Merge commit '65a5eb829264cb279ed66814c961991ae3a0a04b' into eip4844

beacon_node/beacon_chain/src/beacon_block_streamer.rs

@@ -0,0 +1,974 @@
+use crate::{BeaconChain, BeaconChainError, BeaconChainTypes};
+use execution_layer::{ExecutionLayer, ExecutionPayloadBodyV1};
+use slog::{crit, debug, Logger};
+use std::collections::HashMap;
+use std::sync::Arc;
+use store::{DatabaseBlock, ExecutionPayloadEip4844};
+use task_executor::TaskExecutor;
+use tokio::sync::{
+    mpsc::{self, UnboundedSender},
+    RwLock,
+};
+use tokio_stream::{wrappers::UnboundedReceiverStream, Stream};
+use types::{
+    ChainSpec, EthSpec, ExecPayload, ExecutionBlockHash, ForkName, Hash256, SignedBeaconBlock,
+    SignedBlindedBeaconBlock, Slot,
+};
+use types::{
+    ExecutionPayload, ExecutionPayloadCapella, ExecutionPayloadHeader, ExecutionPayloadMerge,
+};
+
+#[derive(PartialEq)]
+pub enum CheckEarlyAttesterCache {
+    Yes,
+    No,
+}
+
+#[derive(Debug)]
+pub enum Error {
+    PayloadReconstruction(String),
+    BlocksByRangeFailure(Box<execution_layer::Error>),
+    RequestNotFound,
+    BlockResultNotFound,
+}
+
+const BLOCKS_PER_RANGE_REQUEST: u64 = 32;
+
+// This is the same as a DatabaseBlock but the Arc allows us to avoid an unnecessary clone.
+enum LoadedBeaconBlock<E: EthSpec> {
+    Full(Arc<SignedBeaconBlock<E>>),
+    Blinded(Box<SignedBlindedBeaconBlock<E>>),
+}
+type LoadResult<E> = Result<Option<LoadedBeaconBlock<E>>, BeaconChainError>;
+type BlockResult<E> = Result<Option<Arc<SignedBeaconBlock<E>>>, BeaconChainError>;
+
+enum RequestState<E: EthSpec> {
+    UnSent(Vec<BlockParts<E>>),
+    Sent(HashMap<Hash256, Arc<BlockResult<E>>>),
+}
+
+struct BodiesByRange<E: EthSpec> {
+    start: u64,
+    count: u64,
+    state: RequestState<E>,
+}
+
+// stores the components of a block for future re-construction in a small form
+struct BlockParts<E: EthSpec> {
+    blinded_block: Box<SignedBlindedBeaconBlock<E>>,
+    header: Box<ExecutionPayloadHeader<E>>,
+    body: Option<Box<ExecutionPayloadBodyV1<E>>>,
+}
+
+impl<E: EthSpec> BlockParts<E> {
+    pub fn new(
+        blinded: Box<SignedBlindedBeaconBlock<E>>,
+        header: ExecutionPayloadHeader<E>,
+    ) -> Self {
+        Self {
+            blinded_block: blinded,
+            header: Box::new(header),
+            body: None,
+        }
+    }
+
+    pub fn root(&self) -> Hash256 {
+        self.blinded_block.canonical_root()
+    }
+
+    pub fn slot(&self) -> Slot {
+        self.blinded_block.message().slot()
+    }
+
+    pub fn block_hash(&self) -> ExecutionBlockHash {
+        self.header.block_hash()
+    }
+}
+
+fn reconstruct_default_header_block<E: EthSpec>(
+    blinded_block: Box<SignedBlindedBeaconBlock<E>>,
+    header_from_block: ExecutionPayloadHeader<E>,
+    spec: &ChainSpec,
+) -> BlockResult<E> {
+    let fork = blinded_block
+        .fork_name(spec)
+        .map_err(BeaconChainError::InconsistentFork)?;
+
+    let payload: ExecutionPayload<E> = match fork {
+        ForkName::Merge => ExecutionPayloadMerge::default().into(),
+        ForkName::Capella => ExecutionPayloadCapella::default().into(),
+        ForkName::Eip4844 => ExecutionPayloadEip4844::default().into(),
+        ForkName::Base | ForkName::Altair => {
+            return Err(Error::PayloadReconstruction(format!(
+                "Block with fork variant {} has execution payload",
+                fork
+            ))
+            .into())
+        }
+    };
+
+    let header_from_payload = ExecutionPayloadHeader::from(payload.to_ref());
+    if header_from_payload == header_from_block {
+        blinded_block
+            .try_into_full_block(Some(payload))
+            .ok_or(BeaconChainError::AddPayloadLogicError)
+            .map(Arc::new)
+            .map(Some)
+    } else {
+        Err(BeaconChainError::InconsistentPayloadReconstructed {
+            slot: blinded_block.slot(),
+            exec_block_hash: header_from_block.block_hash(),
+            canonical_transactions_root: header_from_block.transactions_root(),
+            reconstructed_transactions_root: header_from_payload.transactions_root(),
+        })
+    }
+}
+
+fn reconstruct_blocks<E: EthSpec>(
+    block_map: &mut HashMap<Hash256, Arc<BlockResult<E>>>,
+    block_parts_with_bodies: HashMap<Hash256, BlockParts<E>>,
+    log: &Logger,
+) {
+    for (root, block_parts) in block_parts_with_bodies {
+        if let Some(payload_body) = block_parts.body {
+            match payload_body.to_payload(block_parts.header.as_ref().clone()) {
+                Ok(payload) => {
+                    let header_from_payload = ExecutionPayloadHeader::from(payload.to_ref());
+                    if header_from_payload == *block_parts.header {
+                        block_map.insert(
+                            root,
+                            Arc::new(
+                                block_parts
