Add builder txn to Flashblocks (#89)

* Add changes

* Remove print

Author: ferranbt

crates/op-rbuilder/src/args/op.rs

@@ -95,7 +95,7 @@ pub struct FlashblocksArgs {
 
     /// flashblock block time in milliseconds
     #[arg(
-        long = "flashblock.block-time",
+        long = "flashblocks.block-time",
         default_value = "250",
         env = "FLASHBLOCK_BLOCK_TIME"
     )]

crates/op-rbuilder/src/builders/context.rs

@@ -1,5 +1,5 @@
 use alloy_consensus::{Eip658Value, Transaction, TxEip1559};
-use alloy_eips::{Encodable2718, Typed2718};
+use alloy_eips::{eip7623::TOTAL_COST_FLOOR_PER_TOKEN, Encodable2718, Typed2718};
 use alloy_op_evm::block::receipt_builder::OpReceiptBuilder;
 use alloy_primitives::{Address, Bytes, TxKind, U256};
 use alloy_rpc_types_eth::Withdrawals;
@@ -500,9 +500,9 @@ impl OpPayloadBuilderCtx {
         Ok(None)
     }
 
-    pub fn add_builder_tx<DB>(
+    pub fn add_builder_tx<DB, Extra: Debug + Default>(
         &self,
-        info: &mut ExecutionInfo,
+        info: &mut ExecutionInfo<Extra>,
         db: &mut State<DB>,
         builder_tx_gas: u64,
         message: Vec<u8>,
@@ -583,6 +583,27 @@ impl OpPayloadBuilderCtx {
     }
 }
 
+pub fn estimate_gas_for_builder_tx(input: Vec<u8>) -> u64 {
+    // Count zero and non-zero bytes
+    let (zero_bytes, nonzero_bytes) = input.iter().fold((0, 0), |(zeros, nonzeros), &byte| {
+        if byte == 0 {
+            (zeros + 1, nonzeros)
+        } else {
+            (zeros, nonzeros + 1)
+        }
+    });
+
+    // Calculate gas cost (4 gas per zero byte, 16 gas per non-zero byte)
+    let zero_cost = zero_bytes * 4;
+    let nonzero_cost = nonzero_bytes * 16;
+
+    // Tx gas should be not less than floor gas https://eips.ethereum.org/EIPS/eip-7623
+    let tokens_in_calldata = zero_bytes + nonzero_bytes * 4;
+    let floor_gas = 21_000 + tokens_in_calldata * TOTAL_COST_FLOOR_PER_TOKEN;
+
+    std::cmp::max(zero_cost + nonzero_cost + 21_000, floor_gas)
+}
+
 /// Creates signed builder tx to Address::ZERO and specified message as input
 pub fn signed_builder_tx<DB>(
     db: &mut State<DB>,

crates/op-rbuilder/src/builders/flashblocks/payload.rs

@@ -4,7 +4,7 @@ use std::{sync::Arc, time::Instant};
 use super::{config::FlashblocksConfig, wspub::WebSocketPublisher};
 use crate::{
     builders::{
-        context::OpPayloadBuilderCtx,
+        context::{estimate_gas_for_builder_tx, OpPayloadBuilderCtx},
         flashblocks::config::FlashBlocksConfigExt,
         generator::{BlockCell, BuildArguments},
         BuilderConfig,
@@ -257,6 +257,13 @@ where
             }
         });
 
+        let message = format!("Block Number: {}", ctx.block_number())
+            .as_bytes()
+            .to_vec();
+        let builder_tx_gas = ctx
+            .builder_signer()
+            .map_or(0, |_| estimate_gas_for_builder_tx(message.clone()));
+
         // Process flashblocks in a blocking loop
         loop {
             // Block on receiving a message, break on cancellation or closed channel
@@ -340,6 +347,12 @@ where
                         return Ok(());
                     }
 
+                    // If it is the last flashblocks, add the builder txn to the block if enabled
+                    if flashblock_count == self.config.flashblocks_per_block() - 1 {
+                        // TODO: Account for DA size limits
+                        ctx.add_builder_tx(&mut info, &mut db, builder_tx_gas, message.clone());
+                    }
+
                     let total_block_built_duration = Instant::now();
                     let build_result = build_block(db, &ctx, &mut info);
                     ctx.metrics

crates/op-rbuilder/src/builders/mod.rs

@@ -147,7 +147,7 @@ where
             builder_signer: args.builder_signer,
             revert_protection: args.enable_revert_protection,
             block_time: Duration::from_millis(args.chain_block_time),
-            block_time_leeway: Duration::from_millis(500),
+            block_time_leeway: Duration::from_secs(args.extra_block_deadline_secs),
             da_config: Default::default(),
             specific: S::try_from(args)?,
         })

crates/op-rbuilder/src/builders/standard/payload.rs

@@ -1,9 +1,7 @@
 use alloy_consensus::{
     constants::EMPTY_WITHDRAWALS, proofs, BlockBody, Header, EMPTY_OMMER_ROOT_HASH,
 };
-use alloy_eips::{
-    eip7623::TOTAL_COST_FLOOR_PER_TOKEN, eip7685::EMPTY_REQUESTS_HASH, merge::BEACON_NONCE,
-};
+use alloy_eips::{eip7685::EMPTY_REQUESTS_HASH, merge::BEACON_NONCE};
 use alloy_primitives::U256;
 use reth::payload::PayloadBuilderAttributes;
 use reth_basic_payload_builder::{BuildOutcome, BuildOutcomeKind, MissingPayloadBehaviour};
@@ -38,7 +36,7 @@ use crate::{
     traits::{ClientBounds, NodeBounds, PayloadTxsBounds, PoolBounds},
 };
 
