obs: improve spans use in flashbots submit (#165)

This PR improves span usage in the Flashbots submit task for better tracking in groundcover and analytics.

Author: dylanlott

src/tasks/submit/builder_helper.rs

@@ -262,8 +262,7 @@ impl BuilderHelperTask {
             let host_block_number = sim_result.host_block_number();
 
             let span = sim_result.sim_env.span.clone();
-
-            span_debug!(span, "submit channel received block");
+            span_debug!(span, "builder helper task received block");
 
             // Don't submit empty blocks
             if sim_result.block.is_empty() {

src/tasks/submit/flashbots.rs

@@ -14,7 +14,7 @@ use alloy::{
 use eyre::OptionExt;
 use init4_bin_base::{deps::metrics::counter, utils::signer::LocalOrAws};
 use tokio::{sync::mpsc, task::JoinHandle};
-use tracing::{Instrument, debug};
+use tracing::{Instrument, debug, debug_span};
 
 /// Handles construction, simulation, and submission of rollup blocks to the
 /// Flashbots network.
@@ -117,38 +117,56 @@ impl FlashbotsTask {
                 debug!("upstream task gone - exiting flashbots task");
                 break;
             };
-            let span = sim_result.span();
-            span_debug!(span, "received sim result");
+
+            let span = sim_result.sim_env.clone_span();
+
+            // Don't submit empty blocks
+            if sim_result.block.is_empty() {
+                counter!("signet.builder.flashbots.empty_block").increment(1);
+                span_debug!(span, "received empty block - skipping");
+                continue;
+            }
+            span_debug!(span, "flashbots task received block");
 
             // Prepare a MEV bundle with the configured call type from the sim result
-            let Ok(bundle) =
+            let result =
                 self.prepare(&sim_result).instrument(span.clone()).await.inspect_err(|error| {
                     counter!("signet.builder.flashbots.bundle_prep_failures").increment(1);
                     span_debug!(span, %error, "bundle preparation failed");
-                })
-            else {
-                continue;
+                });
+            let bundle = match result {
+                Ok(bundle) => bundle,
+                Err(_) => continue,
             };
 
-            // Send the bundle to Flashbots
+            // Make a child span to cover submission
+            let submit_span = debug_span!(
+                parent: &span,
+                "flashbots.submit",
+            );
+
+            // Send the bundle to Flashbots, instrumenting the send future so all
+            // events inside the async send are attributed to the submit span.
             let response = self
                 .flashbots()
                 .send_mev_bundle(bundle.clone())
                 .with_auth(self.signer.clone())
+                .into_future()
+                .instrument(submit_span.clone())
                 .await;
 
             match response {
                 Ok(resp) => {
                     counter!("signet.builder.flashbots.bundles_submitted").increment(1);
                     span_debug!(
-                        span,
+                        submit_span,
                         hash = resp.map(|r| r.bundle_hash.to_string()),
                         "received bundle hash after submitted to flashbots"
                     );
                 }
                 Err(err) => {
                     counter!("signet.builder.flashbots.submission_failures").increment(1);
-                    span_error!(span, %err, "MEV bundle submission failed - error returned");
+                    span_error!(submit_span, %err, "MEV bundle submission failed - error returned");
                 }
             }
         }