Add started_elections topic to websockets (#3851)

This PR adds a new topic "started_elections" to websockets.

add observers.active_started for started elections

Update tests

nano/core_test/websocket.cpp

@@ -124,6 +124,54 @@ TEST (websocket, confirmation)
 	ASSERT_TIMELY (5s, future.wait_for (0s) == std::future_status::ready);
 }
 
+// Tests getting notification of a started election
+TEST (websocket, started_election)
+{
+	nano::system system;
+	nano::node_config config (nano::get_available_port (), system.logging);
+	config.websocket_config.enabled = true;
+	config.websocket_config.port = nano::get_available_port ();
+	auto node1 = system.add_node (config);
+
+	std::atomic<bool> ack_ready{ false };
+	auto task = ([&ack_ready, config, &node1] () {
+		fake_websocket_client client (node1->websocket_server->listening_port ());
+		client.send_message (R"json({"action": "subscribe", "topic": "started_election", "ack": "true"})json");
+		client.await_ack ();
+		ack_ready = true;
+		EXPECT_EQ (1, node1->websocket_server->subscriber_count (nano::websocket::topic::started_election));
+		return client.get_response ();
+	});
+	auto future = std::async (std::launch::async, task);
+
+	ASSERT_TIMELY (5s, ack_ready);
+
+	// Create election, causing a websocket message to be emitted
+	nano::keypair key1;
+	nano::block_builder builder;
+	auto send1 = builder
+				 .send ()
+				 .previous (nano::dev::genesis->hash ())
+				 .destination (key1.pub)
+				 .balance (0)
+				 .sign (nano::dev::genesis_key.prv, nano::dev::genesis_key.pub)
+				 .work (*system.work.generate (nano::dev::genesis->hash ()))
+				 .build_shared ();
+	nano::publish publish1{ nano::dev::network_params.network, send1 };
+	auto channel1 = node1->network.udp_channels.create (node1->network.endpoint ());
+	node1->network.inbound (publish1, channel1);
+	ASSERT_TIMELY (1s, node1->active.election (send1->qualified_root ()));
+	ASSERT_TIMELY (5s, future.wait_for (0s) == std::future_status::ready);
+
+	auto response = future.get ();
+	ASSERT_TRUE (response);
+	boost::property_tree::ptree event;
+	std::stringstream stream;
+	stream << response.get ();
+	boost::property_tree::read_json (stream, event);
+	ASSERT_EQ (event.get<std::string> ("topic"), "started_election");
+}
+
 // Tests getting notification of an erased election
 TEST (websocket, stopped_election)
 {

nano/node/active_transactions.cpp

@@ -847,6 +847,7 @@ nano::election_insertion_result nano::active_transactions::insert_impl (nano::un
 				auto const cache = find_inactive_votes_cache_impl (hash);
 				lock_a.unlock ();
 				result.election->insert_inactive_votes_cache (cache);
+				node.observers.active_started.notify (hash);
 				node.stats.inc (nano::stat::type::election, nano::stat::detail::election_start);
 				vacancy_update ();
 			}

nano/node/node.cpp

@@ -282,6 +282,14 @@ nano::node::node (boost::asio::io_context & io_ctx_a, boost::filesystem::path co
 				}
 			});
 
+			observers.active_started.add ([this] (nano::block_hash const & hash_a) {
+				if (this->websocket_server->any_subscriber (nano::websocket::topic::started_election))
+				{
+					nano::websocket::message_builder builder;
+					this->websocket_server->broadcast (builder.started_election (hash_a));
+				}
+			});
+
 			observers.active_stopped.add ([this] (nano::block_hash const & hash_a) {
 				if (this->websocket_server->any_subscriber (nano::websocket::topic::stopped_election))
 				{