+                                    .blinded_block
+                                    .try_into_full_block(Some(payload))
+                                    .ok_or(BeaconChainError::AddPayloadLogicError)
+                                    .map(Arc::new)
+                                    .map(Some),
+                            ),
+                        );
+                    } else {
+                        let error = BeaconChainError::InconsistentPayloadReconstructed {
+                            slot: block_parts.blinded_block.slot(),
+                            exec_block_hash: block_parts.header.block_hash(),
+                            canonical_transactions_root: block_parts.header.transactions_root(),
+                            reconstructed_transactions_root: header_from_payload
+                                .transactions_root(),
+                        };
+                        debug!(log, "Failed to reconstruct block"; "root" => ?root, "error" => ?error);
+                        block_map.insert(root, Arc::new(Err(error)));
+                    }
+                }
+                Err(string) => {
+                    block_map.insert(
+                        root,
+                        Arc::new(Err(Error::PayloadReconstruction(string).into())),
+                    );
+                }
+            }
+        } else {
+            block_map.insert(
+                root,
+                Arc::new(Err(BeaconChainError::BlockHashMissingFromExecutionLayer(
+                    block_parts.block_hash(),
+                ))),
+            );
+        }
+    }
+}
+
+impl<E: EthSpec> BodiesByRange<E> {
+    pub fn new(maybe_block_parts: Option<BlockParts<E>>) -> Self {
+        if let Some(block_parts) = maybe_block_parts {
+            Self {
+                start: block_parts.header.block_number(),
+                count: 1,
+                state: RequestState::UnSent(vec![block_parts]),
+            }
+        } else {
+            Self {
+                start: 0,
+                count: 0,
+                state: RequestState::UnSent(vec![]),
+            }
+        }
+    }
+
+    pub fn is_unsent(&self) -> bool {
+        matches!(self.state, RequestState::UnSent(_))
+    }
+
+    pub fn push_block_parts(&mut self, block_parts: BlockParts<E>) -> Result<(), BlockParts<E>> {
+        if self.count == BLOCKS_PER_RANGE_REQUEST {
+            return Err(block_parts);
+        }
+
+        match &mut self.state {
+            RequestState::Sent(_) => Err(block_parts),
+            RequestState::UnSent(blocks_parts_vec) => {
+                let block_number = block_parts.header.block_number();
+                if self.count == 0 {
+                    self.start = block_number;
+                    self.count = 1;
+                    blocks_parts_vec.push(block_parts);
+                    Ok(())
+                } else {
+                    // need to figure out if this block fits in the request
+                    if block_number < self.start
+                        || self.start + BLOCKS_PER_RANGE_REQUEST <= block_number
+                    {
+                        return Err(block_parts);
+                    }
+
+                    blocks_parts_vec.push(block_parts);
+                    if self.start + self.count <= block_number {
+                        self.count = block_number - self.start + 1;
+                    }
+
+                    Ok(())
+                }
+            }
+        }
+    }
+
+    async fn execute(&mut self, execution_layer: &ExecutionLayer<E>, log: &Logger) {
+        if let RequestState::UnSent(blocks_parts_ref) = &mut self.state {
+            let block_parts_vec = std::mem::take(blocks_parts_ref);
+
+            let mut block_map = HashMap::new();
+            match execution_layer
+                .get_payload_bodies_by_range(self.start, self.count)
+                .await
+            {
+                Ok(bodies) => {
+                    let mut range_map = (self.start..(self.start + self.count))
+                        .zip(bodies.into_iter().chain(std::iter::repeat(None)))
+                        .collect::<HashMap<_, _>>();
+
+                    let mut with_bodies = HashMap::new();
+                    for mut block_parts in block_parts_vec {
+                        with_bodies
+                            // it's possible the same block is requested twice, using
+                            // or_insert_with() skips duplicates
+                            .entry(block_parts.root())
+                            .or_insert_with(|| {
+                                let block_number = block_parts.header.block_number();
+                                block_parts.body =
+                                    range_map.remove(&block_number).flatten().map(Box::new);
+
