feat(ethexe): optimize inheritor field passed to eth

ethexe/common/src/gear.rs

@@ -106,7 +106,7 @@ pub struct ProtocolData {
 pub struct StateTransition {
     pub actor_id: ActorId,
     pub new_state_hash: H256,
-    pub inheritor: ActorId,
+    pub inheritor: Option<ActorId>,
     pub value_to_receive: u128,
     pub value_claims: Vec<ValueClaim>,
     pub messages: Vec<Message>,

ethexe/contracts/src/Mirror.sol

@@ -127,8 +127,8 @@ contract Mirror is IMirror {
         bytes32 valueClaimsHash = _claimValues(_transition.valueClaims);
 
         /// @dev Set inheritor if specified.
-        if (_transition.inheritor != address(0)) {
-            _setInheritor(_transition.inheritor);
+        if (_transition.inheritor.length != 0) {
+            _setInheritor(Gear.decodePackedAddress(_transition.inheritor));
         }
 
         /// @dev Update the state hash if changed.
@@ -232,7 +232,6 @@ contract Mirror is IMirror {
         return keccak256(valueClaimsBytes);
     }
 
-    // TODO (breathx): optimize inheritor to bytes WITHIN THE PR.
     function _setInheritor(address _inheritor) private whileActive {
         /// @dev Set inheritor.
         inheritor = _inheritor;

ethexe/contracts/src/libraries/Gear.sol

@@ -82,7 +82,8 @@ library Gear {
     struct StateTransition {
         address actorId;
         bytes32 newStateHash;
-        address inheritor;
+        /// @dev Must be empty if no inheritor is set, otherwise 20 bytes of an inheritor address.
+        bytes inheritor;
         uint128 valueToReceive;
         ValueClaim[] valueClaims;
         Message[] messages;
@@ -130,6 +131,18 @@ library Gear {
         return keccak256(abi.encodePacked(codeCommitment.id, codeCommitment.valid));
     }
 
+    function decodePackedAddress(bytes memory data) internal pure returns (address) {
+        require(data.length == 20, "Address must be 20 bytes long if exist");
+
+        address addr;
+
+        assembly ("memory-safe") {
+            addr := mload(add(data, 20))
+        }
+
+        return addr;
+    }
+
     function defaultComputationSettings() internal pure returns (ComputationSettings memory) {
         return ComputationSettings(COMPUTATION_THRESHOLD, WVARA_PER_SECOND);
     }
@@ -154,7 +167,7 @@ library Gear {
     function stateTransitionHash(
         address actor,
         bytes32 newStateHash,
-        address inheritor,
+        bytes memory inheritor,
         uint128 valueToReceive,
         bytes32 valueClaimsHash,
         bytes32 messagesHashesHash

ethexe/contracts/test/Router.t.sol

@@ -118,10 +118,11 @@ contract RouterTest is Test {
         );
 
         Gear.StateTransition[] memory transitions = new Gear.StateTransition[](1);
+
         transitions[0] = Gear.StateTransition(
             actorId, // actor id
             bytes32(uint256(42)), // new state hash
-            address(0), // inheritor
+            abi.encodePacked(address(137)), // inheritor
             uint128(0), // value to receive
             new Gear.ValueClaim[](0), // value claims
             messages // messages
@@ -142,6 +143,7 @@ contract RouterTest is Test {
 
         assertEq(actor.stateHash(), bytes32(uint256(42)));
         assertEq(actor.nonce(), uint256(1));
+        assertEq(actor.inheritor(), address(137));
     }
 
