Add new HTTP endpoint to get supply for a given state root

beacon_node/http_api/src/lib.rs

@@ -4448,6 +4448,35 @@ pub fn serve<T: BeaconChainTypes>(
             })
         });
 
+    // GET lighthouse/analysis/global_validator_supply/{state_root}
+    let get_lighthouse_global_validator_supply = warp::path("lighthouse")
+        .and(warp::path("analysis"))
+        .and(warp::path("global_validator_supply"))
+        .and(warp::path::param::<StateId>())
+        .and(warp::path::end())
+        .and(task_spawner_filter.clone())
+        .and(chain_filter.clone())
+        .then(
+            |state_id: StateId,
+             task_spawner: TaskSpawner<T::EthSpec>,
+             chain: Arc<BeaconChain<T>>| {
+                task_spawner.blocking_json_task(Priority::P1, move || {
+                    state_id
+                        .map_state_and_execution_optimistic_and_finalized(
+                            &chain,
+                            |state, execution_optimistic, finalized| {
+                                Ok((
+                                    state.balances().iter().sum::<u64>(),
+                                    execution_optimistic,
+                                    finalized,
+                                ))
+                            },
+                        )
+                        .map(api_types::GenericResponse::from)
+                })
+            },
+        );
+
     // GET lighthouse/analysis/attestation_performance/{index}
     let get_lighthouse_attestation_performance = warp::path("lighthouse")
         .and(warp::path("analysis"))
@@ -4720,6 +4749,7 @@ pub fn serve<T: BeaconChainTypes>(
                 .uor(get_lighthouse_staking)
                 .uor(get_lighthouse_database_info)
                 .uor(get_lighthouse_block_rewards)
+                .uor(get_lighthouse_global_validator_supply)
                 .uor(get_lighthouse_attestation_performance)
                 .uor(get_beacon_light_client_optimistic_update)
                 .uor(get_beacon_light_client_finality_update)

book/src/api_lighthouse.md

@@ -775,6 +775,28 @@ Caveats:
   This is because the state *prior* to the `start_epoch` needs to be loaded from the database, and
   loading a state on a boundary is most efficient.
 
+## `lighthouse/analysis/global_validator_supply/{state_root}`
+
+Returns the sum of all validator balances for a given state root.
+
+```bash
+curl -X GET "http://localhost:5052/lighthouse/analysis/global_validator_supply/0x7e76880eb67bbdc86250aa578958e9d0675e64e714337855204fb5abaaf82c2b" -H "accept: application/json" | jq
+```
+
+```json
+{
+  "data": [
+    674144000000000,
+    false,
+    true
+  ]
+}
+```
+
+The two boolean flags in the response are respectively:
+* `execution_optimistic`: whether the response was computed using optimistically synced data
+* `finalized`: whether the response was computed over finalized dasta
+
 ## `/lighthouse/logs`
 
 This is a Server Side Event subscription endpoint. This allows a user to read