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Optimize delay control in game loops using time_nanosleep

gitbox 2025-05-29

In game development, precise delay control is crucial to ensuring smooth and responsiveness of the game. PHP is a scripting language, although not a traditional game development language, but is often used in some mini-games or server-based game logic. This article will introduce how to use PHP's time_nanosleep function to more accurately optimize delay control in game loops.

What is time_nanosleep?

time_nanosleep is a function provided by PHP that allows the program to pause the execution of specified seconds and nanosecond times. Compared with sleep or usleep , time_nanosleep supports higher precision delay control, which is suitable for scenarios with higher delay requirements.

The function definition is as follows:

 bool time_nanosleep(int $seconds, int $nanoseconds)

  • $seconds is the number of seconds paused, non-negative integer.

  • $nanoseconds is the number of nanoseconds paused, ranging from 0 to 999,999,999.

If the call is successful, the function returns true , otherwise false .

Why use time_nanosleep in the game loop?

In the game loop, it is usually necessary to accurately control the interval time of each frame, such as 60 frames per second (FPS), with an interval of approximately 16.67 milliseconds per frame. The traditional sleep(1) or usleep(10000) functions have limited accuracy, especially sleep only supports second-level delay, while usleep only supports microseconds, but in some system environments, the microsecond accuracy is not stable. time_nanosleep supports nanosecond-level delay, which is more suitable for applications with stricter time interval requirements.

Example: Optimize game loops using time_nanosleep

Here is a simple PHP game loop example, assuming the target is 60 FPS, using time_nanosleep to control each frame interval:

 <?php
$fps = 60;
$frameTimeSec = 1;
$frameTimeNano = (int)(1e9 / $fps); // Every second

while (true) {
    $start = hrtime(true); // Get the current high-precision time，Units in nanoseconds

    // Game logic processing
    // ...

    $end = hrtime(true);
    $elapsed = $end - $start; // This frame consumes time（Nanoseconds）

    // Calculate the time to sleep
    $sleepTime = $frameTimeNano - $elapsed;

    if ($sleepTime > 0) {
        // 拆分成秒和Nanoseconds传入 time_nanosleep
        $sec = intdiv($sleepTime, 1e9);
        $nano = $sleepTime % (int)1e9;

        time_nanosleep($sec, $nano);
    }
}
?>

Code parsing

  • Use hrtime(true) to obtain the high-precision current time, unit nanoseconds, to facilitate time difference calculation.

  • Calculate the number of nanoseconds that should be consumed per frame, for example 1 second/60 = 16,666,666 nanoseconds.

  • Calculate the logical execution time of this frame $elapsed , and then calculate the remaining time for sleep.

  • Use time_nanosleep to accurately pause the remaining time to ensure that each frame interval is as close as possible to the preset time.

Things to note

  • time_nanosleep may have incomplete sleep time due to system scheduling or other processes, and certain errors still need to be tolerated.

  • time_nanosleep does not support negative numbers or parameters that exceed the range, and it is necessary to ensure that the incoming seconds and nanoseconds are reasonable.

  • In Windows environments, the nanosecond accuracy may not be as good as Linux or Unix-like systems, and the effects vary by environment.

  • If you want more fine-grained control, you can also combine hrtime() to achieve dynamic adjustment.

Further optimization suggestions

  1. Dynamic adjustment of frame rate <br> Dynamically adjust the frame rate of the game loop according to the current system load to make the experience more stable.

  2. Segmented Delay Control <br> Use time_nanosleep for long pauses, and use fine-tuning in combination with usleep , etc. to improve the overall time control accuracy.

  3. Avoid blocking operations <br> Ensure the game logic code is efficient, avoid excessive blockage, and reduce the pressure on delay control.

References

Through the above methods, PHP programs can control the delay of game loops with higher accuracy, improve the smoothness and response speed of game running, and meet the server needs of some delay-sensitive mini-games or online games. I hope this article will be helpful for you to optimize the time control of PHP game loops.

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