Forward logging directives to Polkadot workers (#6534)

This pull request forward all the logging directives given to the node
via `RUST_LOG` or `-l` to the workers, instead of only forwarding
`RUST_LOG`.

---------

Co-authored-by: GitHub Action <action@github.com>

polkadot/node/core/pvf/Cargo.toml

@@ -38,6 +38,7 @@ polkadot-node-primitives = { workspace = true, default-features = true }
 polkadot-node-subsystem = { workspace = true, default-features = true }
 polkadot-primitives = { workspace = true, default-features = true }
 
+sc-tracing = { workspace = true }
 sp-core = { workspace = true, default-features = true }
 sp-maybe-compressed-blob = { optional = true, workspace = true, default-features = true }
 polkadot-node-core-pvf-prepare-worker = { optional = true, workspace = true, default-features = true }

polkadot/node/core/pvf/src/worker_interface.rs

@@ -237,10 +237,8 @@ impl WorkerHandle {
 		// Clear all env vars from the spawned process.
 		let mut command = process::Command::new(program.as_ref());
 		command.env_clear();
-		// Add back any env vars we want to keep.
-		if let Ok(value) = std::env::var("RUST_LOG") {
-			command.env("RUST_LOG", value);
-		}
+
+		command.env("RUST_LOG", sc_tracing::logging::get_directives().join(","));
 
 		let mut child = command
 			.args(extra_args)

prdoc/pr_6534.prdoc

@@ -0,0 +1,10 @@
+title: Forward logging directives to Polkadot workers
+doc:
+- audience: Node Dev
+  description: |-
+    This pull request forward all the logging directives given to the node via `RUST_LOG` or `-l` to the workers, instead of only forwarding `RUST_LOG`.
+crates:
+- name: polkadot-node-core-pvf
+  bump: patch
+- name: sc-tracing
+  bump: patch

substrate/client/tracing/src/logging/directives.rs

@@ -40,14 +40,19 @@ pub(crate) fn add_default_directives(directives: &str) {
 	add_directives(directives);
 }
 
-/// Add directives to current directives
+/// Add directives to current directives.
 pub fn add_directives(directives: &str) {
 	CURRENT_DIRECTIVES
 		.get_or_init(|| Mutex::new(Vec::new()))
 		.lock()
 		.push(directives.to_owned());
 }
 
+/// Returns the current directives.
+pub fn get_directives() -> Vec<String> {
+	CURRENT_DIRECTIVES.get_or_init(|| Mutex::new(Vec::new())).lock().clone()
+}
+
 /// Parse `Directive` and add to default directives if successful.
 ///
 /// Ensures the supplied directive will be restored when resetting the log filter.