modules: started documentation

modules/README.md

+# Knot DNS Resolver extensions
+
+The resolver library[^lib] leverages the [processing API][processing] from the libknot to separate packet processing code
+into layers. In order to keep the core library sane and coverable, there are only two built-in layers:
+the [iterator](lib/layer/iterate.c), and the [cache](lib/layer/itercache.c). The resolver context however can
+load shared libraries on runtime, which allows us to build and register external modules as well.
+
+## Supported languages
+
+Currently modules written in C are supported.
+There is also a rudimentary support for writing modules in Go — ⑴ the library has no native Go bindings, library is accessible using [CGO][cgo], ⑵ gc doesn't support building shared libraries, [GCCGO][gccgo] is required, ⑶ no coroutines and no garbage collecting thread, as the Go code is called from C threads.
+
+There is a plan for Lua scriptables, but it's not implemented yet.
+
+## Available services
+
+## The anatomy of an extension
+
+### Writing a module in C
+
+### Writing a module in Go
+
+[^lib]: See the Knot DNS Resolver library [documentation](lib/README.md).
+[processing]: https://gitlab.labs.nic.cz/labs/knot/tree/master/src/libknot/processing
+[cgo]: http://golang.org/cmd/cgo/
+[gccgo]: https://golang.org/doc/install/gccgo
\ No newline at end of file

modules/gostats/gostats.go

@@ -23,22 +23,18 @@ func Api() C.uint32_t {
 }
 
 func Init(module *C.struct_kr_module) C.int {
-	fmt.Printf("go_init(%s)\n", C.GoString((*C.char)(module.data)))
 	return 0
 }
 
 func Deinit(module *C.struct_kr_module) C.int {
-	fmt.Println("go_deinit()")
 	return 0
 }
 
 func Begin(ctx *C.knot_layer_t, param unsafe.Pointer) C.int {
-	fmt.Println("go_begin()")
 	return 0
 }
 
 func Finish(ctx *C.knot_layer_t) C.int {
-	fmt.Println("go_finish()")
 	return 0
 }