Instrumented macro refactoring

Cargo.toml

@@ -1,4 +1,5 @@
-workspace = { members = ["instrumented_macro"] }
+workspace = { members = ["electrs_macros"] }
+
 [package]
 name = "electrs"
 version = "0.4.1"
@@ -17,18 +18,14 @@ default-run = "electrs"
 liquid = ["elements"]
 electrum-discovery = ["electrum-client"]
 bench = []
-default = ["no-otlp-tracing"]
 otlp-tracing = [
-    "tracing/max_level_trace",
+    "tracing",
     "tracing-subscriber",
     "opentelemetry",
     "tracing-opentelemetry",
     "opentelemetry-otlp",
     "opentelemetry-semantic-conventions"
 ]
-no-otlp-tracing = [
-    "tracing/max_level_off"
-]
 
 [dependencies]
 arraydeque = "0.5.1"
@@ -72,12 +69,12 @@ tracing-opentelemetry = {  version = "0.21.0", optional = true }
 opentelemetry-otlp = { version = "0.13.0", default-features = false, features = ["http-proto", "reqwest-client"], optional = true }
 tracing-subscriber = { version = "0.3.17", default-features = false, features = ["env-filter", "fmt"], optional = true }
 opentelemetry-semantic-conventions = { version = "0.12.0", optional = true }
-tracing = { version = "0.1.40", default-features = false, features = ["attributes"] }
+tracing = { version = "0.1.40", default-features = false, features = ["attributes"], optional = true }
 
 # optional dependencies for electrum-discovery
 electrum-client = { version = "0.8", optional = true }
 zmq = "0.10.0"
-instrumented_macro = { path = "instrumented_macro" }
+electrs_macros = { path = "electrs_macros", features = ["otlp-tracing"] }
 
 [dev-dependencies]
 bitcoind = { version = "0.34.3", features = ["25_0"] }

instrumented_macro/Cargo.toml → electrs_macros/Cargo.toml

@@ -1,11 +1,14 @@
 [package]
-name = "instrumented_macro"
+name = "electrs_macros"
 version = "0.1.0"
 edition = "2021"
 
 [lib]
 proc-macro = true
 
+[features]
+otlp-tracing = []
+
 [dependencies]
 syn = "2.0"
 quote = "1.0"

electrs_macros/src/lib.rs

@@ -0,0 +1,35 @@
+use proc_macro::TokenStream;
+
+#[proc_macro_attribute]
+pub fn trace(_attr: TokenStream, item: TokenStream) -> TokenStream {
+    #[cfg(feature = "otlp-tracing")]
+    {
+        use quote::quote;
+        use syn::{parse_macro_input, ItemFn};
+
+        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
+        };
+
+        return expanded.into();
+    }
+
+    #[cfg(not(feature = "otlp-tracing"))]
+    {
+        item
+    }
+}

src/bin/electrs.rs

@@ -159,7 +159,7 @@ fn main_() {
     }
 }
 
-#[cfg(feature = "no-otlp-tracing")]
+#[cfg(not(feature = "otlp-tracing"))]
 fn main() {
     main_();
 }