From: Matt Corallo <git@bluematt.me>
Date: Tue, 23 Jan 2024 21:19:51 +0000 (+0000)
Subject: [C#] Use an instance of the callback delegate, not the fn itself
X-Git-Tag: v0.0.121.0~14
X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=commitdiff_plain;h=52329a425adbefe5776a2fb01b516d31634518d8;p=ldk-java

[C#] Use an instance of the callback delegate, not the fn itself

When passing the callback delegate to C from C# during static init,
it appears (but only on Windows) this actually creates a C# class
instance for the delegate and passes that. However, that class
instance is eventually GC'd and our callbacks will start failing.

Instead, we create a static instance of of the delegate and pass
that to C.
---

diff --git a/csharp_strings.py b/csharp_strings.py
index 9dd23d1f..c1873f3d 100644
--- a/csharp_strings.py
+++ b/csharp_strings.py
@@ -1442,10 +1442,11 @@ public class {struct_name.replace("LDK","")} : CommonBase {{
 		}}
 	}}
 	public delegate {jret} {fn_suffix}_callback(int obj_ptr, int fn_id{jargs});
+	static {fn_suffix}_callback {fn_suffix}_callback_inst = c_callback_{fn_suffix};
 """)
                 bindings.write(self.native_meth_decl(f"register_{fn_suffix}_invoker", "int") + f"({fn_suffix}_callback callee);\n")
                 # Easiest way to get a static run is just define a variable, even if we dont care
-                bindings.write(f"\tstatic int _run_{fn_suffix}_registration = register_{fn_suffix}_invoker(c_callback_{fn_suffix});")
+                bindings.write(f"\tstatic int _run_{fn_suffix}_registration = register_{fn_suffix}_invoker({fn_suffix}_callback_inst);")
 
             bindings.write("""
 }