312 use stellar fee statistics to derive transaction fee

clients/vault/src/requests/structs.rs

@@ -16,10 +16,6 @@ use stellar_relay_lib::sdk::{Asset, TransactionEnvelope, XdrCodec};
 use tokio::sync::RwLock;
 use wallet::{StellarWallet, TransactionResponse};
 
-/// Determines how much the vault is going to pay for the Stellar transaction fees.
-/// We use a fixed fee of 300 stroops for now but might want to make this dynamic in the future.
-const DEFAULT_STROOP_FEE_PER_OPERATION: u32 = 300;
-
 #[derive(Debug, Clone, PartialEq)]
 struct Deadline {
 	parachain: u32,
@@ -291,7 +287,6 @@ impl Request {
 						self.asset.clone(),
 						stroop_amount,
 						request_id,
-						DEFAULT_STROOP_FEE_PER_OPERATION,
 						true,
 					)
 					.await,
@@ -302,7 +297,6 @@ impl Request {
 						self.asset.clone(),
 						stroop_amount,
 						request_id,
-						DEFAULT_STROOP_FEE_PER_OPERATION,
 						false,
 					)
 					.await,

clients/vault/tests/helper/helper.rs

@@ -117,7 +117,6 @@ pub async fn send_payment_to_address(
 	asset: StellarAsset,
 	stroop_amount: StellarStroops,
 	request_id: [u8; 32],
-	stroop_fee_per_operation: u32,
 	is_payment_for_redeem_request: bool,
 ) -> Result<TransactionResponse, Error> {
 	let response;
@@ -130,7 +129,6 @@ pub async fn send_payment_to_address(
 				asset.clone(),
 				stroop_amount,
 				request_id,
-				stroop_fee_per_operation,
 				is_payment_for_redeem_request,
 			)
 			.await;
@@ -175,7 +173,6 @@ pub async fn assert_issue(
 		asset,
 		stroop_amount,
 		issue.issue_id.0,
-		300,
 		false,
 	)
 	.await

clients/vault/tests/vault_integration_tests.rs

@@ -597,7 +597,6 @@ async fn test_issue_overpayment_succeeds() {
 				stellar_asset,
 				stroop_amount.try_into().unwrap(),
 				issue.issue_id.0,
-				300,
 				false,
 			)
 			.await
@@ -685,7 +684,6 @@ async fn test_automatic_issue_execution_succeeds() {
 					stellar_asset,
 					stroop_amount,
 					issue.issue_id.0,
-					300,
 					false,
 				)
 				.await
@@ -822,7 +820,6 @@ async fn test_automatic_issue_execution_succeeds_for_other_vault() {
 					stellar_asset,
 					stroop_amount,
 					issue.issue_id.0,
-					300,
 					false,
 				)
 				.await;
@@ -974,7 +971,6 @@ async fn test_execute_open_requests_succeeds() {
 					asset,
 					stroop_amount,
 					redeem_ids[0].0,
-					300,
 					false
 				)
 				.await

clients/wallet/Cargo.toml

@@ -11,6 +11,7 @@ testing-utils = []
 [dependencies]
 async-trait = "0.1.40"
 futures = "0.3.5"
+cached = { version = "0.47.0", features = ["async"]}
 parity-scale-codec = "3.0.0"
 rand = "0.8.5"
 reqwest = { version = "0.11", features = ["json"] }

clients/wallet/src/error.rs

@@ -35,6 +35,9 @@ pub enum Error {
 
 	#[error("Cannot send payment to self")]
 	SelfPaymentError,
+
+	#[error("Failed to get fee: {0}")]
+	FailedToGetFee(String),
 }
 
