeouts with std::chrono
• Conclusion

Introduction to std::chrono

std::chrono is a header-only library introduced in C++11 that provides facilities for working with time, durations, and clocks. It offers high-resolution timers and allows for precise measurement and manipulation of time intervals.

The library introduces several components, including std::chrono::duration for representing time intervals, std::chrono::time_point for representing points in time, and std::chrono::clock for accessing various clocks.

Using std::chrono to create timers

To create time-based triggers, we can leverage the std::chrono::duration and std::chrono::time_point classes. std::chrono::duration represents a specific period of time, while std::chrono::time_point represents a specific point in time.

Here is an example of how to create a timer using std::chrono:

#include <iostream>
#include <chrono>

int main() {
    // Define the duration of the timer (e.g., 1 second)
    std::chrono::duration<int, std::ratio<1>> duration(1);

    // Get the current time point
    std::chrono::time_point<std::chrono::system_clock> start = std::chrono::system_clock::now();

    // Calculate the end time point
    std::chrono::time_point<std::chrono::system_clock> end = start + duration;

    while (std::chrono::system_clock::now() < end) {
        // Wait for the timer to expire
    }

    // Timer has expired, execute the desired action
    std::cout << "Timer expired!" << std::endl;

    return 0;
}

In this example, we define a duration of 1 second using std::chrono::duration and obtain the current time point using std::chrono::system_clock::now(). We calculate the end time point by adding the duration to the start time point. Finally, we wait in a loop until the current time exceeds the end time, at which point we execute the desired action.

Handling timeouts with std::chrono

Timeouts are a common use case for time-based triggers in event-driven programming. We can utilize std::chrono to handle timeouts in a straightforward manner.

Consider the following example of handling a timeout using std::chrono:

#include <iostream>
#include <chrono>
#include <thread>

void performAction() {
    // Action to be performed on timeout
    std::cout << "Timeout occurred!" << std::endl;
}

int main() {
    // Define the timeout duration
    std::chrono::duration<int, std::ratio<1>> timeout(5);

    // Start a separate thread to execute the desired action
    std::thread action_thread([timeout]() {
        std::this_thread::sleep_for(timeout);
        performAction();
    });

    // Do other work in the main thread

    // Wait for the action thread to complete
    action_thread.join();

    return 0;
}

In this example, we define a timeout duration of 5 seconds and start a separate thread using std::thread. The separate thread sleeps for the specified timeout duration using std::this_thread::sleep_for and then executes the desired action, in this case, calling the performAction() function. Meanwhile, the main thread can continue performing other tasks. The action thread is then joined with the main thread to ensure synchronization.

Conclusion

With std::chrono, creating time-based triggers for event-driven programming becomes easier and more efficient. By utilizing the std::chrono::duration and std::chrono::time_point classes, along with other functionalities provided by the library, developers can accurately measure and control time-based events in their applications.

By employing the concepts explained in this blog post, you can enhance your event-driven programming projects by incorporating time-based triggers using std::chrono efficiently and effectively.

#References

• cppreference - std::chrono