Collect the domain transaction fee and use as the operator reward

domains/client/domain-operator/Cargo.toml

@@ -46,6 +46,7 @@ domain-client-message-relayer = { version = "0.1.0", path = "../relayer" }
 domain-test-service = { version = "0.1.0", path = "../../test/service" }
 domain-test-primitives = { version = "0.1.0", path = "../../test/primitives" }
 evm-domain-test-runtime = { version = "0.1.0", path = "../../test/runtime/evm" }
+frame-system = { version = "4.0.0-dev", default-features = false, git = "https://github.com/subspace/substrate", rev = "55c157cff49b638a59d81a9f971f0f9a66829c71" }
 num-traits = "0.2.15"
 pallet-balances = { version = "4.0.0-dev", git = "https://github.com/subspace/substrate", rev = "55c157cff49b638a59d81a9f971f0f9a66829c71" }
 pallet-domains = { version = "0.1.0", path = "../../../crates/pallet-domains" }

domains/client/domain-operator/src/domain_block_processor.rs

@@ -352,6 +352,13 @@ where
             })?
         };
 
+        // Get the accumulated transaction fee of all transactions included in the block
+        // and used as the operator reward
+        let total_rewards = self
+            .client
+            .runtime_api()
+            .block_transaction_fee(header_hash)?;
+
         let execution_receipt = ExecutionReceipt {
             domain_block_number: header_number,
             domain_block_hash: header_hash,
@@ -363,8 +370,7 @@ where
             final_state_root: state_root,
             execution_trace: trace,
             execution_trace_root: sp_core::H256(trace_root),
-            // TODO: set proper value
-            total_rewards: Default::default(),
+            total_rewards,
         };
 
         Ok(DomainBlockResult {

domains/client/domain-operator/src/tests.rs

@@ -1816,3 +1816,72 @@ async fn test_restart_domain_operator() {
     assert_eq!(ferdie.client.info().best_number, 11);
     assert_eq!(alice.client.info().best_number, 10);
 }
+
+#[substrate_test_utils::test(flavor = "multi_thread")]
+async fn test_domain_transaction_fee_and_operator_reward() {
+    let directory = TempDir::new().expect("Must be able to create temporary directory");
+
+    let mut builder = sc_cli::LoggerBuilder::new("");
+    builder.with_colors(false);
+    let _ = builder.init();
+
+    let tokio_handle = tokio::runtime::Handle::current();
+
+    // Start Ferdie
+    let mut ferdie = MockConsensusNode::run(
+        tokio_handle.clone(),
+        Ferdie,
+        BasePath::new(directory.path().join("ferdie")),
+    );
+
+    // Produce 1 consensus block to initialize genesis domain
+    ferdie.produce_block_with_slot(1.into()).await.unwrap();
+
+    // Run Alice (a evm domain authority node)
+    let mut alice = domain_test_service::DomainNodeBuilder::new(
+        tokio_handle.clone(),
+        Alice,
+        BasePath::new(directory.path().join("alice")),
+    )
+    .build_evm_node(Role::Authority, GENESIS_DOMAIN_ID, &mut ferdie)
+    .await;
+
+    produce_blocks!(ferdie, alice, 3).await.unwrap();
+
+    // Construct and submit an extrinsic with tip
+    let pre_alice_free_balance = alice.free_balance(Alice.to_account_id());
+    let tip = 123456;
+    let tx = alice.construct_extrinsic_with_tip(
+        alice.account_nonce(),
+        tip,
+        frame_system::Call::remark { remark: vec![] },
+    );
+    alice
+        .send_extrinsic(tx)
+        .await
+        .expect("Failed to send extrinsic");
+
+    // Produce a bundle that contains the just sent extrinsic
+    let (slot, bundle) = ferdie.produce_slot_and_wait_for_bundle_submission().await;
+    assert_eq!(bundle.unwrap().extrinsics.len(), 1);
+    produce_block_with!(ferdie.produce_block_with_slot(slot), alice)
+        .await
+        .unwrap();
+    let consensus_block_hash = ferdie.client.info().best_hash;
+
+    // Produce one more bundle, this bundle should contains the ER of the previous bundle
+    let (slot, bundle) = ferdie.produce_slot_and_wait_for_bundle_submission().await;
+    let receipt = bundle.unwrap().into_receipt();
+    assert_eq!(receipt.consensus_block_hash, consensus_block_hash);
+    produce_block_with!(ferdie.produce_block_with_slot(slot), alice)
+        .await
+        .unwrap();
+
+    // Transaction fee (including the tip) is deducted from alice's account
+    let alice_free_balance_changes =
+        pre_alice_free_balance - alice.free_balance(Alice.to_account_id());
+    assert!(alice_free_balance_changes >= tip as u128);
+
+    // All the transaction fee is collected as operator reward
+    assert_eq!(alice_free_balance_changes, receipt.total_rewards);
+}

