(chakra) recursive evaluation

I'm trying to a simple module loading feature which requires recursive script execution:

net -> js -> net -> js

This is currently not possible, because the scriptdispatcher is blocked by the first eval.

JavaScriptEngineSwitcher/src/JavaScriptEngineSwitcher.ChakraCore/ScriptDispatcher.cs

Line 152 in 753deb7

waitHandle.WaitOne();

My current workaround is to use eval, which i don't like. Is there any way to make recursive calls work?

Hello, Michael!

You could give an example of JS code that causes this error.

Simple test case:

_engine.EmbedHostObject("_test", (Action<string>)(c => _engine.Evaluate(c));
_engine.Evaluate("_test('var test;')");

Why are you doing this? You can use a eval keyword.

What about this:

_engine.EmbedHostObject("_test", (Action<string>)(c => _engine.ExecuteFile($"dist/{c}.js"));
_engine.Evaluate("_test('test')");

I'm trying to implement a simple module system.

Try this variant:

Func<string, string> readFileContent = File.ReadAllText;

_engine.EmbedHostObject("readFileContent", readFileContent);
_engine.Execute(@"function loadModule(moduleName) {
    var modulePath = 'dist/' + moduleName + '.js';
    var moduleContent = readFileContent(modulePath);

    return new Function(moduleContent)();
}");
_engine.CallFunction("loadModule", "test");

That's my workaround 😄

Only here, instead of the eval(…) expression used the new Function(…)(), which is more safe.

When there is free time, I will deal with this problem.

Solution

JavaScriptEngineSwitcher/src/JavaScriptEngineSwitcher.ChakraCore/ScriptDispatcher.cs

Lines 147 to 153 in 753deb7

    
           using (var waitHandle = new ManualResetEvent(false)) 
        
           { 
        
           	task = new ScriptTask(del, waitHandle); 
        
           	EnqueueTask(task); 
        
           	waitHandle.WaitOne(); 
        
           }

Inline the execution if we don't specify a max stack size.
Check, if we are the dispatcher thread and inline the execution.

Which solution do you prefer, or another solution? I can send a PR.

Which solution do you prefer, or another solution? I can send a PR.

I'll deal with the problem myself, but later.

OK, the new Function solution is a little bit annoying, because i don't have a filename in the stack traces.

So it is very difficult to find the right source file.

Hello, Michael!

This error is fixed in version 3.0.8.

	using (var waitHandle = new ManualResetEvent(false))
	{
	task = new ScriptTask(del, waitHandle);
	EnqueueTask(task);

	waitHandle.WaitOne();
	}