From 0a8a624906f29d31edce734a2bf4ee25e008c8d3 Mon Sep 17 00:00:00 2001
From: Junha Yang <junhayang1@gmail.com>
Date: Fri, 19 Aug 2022 01:59:38 +0900
Subject: [PATCH] refactor: split background task

---
 network/src/propagation_network/mod.rs | 58 ++++++++++++++------------
 1 file changed, 31 insertions(+), 27 deletions(-)

diff --git a/network/src/propagation_network/mod.rs b/network/src/propagation_network/mod.rs
index 959668d34..174ff1986 100644
--- a/network/src/propagation_network/mod.rs
+++ b/network/src/propagation_network/mod.rs
@@ -26,10 +26,11 @@ use tokio::{
 /// This network discovers peers with Kademlia([`libp2p::kad`]),
 /// and propagates data with FloodSub([`libp2p::floodsub`]).
 pub struct PropagationNetwork {
-    /// A join handle for background network task.
-    ///
-    /// The task running behind this handle is the main routine of [`PropagationNetwork`].
-    _task_join_handle: task::JoinHandle<()>,
+    /// The network event handling routine.
+    _event_handling_task: task::JoinHandle<()>,
+
+    /// The network bootstrapping (node discovery) routine.
+    _peer_discovery_task: task::JoinHandle<()>,
 
     /// A sending endpoint of the queue that collects broadcasted messages through the network
     /// and sends it to the simperby node.
@@ -108,15 +109,19 @@ impl PropagationNetwork {
         // Create a message queue that a simperby node will use to receive messages from other nodes.
         let (sender, _receiver) = broadcast::channel::<Vec<u8>>(config.message_queue_capacity);
 
-        let _task_join_handle = task::spawn(run_background_task(
-            swarm_mutex.clone(),
-            sender.clone(),
+        let _event_handling_task = task::spawn(run_event_handling_task(
+            Arc::clone(&swarm_mutex),
             config.lock_release_interval,
+        ));
+
+        let _peer_discovery_task = task::spawn(run_peer_discovery_task(
+            Arc::clone(&swarm_mutex),
             config.peer_discovery_interval,
         ));
 
         Ok(Self {
-            _task_join_handle,
+            _event_handling_task,
+            _peer_discovery_task,
             sender,
             swarm: swarm_mutex,
         })
@@ -241,36 +246,35 @@ impl PropagationNetwork {
     }
 }
 
-async fn run_background_task(
+async fn run_peer_discovery_task(
     swarm: Arc<Mutex<Swarm<Behaviour>>>,
-    _sender: broadcast::Sender<Vec<u8>>,
-    lock_release_interval: Duration,
     bootstrap_interval: Duration,
+) {
+    loop {
+        // Note: An `Err` is returned only if there is no known peer,
+        //       which is not considered to be an error if this node is
+        //       the first one to join the network. Thus we discard the result.
+        let _ = swarm.lock().await.behaviour_mut().kademlia.bootstrap();
+        tokio::time::sleep(bootstrap_interval).await;
+    }
+}
+
+async fn run_event_handling_task(
+    swarm: Arc<Mutex<Swarm<Behaviour>>>,
+    lock_release_interval: Duration,
 ) {
     // This timer guarantees that the lock for swarm will be released
     // regularly and within a finite time.
     let mut lock_release_timer = time::interval(lock_release_interval);
     lock_release_timer.set_missed_tick_behavior(time::MissedTickBehavior::Delay);
-
-    let mut bootstrap_timer = time::interval(bootstrap_interval);
-
     loop {
         let mut swarm = swarm.lock().await;
         tokio::select! {
-            // Get k-closest peers after every preset interval.
-            // Todo: Update Floodsub publish targets to match them with the k-closest peers.
-            _ = bootstrap_timer.tick() => {
-                // Note: An `Err` is returned only if there is no known peer,
-                //       which is not considered to be an error if this node is
-                //       the first one to join the network.
-                let _ =  swarm.behaviour_mut().kademlia.bootstrap();
-            }
-            // Listen on swarm events.
-            _event = swarm.select_next_some() => {}
-            // Release the lock so that other tasks can use swarm.
-            _ = lock_release_timer.tick() => ()
+            _item = swarm.select_next_some() => {
+                // do something with item
+            },
+            _ = lock_release_timer.tick() => (),
         }
-        // The lock for swarm is automatically released here.
     }
 }