Add LogContext enum in ChannelManager

Can be used to utilise the contextual logger and fallback to module
logger otherwise.

Author: jbesraa

lightning/src/ln/channelmanager.rs

@@ -124,6 +124,31 @@ use crate::ln::script::ShutdownScript;
 // Alternatively, we can fill an outbound HTLC with a HTLCSource::OutboundRoute indicating this is
 // our payment, which we can use to decode errors or inform the user that the payment was sent.
 
+enum LogContext<'a, L: Deref> where L::Target: Logger {
+	Module(&'a L),
+	ChannelContext(WithChannelContext<'a, L>)
+}
+
+impl<'a, L: Deref> std::ops::Deref for LogContext<'a, L> where L::Target: Logger {
+	type Target = L;
+
+	fn deref(&self) -> &Self::Target {
+		match self {
+			LogContext::Module(logger) => *logger,
+			LogContext::ChannelContext(channel_context) => &channel_context.logger
+		}
+	}
+}
+
+impl<'a, L: Deref> Logger for LogContext<'a, L> where L::Target: Logger {
+	fn log(&self, record: crate::util::logger::Record) {
+		match self {
+			LogContext::Module(logger) => logger.log(record),
+			LogContext::ChannelContext(channel_context) => channel_context.log(record)
+		}
+	}
+}
+
 /// Information about where a received HTLC('s onion) has indicated the HTLC should go.
 #[derive(Clone)] // See Channel::revoke_and_ack for why, tl;dr: Rust bug
 #[cfg_attr(test, derive(Debug, PartialEq))]