Control of the ClearScript Engine

[Rison-Hub]

In a script executed by the ClearScript engine, there's a for loop performing a heartbeat-like function. I want to achieve the following:

Send a pause command to the engine to pause the entire engine and halt this for loop.
Send a start command to the engine to restart the engine and resume this for loop.
Send a stop command to the engine to terminate the currently executing script.

[ClearScriptLib]

Hi @Rison-Hub,

The only way to achieve that is to have the host and script implement a play/pause/exit protocol of some sort.

For example, the host could expose a property that the script periodically checks to determine whether to continue, await a continuation signal, or exit.

Good luck!

[Rison-Hub]

Can you provide me with a simple demo for reference?

[ClearScriptLib]

Hi @Rison-Hub,

Can you provide me with a simple demo for reference?

Sure. Here's a class that provides basic pause/resume/terminate support:

public class ScriptControl {
    private readonly ManualResetEventSlim _notPaused = new(true);
    private bool _terminationRequested;
    public void Pause() => _notPaused.Reset();
    public void Resume() => _notPaused.Set();
    public void Terminate() => _terminationRequested = true;
    public bool CanContinue() {
        if (_terminationRequested) return false;
        _notPaused.Wait();
        return true;
    }
}

To use it, let's kick off a script execution thread:

var scriptControl = new ScriptControl();
var scriptThread = new Thread(() => {
    using var engine = new V8ScriptEngine();
    engine.AddHostType(typeof(Console));
    engine.Script.canContinue = new Func<bool>(scriptControl.CanContinue);
    engine.Script.sleep = new Action<int>(Thread.Sleep);
    engine.Execute(@"
        while (true) {
            if (!canContinue()) break;
            Console.WriteLine('Script running...');
            sleep(500);
        }
    ");
});
scriptThread.Start();

We can now control script execution as follows:

Thread.Sleep(2000);
scriptControl.Pause();
Console.WriteLine("Script paused for 5 seconds.");
Thread.Sleep(5000);
scriptControl.Resume();
Thread.Sleep(2000);
scriptControl.Terminate();
scriptThread.Join();
Console.WriteLine("Script terminated.");

This is just a simple example, but hopefully it gives you an idea of what's possible.

Cheers!

[Rison-Hub]

thank you