G1ANT - disposing of unmanaged code in C# macros

Question

I am enjoying using G1ANT's "macros" capability to call unmanaged code, but the unmanaged objects are of course not being automatically garbage collected absent code to do it.

My request is specifically for best practices in disposing of unmanaged code in these G1ANT C# macros, not for disposing of the same in C# generally, and it is not a request to fix the code below, which runs as is just fine.

If I were coding in C# using Visual Studio, I would likely use a System.Runtime.InteropServices.SafeHandle class, override the Finalize method, or use one of the other approaches in common use (see also this post on disposing of unmanaged objects in C#).

But none of these approaches appear to be a good fit for G1ANT macros per se, at least with my novice experience of them.

For illustration purposes I'm referring to this G1ANT code, but WITHOUT the last line in the macro (ahk.Reset()), because it runs fine with that line, more than once. (I'm painfully aware that there must be a much better example, but as I'm new to G1ANT, this is the only thing I have so far.) What I'm after is C# code that works in G1ANT when there is no explicit disposal of the unmanaged object:

addon core version 4.100.19170.929
addon language version 4.100.19170.929
-dialog ♥macrodlls
♥macrodlls = System.dll,System.Drawing.dll,System.Windows.Forms.dll,AutoHotkey.Interop.dll,System.Runtime.InteropServices.dll
-dialog ♥macrodlls
♥macronamespaces = System,AutoHotkey.Interop,System.Windows.Forms
⊂
var ahk = AutoHotkeyEngine.Instance;
//Load a library or exec scripts in a file
ahk.LoadFile("functions.ahk");

//execute a specific function (found in functions.ahk), with 2 parameters
ahk.ExecFunction("MyFunction", "Hello", "World");

string sayHelloFunction = "SayHello(name) \r\n { \r\n MsgBox, Hello %name% \r\n return \r\n }";
ahk.ExecRaw(sayHelloFunction);

//execute's newly made function\
ahk.ExecRaw(@"SayHello(""Mario"") ");

var add5Results = ahk.ExecFunction("Add5", "5");
MessageBox.Show("ExecFunction: Result of 5 with Add5 func is" + add5Results);
addon core version 4.100.19170.929
addon language version 4.100.19170.929
-dialog ♥macrodlls
♥macrodlls = System.dll,System.Drawing.dll,System.Windows.Forms.dll,AutoHotkey.Interop.dll,System.Runtime.InteropServices.dll,System.Reflection.dll,Microsoft.CSharp.dll
-dialog ♥macrodlls
♥macronamespaces = System,AutoHotkey.Interop,System.Windows.Forms,System.Reflection
⊂
var ahk = AutoHotkeyEngine.Instance;
//Load a library or exec scripts in a file
ahk.LoadFile("functions.ahk");

//execute a specific function (found in functions.ahk), with 2 parameters
ahk.ExecFunction("MyFunction", "Hello", "World");

string sayHelloFunction = "SayHello(name) \r\n { \r\n MsgBox, Hello %name% \r\n return \r\n }";
ahk.ExecRaw(sayHelloFunction);

//executes new function
ahk.ExecRaw(@"SayHello(""Mario"") ");

var add5Results = ahk.ExecFunction("Add5", "5");
MessageBox.Show("ExecFunction: Result of 5 with Add5 func is" + add5Results);
ahk.Reset();
⊃
⊃

It's taken nearly verbatim from the AutoHotkey.Interop github page.

Without the last line in the macro ('ahk.Reset()), the code runs perfectly the first time through, but on the second run G1ANT still sees the included AutoHotkey file, and warns of duplicate function definitions, but continues and still functions properly. The as-far-as-I-can-tell-undocumented AutoHotkey.Interop command Reset() takes care of the garbage collection problem by calling

        public void Terminate()
        {
                AutoHotkeyDll.ahkTerminate(1000);
        }

        public void Reset() {
                Terminate();
                AutoHotkeyDll.ahkReload();
                AutoHotkeyDll.ahktextdll("", "", "");
        }

Thus, the AutoHotkeyEngine instance itself appears to be garbage collected, even without the ahk.Reset();, but the AutoHotkey script it loads into an object is not.

Stopping the G1ANT.Robot application and restarting, then reloading the script above (as mentioned, without the line ahk.Reset();), works just fine, but once again only for a single run.

Edit: The given answer's advice on treatment of singletons is what I will use henceforth when loading of AutoHotkey function scripts and the DLL itself. It seems prudent and good practice to check to see if the DLL or function file have been loaded, whether problems exist or not. "An ounce of prevention", etc. In addition, I have forked the AutoHotkey.Interop repo here, adding a boolean check to see if the AutoHotkeyEngine instance is ready.

Best regards,

burque505

Łukasƨ Fronczyk · Answer 1 · 2019-08-12T10:19:50.647

You use AutoHotkeyEngine.Instance, so I guess it's a singleton. It will stay loaded in memory as long as the corresponding dll is kept there, and the latter is loaded and lives as long as the its domain lives. The macro app domain (the place where script stuff is placed) currently lives as long as Robot's app domain, so in fact your singleton instance lives as long as Robot. Either:

don't use singleton,
or reset it right after obtaining the instance (kinda what you already did),
or treat it as a singleton that has life span longer than your app. In this case after obtaining singleton instance do a check if your functions file has been already loaded and only load it if it wasn't done already.

G1ANT - disposing of unmanaged code in C# macros

1 Answers1