Add tracing support to node (#1940)

* drop in tracing to replace log

* add structured logging to trace messages

* add structured logging to debug messages

* add structured logging to info messages

* add structured logging to warn messages

* add structured logging to error messages

* normalize spacing and Display vs Debug

* add instrumentation to the various 'fn run'

* use explicit tracing module throughout

* fix availability distribution test

* don't double-print errors

* remove further redundancy from logs

* fix test errors

* fix more test errors

* remove unused kv_log_macro

* fix unused variable

* add tracing spans to collation generation

* add tracing spans to av-store

* add tracing spans to backing

* add tracing spans to bitfield-signing

* add tracing spans to candidate-selection

* add tracing spans to candidate-validation

* add tracing spans to chain-api

* add tracing spans to provisioner

* add tracing spans to runtime-api

* add tracing spans to availability-distribution

* add tracing spans to bitfield-distribution

* add tracing spans to network-bridge

* add tracing spans to collator-protocol

* add tracing spans to pov-distribution

* add tracing spans to statement-distribution

* add tracing spans to overseer

* cleanup

polkadot/node/core/runtime-api/src/lib.rs

@@ -40,6 +40,8 @@ use sp_api::{ProvideRuntimeApi};
 
 use futures::prelude::*;
 
+const LOG_TARGET: &str = "RuntimeApi";
+
 /// The `RuntimeApiSubsystem`. See module docs for more details.
 pub struct RuntimeApiSubsystem<Client> {
 	client: Arc<Client>,
@@ -66,6 +68,7 @@ impl<Client, Context> Subsystem<Context> for RuntimeApiSubsystem<Client> where
 	}
 }
 
+#[tracing::instrument(skip(ctx, subsystem), fields(subsystem = LOG_TARGET))]
 async fn run<Client>(
 	mut ctx: impl SubsystemContext<Message = RuntimeApiMessage>,
 	subsystem: RuntimeApiSubsystem<Client>,
@@ -90,6 +93,7 @@ async fn run<Client>(
 	}
 }
 
+#[tracing::instrument(level = "trace", skip(client, metrics), fields(subsystem = LOG_TARGET))]
 fn make_runtime_api_request<Client>(
 	client: &Client,
 	metrics: &Metrics,