instrumented macro implementation

Cargo.toml

@@ -1,3 +1,4 @@
+workspace = { members = ["instrumented_macro"] }
 [package]
 name = "electrs"
 version = "0.4.1"
@@ -76,7 +77,7 @@ tracing = { version = "0.1.40", default-features = false, features = ["attribute
 # optional dependencies for electrum-discovery
 electrum-client = { version = "0.8", optional = true }
 zmq = "0.10.0"
-
+instrumented_macro = { path = "instrumented_macro" }
 
 [dev-dependencies]
 bitcoind = { version = "0.34.3", features = ["25_0"] }

instrumented_macro/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "instrumented_macro"
+version = "0.1.0"
+edition = "2021"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+syn = "2.0"
+quote = "1.0"
+proc-macro2 = "1.0"

instrumented_macro/src/lib.rs

@@ -0,0 +1,26 @@
+use proc_macro::TokenStream;
+use quote::quote;
+use syn::{parse_macro_input, ItemFn};
+
+#[proc_macro_attribute]
+pub fn instrumented(attr: TokenStream, item: TokenStream) -> TokenStream {
+    let additional_fields = if !attr.is_empty() {
+        let attr_tokens: proc_macro2::TokenStream = attr.into();
+        quote! {, #attr_tokens }
+    } else {
+        quote! {}
+    };
+
+    let function = parse_macro_input!(item as ItemFn);
+
+    let fields_tokens = quote! {
+        fields(module = module_path!(), file = file!(), line = line!() #additional_fields)
+    };
+
+    let expanded = quote! {
+        #[tracing::instrument(skip_all, #fields_tokens)]
+        #function
+    };
+
+    expanded.into()
+}