 impl Error {

clients/wallet/src/horizon/horizon.rs

@@ -18,7 +18,7 @@ use crate::{
 	error::Error,
 	horizon::{
 		responses::{
-			interpret_response, HorizonAccountResponse, HorizonClaimableBalanceResponse,
+			interpret_response, FeeStats, HorizonAccountResponse, HorizonClaimableBalanceResponse,
 			HorizonTransactionsResponse, TransactionResponse, TransactionsResponseIter,
 		},
 		traits::HorizonClient,
@@ -95,7 +95,7 @@ impl HorizonClient for reqwest::Client {
 	) -> Result<HorizonAccountResponse, Error> {
 		let account_id_encoded = account_id.as_encoded_string()?;
 		let base_url = horizon_url(is_public_network, false);
-		let url = format!("{}/accounts/{}", base_url, account_id_encoded);
+		let url = format!("{base_url}/accounts/{account_id_encoded}");
 
 		self.get_from_url(&url).await
 	}
@@ -107,7 +107,14 @@ impl HorizonClient for reqwest::Client {
 	) -> Result<HorizonClaimableBalanceResponse, Error> {
 		let id_encoded = claimable_balance_id.as_encoded_string()?;
 		let base_url = horizon_url(is_public_network, false);
-		let url = format!("{}/claimable_balances/{}", base_url, id_encoded);
+		let url = format!("{base_url}/claimable_balances/{id_encoded}");
+
+		self.get_from_url(&url).await
+	}
+
+	async fn get_fee_stats(&self, is_public_network: bool) -> Result<FeeStats, Error> {
+		let base_url = horizon_url(is_public_network, false);
+		let url = format!("{base_url}/fee_stats");
 
 		self.get_from_url(&url).await
 	}

clients/wallet/src/horizon/responses.rs

@@ -1,7 +1,7 @@
 use crate::{
 	error::Error,
 	horizon::{serde::*, traits::HorizonClient, Ledger},
-	types::{PagingToken, StatusCode},
+	types::{FeeAttribute, PagingToken, StatusCode},
 };
 use parity_scale_codec::{Decode, Encode};
 use primitives::{
@@ -356,6 +356,71 @@ pub struct HorizonClaimableBalanceResponse {
 	pub claimable_balance: ClaimableBalance,
 }
 
+#[derive(Deserialize, Debug)]
+pub struct FeeDistribution {
+	#[serde(deserialize_with = "de_string_to_u32")]
+	pub max: u32,
+	#[serde(deserialize_with = "de_string_to_u32")]
+	pub min: u32,
+	#[serde(deserialize_with = "de_string_to_u32")]
+	pub mode: u32,
+	#[serde(deserialize_with = "de_string_to_u32")]
+	pub p10: u32,
+	#[serde(deserialize_with = "de_string_to_u32")]
+	pub p20: u32,
+	#[serde(deserialize_with = "de_string_to_u32")]
+	pub p30: u32,
+	#[serde(deserialize_with = "de_string_to_u32")]
+	pub p40: u32,
+	#[serde(deserialize_with = "de_string_to_u32")]
+	pub p50: u32,
+	#[serde(deserialize_with = "de_string_to_u32")]
+	pub p60: u32,
+	#[serde(deserialize_with = "de_string_to_u32")]
+	pub p70: u32,
+	#[serde(deserialize_with = "de_string_to_u32")]
+	pub p80: u32,
+	#[serde(deserialize_with = "de_string_to_u32")]
+	pub p90: u32,
+	#[serde(deserialize_with = "de_string_to_u32")]
+	pub p95: u32,
+	#[serde(deserialize_with = "de_string_to_u32")]
+	pub p99: u32,
+}
+
+#[derive(Deserialize, Debug)]
+pub struct FeeStats {
+	#[serde(deserialize_with = "de_string_to_u32")]
+	pub last_ledger: Ledger,
+	#[serde(deserialize_with = "de_string_to_u32")]
+	pub last_ledger_base_fee: u32,
+	#[serde(deserialize_with = "de_string_to_f64")]
+	pub ledger_capacity_usage: f64,
+	pub fee_charged: FeeDistribution,
+	pub max_fee: FeeDistribution,
+}
+
+impl FeeStats {
+	pub fn fee_charged_by(&self, fee_attr: FeeAttribute) -> u32 {
+		match fee_attr {
+			FeeAttribute::max => self.fee_charged.max,
+			FeeAttribute::min => self.fee_charged.min,
+			FeeAttribute::mode => self.fee_charged.mode,
+			FeeAttribute::p10 => self.fee_charged.p10,
+			FeeAttribute::p20 => self.fee_charged.p20,
+			FeeAttribute::p30 => self.fee_charged.p30,
+			FeeAttribute::p40 => self.fee_charged.p40,
+			FeeAttribute::p50 => self.fee_charged.p50,
+			FeeAttribute::p60 => self.fee_charged.p60,
+			FeeAttribute::p70 => self.fee_charged.p70,
+			FeeAttribute::p80 => self.fee_charged.p80,
+			FeeAttribute::p90 => self.fee_charged.p90,
+			FeeAttribute::p95 => self.fee_charged.p95,
+			FeeAttribute::p99 => self.fee_charged.p99,
+		}
+	}
+}
+
 // This represents each record for a claimable balance in the Horizon API response
 #[derive(Deserialize, Encode, Decode, Default, Debug)]
 pub struct ClaimableBalance {

