use super::many::Web3Rpcs; ///! Keep track of the blockchain as seen by a Web3Rpcs. use super::one::Web3Rpc; use super::transactions::TxStatus; use crate::frontend::authorization::Authorization; use crate::{ config::BlockAndRpc, jsonrpc::JsonRpcRequest, rpcs::synced_connections::ConsensusWeb3Rpcs, }; use anyhow::Context; use derive_more::From; use ethers::prelude::{Block, TxHash, H256, U64}; use hashbrown::{HashMap, HashSet}; use log::{debug, error, warn, Level}; use moka::future::Cache; use serde::Serialize; use serde_json::json; use std::time::{SystemTime, UNIX_EPOCH}; use std::{cmp::Ordering, fmt::Display, sync::Arc}; use tokio::sync::{broadcast, watch}; use tokio::time::Duration; // TODO: type for Hydrated Blocks with their full transactions? pub type ArcBlock = Arc>; pub type BlockHashesCache = Cache; /// A block and its age. #[derive(Clone, Debug, Default, From, Serialize)] pub struct SavedBlock { pub block: ArcBlock, /// number of seconds this block was behind the current time when received pub age: u64, } impl PartialEq for SavedBlock { fn eq(&self, other: &Self) -> bool { match (self.block.hash, other.block.hash) { (None, None) => true, (Some(_), None) => false, (None, Some(_)) => false, (Some(s), Some(o)) => s == o, } } } impl SavedBlock { pub fn new(block: ArcBlock) -> Self { let mut x = Self { block, age: 0 }; // no need to recalulate lag every time // if the head block gets too old, a health check restarts this connection x.age = x.lag(); x } pub fn lag(&self) -> u64 { let now = SystemTime::now() .duration_since(UNIX_EPOCH) .expect("there should always be time"); let block_timestamp = Duration::from_secs(self.block.timestamp.as_u64()); if block_timestamp < now { // this server is still syncing from too far away to serve requests // u64 is safe because ew checked equality above (now - block_timestamp).as_secs() as u64 } else { 0 } } pub fn hash(&self) -> H256 { self.block.hash.expect("saved blocks must have a hash") } // TODO: return as U64 or u64? pub fn number(&self) -> U64 { self.block.number.expect("saved blocks must have a number") } } impl From for SavedBlock { fn from(x: ArcBlock) -> Self { SavedBlock::new(x) } } impl Display for SavedBlock { fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { write!(f, "{} ({}, {}s old)", self.number(), self.hash(), self.age) } } impl Web3Rpcs { /// add a block to our mappings and track the heaviest chain pub async fn save_block( &self, block: ArcBlock, heaviest_chain: bool, ) -> anyhow::Result { // TODO: i think we can rearrange this function to make it faster on the hot path let block_hash = block.hash.as_ref().context("no block hash")?; // skip Block::default() if block_hash.is_zero() { debug!("Skipping block without hash!"); return Ok(block); } let block_num = block.number.as_ref().context("no block num")?; // TODO: think more about heaviest_chain. would be better to do the check inside this function if heaviest_chain { // this is the only place that writes to block_numbers // multiple inserts should be okay though // TODO: info that there was a fork? self.block_numbers.insert(*block_num, *block_hash).await; } // this block is very likely already in block_hashes // TODO: use their get_with let block = self .block_hashes .get_with(*block_hash, async move { block.clone() }) .await; Ok(block) } /// Get a block from caches with fallback. /// Will query a specific node or the best available. /// TODO: return anyhow::Result>? pub async fn block( &self, authorization: &Arc, hash: &H256, rpc: Option<&Arc>, ) -> anyhow::Result { // first, try to get the hash from our cache // the cache is set last, so if its here, its everywhere // TODO: use try_get_with if let Some(block) = self.block_hashes.get(hash) { return Ok(block); } // block not in cache. we need to ask an rpc for it let get_block_params = (*hash, false); // TODO: if error, retry? let block: ArcBlock = match rpc { Some(rpc) => rpc .wait_for_request_handle(authorization, Some(Duration::from_secs(30)), false) .await? .request::<_, Option<_>>( "eth_getBlockByHash", &json!(get_block_params), Level::Error.into(), ) .await? .context("no block!")?, None => { // TODO: helper for method+params => JsonRpcRequest // TODO: does this id matter? let request = json!