Debug instance for the gossipsub behaviour (#1673)

* Add debug instances for MessageCache and GossipSub behaviour

* Manual impl of Debug for GossipsubMessage

* Add pretty printing of protocol_id in debug

* Use hex_fmt instead of hex

* Inline StringOrBytes helper struct

Since it is used only once here

* Limit data of gossipsub msg to 20 bytes

Otherwise they might become very large and useless for debugging

protocols/gossipsub/Cargo.toml

@@ -26,6 +26,7 @@ base64 = "0.11.0"
 lru = "0.4.3"
 smallvec = "1.1.0"
 prost = "0.6.1"
+hex_fmt = "0.3.0"
 
 [dev-dependencies]
 async-std = "1.6.2"

protocols/gossipsub/src/behaviour.rs

@@ -51,6 +51,7 @@ use wasm_timer::{Instant, Interval};
 
 mod tests;
 
+#[derive(Debug)]
 /// Network behaviour that handles the gossipsub protocol.
 pub struct Gossipsub {
     /// Configuration providing gossipsub performance parameters.

protocols/gossipsub/src/config.rs

@@ -232,7 +232,11 @@ impl GossipsubConfigBuilder {
 impl std::fmt::Debug for GossipsubConfig {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         let mut builder = f.debug_struct("GossipsubConfig");
-        let _ = builder.field("protocol_id", &self.protocol_id);
+        let _ = if let Ok(text) = std::str::from_utf8(&self.protocol_id) {
+            builder.field("protocol_id", &text)
+        } else {
+            builder.field("protocol_id", &hex_fmt::HexFmt(&self.protocol_id))
+        };
         let _ = builder.field("history_length", &self.history_length);
         let _ = builder.field("history_gossip", &self.history_gossip);
         let _ = builder.field("mesh_n", &self.mesh_n);

protocols/gossipsub/src/mcache.rs

@@ -22,7 +22,7 @@
 
 use crate::protocol::{GossipsubMessage, MessageId};
 use crate::topic::TopicHash;
-use std::collections::HashMap;
+use std::{collections::HashMap, fmt};
 
 /// CacheEntry stored in the history.
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
@@ -40,6 +40,16 @@ pub struct MessageCache {
     msg_id: fn(&GossipsubMessage) -> MessageId,
 }
 
+impl fmt::Debug for MessageCache {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("MessageCache")
+            .field("msgs", &self.msgs)
+            .field("history", &self.history)
+            .field("gossip", &self.gossip)
+            .finish()
+    }
+}
+
 /// Implementation of the MessageCache.
 impl MessageCache {
     pub fn new(

protocols/gossipsub/src/protocol.rs

@@ -29,7 +29,7 @@ use futures::prelude::*;
 use futures_codec::{Decoder, Encoder, Framed};
 use libp2p_core::{InboundUpgrade, OutboundUpgrade, PeerId, UpgradeInfo};
 use prost::Message as ProtobufMessage;
-use std::{borrow::Cow, io, iter, pin::Pin};
+use std::{borrow::Cow, fmt, io, iter, pin::Pin};
 use unsigned_varint::codec;
 
 /// Implementation of the `ConnectionUpgrade` for the Gossipsub protocol.
@@ -336,7 +336,7 @@ impl Into<String> for MessageId {
 }
 
 /// A message received by the gossipsub system.
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[derive(Clone, PartialEq, Eq, Hash)]
 pub struct GossipsubMessage {
     /// Id of the peer that published this message.
     pub source: PeerId,
@@ -353,6 +353,17 @@ pub struct GossipsubMessage {
     pub topics: Vec<TopicHash>,
 }
 
+impl fmt::Debug for GossipsubMessage {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("GossipsubMessage")
+            .field("data",&format_args!("{:<20}", &hex_fmt::HexFmt(&self.data)))
+            .field("source", &self.source)
+            .field("sequence_number", &self.sequence_number)
+            .field("topics", &self.topics)
+            .finish()
+    }
+}
+
 /// A subscription received by the gossipsub system.
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct GossipsubSubscription {