+                                block_parts
+                            });
+                    }
+
+                    reconstruct_blocks(&mut block_map, with_bodies, log);
+                }
+                Err(e) => {
+                    let block_result =
+                        Arc::new(Err(Error::BlocksByRangeFailure(Box::new(e)).into()));
+                    debug!(log, "Payload bodies by range failure"; "error" => ?block_result);
+                    for block_parts in block_parts_vec {
+                        block_map.insert(block_parts.root(), block_result.clone());
+                    }
+                }
+            }
+            self.state = RequestState::Sent(block_map);
+        }
+    }
+
+    pub async fn get_block_result(
+        &mut self,
+        root: &Hash256,
+        execution_layer: &ExecutionLayer<E>,
+        log: &Logger,
+    ) -> Option<Arc<BlockResult<E>>> {
+        self.execute(execution_layer, log).await;
+        if let RequestState::Sent(map) = &self.state {
+            return map.get(root).cloned();
+        }
+        // Shouldn't reach this point
+        None
+    }
+}
+
+#[derive(Clone)]
+enum EngineRequest<E: EthSpec> {
+    ByRange(Arc<RwLock<BodiesByRange<E>>>),
+    // When we already have the data or there's an error
+    NoRequest(Arc<RwLock<HashMap<Hash256, Arc<BlockResult<E>>>>>),
+}
+
+impl<E: EthSpec> EngineRequest<E> {
+    pub fn new_by_range() -> Self {
+        Self::ByRange(Arc::new(RwLock::new(BodiesByRange::new(None))))
+    }
+    pub fn new_no_request() -> Self {
+        Self::NoRequest(Arc::new(RwLock::new(HashMap::new())))
+    }
+
+    pub async fn is_unsent(&self) -> bool {
+        match self {
+            Self::ByRange(bodies_by_range) => bodies_by_range.read().await.is_unsent(),
+            Self::NoRequest(_) => false,
+        }
+    }
+
+    pub async fn push_block_parts(&mut self, block_parts: BlockParts<E>, log: &Logger) {
+        match self {
+            Self::ByRange(bodies_by_range) => {
+                let mut request = bodies_by_range.write().await;
+
+                if let Err(block_parts) = request.push_block_parts(block_parts) {
+                    drop(request);
+                    let new_by_range = BodiesByRange::new(Some(block_parts));
+                    *self = Self::ByRange(Arc::new(RwLock::new(new_by_range)));
+                }
+            }
+            Self::NoRequest(_) => {
+                // this should _never_ happen
+                crit!(
+                    log,
+                    "Please notify the devs";
+                    "beacon_block_streamer" => "push_block_parts called on NoRequest Variant",
+                );
+            }
+        }
+    }
+
+    pub async fn push_block_result(
+        &mut self,
+        root: Hash256,
+        block_result: BlockResult<E>,
+        log: &Logger,
+    ) {
+        // this function will only fail if something is seriously wrong
+        match self {
+            Self::ByRange(_) => {
+                // this should _never_ happen
+                crit!(
+                    log,
+                    "Please notify the devs";
+                    "beacon_block_streamer" => "push_block_result called on ByRange",
+                );
+            }
+            Self::NoRequest(results) => {
+                results.write().await.insert(root, Arc::new(block_result));
+            }
+        }
+    }
+
+    pub async fn get_block_result(
+        &self,
+        root: &Hash256,
+        execution_layer: &ExecutionLayer<E>,
+        log: &Logger,
+    ) -> Arc<BlockResult<E>> {
+        match self {
+            Self::ByRange(by_range) => {
+                by_range
+                    .write()
+                    .await
+                    .get_block_result(root, execution_layer, log)
+                    .await
+            }
+            Self::NoRequest(map) => map.read().await.get(root).cloned(),
+        }
+        .unwrap_or_else(|| {
+            crit!(
+                log,
+                "Please notify the devs";
+                "beacon_block_streamer" => "block_result not found in request",
+                "root" => ?root,
+            );
+            Arc::new(Err(Error::BlockResultNotFound.into()))
+        })
+    }
+}
+
+pub struct BeaconBlockStreamer<T: BeaconChainTypes> {
+    execution_layer: ExecutionLayer<T::EthSpec>,
+    check_early_attester_cache: CheckEarlyAttesterCache,
+    beacon_chain: Arc<BeaconChain<T>>,
+}
+
+impl<T: BeaconChainTypes> BeaconBlockStreamer<T> {
+    pub fn new(
+        beacon_chain: &Arc<BeaconChain<T>>,
+        check_early_attester_cache: CheckEarlyAttesterCache,
+    ) -> Result<Self, BeaconChainError> {
+        let execution_layer = beacon_chain
+            .execution_layer
+            .as_ref()
+            .ok_or(BeaconChainError::ExecutionLayerMissing)?
