validator: introduce FeeData struct representing fee related data

This commit introduces a new structure known as `FeeData` containing fee-related information within the blockchain network. This data is used for accounting of fees, providing details relating to resource consumption across different transactions.

We have also carried out modifications in the `validator::verification::verify_transaction` function to return all calculated fee related data. The updated function now returns its calculations in the form of `FeeData` struct, housing all the computed fee related data.

The code that depends on the `verify_transaction` function have been modified to adapt to the `FeeData` structure.

bin/darkfid/src/rpc_tx.rs

@@ -258,6 +258,6 @@ impl DarkfiNode {
             return server_error(RpcError::TxGasCalculationFail, id, None)
         };
 
-        JsonResponse::new(JsonValue::Number(result.unwrap() as f64), id).into()
+        JsonResponse::new(JsonValue::Number(result.unwrap().total_gas_used() as f64), id).into()
     }
 }

src/validator/consensus.rs

@@ -751,7 +751,7 @@ impl Fork {
 
             // Verify the transaction against current state
             overlay.lock().unwrap().checkpoint();
-            let (tx_gas_used, tx_gas_paid) = match verify_transaction(
+            let gas_data = match verify_transaction(
                 &overlay,
                 verifying_block_height,
                 block_target,
@@ -770,6 +770,9 @@ impl Fork {
                 }
             };
 
+            // Store the gas used by the verified transaction
+            let tx_gas_used = gas_data.total_gas_used();
+
             // Calculate current accumulated gas usage
             let accumulated_gas_usage = total_gas_used + tx_gas_used;
 
@@ -781,7 +784,7 @@ impl Fork {
 
             // Update accumulated total gas
             total_gas_used += tx_gas_used;
-            total_gas_paid += tx_gas_paid;
+            total_gas_paid += gas_data.gas_paid;
 
             // Push the tx hash into the unproposed transactions vector
             unproposed_txs.push(unproposed_tx);

src/validator/fees.rs

@@ -17,6 +17,7 @@
  */
 
 use darkfi_sdk::crypto::constants::{MERKLE_DEPTH_ORCHARD, SPARSE_MERKLE_DEPTH};
+use darkfi_serial::{async_trait, SerialDecodable, SerialEncodable};
 
 use crate::zkas::{Opcode, VarType, ZkBinary};
 
@@ -92,3 +93,26 @@ pub fn circuit_gas_use(zkbin: &ZkBinary) -> u64 {
 
     accumulator
 }
+
+/// Auxiliary struct representing the full gas usage breakdown of a transaction.
+///
+/// This data is used for accounting of fees, providing details relating to
+/// resource consumption across different transactions.
+#[derive(Default, Clone, Eq, PartialEq, Debug, SerialEncodable, SerialDecodable)]
+pub struct GasData {
+    pub gas_paid: u64,
+    pub wasm_gas_used: u64,
+    pub zk_circuit_gas_used: u64,
+    pub signature_gas_used: u64,
+    pub deploy_gas_used: u64,
+}
+
+impl GasData {
+    /// Calculates the total gas used by summing all individual gas usage fields.
+    pub fn total_gas_used(&self) -> u64 {
+        self.wasm_gas_used +
+            self.zk_circuit_gas_used +
+            self.signature_gas_used +
+            self.deploy_gas_used
+    }
+}

src/validator/mod.rs

@@ -31,6 +31,7 @@ use crate::{
     },
     error::TxVerifyFailed,
     tx::Transaction,
+    validator::fees::GasData,
     zk::VerifyingKey,
     Error, Result,
 };
@@ -133,7 +134,7 @@ impl Validator {
     /// against current best fork.
     /// The function takes a boolean called `verify_fee` to overwrite
     /// the nodes configured `verify_fees` flag.
-    pub async fn calculate_gas(&self, tx: &Transaction, verify_fee: bool) -> Result<u64> {
+    pub async fn calculate_gas(&self, tx: &Transaction, verify_fee: bool) -> Result<GasData> {
         // Grab the best fork to verify against
         let forks = self.consensus.forks.read().await;
         let fork = forks[best_fork_index(&forks)?].full_clone()?;
@@ -158,12 +159,12 @@ impl Validator {
             &mut vks,
             verify_fee,
         )
-        .await;
+        .await?;
 
         // Purge new trees
         fork.overlay.lock().unwrap().overlay.lock().unwrap().purge_new_trees()?;
 
-        Ok(verify_result?.0)
+        Ok(verify_result)
     }
 
     /// The node retrieves a transaction, validates its state transition,

src/validator/verification.rs

@@ -40,7 +40,7 @@ use crate::{
     tx::{Transaction, MAX_TX_CALLS, MIN_TX_CALLS},
     validator::{
         consensus::{Consensus, Fork, Proposal, GAS_LIMIT_UNPROPOSED_TXS},
-        fees::{circuit_gas_use, PALLAS_SCHNORR_SIGNATURE_FEE},
+        fees::{circuit_gas_use, GasData, PALLAS_SCHNORR_SIGNATURE_FEE},
         pow::PoWModule,
     },
     zk::VerifyingKey,
@@ -540,13 +540,12 @@ pub async fn verify_transaction(
     tree: &mut MerkleTree,
     verifying_keys: &mut HashMap<[u8; 32], HashMap<String, VerifyingKey>>,
     verify_fee: bool,
-) -> Result<(u64, u64)> {
+) -> Result<GasData> {
     let tx_hash = tx.hash();
     debug!(target: "validator::verification::verify_transaction", "Validating transaction {}", tx_hash);
 
