Remove unnecessary state variables by constructing TXs on demand

swap/src/database/alice.rs

@@ -1,4 +1,4 @@
-use crate::bitcoin::{EncryptedSignature, TxCancel, TxRefund};
+use crate::bitcoin::EncryptedSignature;
 use crate::monero;
 use crate::monero::monero_private_key;
 use crate::protocol::alice;
@@ -177,37 +177,18 @@ impl From<Alice> for AliceState {
             Alice::BtcCancelled {
                 monero_wallet_restore_blockheight,
                 state3,
-            } => {
-                let tx_cancel = TxCancel::new(
-                    &state3.tx_lock,
-                    state3.cancel_timelock,
-                    state3.a.public(),
-                    state3.B,
-                );
+            } => AliceState::BtcCancelled {
+                monero_wallet_restore_blockheight,
+                state3: Box::new(state3),
+            },
 
-                AliceState::BtcCancelled {
-                    monero_wallet_restore_blockheight,
-                    state3: Box::new(state3),
-                    tx_cancel: Box::new(tx_cancel),
-                }
-            }
             Alice::BtcPunishable {
                 monero_wallet_restore_blockheight,
                 state3,
-            } => {
-                let tx_cancel = TxCancel::new(
-                    &state3.tx_lock,
-                    state3.cancel_timelock,
-                    state3.a.public(),
-                    state3.B,
-                );
-                let tx_refund = TxRefund::new(&tx_cancel, &state3.refund_address);
-                AliceState::BtcPunishable {
-                    monero_wallet_restore_blockheight,
-                    tx_refund: Box::new(tx_refund),
-                    state3: Box::new(state3),
-                }
-            }
+            } => AliceState::BtcPunishable {
+                monero_wallet_restore_blockheight,
+                state3: Box::new(state3),
+            },
             Alice::BtcRefunded {
                 monero_wallet_restore_blockheight,
                 state3,

swap/src/protocol/alice/state.rs

@@ -36,7 +36,6 @@ pub enum AliceState {
     BtcRedeemed,
     BtcCancelled {
         monero_wallet_restore_blockheight: BlockHeight,
-        tx_cancel: Box<TxCancel>,
         state3: Box<State3>,
     },
     BtcRefunded {
@@ -46,7 +45,6 @@ pub enum AliceState {
     },
     BtcPunishable {
         monero_wallet_restore_blockheight: BlockHeight,
-        tx_refund: Box<TxRefund>,
         state3: Box<State3>,
     },
     XmrRefunded,
@@ -337,7 +335,7 @@ impl State3 {
         &self,
         bitcoin_wallet: &bitcoin::Wallet,
     ) -> Result<ExpiredTimelocks> {
-        let tx_cancel = TxCancel::new(&self.tx_lock, self.cancel_timelock, self.a.public(), self.B);
+        let tx_cancel = self.tx_cancel();
 
         let tx_lock_status = bitcoin_wallet
             .status_of_script(&self.tx_lock.script_pubkey(), &self.tx_lock.txid())
@@ -354,10 +352,19 @@ impl State3 {
         ))
     }
 
+    pub fn tx_cancel(&self) -> TxCancel {
+        TxCancel::new(&self.tx_lock, self.cancel_timelock, self.a.public(), self.B)
+    }
+
     pub fn tx_punish(&self) -> TxPunish {
-        let tx_cancel =
-            bitcoin::TxCancel::new(&self.tx_lock, self.cancel_timelock, self.a.public(), self.B);
+        bitcoin::TxPunish::new(
+            &self.tx_cancel(),
+            &self.punish_address,
+            self.punish_timelock,
+        )
+    }
 
-        bitcoin::TxPunish::new(&tx_cancel, &self.punish_address, self.punish_timelock)
+    pub fn tx_refund(&self) -> TxRefund {
+        bitcoin::TxRefund::new(&self.tx_cancel(), &self.refund_address)
     }
 }

swap/src/protocol/alice/steps.rs

@@ -59,7 +59,7 @@ pub async fn publish_cancel_transaction(
     cancel_timelock: CancelTimelock,
     tx_cancel_sig_bob: bitcoin::Signature,
     bitcoin_wallet: &bitcoin::Wallet,
-) -> Result<bitcoin::TxCancel> {
+) -> Result<()> {
     bitcoin_wallet
         .watch_until_status(tx_lock.txid(), tx_lock.script_pubkey(), |status| {
             status.is_confirmed_with(cancel_timelock)
@@ -81,7 +81,6 @@ pub async fn publish_cancel_transaction(
         let sig_b = tx_cancel_sig_bob.clone();
 
         let tx_cancel = tx_cancel
-            .clone()
             .add_signatures((a.public(), sig_a), (B, sig_b))
             .expect("sig_{a,b} to be valid signatures for tx_cancel");
 
@@ -92,7 +91,7 @@ pub async fn publish_cancel_transaction(
         // block height
     }
 
-    Ok(tx_cancel)
+    Ok(())
 }
 
 pub async fn wait_for_bitcoin_refund(

swap/src/protocol/alice/swap.rs

@@ -285,7 +285,7 @@ async fn run_until_internal(
                 state3,
                 monero_wallet_restore_blockheight,
             } => {
-                let tx_cancel = publish_cancel_transaction(
+                publish_cancel_transaction(
                     state3.tx_lock.clone(),
                     state3.a.clone(),
                     state3.B,
@@ -297,7 +297,6 @@ async fn run_until_internal(
 
                 let state = AliceState::BtcCancelled {
                     state3,
-                    tx_cancel: Box::new(tx_cancel),
                     monero_wallet_restore_blockheight,
                 };
                 let db_state = (&state).into();
@@ -317,11 +316,10 @@ async fn run_until_internal(
             }
             AliceState::BtcCancelled {
                 state3,
-                tx_cancel,
                 monero_wallet_restore_blockheight,
             } => {
                 let (tx_refund, published_refund_tx) = wait_for_bitcoin_refund(
-                    &tx_cancel,
+                    &state3.tx_cancel(),
                     state3.punish_timelock,
                     &state3.refund_address,
                     &bitcoin_wallet,
@@ -332,7 +330,6 @@ async fn run_until_internal(
                 match published_refund_tx {
                     None => {
                         let state = AliceState::BtcPunishable {
-                            tx_refund: Box::new(tx_refund),
                             state3,
                             monero_wallet_restore_blockheight,
                         };
@@ -401,7 +398,6 @@ async fn run_until_internal(
                 Ok(state)
             }
             AliceState::BtcPunishable {
-                tx_refund,
                 state3,
                 monero_wallet_restore_blockheight,
             } => {
@@ -424,7 +420,7 @@ async fn run_until_internal(
                 };
 
                 let refund_tx_seen = bitcoin_wallet.watch_until_status(
-                    tx_refund.txid(),
+                    state3.tx_refund().txid(),
                     state3.refund_address.script_pubkey(),
                     |status| status.has_been_seen(),
                 );
@@ -434,12 +430,13 @@ async fn run_until_internal(
 
                 match select(refund_tx_seen, punish_tx_finalised).await {
                     Either::Left((Ok(()), _)) => {
-                        let published_refund_tx =
-                            bitcoin_wallet.get_raw_transaction(tx_refund.txid()).await?;
+                        let published_refund_tx = bitcoin_wallet
+                            .get_raw_transaction(state3.tx_refund().txid())
+                            .await?;
 
                         let spend_key = extract_monero_private_key(
                             published_refund_tx,
-                            &tx_refund,
+                            &state3.tx_refund(),
                             state3.s_a,
                             state3.a.clone(),
                             state3.S_b_bitcoin,