alloy_provider/provider/eth_call/

mod.rs

use crate::ProviderCall;
use alloy_eips::BlockId;
use alloy_json_rpc::RpcRecv;
use alloy_network::Network;
use alloy_primitives::{Address, Bytes};
use alloy_rpc_types_eth::{
    state::{AccountOverride, StateOverride},
    BlockOverrides,
};
use alloy_sol_types::SolCall;
use alloy_transport::TransportResult;
use futures::FutureExt;
use std::{
    future::{Future, IntoFuture},
    marker::PhantomData,
    sync::Arc,
    task::Poll,
    time::Duration,
};

#[cfg(not(all(target_family = "wasm", target_os = "unknown")))]
use tokio::time::{timeout as timeout_future, Timeout};

#[cfg(all(target_family = "wasm", target_os = "unknown"))]
use wasmtimer::tokio::{timeout as timeout_future, Timeout};

mod params;
pub use params::{EthCallManyParams, EthCallParams};

mod call_many;
pub use call_many::EthCallMany;

mod caller;
pub use caller::Caller;

/// The [`EthCallFut`] future is the future type for an `eth_call` RPC request.
#[derive(Debug)]
#[doc(hidden)] // Not public API.
#[expect(unnameable_types)]
#[pin_project::pin_project]
pub struct EthCallFut<N, Resp, Output, Map>
where
    N: Network,
    Resp: RpcRecv,
    Output: 'static,
    Map: Fn(Resp) -> Output,
{
    inner: EthCallFutInner<N, Resp, Output, Map>,
}

enum EthCallFutInner<N, Resp, Output, Map>
where
    N: Network,
    Resp: RpcRecv,
    Map: Fn(Resp) -> Output,
{
    Preparing {
        caller: Arc<dyn Caller<N, Resp>>,
        params: EthCallParams<N>,
        method: &'static str,
        map: Map,
    },
    Running {
        map: Map,
        fut: ProviderCall<EthCallParams<N>, Resp>,
    },
    Polling,
}

impl<N, Resp, Output, Map> core::fmt::Debug for EthCallFutInner<N, Resp, Output, Map>
where
    N: Network,
    Resp: RpcRecv,
    Output: 'static,
    Map: Fn(Resp) -> Output,
{
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        match self {
            Self::Preparing { caller: _, params, method, map: _ } => {
                f.debug_struct("Preparing").field("params", params).field("method", method).finish()
            }
            Self::Running { .. } => f.debug_tuple("Running").finish(),
            Self::Polling => f.debug_tuple("Polling").finish(),
        }
    }
}

impl<N, Resp, Output, Map> EthCallFut<N, Resp, Output, Map>
where
    N: Network,
    Resp: RpcRecv,
    Output: 'static,
    Map: Fn(Resp) -> Output,
{
    /// Returns `true` if the future is in the preparing state.
    const fn is_preparing(&self) -> bool {
        matches!(self.inner, EthCallFutInner::Preparing { .. })
    }

    /// Returns `true` if the future is in the running state.
    const fn is_running(&self) -> bool {
        matches!(self.inner, EthCallFutInner::Running { .. })
    }

    fn poll_preparing(&mut self, cx: &mut std::task::Context<'_>) -> Poll<TransportResult<Output>> {
        let EthCallFutInner::Preparing { caller, params, method, map } =
            std::mem::replace(&mut self.inner, EthCallFutInner::Polling)
        else {
            unreachable!("bad state")
        };

        let fut =
            if method.eq("eth_call") { caller.call(params) } else { caller.estimate_gas(params) }?;

        self.inner = EthCallFutInner::Running { map, fut };

        self.poll_running(cx)
    }

    fn poll_running(&mut self, cx: &mut std::task::Context<'_>) -> Poll<TransportResult<Output>> {
        let EthCallFutInner::Running { ref map, ref mut fut } = self.inner else {
            unreachable!("bad state")
        };

        fut.poll_unpin(cx).map(|res| res.map(map))
    }
}

impl<N, Resp, Output, Map> Future for EthCallFut<N, Resp, Output, Map>
where
    N: Network,
    Resp: RpcRecv,
    Output: 'static,
    Map: Fn(Resp) -> Output,
{
    type Output = TransportResult<Output>;

    fn poll(
        self: std::pin::Pin<&mut Self>,
        cx: &mut std::task::Context<'_>,
    ) -> std::task::Poll<Self::Output> {
        let this = self.get_mut();
        if this.is_preparing() {
            this.poll_preparing(cx)
        } else if this.is_running() {
            this.poll_running(cx)
        } else {
            panic!("unexpected state")
        }
    }
}