-use super::super::context::OpPayloadBuilderCtx;
+use super::super::context::{estimate_gas_for_builder_tx, OpPayloadBuilderCtx};
 
 pub struct StandardPayloadBuilderBuilder(pub BuilderConfig<()>);
 
@@ -566,24 +564,3 @@ impl<Txs: PayloadTxsBounds> OpBuilder<'_, Txs> {
         }
     }
 }
-
-fn estimate_gas_for_builder_tx(input: Vec<u8>) -> u64 {
-    // Count zero and non-zero bytes
-    let (zero_bytes, nonzero_bytes) = input.iter().fold((0, 0), |(zeros, nonzeros), &byte| {
-        if byte == 0 {
-            (zeros + 1, nonzeros)
-        } else {
-            (zeros, nonzeros + 1)
-        }
-    });
-
-    // Calculate gas cost (4 gas per zero byte, 16 gas per non-zero byte)
-    let zero_cost = zero_bytes * 4;
-    let nonzero_cost = nonzero_bytes * 16;
-
-    // Tx gas should be not less than floor gas https://eips.ethereum.org/EIPS/eip-7623
-    let tokens_in_calldata = zero_bytes + nonzero_bytes * 4;
-    let floor_gas = 21_000 + tokens_in_calldata * TOTAL_COST_FLOOR_PER_TOKEN;
-
-    std::cmp::max(zero_cost + nonzero_cost + 21_000, floor_gas)
-}

crates/op-rbuilder/src/tests/flashblocks/smoke.rs

@@ -9,7 +9,6 @@ use tokio_util::sync::CancellationToken;
 use crate::tests::TestHarnessBuilder;
 
 #[tokio::test]
-#[ignore = "Flashblocks tests need more work"]
 async fn chain_produces_blocks() -> eyre::Result<()> {
     let harness = TestHarnessBuilder::new("flashbots_chain_produces_blocks")
         .with_flashblocks_port(1239)
@@ -49,7 +48,9 @@ async fn chain_produces_blocks() -> eyre::Result<()> {
             let _ = harness.send_valid_transaction().await?;
         }
 
-        generator.generate_block().await?;
+        let generated_block = generator.generate_block().await?;
+        assert_eq!(generated_block.num_transactions(), 7); // 5 normal txn + deposit + builder txn
+
         tokio::time::sleep(std::time::Duration::from_secs(1)).await;
     }
 

crates/op-rbuilder/src/tests/framework/blocks.rs

@@ -402,4 +402,8 @@ impl BlockGenerated {
     pub fn not_includes_vec(&self, tx_hashes: Vec<B256>) -> bool {
         tx_hashes.iter().all(|hash| self.not_includes(*hash))
     }
+
+    pub fn num_transactions(&self) -> usize {
+        self.block.transactions.len()
+    }
 }

crates/op-rbuilder/src/tests/framework/harness.rs

@@ -133,6 +133,7 @@ impl TestHarnessBuilder {
             builder_http_port,
             validator_auth_rpc_port,
             builder_log_path,
+            chain_block_time: self.chain_block_time,
         })
     }
 }
@@ -143,6 +144,7 @@ pub struct TestHarness {
     builder_http_port: u16,
     validator_auth_rpc_port: u16,
     builder_log_path: PathBuf,
+    chain_block_time: Option<u64>,
 }
 
 impl TestHarness {
@@ -173,7 +175,13 @@ impl TestHarness {
         let engine_api = EngineApi::new_with_port(self.builder_auth_rpc_port).unwrap();
         let validation_api = Some(EngineApi::new_with_port(self.validator_auth_rpc_port).unwrap());
 
-        let mut generator = BlockGenerator::new(engine_api, validation_api, false, 1, None);
+        let mut generator = BlockGenerator::new(
+            engine_api,
+            validation_api,
+            false,
+            self.chain_block_time.map_or(1, |time| time / 1000), // in seconds
+            None,
+        );
         generator.init().await?;
 
         Ok(generator)

crates/op-rbuilder/src/tests/framework/op.rs

@@ -153,7 +153,7 @@ impl Service for OpRbuilderConfig {
         }
 
         if let Some(flashblocks_port) = &self.flashblocks_port {
-            cmd.arg("--flashblocks.enabled").arg("true");
+            cmd.arg("--flashblocks.enabled");
             cmd.arg("--flashblocks.addr").arg("127.0.0.1");
             cmd.arg("--flashblocks.port")
                 .arg(flashblocks_port.to_string());
@@ -165,7 +165,7 @@ impl Service for OpRbuilderConfig {
         }
 
         if let Some(flashbots_block_time) = self.flashbots_block_time {
-            cmd.arg("--rollup.flashblock-block-time")
+            cmd.arg("--flashblocks.block-time")
                 .arg(flashbots_block_time.to_string());
         }