Add sync batch state metrics (#8847)

Co-Authored-By: Jimmy Chen <jchen.tc@gmail.com>

beacon_node/network/src/sync/batch.rs

@@ -10,10 +10,22 @@ use std::marker::PhantomData;
 use std::ops::Sub;
 use std::time::Duration;
 use std::time::Instant;
-use strum::Display;
+use strum::{Display, EnumIter, IntoStaticStr};
 use types::Slot;
 use types::{DataColumnSidecarList, Epoch, EthSpec};
 
+/// Batch states used as metrics labels.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, EnumIter, IntoStaticStr)]
+#[strum(serialize_all = "snake_case")]
+pub enum BatchMetricsState {
+    AwaitingDownload,
+    Downloading,
+    AwaitingProcessing,
+    Processing,
+    AwaitingValidation,
+    Failed,
+}
+
 pub type BatchId = Epoch;
 
 /// Type of expected batch.
@@ -142,6 +154,18 @@ impl<D: Hash> BatchState<D> {
     pub fn poison(&mut self) -> BatchState<D> {
         std::mem::replace(self, BatchState::Poisoned)
     }
+
+    /// Returns the metrics state for this batch.
+    pub fn metrics_state(&self) -> BatchMetricsState {
+        match self {
+            BatchState::AwaitingDownload => BatchMetricsState::AwaitingDownload,
+            BatchState::Downloading(_) => BatchMetricsState::Downloading,
+            BatchState::AwaitingProcessing(..) => BatchMetricsState::AwaitingProcessing,
+            BatchState::Processing(_) => BatchMetricsState::Processing,
+            BatchState::AwaitingValidation(_) => BatchMetricsState::AwaitingValidation,
+            BatchState::Poisoned | BatchState::Failed => BatchMetricsState::Failed,
+        }
+    }
 }
 
 impl<E: EthSpec, B: BatchConfig, D: Hash> BatchInfo<E, B, D> {