From 654cfff2a87248cc14ed8d820f984c1cf849fb64 Mon Sep 17 00:00:00 2001
From: Thomas Eizinger <thomas@eizinger.io>
Date: Thu, 1 Apr 2021 12:09:51 +1100
Subject: [PATCH] Make `kraken` module emit `PriceUpdate`s instead of `Rate`s

---
 swap/src/bin/asb.rs                   |  4 ++--
 swap/src/bin/kraken_ticker.rs         |  4 ++--
 swap/src/kraken.rs                    | 31 +++++++++++++--------------
 swap/src/protocol/alice/event_loop.rs |  7 ++++--
 4 files changed, 24 insertions(+), 22 deletions(-)

diff --git a/swap/src/bin/asb.rs b/swap/src/bin/asb.rs
index 637e659f..6694e35d 100644
--- a/swap/src/bin/asb.rs
+++ b/swap/src/bin/asb.rs
@@ -92,7 +92,7 @@ async fn main() -> Result<()> {
                 info!("Monero balance: {}", monero_balance);
             }
 
-            let kraken_rate_updates = kraken::connect()?;
+            let kraken_price_updates = kraken::connect()?;
 
             let mut swarm = swarm::new::<Behaviour>(&seed)?;
             Swarm::listen_on(&mut swarm, config.network.listen)
@@ -104,7 +104,7 @@ async fn main() -> Result<()> {
                 Arc::new(bitcoin_wallet),
                 Arc::new(monero_wallet),
                 Arc::new(db),
-                kraken_rate_updates,
+                kraken_price_updates,
                 max_buy,
             )
             .unwrap();
diff --git a/swap/src/bin/kraken_ticker.rs b/swap/src/bin/kraken_ticker.rs
index 9c0d3fdd..a28bac50 100644
--- a/swap/src/bin/kraken_ticker.rs
+++ b/swap/src/bin/kraken_ticker.rs
@@ -9,8 +9,8 @@ async fn main() -> Result<()> {
     let mut ticker = swap::kraken::connect().context("Failed to connect to kraken")?;
 
     loop {
-        match ticker.wait_for_update().await? {
-            Ok(rate) => println!("Rate update: {}", rate),
+        match ticker.wait_for_next_update().await? {
+            Ok(update) => println!("Price update: {}", update.ask),
             Err(e) => println!("Error: {:#}", e),
         }
     }
diff --git a/swap/src/kraken.rs b/swap/src/kraken.rs
index 7aee6c5c..57e2861c 100644
--- a/swap/src/kraken.rs
+++ b/swap/src/kraken.rs
@@ -1,4 +1,3 @@
-use crate::asb::Rate;
 use anyhow::{anyhow, Context, Result};
 use futures::{SinkExt, StreamExt, TryStreamExt};
 use serde::Deserialize;
@@ -10,9 +9,9 @@ use tokio::sync::watch;
 /// Connect to Kraken websocket API for a constant stream of rate updates.
 ///
 /// If the connection fails, it will automatically be re-established.
-pub fn connect() -> Result<RateUpdateStream> {
-    let (rate_update, rate_update_receiver) = watch::channel(Err(Error::NotYetAvailable));
-    let rate_update = Arc::new(rate_update);
+pub fn connect() -> Result<PriceUpdates> {
+    let (price_update, price_update_receiver) = watch::channel(Err(Error::NotYetAvailable));
+    let price_update = Arc::new(price_update);
 
     tokio::spawn(async move {
         // The default backoff config is fine for us apart from one thing:
@@ -26,12 +25,12 @@ pub fn connect() -> Result<RateUpdateStream> {
         let result = backoff::future::retry_notify::<Infallible, _, _, _, _, _>(
             backoff,
             || {
-                let rate_update = rate_update.clone();
+                let price_update = price_update.clone();
                 async move {
                     let mut stream = connection::new().await?;
 
                     while let Some(update) = stream.try_next().await.map_err(to_backoff)? {
-                        let send_result = rate_update.send(Ok(Rate::new(update.ask)));
+                        let send_result = price_update.send(Ok(update));
 
                         if send_result.is_err() {
                             return Err(backoff::Error::Permanent(anyhow!(
@@ -54,30 +53,30 @@ pub fn connect() -> Result<RateUpdateStream> {
                 tracing::warn!("Rate updates incurred an unrecoverable error: {:#}", e);
 
                 // in case the retries fail permanently, let the subscribers know
-                rate_update.send(Err(Error::PermanentFailure))
+                price_update.send(Err(Error::PermanentFailure))
             }
             Ok(never) => match never {},
         }
     });
 
-    Ok(RateUpdateStream {
-        inner: rate_update_receiver,
+    Ok(PriceUpdates {
+        inner: price_update_receiver,
     })
 }
 
 #[derive(Clone, Debug)]
-pub struct RateUpdateStream {
-    inner: watch::Receiver<RateUpdate>,
+pub struct PriceUpdates {
+    inner: watch::Receiver<PriceUpdate>,
 }
 
-impl RateUpdateStream {
-    pub async fn wait_for_update(&mut self) -> Result<RateUpdate> {
+impl PriceUpdates {
+    pub async fn wait_for_next_update(&mut self) -> Result<PriceUpdate> {
         self.inner.changed().await?;
 
         Ok(self.inner.borrow().clone())
     }
 
-    pub fn latest_update(&mut self) -> RateUpdate {
+    pub fn latest_update(&mut self) -> PriceUpdate {
         self.inner.borrow().clone()
     }
 }
@@ -90,7 +89,7 @@ pub enum Error {
     PermanentFailure,
 }
 
-type RateUpdate = Result<Rate, Error>;
+type PriceUpdate = Result<wire::PriceUpdate, Error>;
 
 /// Maps a [`connection::Error`] to a backoff error, effectively defining our
 /// retry strategy.
@@ -246,7 +245,7 @@ mod wire {
     }
 
     /// Represents an update within the price ticker.
-    #[derive(Debug, Deserialize)]
+    #[derive(Clone, Debug, Deserialize)]
     #[serde(try_from = "TickerUpdate")]
     pub struct PriceUpdate {
         pub ask: bitcoin::Amount,
diff --git a/swap/src/protocol/alice/event_loop.rs b/swap/src/protocol/alice/event_loop.rs
index 5179fb6f..f48fd080 100644
--- a/swap/src/protocol/alice/event_loop.rs
+++ b/swap/src/protocol/alice/event_loop.rs
@@ -354,11 +354,14 @@ impl LatestRate for FixedRate {
     }
 }
 
-impl LatestRate for kraken::RateUpdateStream {
+impl LatestRate for kraken::PriceUpdates {
     type Error = kraken::Error;
 
     fn latest_rate(&mut self) -> Result<Rate, Self::Error> {
-        self.latest_update()
+        let update = self.latest_update()?;
+        let rate = Rate::new(update.ask);
+
+        Ok(rate)
     }
 }