Add additional metrics for BeaconChain

beacon_node/http_server/src/metrics.rs

@@ -6,10 +6,12 @@ use beacon_chain::{BeaconChain, BeaconChainTypes};
 use iron::prelude::*;
 use iron::{status::Status, Handler, IronResult, Request, Response};
 use persistent::Read;
-use prometheus::{Encoder, IntGauge, Opts, Registry, TextEncoder};
-use slot_clock::SlotClock;
+use prometheus::{Encoder, Registry, TextEncoder};
 use std::sync::Arc;
-use types::Slot;
+
+pub use local_metrics::LocalMetrics;
+
+mod local_metrics;
 
 /// Yields a handler for the metrics endpoint.
 pub fn build_handler<T: BeaconChainTypes + 'static>(
@@ -28,39 +30,6 @@ pub fn build_handler<T: BeaconChainTypes + 'static>(
     chain
 }
 
-pub struct LocalMetrics {
-    present_slot: IntGauge,
-    best_slot: IntGauge,
-    validator_count: IntGauge,
-}
-
-impl LocalMetrics {
-    pub fn new() -> Result<Self, prometheus::Error> {
-        Ok(Self {
-            present_slot: {
-                let opts = Opts::new("present_slot", "slot_at_time_of_scrape");
-                IntGauge::with_opts(opts)?
-            },
-            best_slot: {
-                let opts = Opts::new("best_slot", "slot_of_block_at_chain_head");
-                IntGauge::with_opts(opts)?
-            },
-            validator_count: {
-                let opts = Opts::new("validator_count", "number_of_validators");
-                IntGauge::with_opts(opts)?
-            },
-        })
-    }
-
-    pub fn register(&self, registry: &Registry) -> Result<(), prometheus::Error> {
-        registry.register(Box::new(self.present_slot.clone()))?;
-        registry.register(Box::new(self.best_slot.clone()))?;
-        registry.register(Box::new(self.validator_count.clone()))?;
-
-        Ok(())
-    }
-}
-
 /// Handle a request for Prometheus metrics.
 ///
 /// Returns a text string containing all metrics.
@@ -77,18 +46,8 @@ fn handle_metrics<T: BeaconChainTypes + 'static>(req: &mut Request) -> IronResul
         .get::<Read<LocalMetricsKey>>()
         .map_err(map_persistent_err_to_500)?;
 
-    let present_slot = beacon_chain
-        .slot_clock
-        .present_slot()
-        .unwrap_or_else(|_| None)
-        .unwrap_or_else(|| Slot::new(0));
-    local_metrics.present_slot.set(present_slot.as_u64() as i64);
-
-    let best_slot = beacon_chain.head().beacon_block.slot;
-    local_metrics.best_slot.set(best_slot.as_u64() as i64);
-
-    let validator_count = beacon_chain.head().beacon_state.validator_registry.len();
-    local_metrics.validator_count.set(validator_count as i64);
+    // Update metrics that are calculated on each scrape.
+    local_metrics.update(&beacon_chain);
 
     let mut buffer = vec![];
     let encoder = TextEncoder::new();

beacon_node/http_server/src/metrics/local_metrics.rs

@@ -0,0 +1,66 @@
+use beacon_chain::{BeaconChain, BeaconChainTypes};
+use prometheus::{IntGauge, Opts, Registry};
+use slot_clock::SlotClock;
+use types::Slot;
+
+pub struct LocalMetrics {
+    present_slot: IntGauge,
+    best_slot: IntGauge,
+    validator_count: IntGauge,
+    justified_epoch: IntGauge,
+    finalized_epoch: IntGauge,
+}
+
+impl LocalMetrics {
+    /// Create a new instance.
+    pub fn new() -> Result<Self, prometheus::Error> {
+        Ok(Self {
+            present_slot: {
+                let opts = Opts::new("present_slot", "slot_at_time_of_scrape");
+                IntGauge::with_opts(opts)?
+            },
+            best_slot: {
+                let opts = Opts::new("best_slot", "slot_of_block_at_chain_head");
+                IntGauge::with_opts(opts)?
+            },
+            validator_count: {
+                let opts = Opts::new("validator_count", "number_of_validators");
+                IntGauge::with_opts(opts)?
+            },
+            justified_epoch: {
+                let opts = Opts::new("justified_epoch", "state_justified_epoch");
+                IntGauge::with_opts(opts)?
+            },
+            finalized_epoch: {
+                let opts = Opts::new("finalized_epoch", "state_finalized_epoch");
+                IntGauge::with_opts(opts)?
+            },
+        })
+    }
+
+    /// Registry this instance with the `registry`.
+    pub fn register(&self, registry: &Registry) -> Result<(), prometheus::Error> {
+        registry.register(Box::new(self.present_slot.clone()))?;
+        registry.register(Box::new(self.best_slot.clone()))?;
+        registry.register(Box::new(self.validator_count.clone()))?;
+
+        Ok(())
+    }
+
+    /// Update the metrics in `self` to the latest values.
+    pub fn update<T: BeaconChainTypes>(&self, beacon_chain: &BeaconChain<T>) {
+        let state = &beacon_chain.head().beacon_state;
+
+        let present_slot = beacon_chain
+            .slot_clock
+            .present_slot()
+            .unwrap_or_else(|_| None)
+            .unwrap_or_else(|| Slot::new(0));
+        self.present_slot.set(present_slot.as_u64() as i64);
+
+        self.best_slot.set(state.slot.as_u64() as i64);
+        self.validator_count.set(state.validator_registry.len() as i64);
+        self.justified_epoch.set(state.current_justified_epoch.as_u64() as i64);
+        self.finalized_epoch.set(state.finalized_epoch.as_u64() as i64);
+    }
+}