BFT-465: Helpful comments in gossip code

node/actors/network/src/gossip/fetch.rs

@@ -64,7 +64,7 @@ impl Queue {
     ) -> ctx::OrCanceled<Call> {
         let sub = &mut self.0.subscribe();
         while ctx.is_active() {
-            // Wait for the lowest requested block to be available.
+            // Wait for the lowest requested block to be available on the remote peer.
             // This scope is always cancelled, so we ignore the result.
             let mut block_number = None;
             let _: Result<(), _> = scope::run!(ctx, |ctx, s| async {

node/actors/network/src/gossip/mod.rs

@@ -49,6 +49,8 @@ pub(crate) struct Network {
     /// Output pipe of the network actor.
     pub(crate) sender: channel::UnboundedSender<io::OutputMessage>,
     /// Queue of block fetching requests.
+    ///
+    /// These are blocks that this node wants to request from remote peers via RPC.
     pub(crate) fetch_queue: fetch::Queue,
     /// Last viewed QC.
     pub(crate) last_viewed_qc: Option<attester::BatchQC>,

node/actors/network/src/gossip/runner.rs

@@ -204,6 +204,7 @@ impl Network {
 
             // Perform get_block calls to peer.
             s.spawn::<()>(async {
+                // Gossiped state of what range of blocks is available on the remote peer.
                 let state = &mut push_block_store_state_server.state.subscribe();
                 loop {
                     let call = get_block_client.reserve(ctx).await?;