nano/node/node_observers.cpp

@@ -6,6 +6,7 @@ std::unique_ptr<nano::container_info_component> nano::collect_container_info (na
 	composite->add_component (collect_container_info (node_observers.blocks, "blocks"));
 	composite->add_component (collect_container_info (node_observers.wallet, "wallet"));
 	composite->add_component (collect_container_info (node_observers.vote, "vote"));
+	composite->add_component (collect_container_info (node_observers.active_started, "active_started"));
 	composite->add_component (collect_container_info (node_observers.active_stopped, "active_stopped"));
 	composite->add_component (collect_container_info (node_observers.account_balance, "account_balance"));
 	composite->add_component (collect_container_info (node_observers.endpoint, "endpoint"));

nano/node/node_observers.hpp

@@ -15,6 +15,7 @@ public:
 	blocks_t blocks;
 	nano::observer_set<bool> wallet;
 	nano::observer_set<std::shared_ptr<nano::vote>, std::shared_ptr<nano::transport::channel>, nano::vote_code> vote;
+	nano::observer_set<nano::block_hash const &> active_started;
 	nano::observer_set<nano::block_hash const &> active_stopped;
 	nano::observer_set<nano::account const &, bool> account_balance;
 	nano::observer_set<std::shared_ptr<nano::transport::channel>> endpoint;

nano/node/websocket.cpp

@@ -375,6 +375,10 @@ nano::websocket::topic to_topic (std::string const & topic_a)
 	{
 		topic = nano::websocket::topic::confirmation;
 	}
+	else if (topic_a == "started_election")
+	{
+		topic = nano::websocket::topic::started_election;
+	}
 	else if (topic_a == "stopped_election")
 	{
 		topic = nano::websocket::topic::stopped_election;
@@ -414,6 +418,10 @@ std::string from_topic (nano::websocket::topic topic_a)
 	{
 		topic = "confirmation";
 	}
+	else if (topic_a == nano::websocket::topic::started_election)
+	{
+		topic = "started_election";
+	}
 	else if (topic_a == nano::websocket::topic::stopped_election)
 	{
 		topic = "stopped_election";
@@ -689,6 +697,18 @@ void nano::websocket::listener::decrease_subscriber_count (nano::websocket::topi
 	count -= 1;
 }
 
+nano::websocket::message nano::websocket::message_builder::started_election (nano::block_hash const & hash_a)
+{
+	nano::websocket::message message_l (nano::websocket::topic::started_election);
+	set_common_fields (message_l);
+
+	boost::property_tree::ptree message_node_l;
+	message_node_l.add ("hash", hash_a.to_string ());
+	message_l.contents.add_child ("message", message_node_l);
+
+	return message_l;
+}
+
 nano::websocket::message nano::websocket::message_builder::stopped_election (nano::block_hash const & hash_a)
 {
 	nano::websocket::message message_l (nano::websocket::topic::stopped_election);

nano/node/websocket.hpp

@@ -41,6 +41,8 @@ namespace websocket
 		ack,
 		/** A confirmation message */
 		confirmation,
+		/** Started election message*/
+		started_election,
 		/** Stopped election message (dropped elections due to bounding or block lost the elections) */
 		stopped_election,
 		/** A vote message **/
@@ -81,6 +83,7 @@ namespace websocket
 	{
 	public:
 		message block_confirmed (std::shared_ptr<nano::block> const & block_a, nano::account const & account_a, nano::amount const & amount_a, std::string subtype, bool include_block, nano::election_status const & election_status_a, std::vector<nano::vote_with_weight_info> const & election_votes_a, nano::websocket::confirmation_options const & options_a);
+		message started_election (nano::block_hash const & hash_a);
 		message stopped_election (nano::block_hash const & hash_a);
 		message vote_received (std::shared_ptr<nano::vote> const & vote_a, nano::vote_code code_a);
 		message work_generation (nano::work_version const version_a, nano::block_hash const & root_a, uint64_t const work_a, uint64_t const difficulty_a, uint64_t const publish_threshold_a, std::chrono::milliseconds const & duration_a, std::string const & peer_a, std::vector<std::string> const & bad_peers_a, bool const completed_a = true, bool const cancelled_a = false);