From 78f62dd34c8c6c1b0a045990d4bf0d235a9d32b2 Mon Sep 17 00:00:00 2001
From: Daniel Ramirez <javamonn@hey.com>
Date: Thu, 2 May 2024 10:30:04 -0400
Subject: [PATCH] feat: add spawn_replay_transaction to EthTransactions (#8036)

Co-authored-by: Oliver Nordbjerg <onbjerg@users.noreply.github.com>
---
 crates/rpc/rpc/src/eth/api/transactions.rs | 55 ++++++++++++++++++++++
 crates/rpc/rpc/src/otterscan.rs            | 13 ++---
 2 files changed, 59 insertions(+), 9 deletions(-)

diff --git a/crates/rpc/rpc/src/eth/api/transactions.rs b/crates/rpc/rpc/src/eth/api/transactions.rs
index 15e2b6f565..51bde5bfaa 100644
--- a/crates/rpc/rpc/src/eth/api/transactions.rs
+++ b/crates/rpc/rpc/src/eth/api/transactions.rs
@@ -376,6 +376,20 @@ pub trait EthTransactions: Send + Sync {
             .await
     }
 
+    /// Retrieves the transaction if it exists and returns its trace.
+    ///
+    /// Before the transaction is traced, all previous transaction in the block are applied to the
+    /// state by executing them first.
+    /// The callback `f` is invoked with the [ResultAndState] after the transaction was executed and
+    /// the database that points to the beginning of the transaction.
+    ///
+    /// Note: Implementers should use a threadpool where blocking is allowed, such as
+    /// [BlockingTaskPool](reth_tasks::pool::BlockingTaskPool).
+    async fn spawn_replay_transaction<F, R>(&self, hash: B256, f: F) -> EthResult<Option<R>>
+    where
+        F: FnOnce(TransactionInfo, ResultAndState, StateCacheDB) -> EthResult<R> + Send + 'static,
+        R: Send + 'static;
+
     /// Retrieves the transaction if it exists and returns its trace.
     ///
     /// Before the transaction is traced, all previous transaction in the block are applied to the
@@ -1173,6 +1187,47 @@ where
         Ok(block.map(|block| (transaction, block.seal(block_hash))))
     }
 
+    async fn spawn_replay_transaction<F, R>(&self, hash: B256, f: F) -> EthResult<Option<R>>
+    where
+        F: FnOnce(TransactionInfo, ResultAndState, StateCacheDB) -> EthResult<R> + Send + 'static,
+        R: Send + 'static,
+    {
+        let (transaction, block) = match self.transaction_and_block(hash).await? {
+            None => return Ok(None),
+            Some(res) => res,
+        };
+        let (tx, tx_info) = transaction.split();
+
+        let (cfg, block_env, _) = self.evm_env_at(block.hash().into()).await?;
+
+        // we need to get the state of the parent block because we're essentially replaying the
+        // block the transaction is included in
+        let parent_block = block.parent_hash;
+        let block_txs = block.into_transactions_ecrecovered();
+
+        let this = self.clone();
+        self.spawn_with_state_at_block(parent_block.into(), move |state| {
+            let mut db = CacheDB::new(StateProviderDatabase::new(state));
+
+            // replay all transactions prior to the targeted transaction
+            this.replay_transactions_until(
+                &mut db,
+                cfg.clone(),
+                block_env.clone(),
+                block_txs,
+                tx.hash,
+            )?;
+
+            let env =
+                EnvWithHandlerCfg::new_with_cfg_env(cfg, block_env, tx_env_with_recovered(&tx));
+
+            let (res, _) = this.transact(&mut db, env)?;
+            f(tx_info, res, db)
+        })
+        .await
+        .map(Some)
+    }
+
     async fn spawn_trace_transaction_in_block_with_inspector<Insp, F, R>(
         &self,
         hash: B256,
diff --git a/crates/rpc/rpc/src/otterscan.rs b/crates/rpc/rpc/src/otterscan.rs
index bdfbc1293e..2f62e66a31 100644
--- a/crates/rpc/rpc/src/otterscan.rs
+++ b/crates/rpc/rpc/src/otterscan.rs
@@ -1,7 +1,6 @@
 use alloy_primitives::Bytes;
 use async_trait::async_trait;
 use jsonrpsee::core::RpcResult;
-use revm::inspectors::NoOpInspector;
 use revm_inspectors::transfer::{TransferInspector, TransferKind};
 use revm_primitives::ExecutionResult;
 
@@ -81,14 +80,10 @@ where
     async fn get_transaction_error(&self, tx_hash: TxHash) -> RpcResult<Option<Bytes>> {
         let maybe_revert = self
             .eth
-            .spawn_trace_transaction_in_block_with_inspector(
-                tx_hash,
-                NoOpInspector,
-                |_tx_info, _inspector, res, _| match res.result {
-                    ExecutionResult::Revert { output, .. } => Ok(Some(output)),
-                    _ => Ok(None),
-                },
-            )
+            .spawn_replay_transaction(tx_hash, |_tx_info, res, _| match res.result {
+                ExecutionResult::Revert { output, .. } => Ok(Some(output)),
+                _ => Ok(None),
+            })
             .await
             .map(Option::flatten)?;
         Ok(maybe_revert)