feat(o11y): add error extraction to DiscoveryOperation

Author: haphungw

src/lro/src/internal/discovery.rs

@@ -27,6 +27,7 @@ use crate::{
     Poller, PollingBackoffPolicy, PollingErrorPolicy, PollingResult, Result,
     sealed::Poller as SealedPoller,
 };
+use google_cloud_gax::error::rpc::Status;
 use google_cloud_gax::polling_state::PollingState;
 use google_cloud_gax::retry_result::RetryResult;
 use std::sync::Arc;
@@ -54,6 +55,11 @@ pub trait DiscoveryOperation {
     ///
     /// It may be `None` in which case the polling loop stops.
     fn name(&self) -> Option<&String>;
+
+    /// Returns the error status of the operation, if any.
+    fn error(&self) -> Option<Status> {
+        None
+    }
 }
 
 pub fn new_discovery_poller<S, SF, Q, QF, O>(

src/lro/src/internal/tracing.rs

@@ -67,7 +67,32 @@ impl LroRecorder {
     pub fn attempt_count(&self) -> Option<u32> {
         self.attempt_count
     }
+}
 
+/// Helper macro to record telemetry for Discovery LROs.
+#[macro_export]
+#[doc(hidden)]
+macro_rules! record_discovery_polling_result {
+    ($span:expr, $op:expr) => {
+        let span = &$span;
+        let op = &$op;
+        let done = $crate::internal::DiscoveryOperation::done(op);
+        span.record("gcp.longrunning.done", done);
+        if done {
+            let error = $crate::internal::DiscoveryOperation::error(op);
+            let code = error.as_ref().map(|e| e.code as i32).unwrap_or(0);
+            span.record("gcp.longrunning.status_code", code);
+            if let Some(status) = error {
+                span.record("otel.status_code", "ERROR");
+                span.record("otel.status_description", &status.message);
+                span.record("rpc.response.status_code", status.code as i32);
+                span.record("error.type", status.code.to_string());
+            }
+        }
+    };
+}
+
+impl LroRecorder {
     /// Creates a new clone of `LroRecorder` carrying the specified LRO polling attempt count.
     ///
     /// Since `LroRecorder` is immutable to guarantee thread-safety, this updates the context