Move transaction broadcasting and fee estimation to dedicated modules

[tnull]

Fixes #22.

Previously, transaction broadcasting and fee estimation was the concern of our BDK-based onchain wallet and its EsploraBlockchain. However, this for one meant these functions would also be subject to BDK's locking requirements, pontentially even requiring additional runtime threads. Given that the Blockchain trait is going away in BDK 1.0 anyways, the little convenience it gave us wasn't worth the additional complexity. Moreover, the prior design was not particularly modular, which made creating mock objects for tests hard, e.g., in #152.

Here, we therefore move transaction broadcasting and fee estimation to two dedicated modules which take a cloned EsploraClient instance. This also allows us to make the calls in an async fashion while providing the blocking interface to LDK objects in a more reasonable manner that doesn't lean on tokio's block_in_place.

While general rebroadcasting of transactions will be initiated via the OutputSweeper to come in #152, we now also immediately retry rebroadcasts after a small delay if they fail due to connection (or HTTP) errors.

[tnull]

Rebased on main to resolve minor conflicts.

[wpaulino]

LGTM

[wpaulino]

Rather than just processing one package, are we able to keep reading until nothing's left?

[tnull]

Yeah, I originally avoided that since broadcasting might also trigger the Esplora rate limits. So I thought it might make sense to let the server breathe for ~1sec between packages. However, probably doesn't make a big difference and we already have the 500ms retry delay now. So made it a while let Some(..) now.

[tnull]

Added new tranaction-bytes-logging commit and included minor requested changes:

> git diff-tree -U2 69710b7 ea31d2d
diff --git a/src/lib.rs b/src/lib.rs
index 8adfe55..ae0fda1 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -686,5 +686,5 @@ impl<K: KVStore + Sync + Send + 'static> Node<K> {
                                                }
                                                _ = interval.tick() => {
-                                                       tx_bcaster.process_next_package().await;
+                                                       tx_bcaster.process_queue().await;
                                                }
                                }
diff --git a/src/logger.rs b/src/logger.rs
index cab62c6..b0504a3 100644
--- a/src/logger.rs
+++ b/src/logger.rs
@@ -1,4 +1,4 @@
 pub(crate) use lightning::util::logger::Logger;
-pub(crate) use lightning::{log_debug, log_error, log_info, log_trace};
+pub(crate) use lightning::{log_bytes, log_debug, log_error, log_info, log_trace};

 use lightning::util::logger::{Level, Record};
diff --git a/src/tx_broadcaster.rs b/src/tx_broadcaster.rs
index ae98373..4e56cba 100644
--- a/src/tx_broadcaster.rs
+++ b/src/tx_broadcaster.rs
@@ -1,5 +1,6 @@
-use crate::logger::{log_debug, log_error, log_trace, Logger};
+use crate::logger::{log_bytes, log_debug, log_error, log_trace, Logger};

 use lightning::chain::chaininterface::BroadcasterInterface;
+use lightning::util::ser::Writeable;

 use esplora_client::AsyncClient as EsploraClient;
@@ -34,7 +35,7 @@ where
        }

-       pub(crate) async fn process_next_package(&self) {
+       pub(crate) async fn process_queue(&self) {
                let mut receiver = self.queue_receiver.lock().await;
-               if let Some(next_package) = receiver.recv().await {
+               while let Some(next_package) = receiver.recv().await {
                        for tx in &next_package {
                                match self.esplora_client.broadcast(tx).await {
@@ -67,4 +68,9 @@ where
                                                                                e
                                                                        );
+                                                                       log_trace!(
+                                                                               self.logger,
+                                                                               "Failed broadcast transaction bytes: {}",
+                                                                               log_bytes!(tx.encode())
+                                                                       );
                                                                }
                                                        }
@@ -77,4 +83,9 @@ where
                                                                e
                                                        );
+                                                       log_trace!(
+                                                               self.logger,
+                                                               "Failed broadcast transaction bytes: {}",
+                                                               log_bytes!(tx.encode())
+                                                       );
                                                }
                                        },