Allow Bob to exit execution at a specified state

Cargo.lock

@@ -3369,6 +3369,7 @@ dependencies = [
  "bitcoin",
  "bitcoin-harness",
  "conquer-once",
+ "conquer-once",
  "derivative",
  "ecdsa_fun",
  "futures",

swap/src/bob/swap.rs

@@ -33,10 +33,31 @@ pub enum BobState {
     SafelyAborted,
 }
 
-// State machine driver for swap execution
-#[async_recursion]
 pub async fn swap<R>(
     state: BobState,
+    swarm: Swarm,
+    db: Database,
+    bitcoin_wallet: Arc<crate::bitcoin::Wallet>,
+    monero_wallet: Arc<crate::monero::Wallet>,
+    rng: R,
+    swap_id: Uuid,
+) -> Result<BobState>
+    where
+        R: RngCore + CryptoRng + Send,
+{
+    run_until(state, is_complete, swarm, db, bitcoin_wallet, monero_wallet, rng, swap_id).await
+}
+
+// TODO: use macro or generics
+pub fn is_complete(state: &BobState) -> bool {
+    matches!(state, BobState::BtcRefunded| BobState::XmrRedeemed | BobState::Punished | BobState::SafelyAborted)
+}
+
+// State machine driver for swap execution
+#[async_recursion]
+pub async fn run_until<R>(
+    state: BobState,
+    is_state: fn(&BobState) -> bool,
     mut swarm: Swarm,
     db: Database,
     bitcoin_wallet: Arc<crate::bitcoin::Wallet>,
@@ -47,6 +68,9 @@ pub async fn swap<R>(
 where
     R: RngCore + CryptoRng + Send,
 {
+    if is_state(&state) {
+        Ok(state)
+    } else {
         match state {
             BobState::Started {
                 state0,
@@ -63,8 +87,9 @@ where
                     bitcoin_wallet.clone(),
                 )
                     .await?;
-            swap(
+                run_until(
                     BobState::Negotiated(state2, peer_id),
+                    is_state,
                     swarm,
                     db,
                     bitcoin_wallet,
@@ -78,8 +103,9 @@ where
                 // Alice and Bob have exchanged info
                 let state3 = state2.lock_btc(bitcoin_wallet.as_ref()).await?;
                 // db.insert_latest_state(state);
-            swap(
+                run_until(
                     BobState::BtcLocked(state3, alice_peer_id),
+                    is_state,
                     swarm,
                     db,
                     bitcoin_wallet,
@@ -101,8 +127,9 @@ where
                     }
                     other => panic!("unexpected event: {:?}", other),
                 };
-            swap(
+                run_until(
                     BobState::XmrLocked(state4, alice_peer_id),
+                    is_state,
                     swarm,
                     db,
                     bitcoin_wallet,
@@ -133,8 +160,9 @@ where
                     other => panic!("unexpected event: {:?}", other),
                 };
 
-            swap(
+                run_until(
                     BobState::EncSigSent(state, alice_peer_id),
+                    is_state,
                     swarm,
                     db,
                     bitcoin_wallet,
@@ -151,8 +179,9 @@ where
 
                 tokio::select! {
                 val = redeem_watcher => {
-                    swap(
+                    run_until(
                         BobState::BtcRedeemed(val?),
+                             is_state,
                         swarm,
                         db,
                         bitcoin_wallet,
@@ -169,8 +198,9 @@ where
                         state.submit_tx_cancel(bitcoin_wallet.as_ref()).await?;
                     }
 
-                    swap(
+                    run_until(
                         BobState::Cancelled(state),
+                             is_state,
                         swarm,
                         db,
                         bitcoin_wallet,
@@ -186,8 +216,9 @@ where
             BobState::BtcRedeemed(state) => {
                 // Bob redeems XMR using revealed s_a
                 state.claim_xmr(monero_wallet.as_ref()).await?;
-            swap(
+                run_until(
                     BobState::XmrRedeemed,
+                    is_state,
                     swarm,
                     db,
                     bitcoin_wallet,
@@ -203,8 +234,13 @@ where
             BobState::SafelyAborted => Ok(BobState::SafelyAborted),
             BobState::XmrRedeemed => Ok(BobState::XmrRedeemed),
         }
+    }
 }
 
+
+
+
+
 // // State machine driver for recovery execution
 // #[async_recursion]
 // pub async fn abort(state: BobState, io: Io) -> Result<BobState> {