domains/pallets/operator-rewards/Cargo.toml

@@ -0,0 +1,32 @@
+[package]
+name = "pallet-operator-rewards"
+version = "0.1.0"
+authors = ["Subspace Labs <https://subspace.network>"]
+edition = "2021"
+license = "Apache-2.0"
+homepage = "https://subspace.network"
+repository = "https://github.com/subspace/subspace"
+description = "Subspace node pallet for charging and re-distributing domain transaction fees"
+include = [
+  "/src",
+  "/Cargo.toml",
+]
+
+[dependencies]
+codec = { package = "parity-scale-codec", version = "3.6.3", default-features = false, features = ["derive"] }
+frame-support = { version = "4.0.0-dev", default-features = false, git = "https://github.com/subspace/substrate", rev = "55c157cff49b638a59d81a9f971f0f9a66829c71" }
+frame-system = { version = "4.0.0-dev", default-features = false, git = "https://github.com/subspace/substrate", rev = "55c157cff49b638a59d81a9f971f0f9a66829c71" }
+scale-info = { version = "2.7.0", default-features = false, features = ["derive"] }
+sp-runtime = { version = "24.0.0", default-features = false, git = "https://github.com/subspace/substrate", rev = "55c157cff49b638a59d81a9f971f0f9a66829c71" }
+sp-std = { version = "8.0.0", default-features = false, git = "https://github.com/subspace/substrate", rev = "55c157cff49b638a59d81a9f971f0f9a66829c71" }
+
+[features]
+default = ["std"]
+std = [
+  "codec/std",
+  "frame-support/std",
+  "frame-system/std",
+  "scale-info/std",
+  "sp-runtime/std",
+  "sp-std/std",
+]

domains/pallets/operator-rewards/src/lib.rs

@@ -0,0 +1,75 @@
+// Copyright (C) 2023 Subspace Labs, Inc.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Pallet Domain Transaction Fees
+
+#![cfg_attr(not(feature = "std"), no_std)]
+
+pub use pallet::*;
+
+#[frame_support::pallet]
+mod pallet {
+    use codec::{Codec, MaxEncodedLen};
+    use frame_support::pallet_prelude::*;
+    use frame_system::pallet_prelude::*;
+    use scale_info::TypeInfo;
+    use sp_runtime::traits::{AtLeast32BitUnsigned, MaybeSerializeDeserialize, Saturating, Zero};
+    use sp_runtime::FixedPointOperand;
+    use sp_std::fmt::Debug;
+
+    #[pallet::config]
+    pub trait Config: frame_system::Config {
+        /// The balance of an account.
+        type Balance: Parameter
+            + Member
+            + AtLeast32BitUnsigned
+            + Codec
+            + Default
+            + Copy
+            + MaybeSerializeDeserialize
+            + Debug
+            + MaxEncodedLen
+            + TypeInfo
+            + FixedPointOperand;
+    }
+
+    /// The accumulated rewards of the current block
+    ///
+    /// Currently, the only source of rewards is the transaction fees, in the furture it
+    /// will include the XDM reward.
+    #[pallet::storage]
+    #[pallet::getter(fn block_transaction_fee)]
+    pub(super) type BlockRewards<T: Config> = StorageValue<_, T::Balance, ValueQuery>;
+
+    /// Pallet operator-rewards to store the accumulated rewards of the current block
+    #[pallet::pallet]
+    #[pallet::without_storage_info]
+    pub struct Pallet<T>(_);
+
+    #[pallet::hooks]
+    impl<T: Config> Hooks<BlockNumberFor<T>> for Pallet<T> {
+        fn on_initialize(_now: BlockNumberFor<T>) -> Weight {
+            BlockRewards::<T>::set(Zero::zero());
+            T::DbWeight::get().writes(1)
+        }
+    }
+
+    impl<T: Config> Pallet<T> {
+        pub fn note_transaction_fees(tx_fee: T::Balance) {
+            let next_block_rewards = BlockRewards::<T>::get().saturating_add(tx_fee);
+            BlockRewards::<T>::set(next_block_rewards);
+        }
+    }
+}

domains/primitives/runtime/src/lib.rs

@@ -195,6 +195,9 @@ sp_api::decl_runtime_apis! {
 
         /// Return the extrinsic weight
         fn extrinsic_weight(ext: &Block::Extrinsic) -> Weight;
+
+        /// The accumulated transaction fee of all transactions included in the block
+        fn block_transaction_fee() -> Balance;
     }
 
     /// Api that construct inherent extrinsics.

domains/runtime/evm/Cargo.toml

@@ -34,6 +34,7 @@ log = { version = "0.4.19", default-features = false }
 pallet-balances = { version = "4.0.0-dev", default-features = false, git = "https://github.com/subspace/substrate", rev = "55c157cff49b638a59d81a9f971f0f9a66829c71" }
 pallet-base-fee = { version = "1.0.0-dev", default-features = false, git = "https://github.com/subspace/frontier", rev = "74483666645e121c0c5e6616f43fdfd8664ea0d3" }
 pallet-domain-id = { version = "0.1.0", path = "../../pallets/domain-id", default-features = false }
+pallet-operator-rewards = { version = "0.1.0", path = "../../pallets/operator-rewards", default-features = false }
 pallet-ethereum = { version = "4.0.0-dev", default-features = false, git = "https://github.com/subspace/frontier", rev = "74483666645e121c0c5e6616f43fdfd8664ea0d3" }
 pallet-evm = { version = "6.0.0-dev", default-features = false, git = "https://github.com/subspace/frontier", rev = "74483666645e121c0c5e6616f43fdfd8664ea0d3" }
 pallet-evm-chain-id = { version = "1.0.0-dev", default-features = false, git = "https://github.com/subspace/frontier", rev = "74483666645e121c0c5e6616f43fdfd8664ea0d3" }
@@ -85,6 +86,7 @@ std = [
 	"pallet-balances/std",
 	"pallet-base-fee/std",
 	"pallet-domain-id/std",
+	"pallet-operator-rewards/std",
 	"pallet-ethereum/std",
 	"pallet-evm/std",
 	"pallet-evm-chain-id/std",