feat: remove signet system txns before sending to fee cache

Author: prestwich

crates/rpc/Cargo.toml

@@ -40,6 +40,7 @@ tokio-util = "0.7.13"
 tower-http = { version = "0.6.2", features = ["cors"] }
 tracing.workspace = true
 serde_json.workspace = true
+futures-util = "0.3.31"
 
 [dev-dependencies]
 signet-zenith.workspace = true

crates/rpc/src/ctx/fee_hist.rs

@@ -1 +1,56 @@
+use reth::{
+    core::primitives::SealedBlock,
+    primitives::{Block, RecoveredBlock},
+    providers::{CanonStateNotification, Chain},
+};
+use signet_types::MagicSig;
+use std::sync::Arc;
 
+/// Removes Signet system transactions from the block.
+fn strip_block(block: RecoveredBlock<Block>) -> RecoveredBlock<Block> {
+    let (sealed, senders) = block.split_sealed();
+    let (header, mut body) = sealed.split_sealed_header_body();
+
+    // This is the index of the first transaction that has a system magic
+    // signature.
+    let sys_index = body
+        .transactions
+        .partition_point(|tx| MagicSig::try_from_signature(tx.signature()).is_some());
+
+    body.transactions.truncate(sys_index);
+
+    let sealed = SealedBlock::from_sealed_parts(header, body);
+    RecoveredBlock::new_sealed(sealed, senders)
+}
+
+/// Removes Signet system transactions from the chain. This function uses
+/// `Arc::make_mut` to clone the contents of the Arc and modify the new
+/// instance.
+fn strip_chain(chain: &mut Arc<Chain>) {
+    let chain = Arc::make_mut(chain);
+
+    let (blocks, outcome, trie) = std::mem::take(chain).into_inner();
+    let blocks = blocks.into_blocks().map(strip_block);
+
+    *chain = Chain::new(blocks, outcome, trie);
+}
+
+/// Strips Signet system transactions from the `CanonStateNotification`.
+pub(crate) fn strip_signet_system_txns(notif: CanonStateNotification) -> CanonStateNotification {
+    // Cloning here ensures that the `make_mut` invocations in
+    // `strip_chain` do not ever modify the original `notif` object.
+    let _c = notif.clone();
+
+    match notif {
+        CanonStateNotification::Commit { mut new } => {
+            strip_chain(&mut new);
+            CanonStateNotification::Commit { new }
+        }
+        CanonStateNotification::Reorg { mut old, mut new } => {
+            strip_chain(&mut old);
+            strip_chain(&mut new);
+
+            CanonStateNotification::Reorg { old, new }
+        }
+    }
+}

crates/rpc/src/ctx/mod.rs

@@ -5,6 +5,7 @@ mod full;
 pub use full::RpcCtx;
 
 mod fee_hist;
+pub(crate) use fee_hist::strip_signet_system_txns;
 
 /// Type alias for EVMs using a [`StateProviderBox`] as the `DB` type for
 /// trevm.

crates/rpc/src/ctx/signet.rs

@@ -1,5 +1,6 @@
 use crate::{
     RuRevmState,
+    ctx::strip_signet_system_txns,
     eth::EthError,
     interest::{ActiveFilter, FilterManager, FilterOutput, SubscriptionManager},
     receipts::build_signet_receipt,
@@ -12,6 +13,7 @@ use alloy::{
     primitives::{B256, U64},
     rpc::types::{FeeHistory, Filter, Log},
 };
+use futures_util::StreamExt;
 use reth::{
     core::primitives::SignerRecoverable,
     primitives::{Block, Receipt, Recovered, RecoveredBlock, TransactionSigned},
@@ -106,11 +108,14 @@ where
         let cache = EthStateCache::spawn_with(provider.clone(), eth_config.cache, spawner.clone());
         let gas_oracle =
             GasPriceOracle::new(provider.clone(), eth_config.gas_oracle, cache.clone());
+
         let fee_history = FeeHistoryCache::new(eth_config.fee_history_cache);
 
+        // The fee task pre-calculates and caches common percentiles for the
+        // `eth_feeHistory` RPC method.
         let fee_task = fee_history_cache_new_blocks_task(
             fee_history.clone(),
-            provider.canonical_state_stream(),
+            provider.canonical_state_stream().map(strip_signet_system_txns),
             provider.clone(),
             cache.clone(),
         );