+            .clone();
+
+        Ok(Self {
+            execution_layer,
+            check_early_attester_cache,
+            beacon_chain: beacon_chain.clone(),
+        })
+    }
+
+    fn check_early_attester_cache(
+        &self,
+        root: Hash256,
+    ) -> Option<Arc<SignedBeaconBlock<T::EthSpec>>> {
+        if self.check_early_attester_cache == CheckEarlyAttesterCache::Yes {
+            self.beacon_chain.early_attester_cache.get_block(root)
+        } else {
+            None
+        }
+    }
+
+    fn load_payloads(&self, block_roots: Vec<Hash256>) -> Vec<(Hash256, LoadResult<T::EthSpec>)> {
+        let mut db_blocks = Vec::new();
+
+        for root in block_roots {
+            if let Some(cached_block) = self
+                .check_early_attester_cache(root)
+                .map(LoadedBeaconBlock::Full)
+            {
+                db_blocks.push((root, Ok(Some(cached_block))));
+                continue;
+            }
+
+            match self.beacon_chain.store.try_get_full_block(&root) {
+                Err(e) => db_blocks.push((root, Err(e.into()))),
+                Ok(opt_block) => db_blocks.push((
+                    root,
+                    Ok(opt_block.map(|db_block| match db_block {
+                        DatabaseBlock::Full(block) => LoadedBeaconBlock::Full(Arc::new(block)),
+                        DatabaseBlock::Blinded(block) => {
+                            LoadedBeaconBlock::Blinded(Box::new(block))
+                        }
+                    })),
+                )),
+            }
+        }
+
+        db_blocks
+    }
+
+    /// Pre-process the loaded blocks into execution engine requests.
+    ///
+    /// The purpose of this function is to separate the blocks into 2 categories:
+    /// 1) no_request - when we already have the full block or there's an error
+    /// 2) blocks_by_range - used for blinded blocks
+    ///
+    /// The function returns a vector of block roots in the same order as requested
+    /// along with the engine request that each root corresponds to.
+    async fn get_requests(
+        &self,
+        payloads: Vec<(Hash256, LoadResult<T::EthSpec>)>,
+    ) -> Vec<(Hash256, EngineRequest<T::EthSpec>)> {
+        let mut ordered_block_roots = Vec::new();
+        let mut requests = HashMap::new();
+
+        // we sort the by range blocks by slot before adding them to the
+        // request as it should *better* optimize the number of blocks that
+        // can fit in the same request
+        let mut by_range_blocks: Vec<BlockParts<T::EthSpec>> = vec![];
+        let mut no_request = EngineRequest::new_no_request();
+
+        for (root, load_result) in payloads {
+            // preserve the order of the requested blocks
+            ordered_block_roots.push(root);
+
+            let block_result = match load_result {
+                Err(e) => Err(e),
+                Ok(None) => Ok(None),
+                Ok(Some(LoadedBeaconBlock::Full(full_block))) => Ok(Some(full_block)),
+                Ok(Some(LoadedBeaconBlock::Blinded(blinded_block))) => {
+                    match blinded_block
+                        .message()
+                        .execution_payload()
+                        .map(|payload| payload.to_execution_payload_header())
+                    {
+                        Ok(header) => {
+                            if header.block_hash() == ExecutionBlockHash::zero() {
+                                reconstruct_default_header_block(
+                                    blinded_block,
+                                    header,
+                                    &self.beacon_chain.spec,
+                                )
+                            } else {
+                                // Add the block to the set requiring a by-range request.
+                                let block_parts = BlockParts::new(blinded_block, header);
+                                by_range_blocks.push(block_parts);
+                                continue;
+                            }
+                        }
+                        Err(e) => Err(BeaconChainError::BeaconStateError(e)),
+                    }
+                }
+            };
+
+            no_request
+                .push_block_result(root, block_result, &self.beacon_chain.log)
+                .await;
+            requests.insert(root, no_request.clone());
+        }
+
+        // Now deal with the by_range requests. Sort them in order of increasing slot
+        let mut by_range = EngineRequest::<T::EthSpec>::new_by_range();
+        by_range_blocks.sort_by_key(|block_parts| block_parts.slot());
+        for block_parts in by_range_blocks {
+            let root = block_parts.root();
+            by_range
+                .push_block_parts(block_parts, &self.beacon_chain.log)
+                .await;
+            requests.insert(root, by_range.clone());
+        }
+
+        let mut result = vec![];
+        for root in ordered_block_roots {
+            if let Some(request) = requests.get(&root) {
+                result.push((root, request.clone()))
+            } else {
+                crit!(
+                    self.beacon_chain.log,
+                    "Please notify the devs";
+                    "beacon_block_streamer" => "request not found",
