feat: implement getEpochInfo RPC method

crates/superbank-rpc/README.md

@@ -11,6 +11,7 @@ writer that matches the same schemas).
 - `getBlock`
 - `getBlockHeight`
 - `getSlot`
+- `getEpochInfo`
 - `getTransactionCount`
 - `getLatestBlockhash`
 - `getBlockTime`
@@ -31,7 +32,7 @@ Notes:
 - `processed` commitment is supported for a subset of methods when compiled with
   `--features grpc-head-cache` and enabled at runtime with `HEAD_CACHE_ENABLED=true`
   (see "Optional gRPC head cache" below).
-- `getBlockHeight`, `getSlot`, and `getTransactionCount` accept an optional single config object as the sole param:
+- `getBlockHeight`, `getSlot`, `getEpochInfo`, and `getTransactionCount` accept an optional single config object as the sole param:
   - `commitment`: `processed|confirmed|finalized` (defaults to `finalized`; `processed` requires the head cache)
   - `minContextSlot`: optional `u64`; if the server's current context slot is below this value, the
     call fails with JSON-RPC error `-32016` ("Minimum context slot has not been reached") and

crates/superbank-rpc/src/handlers/blocks.rs

@@ -23,9 +23,9 @@ use crate::clickhouse::{QueryTimings, StoredBlockPayload, StoredBlockRecord};
 use crate::handlers::{
     RouteMetric,
     types::{
-        GetBlockHeightConfig, GetBlocksConfig, GetInflationRewardConfig, GetLatestBlockhashConfig,
-        GetLatestBlockhashResult, GetLatestBlockhashValue, GetSlotConfig, InflationRewardInfo,
-        MAX_GET_BLOCKS_RANGE, RpcContextSlot, reject_unknown_fields,
+        EpochInfo, GetBlockHeightConfig, GetBlocksConfig, GetInflationRewardConfig,
+        GetLatestBlockhashConfig, GetLatestBlockhashResult, GetLatestBlockhashValue, GetSlotConfig,
+        InflationRewardInfo, MAX_GET_BLOCKS_RANGE, RpcContextSlot, reject_unknown_fields,
     },
 };
 use crate::hydration::{BlockHydrationError, hydrate_block_payload};
@@ -626,6 +626,251 @@ pub(crate) async fn handle_get_slot(
     Ok(json_rpc_success_response(id, json!(slot)))
 }
 