/// A builder for an `"eth_call"` request. This type is returned by the
/// [`Provider::call`] method.
///
/// Builders returned by the default [`Provider::call`] and estimation paths retain only a weak
/// client handle. Keep the provider alive until such a call is awaited, or awaiting it returns a
/// backend-gone transport error. Provider layers may supply a custom caller that retains additional
/// state, as the batching layer does.
///
/// [`Provider::call`]: crate::Provider::call
#[must_use = "EthCall must be awaited to execute the call"]
#[derive(Clone)]
pub struct EthCall<N, Resp, Output = Resp, Map = fn(Resp) -> Output>
where
    N: Network,
    Resp: RpcRecv,
    Map: Fn(Resp) -> Output,
{
    caller: Arc<dyn Caller<N, Resp>>,
    params: EthCallParams<N>,
    method: &'static str,
    map: Map,
    _pd: PhantomData<fn() -> (Resp, Output)>,
}

impl<N, Resp> core::fmt::Debug for EthCall<N, Resp>
where
    N: Network,
    Resp: RpcRecv,
{
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        f.debug_struct("EthCall")
            .field("params", &self.params)
            .field("method", &self.method)
            .finish()
    }
}

impl<N, Resp> EthCall<N, Resp>
where
    N: Network,
    Resp: RpcRecv,
{
    /// Create a new [`EthCall`].
    pub fn new(
        caller: impl Caller<N, Resp> + 'static,
        method: &'static str,
        data: N::TransactionRequest,
    ) -> Self {
        Self {
            caller: Arc::new(caller),
            params: EthCallParams::new(data),
            method,
            map: std::convert::identity,
            _pd: PhantomData,
        }
    }

    /// Create a new [`EthCall`] with method set to `"eth_call"`.
    pub fn call(caller: impl Caller<N, Resp> + 'static, data: N::TransactionRequest) -> Self {
        Self::new(caller, "eth_call", data)
    }

    /// Create a new [`EthCall`] with method set to `"eth_estimateGas"`.
    pub fn gas_estimate(
        caller: impl Caller<N, Resp> + 'static,
        data: N::TransactionRequest,
    ) -> Self {
        Self::new(caller, "eth_estimateGas", data)
    }
}

impl<N, Resp, Output, Map> EthCall<N, Resp, Output, Map>
where
    N: Network,
    Resp: RpcRecv,
    Map: Fn(Resp) -> Output,
{
    /// Map the response to a different type. This is usable for converting
    /// the response to a more usable type, e.g. changing `U64` to `u64`.
    ///
    /// ## Note
    ///
    /// Carefully review the rust documentation on [fn pointers] before passing
    /// them to this function. Unless the pointer is specifically coerced to a
    /// `fn(_) -> _`, the `NewMap` will be inferred as that function's unique
    /// type. This can lead to confusing error messages.
    ///
    /// [fn pointers]: https://doc.rust-lang.org/std/primitive.fn.html#creating-function-pointers
    pub fn map_resp<NewOutput, NewMap>(self, map: NewMap) -> EthCall<N, Resp, NewOutput, NewMap>
    where
        NewMap: Fn(Resp) -> NewOutput,
    {
        EthCall {
            caller: self.caller,
            params: self.params,
            method: self.method,
            map,
            _pd: PhantomData,
        }
    }

    /// Wraps this call in a client-side timeout that only stops waiting for the response.
    ///
    /// Awaiting the returned future produces a timeout result around the existing transport result,
    /// so the two error cases can be handled separately.
    ///
    /// ```no_run
    /// # async fn example<P: alloy_provider::Provider>(
    /// #     provider: P,
    /// #     tx: alloy_rpc_types_eth::TransactionRequest,
    /// # ) -> Result<(), Box<dyn std::error::Error>> {
    /// use alloy_provider::Provider as _;
    /// use std::time::Duration;
    ///
    /// let output = provider.call(tx).timeout(Duration::from_secs(10)).await??;
    /// # let _: alloy_primitives::Bytes = output;
    /// # Ok(())
    /// # }
    /// ```
    ///
    /// # Panics
    ///
    /// On Tokio-backed targets, including WASI, the returned future panics when polled if there
    /// is no current Tokio timer, for example when polled outside of a Tokio runtime.
    pub fn timeout(self, duration: Duration) -> Timeout<<Self as IntoFuture>::IntoFuture>
    where
        Output: 'static,
    {
        timeout_future(duration, self.into_future())
    }

    /// Set the state overrides for this call.
    pub fn overrides(mut self, overrides: impl Into<StateOverride>) -> Self {
        self.params.overrides = Some(overrides.into());
        self
    }