({ "id": "1", "method": "eth_getBlockByHash", "params": get_block_params }); let request: JsonRpcRequest = serde_json::from_value(request)?; // TODO: request_metadata? maybe we should put it in the authorization? // TODO: think more about this wait_for_sync let response = self .try_send_best_consensus_head_connection(authorization, request, None, None) .await?; let block = response.result.context("failed fetching block")?; let block: Option = serde_json::from_str(block.get())?; block.context("no block!")? } }; // the block was fetched using eth_getBlockByHash, so it should have all fields // TODO: fill in heaviest_chain! if the block is old enough, is this definitely true? let block = self.save_block(block, false).await?; Ok(block) } /// Convenience method to get the cannonical block at a given block height. pub async fn block_hash( &self, authorization: &Arc, num: &U64, ) -> anyhow::Result<(H256, u64)> { let (block, block_depth) = self.cannonical_block(authorization, num).await?; let hash = block.hash.expect("Saved blocks should always have hashes"); Ok((hash, block_depth)) } /// Get the heaviest chain's block from cache or backend rpc /// Caution! If a future block is requested, this might wait forever. Be sure to have a timeout outside of this! pub async fn cannonical_block( &self, authorization: &Arc, num: &U64, ) -> anyhow::Result<(ArcBlock, u64)> { // we only have blocks by hash now // maybe save them during save_block in a blocks_by_number Cache> // if theres multiple, use petgraph to find the one on the main chain (and remove the others if they have enough confirmations) let mut consensus_head_receiver = self .watch_consensus_head_receiver .as_ref() .context("need new head subscriptions to fetch cannonical_block")? .clone(); // be sure the requested block num exists let mut head_block_num = consensus_head_receiver.borrow_and_update().number; loop { if let Some(head_block_num) = head_block_num { if num <= &head_block_num { break; } } consensus_head_receiver.changed().await?; head_block_num = consensus_head_receiver.borrow_and_update().number; } let head_block_num = head_block_num.expect("we should only get here if we have a head block"); let block_depth = if num >= &head_block_num { 0 } else { (head_block_num - num).as_u64() }; // try to get the hash from our cache // deref to not keep the lock open if let Some(block_hash) = self.block_numbers.get(num) { // TODO: sometimes this needs to fetch the block. why? i thought block_numbers would only be set if the block hash was set // TODO: pass authorization through here? let block = self.block(authorization, &block_hash, None).await?; return Ok((block, block_depth)); } // block number not in cache. we need to ask an rpc for it // TODO: helper for method+params => JsonRpcRequest let request = json!({ "jsonrpc": "2.0", "id": "1", "method": "eth_getBlockByNumber", "params": (num, false) }); let request: JsonRpcRequest = serde_json::from_value(request)?; // TODO: if error, retry? // TODO: request_metadata or authorization? // we don't actually set min_block_needed here because all nodes have all blocks let response = self .try_send_best_consensus_head_connection(authorization, request, None, None) .await?; if let Some(err) = response.error { debug!("could not find canonical block {}: {:?}", num, err); } let raw_block = response.result.context("no cannonical block result")?; let block: ArcBlock = serde_json::from_str(raw_block.get())?; // the block was fetched using eth_getBlockByNumber, so it should have all fields and be on the heaviest chain let block = self.save_block(block, true).await?; Ok((block, block_depth)) } pub(super) async fn process_incoming_blocks( &self, authorization: &Arc, block_receiver: flume::Receiver, // TODO: document that this is a watch sender and not a broadcast! if things get busy, blocks might get missed // Geth's subscriptions have the same potential for skipping blocks. head_block_sender: watch::Sender, pending_tx_sender: Option>, ) -> anyhow::Result<()> { // TODO: indexmap or hashmap? what hasher? with_capacity? // TODO: this will grow unbounded. prune old heads on this at the same time we prune the graph? let mut connection_heads = ConsensusFinder::default(); loop { match block_receiver.recv_async().await { Ok((new_block, rpc)) => { let new_block = new_block.map(Into::into); let rpc_name = rpc.name.clone(); if let Err(err) = self .process_block_from_rpc( authorization, &mut connection_heads, new_block, rpc, &head_block_sender, &pending_tx_sender, ) .await { warn!