+pub(crate) async fn handle_get_epoch_info(
+    state: Arc<AppState>,
+    id: Value,
+    params: Option<Vec<Value>>,
+) -> Result<Response, StatusCode> {
+    let mut route = RouteMetric::for_state("getEpochInfo", state.as_ref());
+
+    // getEpochInfo accepts the same optional config as getSlot: an object with
+    // an optional commitment and minContextSlot.
+    let config = match params.filter(|v| !v.is_empty()) {
+        None => GetSlotConfig::default(),
+        Some(mut params) => {
+            if params.len() != 1 {
+                route.invalid_params();
+                return Ok(json_rpc_error_response(
+                    id,
+                    -32602,
+                    "Invalid params: expected a single config object",
+                    None,
+                ));
+            }
+
+            let value = params.remove(0);
+            if value.is_null() {
+                GetSlotConfig::default()
+            } else if value.is_object() {
+                match serde_json::from_value::<GetSlotConfig>(value) {
+                    Ok(config) => config,
+                    Err(e) => {
+                        route.invalid_params();
+                        return Ok(json_rpc_error_response(
+                            id,
+                            -32602,
+                            format!("Invalid params: failed to parse config ({e})"),
+                            None,
+                        ));
+                    }
+                }
+            } else {
+                route.invalid_params();
+                return Ok(json_rpc_error_response(
+                    id,
+                    -32602,
+                    "Invalid params: config must be an object",
+                    None,
+                ));
+            }
+        }
+    };
+
+    let commitment = config.commitment.unwrap_or_default();
+
+    if commitment.is_processed() {
+        #[cfg(feature = "grpc-head-cache")]
+        {
+            if state.head_cache.is_none() {
+                route.invalid_params();
+                return Ok(json_rpc_error_response(
+                    id,
+                    -32602,
+                    "Only confirmed or finalized commitments are supported",
+                    Some(json!({ "requestedCommitment": commitment.commitment })),
+                ));
+            }
+        }
+        #[cfg(not(feature = "grpc-head-cache"))]
+        {
+            route.invalid_params();
+            return Ok(json_rpc_error_response(
+                id,
+                -32602,
+                "Only confirmed or finalized commitments are supported",
+                Some(json!({ "requestedCommitment": commitment.commitment })),
+            ));
+        }
+    }
+
+    // Resolve the context slot honoring the requested commitment. Start from the
+    // latest ClickHouse-ingested slot, then, when the head cache holds a newer
+    // slot that meets the commitment (e.g. a confirmed slot not yet in
+    // ClickHouse), derive the snapshot from it instead. This keeps getEpochInfo
+    // consistent with getSlot/getBlockHeight/getTransactionCount, which all use
+    // the head cache for confirmed reads. With the head cache off, every field
+    // resolves to the finalized ClickHouse slot. Reuses TransactionCountPlan
+    // since the slot/count resolution is identical. Epoch math assumes the
+    // default schedule with no warmup, matching getInflationReward.
+    let clickhouse_slot = match state
+        .latest_slot_cache
+        .get_or_refresh(&state.clickhouse)
+        .await
+    {
+        Ok(slot) => slot,
+        Err(e) => {
+            metrics::backend_error("get_latest_finalized_slot");
+            error!("Failed to fetch latest slot for getEpochInfo: {}", e);
+            return Ok(json_rpc_internal_error_response(id));
+        }
+    };
+
+    #[cfg(feature = "grpc-head-cache")]
+    let plan = {
+        let mut plan = TransactionCountPlan::ClickHouseThroughSlot {
+            context_slot: clickhouse_slot,
+        };
+        if let Some(cache) = state.head_cache.as_ref()
+            && let Some(overlay) =
+                cache.transaction_count_overlay_at_least(commitment.commitment, clickhouse_slot)
+            && overlay.context_slot > clickhouse_slot
+        {
+            plan = TransactionCountPlan::ClickHouseBeforeSlotPlusHead {
+                context_slot: overlay.context_slot,
+                clickhouse_before_slot: overlay.start_slot,
+                head_transaction_count: overlay.transaction_count,
+            };
+        }
+        plan
+    };
+    #[cfg(not(feature = "grpc-head-cache"))]
+    let plan = TransactionCountPlan::ClickHouseThroughSlot {
+        context_slot: clickhouse_slot,
+    };
+
+    let context_slot = plan.context_slot();
+    match &plan {
+        TransactionCountPlan::ClickHouseThroughSlot { .. } => route.source_clickhouse(),
+        #[cfg(feature = "grpc-head-cache")]
+        TransactionCountPlan::ClickHouseBeforeSlotPlusHead { .. } => route.source_head_cache(),
+    }
+
+    if let Some(min_context_slot) = config.min_context_slot
+        && context_slot < min_context_slot
+    {
+        route.rpc_error();
+        return Ok(json_rpc_error_response(
+            id,
+            JSON_RPC_SERVER_ERROR_MIN_CONTEXT_SLOT_NOT_REACHED as i32,
+            "Minimum context slot has not been reached",
+            Some(json!({ "contextSlot": context_slot })),
+        ));
+    }
+
+    // Block height for the resolved slot: the ClickHouse path reads it from the
+    // block-height cache; the head path reads it from the head cache, since a
+    // confirmed slot isn't ingested into ClickHouse yet (getBlockHeight pattern).
+    let block_height = match &plan {
+        TransactionCountPlan::ClickHouseThroughSlot { .. } => match state
+            .latest_block_height_cache
+            .get_or_refresh(context_slot, &state.clickhouse)
+            .await
+        {
+            Ok(Some(height)) => height,
+            Ok(None) => {
+                route.source_none();
+                error!(
+                    slot = context_slot,
+                    "Block height unavailable for getEpochInfo"
+                );
+                return Ok(json_rpc_internal_error_response(id));
+            }
+            Err(e) => {
+                metrics::backend_error("get_block_height_by_slot");
+                error!(
+                    "Failed to query ClickHouse block height at slot {} for getEpochInfo: {}",
+                    context_slot, e
+                );
+                return Ok(json_rpc_internal_error_response(id));
+            }
+        },
+        #[cfg(feature = "grpc-head-cache")]
+        TransactionCountPlan::ClickHouseBeforeSlotPlusHead { .. } => match state
+            .head_cache
+            .as_ref()
+            .and_then(|cache| cache.latest_block_height_at_least(commitment.commitment))
+        {
+            Some(height) => height,
+            None => {
+                route.source_none();
+                error!(
+                    slot = context_slot,
+                    "Head block height unavailable for getEpochInfo"
+                );
+                return Ok(json_rpc_internal_error_response(id));
+            }
+        },
+    };
+
+    // Transaction count through the resolved slot, following getTransactionCount.
+    let (transaction_count, timings) = match plan {
+        TransactionCountPlan::ClickHouseThroughSlot { context_slot } => {
+            match state
+                .clickhouse
+                .get_transaction_count_by_slot(context_slot)
+                .await
+            {
+                Ok(result) => result,
+                Err(e) => {
+                    metrics::backend_error("get_transaction_count_by_slot");
+                    error!(
+                        "Failed to query ClickHouse transaction count at slot {} for getEpochInfo: {}",
+                        context_slot, e
+                    );
+                    return Ok(json_rpc_internal_error_response(id));
+                }
+            }
+        }
+        #[cfg(feature = "grpc-head-cache")]
+        TransactionCountPlan::ClickHouseBeforeSlotPlusHead {
+            context_slot,
+            clickhouse_before_slot,
+            head_transaction_count,
+        } => match state
+            .clickhouse
+            .get_transaction_count_before_slot(clickhouse_before_slot)
+            .await
+        {
+            Ok((base_transaction_count, timings)) => (
+                base_transaction_count.saturating_add(head_transaction_count),
+                timings,
+            ),
+            Err(e) => {
+                metrics::backend_error("get_transaction_count_before_slot");
+                error!(
+                    "Failed to query ClickHouse transaction count before slot {} for context slot {} (getEpochInfo): {}",
+                    clickhouse_before_slot, context_slot, e
+                );
+                return Ok(json_rpc_internal_error_response(id));
+            }
+        },
+    };
+
+    let epoch_info = EpochInfo {
+        absolute_slot: context_slot,
+        block_height,
+        epoch: context_slot / DEFAULT_SLOTS_PER_EPOCH,
+        slot_index: context_slot % DEFAULT_SLOTS_PER_EPOCH,
+        slots_in_epoch: DEFAULT_SLOTS_PER_EPOCH,
+        transaction_count: Some(transaction_count),
+    };
+
+    route.success();
+    let mut resp = json_rpc_success_response(id, json!(epoch_info));
+    add_downstream_header(&mut resp, &timings);
+    Ok(resp)
+}
+
 enum TransactionCountPlan {
     ClickHouseThroughSlot {
         context_slot: u64,