    /// Set the state overrides for this call, if any.
    pub fn overrides_opt(mut self, overrides: Option<StateOverride>) -> Self {
        self.params.overrides = overrides;
        self
    }

    /// Appends a single [AccountOverride] to the state override.
    ///
    /// Creates a new [`StateOverride`] if none has been set yet.
    pub fn account_override(mut self, address: Address, account_override: AccountOverride) -> Self {
        let mut overrides = self.params.overrides.unwrap_or_default();
        overrides.insert(address, account_override);
        self.params.overrides = Some(overrides);

        self
    }

    /// Extends the given [AccountOverride] to the state override.
    ///
    /// Creates a new [`StateOverride`] if none has been set yet.
    pub fn account_overrides(
        mut self,
        overrides: impl IntoIterator<Item = (Address, AccountOverride)>,
    ) -> Self {
        for (addr, account_override) in overrides.into_iter() {
            self = self.account_override(addr, account_override);
        }
        self
    }

    /// Sets the block overrides for this call.
    pub fn with_block_overrides(mut self, overrides: BlockOverrides) -> Self {
        self.params.block_overrides = Some(overrides);
        self
    }

    /// Sets the block overrides for this call, if any.
    pub fn with_block_overrides_opt(mut self, overrides: Option<BlockOverrides>) -> Self {
        self.params.block_overrides = overrides;
        self
    }

    /// Set the block to use for this call.
    pub const fn block(mut self, block: BlockId) -> Self {
        self.params.block = Some(block);
        self
    }

    /// Set the block id to "pending".
    pub const fn pending(self) -> Self {
        self.block(BlockId::pending())
    }

    /// Set the block id to "latest".
    pub const fn latest(self) -> Self {
        self.block(BlockId::latest())
    }

    /// Set the block id to "earliest".
    pub const fn earliest(self) -> Self {
        self.block(BlockId::earliest())
    }

    /// Set the block id to "finalized".
    pub const fn finalized(self) -> Self {
        self.block(BlockId::finalized())
    }

    /// Set the block id to "safe".
    pub const fn safe(self) -> Self {
        self.block(BlockId::safe())
    }

    /// Set the block id to a specific height.
    pub const fn number(self, number: u64) -> Self {
        self.block(BlockId::number(number))
    }

    /// Set the block id to a specific hash, without requiring the hash be part
    /// of the canonical chain.
    pub const fn hash(self, hash: alloy_primitives::B256) -> Self {
        self.block(BlockId::hash(hash))
    }

    /// Set the block id to a specific hash and require the hash be part of the
    /// canonical chain.
    pub const fn hash_canonical(self, hash: alloy_primitives::B256) -> Self {
        self.block(BlockId::hash_canonical(hash))
    }
}

impl<N> EthCall<N, Bytes>
where
    N: Network,
{
    /// Decode the [`Bytes`] returned by an `"eth_call"` into a [`SolCall::Return`] type.
    ///
    /// ## Note
    ///
    /// The result of the `eth_call` will be [`alloy_sol_types::Result`] with the Ok variant
    /// containing the decoded [`SolCall::Return`] type.
    ///
    /// # Examples
    ///
    /// ```ignore
    /// let call = EthCall::call(provider, data).decode_resp::<MySolCall>().await?.unwrap();
    ///
    /// assert!(matches!(call.return_value, MySolCall::MyStruct { .. }));
    /// ```
    pub fn decode_resp<S: SolCall>(self) -> EthCall<N, Bytes, alloy_sol_types::Result<S::Return>> {
        self.map_resp(|data| S::abi_decode_returns(&data))
    }
}

impl<N, Resp, Output, Map> std::future::IntoFuture for EthCall<N, Resp, Output, Map>
where
    N: Network,
    Resp: RpcRecv,
    Output: 'static,
    Map: Fn(Resp) -> Output,
{
    type Output = TransportResult<Output>;

    type IntoFuture = EthCallFut<N, Resp, Output, Map>;

    fn into_future(self) -> Self::IntoFuture {
        EthCallFut {
            inner: EthCallFutInner::Preparing {
                caller: self.caller,
                params: self.params,
                method: self.method,
                map: self.map,
            },
        }
    }
}

#[cfg(test)]
mod test {
    use super::*;
    use alloy_eips::BlockNumberOrTag;
    use alloy_network::{Ethereum, TransactionBuilder};
    use alloy_primitives::{address, U256};
    use alloy_rpc_types_eth::{state::StateOverride, TransactionRequest};