clients/wallet/src/horizon/serde.rs

@@ -41,6 +41,14 @@ where
 	f64::from_str(s).map_err(serde::de::Error::custom)
 }
 
+pub fn de_string_to_u32<'de, D>(de: D) -> Result<u32, D::Error>
+where
+	D: Deserializer<'de>,
+{
+	let s: &str = Deserialize::deserialize(de)?;
+	u32::from_str(s).map_err(serde::de::Error::custom)
+}
+
 pub fn de_string_to_optional_bytes<'de, D>(de: D) -> Result<Option<Vec<u8>>, D::Error>
 where
 	D: Deserializer<'de>,

clients/wallet/src/horizon/tests.rs

@@ -213,3 +213,10 @@ async fn fetch_horizon_and_process_new_transactions_success() {
 
 	assert!(!slot_env_map.read().await.is_empty());
 }
+
+#[tokio::test(flavor = "multi_thread")]
+async fn horizon_get_fee() {
+	let horizon_client = reqwest::Client::new();
+	assert!(horizon_client.get_fee_stats(false).await.is_ok());
+	assert!(horizon_client.get_fee_stats(true).await.is_ok());
+}

clients/wallet/src/horizon/traits.rs

@@ -1,8 +1,8 @@
 use crate::{
 	error::Error,
 	horizon::responses::{
-		HorizonAccountResponse, HorizonClaimableBalanceResponse, HorizonTransactionsResponse,
-		TransactionResponse,
+		FeeStats, HorizonAccountResponse, HorizonClaimableBalanceResponse,
+		HorizonTransactionsResponse, TransactionResponse,
 	},
 	types::PagingToken,
 };
@@ -37,6 +37,8 @@ pub trait HorizonClient {
 		is_public_network: bool,
 	) -> Result<HorizonClaimableBalanceResponse, Error>;
 
+	async fn get_fee_stats(&self, is_public_network: bool) -> Result<FeeStats, Error>;
+
 	async fn submit_transaction(
 		&self,
 		transaction: TransactionEnvelope,

clients/wallet/src/mock.rs

@@ -42,8 +42,7 @@ impl StellarWallet {
 		let account_merge_op =
 			create_account_merge_operation(destination_address, self.public_key())?;
 
-		self.send_to_address([9u8; 32], DEFAULT_STROOP_FEE_PER_OPERATION, vec![account_merge_op])
-			.await
+		self.send_to_address([9u8; 32], vec![account_merge_op]).await
 	}
 
 	pub fn create_payment_envelope(

clients/wallet/src/resubmissions.rs

@@ -344,7 +344,6 @@ mod test {
 					asset.clone(),
 					amount,
 					rand::random(),
-					DEFAULT_STROOP_FEE_PER_OPERATION,
 					false,
 				)
 				.await