-    // Gas accumulator
-    let mut gas_used = 0;
-    let mut gas_paid = 0;
+    // Create a FeeData instance to hold the calculated fee data
+    let mut gas_data = GasData::default();
 
     // Verify calls indexes integrity
     if verify_fee {
@@ -697,9 +696,7 @@ pub async fn verify_transaction(
 
             let deploy_gas_used = deploy_runtime.gas_used();
             debug!(target: "validator::verification::verify_transaction", "The gas used for deployment call {:?} of transaction {}: {}", call, tx_hash, deploy_gas_used);
-
-            // Append the used deployment gas
-            gas_used += deploy_gas_used;
+            gas_data.deploy_gas_used += deploy_gas_used;
         }
 
         // At this point we're done with the call and move on to the next one.
@@ -708,16 +705,13 @@ pub async fn verify_transaction(
         debug!(target: "validator::verification::verify_transaction", "The gas used for WASM call {:?} of transaction {}: {}", call, tx_hash, wasm_gas_used);
 
         // Append the used wasm gas
-        gas_used += wasm_gas_used;
+        gas_data.wasm_gas_used += wasm_gas_used;
     }
 
     // The signature fee is tx_size + fixed_sig_fee * n_signatures
-    let signature_fee = (PALLAS_SCHNORR_SIGNATURE_FEE * tx.signatures.len() as u64) +
+    gas_data.signature_gas_used = (PALLAS_SCHNORR_SIGNATURE_FEE * tx.signatures.len() as u64) +
         serialize_async(tx).await.len() as u64;
-    debug!(target: "validator::verification::verify_transaction", "The gas used for signature of transaction {}: {}", tx_hash, signature_fee);
-
-    // Append the used signature gas
-    gas_used += signature_fee;
+    debug!(target: "validator::verification::verify_transaction", "The gas used for signature of transaction {}: {}", tx_hash, gas_data.signature_gas_used);
 
     // The ZK circuit fee is calculated using a function in validator/fees.rs
     for zkbin in circuits_to_verify.iter() {
@@ -725,9 +719,12 @@ pub async fn verify_transaction(
         debug!(target: "validator::verification::verify_transaction", "The gas used for ZK circuit in namespace {} of transaction {}: {}", zkbin.namespace, tx_hash, zk_circuit_gas_used);
 
         // Append the used zk circuit gas
-        gas_used += zk_circuit_gas_used;
+        gas_data.zk_circuit_gas_used += zk_circuit_gas_used;
     }
 
+    // Store the calculated total gas used to avoid recalculating it for subsequent uses
+    let total_gas_used = gas_data.total_gas_used();
+
     if verify_fee {
         // Deserialize the fee call to find the paid fee
         let fee: u64 = match deserialize_async(&tx.calls[fee_call_idx].data.data[1..9]).await {
@@ -743,18 +740,18 @@ pub async fn verify_transaction(
 
         // TODO: This counts 1 gas as 1 token unit. Pricing should be better specified.
         // Check that enough fee has been paid for the used gas in this transaction.
-        if gas_used > fee {
+        if total_gas_used > fee {
             error!(
                 target: "validator::verification::verify_transaction",
                 "[VALIDATOR] Transaction {} has insufficient fee. Required: {}, Paid: {}",
-                tx_hash, gas_used, fee,
+                tx_hash, total_gas_used, fee,
             );
             return Err(TxVerifyFailed::InsufficientFee.into())
         }
-        debug!(target: "validator::verification::verify_transaction", "The gas paid for transaction {}: {}", tx_hash, gas_paid);
+        debug!(target: "validator::verification::verify_transaction", "The gas paid for transaction {}: {}", tx_hash, gas_data.gas_paid);
 
         // Store paid fee
-        gas_paid = fee;
+        gas_data.gas_paid = fee;
     }
 
     // When we're done looping and executing over the tx's contract calls and
@@ -792,9 +789,9 @@ pub async fn verify_transaction(
     // Append hash to merkle tree
     append_tx_to_merkle_tree(tree, tx);
 
-    debug!(target: "validator::verification::verify_transaction", "The total gas used for transaction {}: {}", tx_hash, gas_used);
+    debug!(target: "validator::verification::verify_transaction", "The total gas used for transaction {}: {}", tx_hash, total_gas_used);
     debug!(target: "validator::verification::verify_transaction", "Transaction {} verified successfully", tx_hash);
-    Ok((gas_used, gas_paid))
+    Ok(gas_data)
 }
 
 /// Apply given [`Transaction`] to the provided overlay.
@@ -910,7 +907,7 @@ pub async fn verify_transactions(
     // Iterate over transactions and attempt to verify them
     for tx in txs {
         overlay.lock().unwrap().checkpoint();
-        let (tx_gas_used, tx_gas_paid) = match verify_transaction(
+        let gas_data = match verify_transaction(
             overlay,
             verifying_block_height,
             block_target,
@@ -930,6 +927,9 @@ pub async fn verify_transactions(
             }
         };
 
+        // Store the gas used by the verified transaction
+        let tx_gas_used = gas_data.total_gas_used();
+
         // Calculate current accumulated gas usage
         let accumulated_gas_usage = total_gas_used + tx_gas_used;
 
@@ -943,7 +943,7 @@ pub async fn verify_transactions(
 
         // Update accumulated total gas
         total_gas_used += tx_gas_used;
-        total_gas_paid += tx_gas_paid;
+        total_gas_paid += gas_data.gas_paid;
     }
 
     if !erroneous_txs.is_empty() {