kona_engine/
query.rs

1use std::sync::Arc;
2
3use alloy_eips::BlockNumberOrTag;
4use alloy_provider::Provider;
5use alloy_transport::{RpcError, TransportErrorKind};
6use kona_genesis::RollupConfig;
7use kona_protocol::{L2BlockInfo, OutputRoot, Predeploys};
8use tokio::sync::oneshot::Sender;
9
10use crate::{EngineClient, EngineClientError, EngineState};
11
12/// The type of data that can be requested from the engine.
13pub type EngineQuerySender = tokio::sync::mpsc::Sender<EngineQueries>;
14
15/// Returns the full engine state.
16#[derive(Debug)]
17pub enum EngineQueries {
18    /// Returns the rollup config.
19    Config(Sender<RollupConfig>),
20    /// Returns current L2 engine state information.
21    State(Sender<EngineState>),
22    /// Returns the L2 output at the specified block with a tuple of the block info and associated
23    /// engine state.
24    OutputAtBlock {
25        /// The block number or tag of the block to retrieve the output for.
26        block: BlockNumberOrTag,
27        /// A channel to send back the output and engine state.
28        sender: Sender<(L2BlockInfo, OutputRoot, EngineState)>,
29    },
30    /// Returns a subscription to the updates of the engine state.
31    StateReceiver(Sender<tokio::sync::watch::Receiver<EngineState>>),
32}
33
34/// An error that can occur when querying the engine.
35#[derive(Debug, thiserror::Error)]
36pub enum EngineQueriesError {
37    /// The output channel was closed unexpectedly. Impossible to send query response.
38    #[error("Output channel closed unexpectedly. Impossible to send query response")]
39    OutputChannelClosed,
40    /// Failed to retrieve the L2 block by label.
41    #[error("Failed to retrieve L2 block by label: {0}")]
42    BlockRetrievalFailed(#[from] EngineClientError),
43    /// No block withdrawals root while Isthmus is active.
44    #[error("No block withdrawals root while Isthmus is active")]
45    NoWithdrawalsRoot,
46    /// No L2 block found for block number or tag.
47    #[error("No L2 block found for block number or tag: {0}")]
48    NoL2BlockFound(BlockNumberOrTag),
49    /// Impossible to retrieve L2 withdrawals root from state.
50    #[error("Impossible to retrieve L2 withdrawals root from state. {0}")]
51    FailedToRetrieveWithdrawalsRoot(#[from] RpcError<TransportErrorKind>),
52}
53
54impl EngineQueries {
55    /// Handles the engine query request.
56    pub async fn handle(
57        self,
58        state_recv: &tokio::sync::watch::Receiver<EngineState>,
59        client: &Arc<EngineClient>,
60        rollup_config: &Arc<RollupConfig>,
61    ) -> Result<(), EngineQueriesError> {
62        let state = *state_recv.borrow();
63        match self {
64            Self::Config(sender) => sender
65                .send((**rollup_config).clone())
66                .map_err(|_| EngineQueriesError::OutputChannelClosed),
67            Self::State(sender) => {
68                sender.send(state).map_err(|_| EngineQueriesError::OutputChannelClosed)
69            }
70            Self::OutputAtBlock { block, sender } => {
71                let output_block = client.l2_block_by_label(block).await?;
72                let output_block = output_block.ok_or(EngineQueriesError::NoL2BlockFound(block))?;
73                // Cloning the l2 block below is cheaper than sending a network request to get the
74                // l2 block info. Querying the `L2BlockInfo` from the client ends up
75                // fetching the full l2 block again.
76                let consensus_block = output_block.clone().into_consensus();
77                let output_block_info =
78                    L2BlockInfo::from_block_and_genesis::<op_alloy_consensus::OpTxEnvelope>(
79                        &consensus_block.map_transactions(|tx| tx.inner.inner.into_inner()),
80                        &rollup_config.genesis,
81                    )
82                    .map_err(|_| EngineQueriesError::NoL2BlockFound(block))?;
83
84                let state_root = output_block.header.state_root;
85
86                let message_passer_storage_root =
87                    if rollup_config.is_isthmus_active(output_block.header.timestamp) {
88                        output_block
89                            .header
90                            .withdrawals_root
91                            .ok_or(EngineQueriesError::NoWithdrawalsRoot)?
92                    } else {
93                        // Fetch the storage root for the L2 head block.
94                        let l2_to_l1_message_passer = client
95                            .get_proof(Predeploys::L2_TO_L1_MESSAGE_PASSER, Default::default())
96                            .block_id(block.into())
97                            .await?;
98
99                        l2_to_l1_message_passer.storage_hash
100                    };
101
102                let output_response_v0 = OutputRoot::from_parts(
103                    state_root,
104                    message_passer_storage_root,
105                    output_block.header.hash,
106                );
107
108                sender
109                    .send((output_block_info, output_response_v0, state))
110                    .map_err(|_| EngineQueriesError::OutputChannelClosed)
111            }
112            Self::StateReceiver(subscription) => subscription
113                .send(state_recv.clone())
114                .map_err(|_| EngineQueriesError::OutputChannelClosed),
115        }
116    }
117}
kona_engine/query.rs

kona_engine/
query.rs
