Handle transition to Funded inline, without remove+readd from map

lightning/src/ln/channel.rs

@@ -1139,6 +1139,7 @@ impl<'a, SP: Deref> ChannelPhase<SP> where
 	SP::Target: SignerProvider,
 	<SP::Target as SignerProvider>::EcdsaSigner: ChannelSigner,
 {
+	#[inline]
 	pub fn context(&'a self) -> &'a ChannelContext<SP> {
 		match self {
 			ChannelPhase::Funded(chan) => &chan.context,
@@ -1149,6 +1150,7 @@ impl<'a, SP: Deref> ChannelPhase<SP> where
 		}
 	}
 
+	#[inline]
 	pub fn context_mut(&'a mut self) -> &'a mut ChannelContext<SP> {
 		match self {
 			ChannelPhase::Funded(ref mut chan) => &mut chan.context,
@@ -1162,40 +1164,72 @@ impl<'a, SP: Deref> ChannelPhase<SP> where
 
 /// A top-level channel struct, containing a channel phase
 pub(super) struct ChannelWrapper<SP: Deref> where SP::Target: SignerProvider {
-	phase: ChannelPhase<SP>,
+	/// The inner channel phase
+	/// Option is used to facilitate in-place replacement (see e.g. move_v2_to_funded),
+	/// but it is never None, ensured in new() and set_phase()
+	phase: Option<ChannelPhase<SP>>,
 }
 
 impl<'a, SP: Deref> ChannelWrapper<SP> where SP::Target: SignerProvider {
 	pub fn new(phase: ChannelPhase<SP>) -> Self {
-		Self { phase }
+		Self {
+			phase: Some(phase),
+		}
 	}
 
+	#[inline]
 	pub fn phase(&self) -> &ChannelPhase<SP> {
-		&self.phase
+		self.phase.as_ref().unwrap()
 	}
 
+	#[inline]
 	pub fn phase_mut(&mut self) -> &mut ChannelPhase<SP> {
-		&mut self.phase
+		self.phase.as_mut().unwrap()
 	}
 
 	pub fn phase_take(self) -> ChannelPhase<SP> {
-		self.phase
+		match self.phase {
+			Some(phase) => phase,
+			None => panic!("None phase"),
+		}
 	}
 
 	pub fn get_funded_channel(&self) -> Option<&Channel<SP>> {
-		if let ChannelPhase::Funded(chan) = &self.phase {
+		if let ChannelPhase::Funded(chan) = &self.phase.as_ref().unwrap() {
 			Some(chan)
 		} else {
 			None
 		}
 	}
 
+	/// Change the internal phase
+	#[inline]
+	pub fn set_phase(&mut self, new_phase: ChannelPhase<SP>) {
+		self.phase = Some(new_phase);
+	}
+
+	pub fn move_v2_to_funded(&mut self, signing_session: InteractiveTxSigningSession) -> Result<(), ChannelError> {
+		// We need a borrow to the phase field, but self is only a mut ref
+		let phase_inline = self.phase.take().unwrap();
+		let new_phase = match phase_inline {
+			ChannelPhase::UnfundedOutboundV2(chan) =>
+				ChannelPhase::Funded(chan.into_funded_channel(signing_session)?),
+			ChannelPhase::UnfundedInboundV2(chan) =>
+				ChannelPhase::Funded(chan.into_funded_channel(signing_session)?),
+			_ => phase_inline,
+		};
+		self.set_phase(new_phase);
+		Ok(())
+	}
+
+	#[inline]
 	pub fn context(&'a self) -> &'a ChannelContext<SP> {
-		self.phase.context()
+		self.phase().context()
 	}
 
+	#[inline]
 	pub fn context_mut(&'a mut self) -> &'a mut ChannelContext<SP> {
-		self.phase.context_mut()
+		self.phase_mut().context_mut()
 	}
 }
 
@@ -8888,7 +8922,7 @@ impl<SP: Deref> OutboundV2Channel<SP> where SP::Target: SignerProvider {
 		}
 	}
 
-	pub fn into_channel(self, signing_session: InteractiveTxSigningSession) -> Result<Channel<SP>, ChannelError>{
+	pub fn into_funded_channel(self, signing_session: InteractiveTxSigningSession) -> Result<Channel<SP>, ChannelError>{
 		let channel = Channel {
 			context: self.context,
 			interactive_tx_signing_session: Some(signing_session),
@@ -9082,7 +9116,7 @@ impl<SP: Deref> InboundV2Channel<SP> where SP::Target: SignerProvider {
 		self.generate_accept_channel_v2_message()
 	}
 
-	pub fn into_channel(self, signing_session: InteractiveTxSigningSession) -> Result<Channel<SP>, ChannelError>{
+	pub fn into_funded_channel(self, signing_session: InteractiveTxSigningSession) -> Result<Channel<SP>, ChannelError>{
 		let channel = Channel {
 			context: self.context,
 			interactive_tx_signing_session: Some(signing_session),

lightning/src/ln/channelmanager.rs

@@ -5037,6 +5037,7 @@ where
 						}
 					}
 				} else {
+					// put it back
 					peer_state.channel_by_id.insert(temporary_channel_id, ChannelWrapper::new(phase));
 					return Err(APIError::APIMisuseError {
 						err: format!(
@@ -8368,18 +8369,16 @@ where
 							"Got a tx_complete message with no interactive transaction construction expected or in-progress"
 							.into())),
 					}.map_err(|err| MsgHandleErrInternal::send_err_msg_no_close(format!("{}", err), msg.channel_id))?;
-					let (channel_id, channel) = chan_entry.remove_entry();
-					let channel = match channel.phase_take() {
-						ChannelPhase::UnfundedOutboundV2(chan) => chan.into_channel(signing_session),
-						ChannelPhase::UnfundedInboundV2(chan) => chan.into_channel(signing_session),
-						_ => {
+
+					// change the channel phase inline
+					match chan_entry.get_mut().move_v2_to_funded(signing_session) {
+						Ok(_) => {},
+						Err(err) => {
 							debug_assert!(false); // It cannot be another variant as we are in the `Ok` branch of the above match.
-							Err(ChannelError::Warn(
-								"Got a tx_complete message with no interactive transaction construction expected or in-progress"
-									.into()))
-						},
-					}.map_err(|err| MsgHandleErrInternal::send_err_msg_no_close(format!("{}", err), msg.channel_id))?;
-					peer_state.channel_by_id.insert(channel_id, ChannelWrapper::new(ChannelPhase::Funded(channel)));
+							return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Got a tx_complete message, could not transition to funding, {}", err), msg.channel_id))?;
+						}
+					}
+
 					if let Some(funding_ready_for_sig_event) = funding_ready_for_sig_event_opt {
 						let mut pending_events = self.pending_events.lock().unwrap();
 						pending_events.push_back((funding_ready_for_sig_event, None));