    #[derive(Clone, Copy, Debug)]
    struct PendingCaller;

    impl Caller<Ethereum, U256> for PendingCaller {
        fn call(
            &self,
            _params: EthCallParams<Ethereum>,
        ) -> TransportResult<ProviderCall<EthCallParams<Ethereum>, U256>> {
            Ok(ProviderCall::BoxedFuture(Box::pin(std::future::pending())))
        }

        fn estimate_gas(
            &self,
            _params: EthCallParams<Ethereum>,
        ) -> TransportResult<ProviderCall<EthCallParams<Ethereum>, U256>> {
            Ok(ProviderCall::BoxedFuture(Box::pin(std::future::pending())))
        }

        fn call_many(
            &self,
            _params: EthCallManyParams<'_>,
        ) -> TransportResult<ProviderCall<EthCallManyParams<'static>, U256>> {
            Ok(ProviderCall::BoxedFuture(Box::pin(std::future::pending())))
        }
    }

    #[tokio::test]
    async fn test_eth_call_with_timeout() {
        let call = EthCall::call(PendingCaller, TransactionRequest::default());

        assert!(call.timeout(Duration::ZERO).await.is_err());
    }

    #[test]
    fn test_serialize_eth_call_params() {
        let alice = address!("0000000000000000000000000000000000000001");
        let bob = address!("0000000000000000000000000000000000000002");
        let data = TransactionRequest::default()
            .with_from(alice)
            .with_to(bob)
            .with_nonce(0)
            .with_chain_id(1)
            .value(U256::from(100))
            .with_gas_limit(21_000)
            .with_max_priority_fee_per_gas(1_000_000_000)
            .with_max_fee_per_gas(20_000_000_000);

        let block = BlockId::Number(BlockNumberOrTag::Number(1));
        let overrides = StateOverride::default();

        // Expected: [data]
        let params: EthCallParams<Ethereum> = EthCallParams::new(data.clone());

        assert_eq!(params.data(), &data);
        assert_eq!(params.block(), None);
        assert_eq!(params.overrides(), None);
        assert_eq!(
            serde_json::to_string(&params).unwrap(),
            r#"[{"from":"0x0000000000000000000000000000000000000001","to":"0x0000000000000000000000000000000000000002","maxFeePerGas":"0x4a817c800","maxPriorityFeePerGas":"0x3b9aca00","gas":"0x5208","value":"0x64","nonce":"0x0","chainId":"0x1"}]"#
        );

        // Expected: [data, block, overrides]
        let params: EthCallParams<Ethereum> =
            EthCallParams::new(data.clone()).with_block(block).with_overrides(overrides.clone());

        assert_eq!(params.data(), &data);
        assert_eq!(params.block(), Some(block));
        assert_eq!(params.overrides(), Some(&overrides));
        assert_eq!(
            serde_json::to_string(&params).unwrap(),
            r#"[{"from":"0x0000000000000000000000000000000000000001","to":"0x0000000000000000000000000000000000000002","maxFeePerGas":"0x4a817c800","maxPriorityFeePerGas":"0x3b9aca00","gas":"0x5208","value":"0x64","nonce":"0x0","chainId":"0x1"},"0x1",{}]"#
        );

        // Expected: [data, (default), overrides]
        let params: EthCallParams<Ethereum> =
            EthCallParams::new(data.clone()).with_overrides(overrides.clone());

        assert_eq!(params.data(), &data);
        assert_eq!(params.block(), None);
        assert_eq!(params.overrides(), Some(&overrides));
        assert_eq!(
            serde_json::to_string(&params).unwrap(),
            r#"[{"from":"0x0000000000000000000000000000000000000001","to":"0x0000000000000000000000000000000000000002","maxFeePerGas":"0x4a817c800","maxPriorityFeePerGas":"0x3b9aca00","gas":"0x5208","value":"0x64","nonce":"0x0","chainId":"0x1"},"latest",{}]"#
        );

        // Expected: [data, block]
        let params: EthCallParams<Ethereum> = EthCallParams::new(data.clone()).with_block(block);

        assert_eq!(params.data(), &data);
        assert_eq!(params.block(), Some(block));
        assert_eq!(params.overrides(), None);
        assert_eq!(
            serde_json::to_string(&params).unwrap(),
            r#"[{"from":"0x0000000000000000000000000000000000000001","to":"0x0000000000000000000000000000000000000002","maxFeePerGas":"0x4a817c800","maxPriorityFeePerGas":"0x3b9aca00","gas":"0x5208","value":"0x64","nonce":"0x0","chainId":"0x1"},"0x1"]"#
        );
    }
}