+                    "root" => ?root,
+                );
+                no_request
+                    .push_block_result(
+                        root,
+                        Err(Error::RequestNotFound.into()),
+                        &self.beacon_chain.log,
+                    )
+                    .await;
+                result.push((root, no_request.clone()));
+            }
+        }
+
+        result
+    }
+
+    // used when the execution engine doesn't support the payload bodies methods
+    async fn stream_blocks_fallback(
+        &self,
+        block_roots: Vec<Hash256>,
+        sender: UnboundedSender<(Hash256, Arc<BlockResult<T::EthSpec>>)>,
+    ) {
+        debug!(
+            self.beacon_chain.log,
+            "Using slower fallback method of eth_getBlockByHash()"
+        );
+        for root in block_roots {
+            let cached_block = self.check_early_attester_cache(root);
+            let block_result = if cached_block.is_some() {
+                Ok(cached_block)
+            } else {
+                self.beacon_chain
+                    .get_block(&root)
+                    .await
+                    .map(|opt_block| opt_block.map(Arc::new))
+            };
+
+            if sender.send((root, Arc::new(block_result))).is_err() {
+                break;
+            }
+        }
+    }
+
+    async fn stream_blocks(
+        &self,
+        block_roots: Vec<Hash256>,
+        sender: UnboundedSender<(Hash256, Arc<BlockResult<T::EthSpec>>)>,
+    ) {
+        let n_roots = block_roots.len();
+        let mut n_success = 0usize;
+        let mut n_sent = 0usize;
+        let mut engine_requests = 0usize;
+
+        let payloads = self.load_payloads(block_roots);
+        let requests = self.get_requests(payloads).await;
+
+        for (root, request) in requests {
+            if request.is_unsent().await {
+                engine_requests += 1;
+            }
+
+            let result = request
+                .get_block_result(&root, &self.execution_layer, &self.beacon_chain.log)
+                .await;
+
+            let successful = result
+                .as_ref()
+                .as_ref()
+                .map(|opt| opt.is_some())
+                .unwrap_or(false);
+
+            if sender.send((root, result)).is_err() {
+                break;
+            } else {
+                n_sent += 1;
+                if successful {
+                    n_success += 1;
+                }
+            }
+        }
+
+        debug!(
+            self.beacon_chain.log,
+            "BeaconBlockStreamer finished";
+            "requested blocks" => n_roots,
+            "sent" => n_sent,
+            "succeeded" => n_success,
+            "failed" => (n_sent - n_success),
+            "engine requests" => engine_requests,
+        );
+    }
+
+    pub async fn stream(
+        self,
+        block_roots: Vec<Hash256>,
+        sender: UnboundedSender<(Hash256, Arc<BlockResult<T::EthSpec>>)>,
+    ) {
+        match self
+            .execution_layer
+            .get_engine_capabilities(None)
+            .await
+            .map_err(Box::new)
+            .map_err(BeaconChainError::EngineGetCapabilititesFailed)
+        {
+            Ok(engine_capabilities) => {
+                if engine_capabilities.get_payload_bodies_by_range_v1 {
+                    self.stream_blocks(block_roots, sender).await;
+                } else {
+                    // use the fallback method
+                    self.stream_blocks_fallback(block_roots, sender).await;
+                }
+            }
+            Err(e) => {
+                send_errors(block_roots, sender, e).await;
+            }
+        }
+    }
+
+    pub fn launch_stream(
+        self,
+        block_roots: Vec<Hash256>,
+        executor: &TaskExecutor,
+    ) -> impl Stream<Item = (Hash256, Arc<BlockResult<T::EthSpec>>)> {
+        let (block_tx, block_rx) = mpsc::unbounded_channel();
+        debug!(
+            self.beacon_chain.log,
+            "Launching a BeaconBlockStreamer";
+            "blocks" => block_roots.len(),
+        );
+        executor.spawn(self.stream(block_roots, block_tx), "get_blocks_sender");
+        UnboundedReceiverStream::new(block_rx)
+    }
+}
+
+async fn send_errors<E: EthSpec>(
+    block_roots: Vec<Hash256>,
+    sender: UnboundedSender<(Hash256, Arc<BlockResult<E>>)>,
+    beacon_chain_error: BeaconChainError,
+) {
+    let result = Arc::new(Err(beacon_chain_error));
+    for root in block_roots {
+        if sender.send((root, result.clone())).is_err() {
+            break;
+        }
+    }
+}
+
+impl From<Error> for BeaconChainError {
+    fn from(value: Error) -> Self {
+        BeaconChainError::BlockStreamerError(value)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::beacon_block_streamer::{BeaconBlockStreamer, CheckEarlyAttesterCache};
+    use crate::test_utils::{test_spec, BeaconChainHarness, EphemeralHarnessType};
+    use execution_layer::test_utils::{Block, DEFAULT_ENGINE_CAPABILITIES};
+    use execution_layer::EngineCapabilities;
+    use lazy_static::lazy_static;
+    use std::time::Duration;
+    use tokio::sync::mpsc;
+    use types::{ChainSpec, Epoch, EthSpec, Hash256, Keypair, MinimalEthSpec, Slot};
+
+    const VALIDATOR_COUNT: usize = 48;
+    lazy_static! {
+        /// A cached set of keys.