     /* helper functions */

ethexe/ethereum/src/abi/gear.rs

@@ -79,7 +79,7 @@ impl From<StateTransition> for Gear::StateTransition {
         Self {
             actorId: actor_id_to_address_lossy(value.actor_id),
             newStateHash: h256_to_bytes32(value.new_state_hash),
-            inheritor: actor_id_to_address_lossy(value.inheritor),
+            inheritor: maybe_actor_id_to_addr_bytes(value.inheritor),
             valueToReceive: value.value_to_receive,
             valueClaims: value.value_claims.into_iter().map(Into::into).collect(),
             messages: value.messages.into_iter().map(Into::into).collect(),

ethexe/ethereum/src/abi/mod.rs

@@ -59,7 +59,7 @@ sol!(
 );
 
 pub(crate) mod utils {
-    use alloy::primitives::{FixedBytes, Uint};
+    use alloy::primitives::{Bytes, FixedBytes, Uint};
     use gprimitives::{ActorId, CodeId, MessageId, H256};
 
     pub type Bytes32 = FixedBytes<32>;
@@ -90,6 +90,12 @@ pub(crate) mod utils {
         code_id.into_bytes().into()
     }
 
+    pub fn maybe_actor_id_to_addr_bytes(maybe_actor_id: Option<ActorId>) -> Bytes {
+        maybe_actor_id
+            .map(|actor_id| actor_id_to_address_lossy(actor_id).0.into())
+            .unwrap_or_default()
+    }
+
     pub fn message_id_to_bytes32(message_id: MessageId) -> Bytes32 {
         message_id.into_bytes().into()
     }

ethexe/runtime/common/src/journal.rs

@@ -174,7 +174,7 @@ impl<S: Storage> JournalHandler for Handler<'_, S> {
             state.program = Program::Exited(value_destination);
 
             transitions.modify_transition(id_exited, |transition| {
-                transition.inheritor = value_destination
+                transition.inheritor = Some(value_destination);
             });
 
             mem::replace(&mut state.balance, 0)

ethexe/runtime/common/src/transitions.rs

@@ -172,7 +172,7 @@ impl InBlockTransitions {
                 res.push(StateTransition {
                     actor_id,
                     new_state_hash,
-                    inheritor: ActorId::zero(),
+                    inheritor: modification.inheritor,
                     value_to_receive: modification.value_to_receive,
                     value_claims: modification.claims,
                     messages: modification.messages,
@@ -187,7 +187,7 @@ impl InBlockTransitions {
 #[derive(Debug, Default)]
 pub struct NonFinalTransition {
     initial_state: H256,
-    pub inheritor: ActorId,
+    pub inheritor: Option<ActorId>,
     pub value_to_receive: u128,
     pub claims: Vec<ValueClaim>,
     pub messages: Vec<Message>,
@@ -200,6 +200,6 @@ impl NonFinalTransition {
             // check if state hash changed at final (always op)
             && current_state == self.initial_state
             // check if with unchanged state needs commitment (op)
-            && (self.inheritor.is_zero() && self.value_to_receive == 0 && self.claims.is_empty() && self.messages.is_empty())
+            && (self.inheritor.is_none() && self.value_to_receive == 0 && self.claims.is_empty() && self.messages.is_empty())
     }
 }

ethexe/signer/src/digest.rs

@@ -128,7 +128,9 @@ impl ToDigest for StateTransition {
 
         hasher.update(actor_id.to_address_lossy().as_bytes());
         hasher.update(new_state_hash.as_bytes());
-        hasher.update(inheritor.to_address_lossy().as_bytes());
+        if let Some(inheritor) = inheritor {
+            hasher.update(inheritor.to_address_lossy().as_bytes());
+        }
         hasher.update(value_to_receive.to_be_bytes().as_slice());
 
         let mut value_hasher = sha3::Keccak256::new();
@@ -208,7 +210,8 @@ mod tests {
         let state_transition = StateTransition {
             actor_id: ActorId::from(0),
             new_state_hash: H256::from([1; 32]),
-            inheritor: ActorId::from(0),
+            // TODO (breathx): change from u64 impl WITHIN THE PR.
+            inheritor: Some(ActorId::from(0)),
             value_to_receive: 0,
             value_claims: vec![],
             messages: vec![Message {

ethexe/validator/src/lib.rs

@@ -281,7 +281,7 @@ mod tests {
         let transition = StateTransition {
             actor_id: H256::random().0.into(),
             new_state_hash: H256::random(),
-            inheritor: H256::random().0.into(),
+            inheritor: Some(H256::random().0.into()),
             value_to_receive: 123,
             value_claims: vec![],
             messages: vec![],