Use channel as telemetry data key (#4697)

* Use channel as telemetry data key

* Erase dead channels

nano/lib/stats_enums.hpp

@@ -369,6 +369,7 @@ enum class detail
 	failed_send_telemetry_req,
 	empty_payload,
 	cleanup_outdated,
+	erase_stale,
 
 	// vote generator
 	generator_broadcasts,

nano/node/telemetry.cpp

@@ -96,22 +96,19 @@ void nano::telemetry::process (const nano::telemetry_ack & telemetry, const std:
 
 	nano::unique_lock<nano::mutex> lock{ mutex };
 
-	const auto endpoint = channel->get_endpoint ();
-
-	if (auto it = telemetries.get<tag_endpoint> ().find (endpoint); it != telemetries.get<tag_endpoint> ().end ())
+	if (auto it = telemetries.get<tag_channel> ().find (channel); it != telemetries.get<tag_channel> ().end ())
 	{
 		stats.inc (nano::stat::type::telemetry, nano::stat::detail::update);
 
-		telemetries.get<tag_endpoint> ().modify (it, [&telemetry, &endpoint] (auto & entry) {
-			debug_assert (entry.endpoint == endpoint);
+		telemetries.get<tag_channel> ().modify (it, [&telemetry, &channel] (auto & entry) {
 			entry.data = telemetry.data;
 			entry.last_updated = std::chrono::steady_clock::now ();
 		});
 	}
 	else
 	{
 		stats.inc (nano::stat::type::telemetry, nano::stat::detail::insert);
-		telemetries.get<tag_endpoint> ().insert ({ endpoint, telemetry.data, std::chrono::steady_clock::now (), channel });
+		telemetries.get<tag_channel> ().insert ({ channel, telemetry.data, std::chrono::steady_clock::now () });
 
 		if (telemetries.size () > max_size)
 		{
@@ -247,10 +244,14 @@ void nano::telemetry::cleanup ()
 		// Remove if telemetry data is stale
 		if (!check_timeout (entry))
 		{
-			stats.inc (nano::stat::type::telemetry, nano::stat::detail::cleanup_outdated);
+			stats.inc (nano::stat::type::telemetry, nano::stat::detail::erase_stale);
+			return true; // Erase
+		}
+		if (!entry.channel->alive ())
+		{
+			stats.inc (nano::stat::type::telemetry, nano::stat::detail::erase_dead);
 			return true; // Erase
 		}
-
 		return false; // Do not erase
 	});
 }
@@ -283,7 +284,7 @@ std::unordered_map<nano::endpoint, nano::telemetry_data> nano::telemetry::get_al
 	{
 		if (check_timeout (entry))
 		{
-			result[entry.endpoint] = entry.data;
+			result[entry.endpoint ()] = entry.data;
 		}
 	}
 	return result;

nano/node/telemetry.hpp

@@ -86,10 +86,14 @@ class telemetry
 private:
 	struct entry
 	{
-		nano::endpoint endpoint;
+		std::shared_ptr<nano::transport::channel> channel;
 		nano::telemetry_data data;
 		std::chrono::steady_clock::time_point last_updated;
-		std::shared_ptr<nano::transport::channel> channel;
+
+		nano::endpoint endpoint () const
+		{
+			return channel->get_endpoint ();
+		}
 	};
 
 private:
@@ -110,13 +114,16 @@ class telemetry
 private:
 	// clang-format off
 	class tag_sequenced {};
+	class tag_channel {};
 	class tag_endpoint {};
 
 	using ordered_telemetries = boost::multi_index_container<entry,
 	mi::indexed_by<
 		mi::sequenced<mi::tag<tag_sequenced>>,
-		mi::hashed_unique<mi::tag<tag_endpoint>,
-			mi::member<entry, nano::endpoint, &entry::endpoint>>
+		mi::ordered_unique<mi::tag<tag_channel>,
+			mi::member<entry,  std::shared_ptr<nano::transport::channel>, &entry::channel>>,
+		mi::hashed_non_unique<mi::tag<tag_endpoint>,
+			mi::const_mem_fun<entry, nano::endpoint, &entry::endpoint>>
 	>>;
 	// clang-format on