+        static ref KEYPAIRS: Vec<Keypair> = types::test_utils::generate_deterministic_keypairs(VALIDATOR_COUNT);
+    }
+
+    fn get_harness(
+        validator_count: usize,
+        spec: ChainSpec,
+    ) -> BeaconChainHarness<EphemeralHarnessType<MinimalEthSpec>> {
+        let harness = BeaconChainHarness::builder(MinimalEthSpec)
+            .spec(spec)
+            .keypairs(KEYPAIRS[0..validator_count].to_vec())
+            .logger(logging::test_logger())
+            .fresh_ephemeral_store()
+            .mock_execution_layer()
+            .build();
+
+        harness.advance_slot();
+
+        harness
+    }
+
+    #[tokio::test]
+    async fn check_all_blocks_from_altair_to_capella() {
+        let slots_per_epoch = MinimalEthSpec::slots_per_epoch() as usize;
+        let num_epochs = 8;
+        let bellatrix_fork_epoch = 2usize;
+        let capella_fork_epoch = 4usize;
+        let num_blocks_produced = num_epochs * slots_per_epoch;
+
+        let mut spec = test_spec::<MinimalEthSpec>();
+        spec.altair_fork_epoch = Some(Epoch::new(0));
+        spec.bellatrix_fork_epoch = Some(Epoch::new(bellatrix_fork_epoch as u64));
+        spec.capella_fork_epoch = Some(Epoch::new(capella_fork_epoch as u64));
+
+        let harness = get_harness(VALIDATOR_COUNT, spec);
+        // go to bellatrix fork
+        harness
+            .extend_slots(bellatrix_fork_epoch * slots_per_epoch)
+            .await;
+        // extend half an epoch
+        harness.extend_slots(slots_per_epoch / 2).await;
+        // trigger merge
+        harness
+            .execution_block_generator()
+            .move_to_terminal_block()
+            .expect("should move to terminal block");
+        let timestamp = harness.get_timestamp_at_slot() + harness.spec.seconds_per_slot;
+        harness
+            .execution_block_generator()
+            .modify_last_block(|block| {
+                if let Block::PoW(terminal_block) = block {
+                    terminal_block.timestamp = timestamp;
+                }
+            });
+        // finish out merge epoch
+        harness.extend_slots(slots_per_epoch / 2).await;
+        // finish rest of epochs
+        harness
+            .extend_slots((num_epochs - 1 - bellatrix_fork_epoch) * slots_per_epoch)
+            .await;
+
+        let head = harness.chain.head_snapshot();
+        let state = &head.beacon_state;
+
+        assert_eq!(
+            state.slot(),
+            Slot::new(num_blocks_produced as u64),
+            "head should be at the current slot"
+        );
+        assert_eq!(
+            state.current_epoch(),
+            num_blocks_produced as u64 / MinimalEthSpec::slots_per_epoch(),
+            "head should be at the expected epoch"
+        );
+        assert_eq!(
+            state.current_justified_checkpoint().epoch,
+            state.current_epoch() - 1,
+            "the head should be justified one behind the current epoch"
+        );
+        assert_eq!(
+            state.finalized_checkpoint().epoch,
+            state.current_epoch() - 2,
+            "the head should be finalized two behind the current epoch"
+        );
+
+        let block_roots: Vec<Hash256> = harness
+            .chain
+            .forwards_iter_block_roots(Slot::new(0))
+            .expect("should get iter")
+            .map(Result::unwrap)
+            .map(|(root, _)| root)
+            .collect();
+
+        let mut expected_blocks = vec![];
+        // get all blocks the old fashioned way
+        for root in &block_roots {
+            let block = harness
+                .chain
+                .get_block(root)
+                .await
+                .expect("should get block")
+                .expect("block should exist");
+            expected_blocks.push(block);
+        }
+
+        for epoch in 0..num_epochs {
+            let start = epoch * slots_per_epoch;
+            let mut epoch_roots = vec![Hash256::zero(); slots_per_epoch];
+            epoch_roots[..].clone_from_slice(&block_roots[start..(start + slots_per_epoch)]);
+            let streamer = BeaconBlockStreamer::new(&harness.chain, CheckEarlyAttesterCache::No)
+                .expect("should create streamer");
+            let (block_tx, mut block_rx) = mpsc::unbounded_channel();
+            streamer.stream(epoch_roots.clone(), block_tx).await;
+
+            for (i, expected_root) in epoch_roots.into_iter().enumerate() {
+                let (found_root, found_block_result) =
+                    block_rx.recv().await.expect("should get block");
+
+                assert_eq!(
+                    found_root, expected_root,
+                    "expected block root should match"
+                );
+                match found_block_result.as_ref() {
+                    Ok(maybe_block) => {
+                        let found_block = maybe_block.clone().expect("should have a block");
+                        let expected_block = expected_blocks