crates/superbank-rpc/src/handlers/mod.rs

@@ -535,6 +535,7 @@ fn metrics_method_label(method: &str) -> &'static str {
         "getBlock" => "getBlock",
         "getBlockHeight" => "getBlockHeight",
         "getSlot" => "getSlot",
+        "getEpochInfo" => "getEpochInfo",
         "getTransactionCount" => "getTransactionCount",
         "getLatestBlockhash" => "getLatestBlockhash",
         "getBlockTime" => "getBlockTime",
@@ -861,6 +862,7 @@ async fn dispatch_json_rpc_request(
                 blocks::handle_get_block_height(state, id_for_dispatch, params).await
             }
             "getSlot" => blocks::handle_get_slot(state, id_for_dispatch, params).await,
+            "getEpochInfo" => blocks::handle_get_epoch_info(state, id_for_dispatch, params).await,
             "getTransactionCount" => {
                 blocks::handle_get_transaction_count(state, id_for_dispatch, params).await
             }

crates/superbank-rpc/src/handlers/types.rs

@@ -256,6 +256,17 @@ pub(crate) struct InflationRewardInfo {
     pub(crate) commission: Option<u8>,
 }
 
+#[derive(Debug, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub(crate) struct EpochInfo {
+    pub(crate) absolute_slot: u64,
+    pub(crate) block_height: u64,
+    pub(crate) epoch: u64,
+    pub(crate) slot_index: u64,
+    pub(crate) slots_in_epoch: u64,
+    pub(crate) transaction_count: Option<u64>,
+}
+
 #[derive(Debug, Serialize)]
 pub(crate) struct GetLatestBlockhashResult {
     pub(crate) context: RpcContextSlot,