("unable to process block from rpc {}: {:?}", rpc_name, err); } } Err(err) => { warn!("block_receiver exited! {:#?}", err); return Err(err.into()); } } } } /// `connection_heads` is a mapping of rpc_names to head block hashes. /// self.blockchain_map is a mapping of hashes to the complete ArcBlock. /// TODO: return something? pub(crate) async fn process_block_from_rpc( &self, authorization: &Arc, consensus_finder: &mut ConsensusFinder, rpc_head_block: Option, rpc: Arc, head_block_sender: &watch::Sender, pending_tx_sender: &Option>, ) -> anyhow::Result<()> { // TODO: how should we handle an error here? if !consensus_finder .update_rpc(rpc_head_block.clone(), rpc.clone(), self) .await? { // nothing changed. no need return Ok(()); } let new_synced_connections = consensus_finder .best_consensus_connections(authorization, self) .await; // TODO: what should we do if the block number of new_synced_connections is < old_synced_connections? wait? let includes_backups = new_synced_connections.includes_backups; let consensus_head_block = new_synced_connections.head_block.clone(); let num_consensus_rpcs = new_synced_connections.num_conns(); let num_checked_rpcs = new_synced_connections.num_checked_conns; let num_active_rpcs = consensus_finder.all.rpc_name_to_hash.len(); let total_rpcs = self.conns.len(); let old_consensus_head_connections = self .watch_consensus_connections_sender .send_replace(Arc::new(new_synced_connections)); let includes_backups_str = if includes_backups { "B " } else { "" }; if let Some(consensus_saved_block) = consensus_head_block { match &old_consensus_head_connections.head_block { None => { debug!( "first {}{}/{}/{}/{} block={}, rpc={}", includes_backups_str, num_consensus_rpcs, num_checked_rpcs, num_active_rpcs, total_rpcs, consensus_saved_block, rpc, ); if includes_backups { // TODO: what else should be in this error? warn!("Backup RPCs are in use!"); } let consensus_head_block = self.save_block(consensus_saved_block.block, true).await?; head_block_sender .send(consensus_head_block) .context("head_block_sender sending consensus_head_block")?; } Some(old_head_block) => { // TODO: do this log item better let rpc_head_str = rpc_head_block .map(|x| x.to_string()) .unwrap_or_else(|| "None".to_string()); match consensus_saved_block.number().cmp(&old_head_block.number()) { Ordering::Equal => { // multiple blocks with the same fork! if consensus_saved_block.hash() == old_head_block.hash() { // no change in hash. no need to use head_block_sender // TODO: trace level if rpc is backup debug!( "con {}{}/{}/{}/{} con={} rpc={}@{}", includes_backups_str, num_consensus_rpcs, num_checked_rpcs, num_active_rpcs, total_rpcs, consensus_saved_block, rpc, rpc_head_str, ) } else { // hash changed if includes_backups { // TODO: what else should be in this error? warn!("Backup RPCs are in use!"); } debug!( "unc {}{}/{}/{}/{} con_head={} old={} rpc={}@{}", includes_backups_str, num_consensus_rpcs, num_checked_rpcs, num_active_rpcs, total_rpcs, consensus_saved_block, old_head_block, rpc, rpc_head_str, ); let consensus_head_block = self .save_block(consensus_saved_block.block, true) .await .context("save consensus_head_block as heaviest chain")?; head_block_sender .send(consensus_head_block) .context("head_block_sender sending consensus_head_block")?; } } Ordering::Less => { // this is unlikely but possible // TODO: better log warn!( "chain rolled back {}{}/{}/{}/{} con={} old={} rpc={}@{}", includes_backups_str, num_consensus_rpcs, num_checked_rpcs, num_active_rpcs, total_rpcs, consensus_saved_block, old_head_block, rpc, rpc_head_str, ); if includes_backups { // TODO: what else should be in this error? warn!