+                            .get(start + i)
+                            .expect("should get expected block");
+                        assert_eq!(
+                            found_block.as_ref(),
+                            expected_block,
+                            "expected block should match found block"
+                        );
+                    }
+                    Err(e) => panic!("Error retrieving block {}: {:?}", expected_root, e),
+                }
+            }
+        }
+    }
+
+    #[tokio::test]
+    async fn check_fallback_altair_to_capella() {
+        let slots_per_epoch = MinimalEthSpec::slots_per_epoch() as usize;
+        let num_epochs = 8;
+        let bellatrix_fork_epoch = 2usize;
+        let capella_fork_epoch = 4usize;
+        let num_blocks_produced = num_epochs * slots_per_epoch;
+
+        let mut spec = test_spec::<MinimalEthSpec>();
+        spec.altair_fork_epoch = Some(Epoch::new(0));
+        spec.bellatrix_fork_epoch = Some(Epoch::new(bellatrix_fork_epoch as u64));
+        spec.capella_fork_epoch = Some(Epoch::new(capella_fork_epoch as u64));
+
+        let harness = get_harness(VALIDATOR_COUNT, spec);
+
+        // modify execution engine so it doesn't support engine_payloadBodiesBy* methods
+        let mock_execution_layer = harness.mock_execution_layer.as_ref().unwrap();
+        mock_execution_layer
+            .server
+            .set_engine_capabilities(EngineCapabilities {
+                get_payload_bodies_by_hash_v1: false,
+                get_payload_bodies_by_range_v1: false,
+                ..DEFAULT_ENGINE_CAPABILITIES
+            });
+        // refresh capabilities cache
+        harness
+            .chain
+            .execution_layer
+            .as_ref()
+            .unwrap()
+            .get_engine_capabilities(Some(Duration::ZERO))
+            .await
+            .unwrap();
+
+        // go to bellatrix fork
+        harness
+            .extend_slots(bellatrix_fork_epoch * slots_per_epoch)
+            .await;
+        // extend half an epoch
+        harness.extend_slots(slots_per_epoch / 2).await;
+        // trigger merge
+        harness
+            .execution_block_generator()
+            .move_to_terminal_block()
+            .expect("should move to terminal block");
+        let timestamp = harness.get_timestamp_at_slot() + harness.spec.seconds_per_slot;
+        harness
+            .execution_block_generator()
+            .modify_last_block(|block| {
+                if let Block::PoW(terminal_block) = block {
+                    terminal_block.timestamp = timestamp;
+                }
+            });
+        // finish out merge epoch
+        harness.extend_slots(slots_per_epoch / 2).await;
+        // finish rest of epochs
+        harness
+            .extend_slots((num_epochs - 1 - bellatrix_fork_epoch) * slots_per_epoch)
+            .await;
+
+        let head = harness.chain.head_snapshot();
+        let state = &head.beacon_state;
+
+        assert_eq!(
+            state.slot(),
+            Slot::new(num_blocks_produced as u64),
+            "head should be at the current slot"
+        );
+        assert_eq!(
+            state.current_epoch(),
+            num_blocks_produced as u64 / MinimalEthSpec::slots_per_epoch(),
+            "head should be at the expected epoch"
+        );
+        assert_eq!(
+            state.current_justified_checkpoint().epoch,
+            state.current_epoch() - 1,
+            "the head should be justified one behind the current epoch"
+        );
+        assert_eq!(
+            state.finalized_checkpoint().epoch,
+            state.current_epoch() - 2,
+            "the head should be finalized two behind the current epoch"
+        );
+
+        let block_roots: Vec<Hash256> = harness
+            .chain
+            .forwards_iter_block_roots(Slot::new(0))
+            .expect("should get iter")
+            .map(Result::unwrap)
+            .map(|(root, _)| root)
+            .collect();
+
+        let mut expected_blocks = vec![];
+        // get all blocks the old fashioned way
+        for root in &block_roots {
+            let block = harness
+                .chain
+                .get_block(root)
+                .await
+                .expect("should get block")
+                .expect("block should exist");
+            expected_blocks.push(block);
+        }
+
+        for epoch in 0..num_epochs {
+            let start = epoch * slots_per_epoch;
+            let mut epoch_roots = vec![Hash256::zero(); slots_per_epoch];
+            epoch_roots[..].clone_from_slice(&block_roots[start..(start + slots_per_epoch)]);
+            let streamer = BeaconBlockStreamer::new(&harness.chain, CheckEarlyAttesterCache::No)
+                .expect("should create streamer");
+            let (block_tx, mut block_rx) = mpsc::unbounded_channel();
+            streamer.stream(epoch_roots.clone(), block_tx).await;
