estimate transaction fee (#1015)

bridges/relays/client-substrate/src/chain.rs

@@ -17,14 +17,15 @@
 use bp_runtime::Chain as ChainBase;
 use frame_support::Parameter;
 use jsonrpsee_ws_client::{DeserializeOwned, Serialize};
-use num_traits::{CheckedSub, SaturatingAdd, Zero};
+use num_traits::{Bounded, CheckedSub, SaturatingAdd, Zero};
 use sp_core::{storage::StorageKey, Pair};
 use sp_runtime::{
 	generic::SignedBlock,
 	traits::{
-		AtLeast32Bit, Block as BlockT, Dispatchable, MaybeDisplay, MaybeSerialize, MaybeSerializeDeserialize, Member,
+		AtLeast32Bit, AtLeast32BitUnsigned, Block as BlockT, Dispatchable, MaybeDisplay, MaybeSerialize,
+		MaybeSerializeDeserialize, Member,
 	},
-	EncodedJustification,
+	EncodedJustification, FixedPointOperand,
 };
 use std::{fmt::Debug, time::Duration};
 
@@ -37,6 +38,10 @@ pub trait Chain: ChainBase + Clone {
 	/// How often blocks are produced on that chain. It's suggested to set this value
 	/// to match the block time of the chain.
 	const AVERAGE_BLOCK_INTERVAL: Duration;
+	/// Maximal expected storage proof overhead (in bytes).
+	const STORAGE_PROOF_OVERHEAD: u32;
+	/// Maximal size (in bytes) of SCALE-encoded account id on this chain.
+	const MAXIMAL_ENCODED_ACCOUNT_ID_SIZE: u32;
 
 	/// The user account identifier type for the runtime.
 	type AccountId: Parameter + Member + MaybeSerializeDeserialize + Debug + MaybeDisplay + Ord + Default;
@@ -58,7 +63,20 @@ pub trait Chain: ChainBase + Clone {
 	///
 	/// The chain may suport multiple tokens, but this particular type is for token that is used
 	/// to pay for transaction dispatch, to reward different relayers (headers, messages), etc.
-	type Balance: Parameter + Member + DeserializeOwned + Clone + Copy + CheckedSub + PartialOrd + SaturatingAdd + Zero;
+	type Balance: AtLeast32BitUnsigned
+		+ FixedPointOperand
+		+ Parameter
+		+ Parameter
+		+ Member
+		+ DeserializeOwned
+		+ Clone
+		+ Copy
+		+ Bounded
+		+ CheckedSub
+		+ PartialOrd
+		+ SaturatingAdd
+		+ Zero
+		+ std::convert::TryFrom<sp_core::U256>;
 }
 
 /// Substrate-based chain with `frame_system::Config::AccountData` set to

bridges/relays/client-substrate/src/client.rs

@@ -25,12 +25,14 @@ use codec::Decode;
 use frame_system::AccountInfo;
 use jsonrpsee_ws_client::{traits::SubscriptionClient, v2::params::JsonRpcParams, DeserializeOwned};
 use jsonrpsee_ws_client::{Subscription, WsClient as RpcClient, WsClientBuilder as RpcClientBuilder};
-use num_traits::Zero;
+use num_traits::{Bounded, Zero};
 use pallet_balances::AccountData;
+use pallet_transaction_payment::InclusionFee;
 use relay_utils::relay_loop::RECONNECT_DELAY;
 use sp_core::{storage::StorageKey, Bytes};
 use sp_trie::StorageProof;
 use sp_version::RuntimeVersion;
+use std::convert::TryFrom;
 
 const SUB_API_GRANDPA_AUTHORITIES: &str = "GrandpaApi_grandpa_authorities";
 const MAX_SUBSCRIPTION_CAPACITY: usize = 4096;
@@ -258,6 +260,26 @@ impl<C: Chain> Client<C> {
 		Ok(tx_hash)
 	}
 
+	/// Estimate fee that will be spent on given extrinsic.
+	pub async fn estimate_extrinsic_fee(&self, transaction: Bytes) -> Result<C::Balance> {
+		let fee_details = Substrate::<C>::payment_query_fee_details(&*self.client, transaction, None).await?;
+		let inclusion_fee = fee_details
+			.inclusion_fee
+			.map(|inclusion_fee| {
+				InclusionFee {
+					base_fee: C::Balance::try_from(inclusion_fee.base_fee.into_u256())
+						.unwrap_or_else(|_| C::Balance::max_value()),
+					len_fee: C::Balance::try_from(inclusion_fee.len_fee.into_u256())
+						.unwrap_or_else(|_| C::Balance::max_value()),
+					adjusted_weight_fee: C::Balance::try_from(inclusion_fee.adjusted_weight_fee.into_u256())
+						.unwrap_or_else(|_| C::Balance::max_value()),
+				}
+				.inclusion_fee()
+			})
+			.unwrap_or_else(Zero::zero);
+		Ok(inclusion_fee)
+	}
+
 	/// Get the GRANDPA authority set at given block.
 	pub async fn grandpa_authorities_set(&self, block: C::Hash) -> Result<OpaqueGrandpaAuthoritiesSet> {
 		let call = SUB_API_GRANDPA_AUTHORITIES.to_string();

bridges/relays/client-substrate/src/guard.rs

@@ -185,6 +185,8 @@ mod tests {
 	impl Chain for TestChain {
 		const NAME: &'static str = "Test";
 		const AVERAGE_BLOCK_INTERVAL: Duration = Duration::from_millis(1);
+		const STORAGE_PROOF_OVERHEAD: u32 = 0;
+		const MAXIMAL_ENCODED_ACCOUNT_ID_SIZE: u32 = 0;
 
 		type AccountId = u32;
 		type Index = u32;

bridges/relays/client-substrate/src/rpc.rs

@@ -18,11 +18,13 @@
 
 use crate::chain::Chain;
 
+use pallet_transaction_payment_rpc_runtime_api::FeeDetails;
 use sc_rpc_api::{state::ReadProof, system::Health};
 use sp_core::{
 	storage::{StorageData, StorageKey},
 	Bytes,
 };
+use sp_rpc::number::NumberOrHex;
 use sp_version::RuntimeVersion;
 
 jsonrpsee_proc_macros::rpc_client_api! {
@@ -49,5 +51,7 @@ jsonrpsee_proc_macros::rpc_client_api! {
 		fn state_prove_storage(keys: Vec<StorageKey>, hash: Option<C::Hash>) -> ReadProof<C::Hash>;
 		#[rpc(method = "state_getRuntimeVersion", positional_params)]
 		fn state_runtime_version() -> RuntimeVersion;
+		#[rpc(method = "payment_queryFeeDetails", positional_params)]
+		fn payment_query_fee_details(extrinsic: Bytes, at_block: Option<C::Hash>) -> FeeDetails<NumberOrHex>;
 	}
 }