("Backup RPCs are in use!"); } // TODO: tell save_block to remove any higher block numbers from the cache. not needed because we have other checks on requested blocks being > head, but still seems like a good idea let consensus_head_block = self .save_block(consensus_saved_block.block, true) .await .context( "save_block sending consensus_head_block as heaviest chain", )?; head_block_sender .send(consensus_head_block) .context("head_block_sender sending consensus_head_block")?; } Ordering::Greater => { debug!( "new {}{}/{}/{}/{} con={} rpc={}@{}", includes_backups_str, num_consensus_rpcs, num_checked_rpcs, num_active_rpcs, total_rpcs, consensus_saved_block, rpc, rpc_head_str, ); if includes_backups { // TODO: what else should be in this error? warn!("Backup RPCs are in use!"); } let consensus_head_block = self.save_block(consensus_saved_block.block, true).await?; head_block_sender.send(consensus_head_block)?; } } } } } else { // TODO: do this log item better let rpc_head_str = rpc_head_block .map(|x| x.to_string()) .unwrap_or_else(|| "None".to_string()); if num_checked_rpcs >= self.min_head_rpcs { error!( "non {}{}/{}/{}/{} rpc={}@{}", includes_backups_str, num_consensus_rpcs, num_checked_rpcs, num_active_rpcs, total_rpcs, rpc, rpc_head_str, ); } else { debug!( "non {}{}/{}/{}/{} rpc={}@{}", includes_backups_str, num_consensus_rpcs, num_checked_rpcs, num_active_rpcs, total_rpcs, rpc, rpc_head_str, ); } } Ok(()) } } struct ConnectionsGroup { /// TODO: this group might not actually include backups, but they were at leastchecked includes_backups: bool, rpc_name_to_hash: HashMap, } impl ConnectionsGroup { fn new(with_backups: bool) -> Self { Self { includes_backups: with_backups, rpc_name_to_hash: Default::default(), } } fn without_backups() -> Self { Self::new(false) } fn with_backups() -> Self { Self::new(true) } fn remove(&mut self, rpc: &Web3Rpc) -> Option { self.rpc_name_to_hash.remove(rpc.name.as_str()) } fn insert(&mut self, rpc: &Web3Rpc, block_hash: H256) -> Option { self.rpc_name_to_hash.insert(rpc.name.clone(), block_hash) } // TODO: i don't love having this here. move to web3_connections? async fn get_block_from_rpc( &self, rpc_name: &str, hash: &H256, authorization: &Arc, web3_rpcs: &Web3Rpcs, ) -> anyhow::Result { // // TODO: why does this happen?!?! seems to only happen with uncled blocks // // TODO: maybe we should do try_get_with? // // TODO: maybe we should just continue. this only seems to happen when an older block is received // warn!( // "Missing connection_head_block in block_hashes. Fetching now. hash={}. other={}", // connection_head_hash, conn_name // ); // this option should almost always be populated. if the connection reconnects at a bad time it might not be available though // TODO: if this is None, I think we should error. let rpc = web3_rpcs.conns.get(rpc_name); web3_rpcs.block(authorization, hash, rpc).await } // TODO: do this during insert/remove? pub(self) async fn highest_block( &self, authorization: &Arc, web3_rpcs: &Web3Rpcs, ) -> Option { let mut checked_heads = HashSet::with_capacity(self.rpc_name_to_hash.len()); let mut highest_block = None::; for (rpc_name, rpc_head_hash) in self.rpc_name_to_hash.iter() { // don't waste time checking the same hash multiple times if checked_heads.contains(rpc_head_hash) { continue; } let rpc_block = match self .get_block_from_rpc(rpc_name, rpc_head_hash, authorization, web3_rpcs) .await { Ok(x) => x, Err(err) => { warn!( "failed getting block {} from {} while finding highest block number: {:?}", rpc_head_hash, rpc_name, err, ); continue; } }; checked_heads.insert(rpc_head_hash); // if this is the first block we've tried // or if this rpc's newest block has a higher number // we used to check total difficulty, but that isn't a thing anymore on ETH // TODO: we still need total difficulty on some other PoW chains. whats annoying is it isn't considered part of the "block header" just the block. so websockets don't return it let highest_num = highest_block .as_ref() .map(|x| x.number.expect("blocks here should always have a number")); let rpc_num = rpc_block.as_ref().number; if rpc_num > highest_num { highest_block = Some(rpc_block); } } highest_block } pub(self) async fn consensus_head_connections( &self, authorization: &Arc, web3_rpcs: &Web3Rpcs, ) -> anyhow::Result { let mut maybe_head_block = match self.highest_block(authorization, web3_rpcs).await { None => return Err(anyhow::anyhow!