+
+            for (i, expected_root) in epoch_roots.into_iter().enumerate() {
+                let (found_root, found_block_result) =
+                    block_rx.recv().await.expect("should get block");
+
+                assert_eq!(
+                    found_root, expected_root,
+                    "expected block root should match"
+                );
+                match found_block_result.as_ref() {
+                    Ok(maybe_block) => {
+                        let found_block = maybe_block.clone().expect("should have a block");
+                        let expected_block = expected_blocks
+                            .get(start + i)
+                            .expect("should get expected block");
+                        assert_eq!(
+                            found_block.as_ref(),
+                            expected_block,
+                            "expected block should match found block"
+                        );
+                    }
+                    Err(e) => panic!("Error retrieving block {}: {:?}", expected_root, e),
+                }
+            }
+        }
+    }
+}

beacon_node/beacon_chain/src/beacon_chain.rs

@@ -4,6 +4,7 @@ use crate::attestation_verification::{
     VerifiedUnaggregatedAttestation,
 };
 use crate::attester_cache::{AttesterCache, AttesterCacheKey};
+use crate::beacon_block_streamer::{BeaconBlockStreamer, CheckEarlyAttesterCache};
 use crate::beacon_proposer_cache::compute_proposer_duties_from_head;
 use crate::beacon_proposer_cache::BeaconProposerCache;
 use crate::blob_cache::BlobCache;
@@ -105,6 +106,7 @@ use store::{
     DatabaseBlock, Error as DBError, HotColdDB, KeyValueStore, KeyValueStoreOp, StoreItem, StoreOp,
 };
 use task_executor::{ShutdownReason, TaskExecutor};
+use tokio_stream::Stream;
 use tree_hash::TreeHash;
 use types::beacon_state::CloneConfig;
 use types::consts::eip4844::MIN_EPOCHS_FOR_BLOBS_SIDECARS_REQUESTS;
@@ -947,14 +949,42 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     /// ## Errors
     ///
     /// May return a database error.
-    pub async fn get_block_checking_early_attester_cache(
-        &self,
-        block_root: &Hash256,
-    ) -> Result<Option<Arc<SignedBeaconBlock<T::EthSpec>>>, Error> {
-        if let Some(block) = self.early_attester_cache.get_block(*block_root) {
-            return Ok(Some(block));
-        }
-        Ok(self.get_block(block_root).await?.map(Arc::new))
+    pub fn get_blocks_checking_early_attester_cache(
+        self: &Arc<Self>,
+        block_roots: Vec<Hash256>,
+        executor: &TaskExecutor,
+    ) -> Result<
+        impl Stream<
+            Item = (
+                Hash256,
+                Arc<Result<Option<Arc<SignedBeaconBlock<T::EthSpec>>>, Error>>,
+            ),
+        >,
+        Error,
+    > {
+        Ok(
+            BeaconBlockStreamer::<T>::new(self, CheckEarlyAttesterCache::Yes)?
+                .launch_stream(block_roots, executor),
+        )
+    }
+
+    pub fn get_blocks(
+        self: &Arc<Self>,
+        block_roots: Vec<Hash256>,
+        executor: &TaskExecutor,
+    ) -> Result<
+        impl Stream<
+            Item = (
+                Hash256,
+                Arc<Result<Option<Arc<SignedBeaconBlock<T::EthSpec>>>, Error>>,
+            ),
+        >,
+        Error,
+    > {
+        Ok(
+            BeaconBlockStreamer::<T>::new(self, CheckEarlyAttesterCache::No)?
+                .launch_stream(block_roots, executor),
+        )
     }
 
     pub async fn get_block_and_blobs_checking_early_attester_cache(

beacon_node/beacon_chain/src/errors.rs

@@ -1,4 +1,5 @@
 use crate::attester_cache::Error as AttesterCacheError;
+use crate::beacon_block_streamer::Error as BlockStreamerError;
 use crate::beacon_chain::ForkChoiceError;
 use crate::beacon_fork_choice_store::Error as ForkChoiceStoreError;
 use crate::eth1_chain::Error as Eth1ChainError;
@@ -143,6 +144,7 @@ pub enum BeaconChainError {
     ExecutionLayerMissing,
     BlockVariantLacksExecutionPayload(Hash256),
     ExecutionLayerErrorPayloadReconstruction(ExecutionBlockHash, Box<execution_layer::Error>),
+    EngineGetCapabilititesFailed(Box<execution_layer::Error>),
     BlockHashMissingFromExecutionLayer(ExecutionBlockHash),
     InconsistentPayloadReconstructed {
         slot: Slot,
@@ -150,6 +152,7 @@ pub enum BeaconChainError {
         canonical_transactions_root: Hash256,
         reconstructed_transactions_root: Hash256,
     },
+    BlockStreamerError(BlockStreamerError),
     AddPayloadLogicError,
     ExecutionForkChoiceUpdateFailed(execution_layer::Error),
     PrepareProposerFailed(BlockProcessingError),

beacon_node/beacon_chain/src/lib.rs

@@ -2,6 +2,7 @@ pub mod attestation_rewards;
 pub mod attestation_verification;
 mod attester_cache;
 pub mod beacon_block_reward;
+mod beacon_block_streamer;
 mod beacon_chain;
 mod beacon_fork_choice_store;
 pub mod beacon_proposer_cache;