("No blocks known")), Some(x) => x, }; let num_known = self.rpc_name_to_hash.len(); // track rpcs on this heaviest chain so we can build a new ConsensusConnections let mut highest_rpcs = HashSet::<&str>::new(); // a running total of the soft limits covered by the rpcs that agree on the head block let mut highest_rpcs_sum_soft_limit: u32 = 0; // TODO: also track highest_rpcs_sum_hard_limit? llama doesn't need this, so it can wait // check the highest work block for a set of rpcs that can serve our request load // if it doesn't have enough rpcs for our request load, check the parent block // TODO: loop for how many parent blocks? we don't want to serve blocks that are too far behind. probably different per chain // TODO: this loop is pretty long. any way to clean up this code? for _ in 0..6 { let maybe_head_hash = maybe_head_block .hash .as_ref() .expect("blocks here always need hashes"); // find all rpcs with maybe_head_block as their current head for (rpc_name, rpc_head_hash) in self.rpc_name_to_hash.iter() { if rpc_head_hash != maybe_head_hash { // connection is not on the desired block continue; } if highest_rpcs.contains(rpc_name.as_str()) { // connection is on a child block continue; } if let Some(rpc) = web3_rpcs.conns.get(rpc_name.as_str()) { highest_rpcs.insert(rpc_name); highest_rpcs_sum_soft_limit += rpc.soft_limit; } else { // i don't think this is an error. i think its just if a reconnect is currently happening warn!("connection missing: {}", rpc_name); debug!("web3_rpcs.conns: {:#?}", web3_rpcs.conns); } } if highest_rpcs_sum_soft_limit >= web3_rpcs.min_sum_soft_limit && highest_rpcs.len() >= web3_rpcs.min_head_rpcs { // we have enough servers with enough requests break; } // not enough rpcs yet. check the parent block if let Some(parent_block) = web3_rpcs.block_hashes.get(&maybe_head_block.parent_hash) { // trace!( // child=%maybe_head_hash, parent=%parent_block.hash.unwrap(), "avoiding thundering herd", // ); maybe_head_block = parent_block; continue; } else { if num_known < web3_rpcs.min_head_rpcs { return Err(anyhow::anyhow!( "not enough rpcs connected: {}/{}/{}", highest_rpcs.len(), num_known, web3_rpcs.min_head_rpcs, )); } else { let soft_limit_percent = (highest_rpcs_sum_soft_limit as f32 / web3_rpcs.min_sum_soft_limit as f32) * 100.0; return Err(anyhow::anyhow!( "ran out of parents to check. rpcs {}/{}/{}. soft limit: {:.2}% ({}/{})", highest_rpcs.len(), num_known, web3_rpcs.min_head_rpcs, highest_rpcs_sum_soft_limit, web3_rpcs.min_sum_soft_limit, soft_limit_percent, )); } } } // TODO: if consensus_head_rpcs.is_empty, try another method of finding the head block. will need to change the return Err above into breaks. // we've done all the searching for the heaviest block that we can if highest_rpcs.len() < web3_rpcs.min_head_rpcs || highest_rpcs_sum_soft_limit < web3_rpcs.min_sum_soft_limit { // if we get here, not enough servers are synced. return an error let soft_limit_percent = (highest_rpcs_sum_soft_limit as f32 / web3_rpcs.min_sum_soft_limit as f32) * 100.0; return Err(anyhow::anyhow!( "Not enough resources. rpcs {}/{}/{}. soft limit: {:.2}% ({}/{})", highest_rpcs.len(), num_known, web3_rpcs.min_head_rpcs, highest_rpcs_sum_soft_limit, web3_rpcs.min_sum_soft_limit, soft_limit_percent, )); } // success! this block has enough soft limit and nodes on it (or on later blocks) let conns: Vec> = highest_rpcs .into_iter() .filter_map(|conn_name| web3_rpcs.conns.get(conn_name).cloned()) .collect(); // TODO: DEBUG only check let _ = maybe_head_block .hash .expect("head blocks always have hashes"); let _ = maybe_head_block .number .expect("head blocks always have numbers"); let consensus_head_block: SavedBlock = maybe_head_block.into(); Ok(ConsensusWeb3Rpcs { head_block: Some(consensus_head_block), conns, num_checked_conns: self.rpc_name_to_hash.len(), includes_backups: self.includes_backups, }) } } /// A ConsensusConnections builder that tracks all connection heads across multiple groups of servers pub struct ConsensusFinder { /// only main servers main: ConnectionsGroup, /// main and backup servers all: ConnectionsGroup, } impl Default for ConsensusFinder { fn default() -> Self { Self { main: ConnectionsGroup::without_backups(), all: ConnectionsGroup::with_backups(), } } } impl ConsensusFinder { fn remove(&mut self, rpc: &Web3Rpc) -> Option { // TODO: should we have multiple backup tiers? (remote datacenters vs third party) if !rpc.backup { self.main.remove(rpc); } self.all.remove(rpc) } fn insert(&mut self, rpc: &Web3Rpc, new_hash: H256) -> Option { // TODO: should we have multiple backup tiers? (remote datacenters vs third party) if !rpc.backup { self.main.insert(rpc, new_hash); } self.all.insert(rpc, new_hash) } /// Update our tracking of the rpc and return true if something changed async fn update_rpc( &mut self, rpc_head_block: Option, rpc: Arc, // we need this so we can save the block to caches. i don't like it though. maybe we should use a lazy_static Cache wrapper that has a "save_block" method?. i generally dislike globals but i also dislike all the types having to pass eachother around web3_connections: &Web3Rpcs, ) -> anyhow::Result { // add the rpc's block to connection_heads, or remove the rpc from connection_heads let changed = match rpc_head_block { Some(mut rpc_head_block) => { // we don't know if its on the heaviest chain yet rpc_head_block.block = web3_connections .save_block(rpc_head_block.block, false) .await?; // we used to remove here if the block was too far behind. but it just made things more complicated let rpc_head_hash = rpc_head_block.hash(); if let Some(prev_hash) = self.insert(&rpc, rpc_head_hash) { if prev_hash == rpc_head_hash { // this block was already sent by this rpc. return early false } else { // new block for this rpc true } } else { // first block for this rpc true } } None => { if self.remove(&rpc).is_none() { // this rpc was already removed false } else { // rpc head changed from being synced to not true } } }; Ok(changed) } // TODO: this could definitely be cleaner. i don't like the error handling/unwrapping async fn best_consensus_connections( &mut self, authorization: &Arc, web3_connections: &Web3Rpcs, ) -> ConsensusWeb3Rpcs { let highest_block_num = match self .all .highest_block(authorization, web3_connections) .await { None => { return ConsensusWeb3Rpcs::default(); } Some(x) => x.number.expect("blocks here should always have a number"), }; // TODO: also needs to be not less than our current head let mut min_block_num = highest_block_num.saturating_sub(U64::from(5)); // we also want to be sure we don't ever go backwards! if let Some(current_consensus_head_num) = web3_connections.head_block_num() { min_block_num = min_block_num.max(current_consensus_head_num); } // TODO: pass `min_block_num` to consensus_head_connections? let consensus_head_for_main = self .main .consensus_head_connections(authorization, web3_connections) .await .map_err(|err| err.context("cannot use main group")); let consensus_num_for_main = consensus_head_for_main .as_ref() .ok() .map(|x| x.head_block.as_ref().unwrap().number()); if let Some(consensus_num_for_main) = consensus_num_for_main { if consensus_num_for_main >= min_block_num { return consensus_head_for_main.unwrap(); } } // TODO: pass `min_block_num` to consensus_head_connections? let consensus_connections_for_all = match self .all .consensus_head_connections(authorization, web3_connections) .await { Err(err) => { if self.all.rpc_name_to_hash.len() < web3_connections.min_head_rpcs { debug!("No consensus head yet: {}", err); } return ConsensusWeb3Rpcs::default(); } Ok(x) => x, }; let consensus_num_for_all = consensus_connections_for_all .head_block .as_ref() .map(|x| x.number()); if consensus_num_for_all > consensus_num_for_main { if consensus_num_for_all < Some(min_block_num) { // TODO: this should have an alarm in sentry error!("CONSENSUS HEAD w/ BACKUP NODES IS VERY OLD!"); } consensus_connections_for_all } else { if let Ok(x) = consensus_head_for_main { error!("CONSENSUS HEAD IS VERY OLD! Backup RPCs did not improve this situation"); x } else { // TODO: i don't think we need this error. and i doublt we'll ever even get here error!("NO CONSENSUS HEAD!"); ConsensusWeb3Rpcs::default() } } } }