Moving voting constants in to their own class (#3071)

* Currently there is no rate limiter on vote generation for a particular root and this can lead to increased, unnecessary vote traffic.

This patch adds a delay between constructing non-cached votes.

* Removing check on hash since we won't produce a new vote if there's an existing one.

* Moving delay in to voting_constants and referencing voting_constants from local_vote_history instead of copying values on construction.

* Erasing duplicate roots.

* Adding test for correct broadcast deduplication.

* Retaining historical blocks until election completion. history::votes filters by root+hash so it won't pick up votes for hashes it's not looking for.

* Moving vote spacing to its own data structure.

* Testing vote_spacing class and adding trimming.

* Revert "Retaining historical blocks until election completion. history::votes filters by root+hash so it won't pick up votes for hashes it's not looking for."

This reverts commit 9890305eaeb745b4c86bac36b8ad19d55975c61d.

Co-authored-by: Russel <russel@nano.org>

nano/core_test/voting.cpp

@@ -11,7 +11,8 @@ namespace nano
 {
 TEST (local_vote_history, basic)
 {
-	nano::local_vote_history history;
+	nano::network_params params;
+	nano::local_vote_history history{ params.voting };
 	ASSERT_FALSE (history.exists (1));
 	ASSERT_FALSE (history.exists (2));
 	ASSERT_TRUE (history.votes (1).empty ());

nano/node/node.cpp

@@ -119,6 +119,7 @@ block_processor_thread ([this]() {
 }),
 // clang-format on
 online_reps (ledger, config),
+history{ config.network_params.voting },
 vote_uniquer (block_uniquer),
 confirmation_height_processor (ledger, write_database_queue, config.conf_height_processor_batch_min_time, config.logging, logger, node_initialized_latch, flags.confirmation_height_processor_mode),
 active (*this, confirmation_height_processor),

nano/node/voting.cpp

@@ -87,9 +87,9 @@ bool nano::local_vote_history::exists (nano::root const & root_a) const
 
 void nano::local_vote_history::clean ()
 {
-	debug_assert (max_size > 0);
+	debug_assert (constants.max_cache > 0);
 	auto & history_by_sequence (history.get<tag_sequence> ());
-	while (history_by_sequence.size () > max_size)
+	while (history_by_sequence.size () > constants.max_cache)
 	{
 		history_by_sequence.erase (history_by_sequence.begin ());
 	}
@@ -247,7 +247,8 @@ void nano::vote_generator::reply (nano::unique_lock<std::mutex> & lock_a, reques
 		roots.reserve (nano::network::confirm_ack_hashes_max);
 		for (; i != n && hashes.size () < nano::network::confirm_ack_hashes_max; ++i)
 		{
-			auto cached_votes = history.votes (i->first, i->second);
+			auto const & [root, hash] = *i;
+			auto cached_votes = history.votes (root, hash);
 			for (auto const & cached_vote : cached_votes)
 			{
 				if (cached_sent.insert (cached_vote).second)

nano/node/voting.hpp

@@ -48,6 +48,10 @@ class local_vote_history final
 	};
 
 public:
+	local_vote_history (nano::voting_constants const & constants) :
+	constants{ constants }
+	{
+	}
 	void add (nano::root const & root_a, nano::block_hash const & hash_a, std::shared_ptr<nano::vote> const & vote_a);
 	void erase (nano::root const & root_a);
 
@@ -65,7 +69,7 @@ private:
 	history;
 	// clang-format on
 
-	size_t const max_size{ nano::network_params{}.voting.max_cache };
+	nano::voting_constants const & constants;
 	void clean ();
 	std::vector<std::shared_ptr<nano::vote>> votes (nano::root const & root_a) const;
 	// Only used in Debug

nano/secure/common.cpp

@@ -155,9 +155,10 @@ nano::node_constants::node_constants (nano::network_constants & network_constant
 	weight_period = 5 * 60; // 5 minutes
 }
 
-nano::voting_constants::voting_constants (nano::network_constants & network_constants)
+nano::voting_constants::voting_constants (nano::network_constants & network_constants) :
+max_cache{ network_constants.is_dev_network () ? 256U : 128U * 1024 },
+delay{ network_constants.is_dev_network () ? 1 : 15 }
 {
-	max_cache = network_constants.is_dev_network () ? 256 : 128 * 1024;
 }
 
 nano::portmapping_constants::portmapping_constants (nano::network_constants & network_constants)

nano/secure/common.hpp

@@ -428,7 +428,8 @@ class voting_constants
 {
 public:
 	voting_constants (nano::network_constants & network_constants);
-	size_t max_cache;
+	size_t const max_cache;
+	std::chrono::seconds const delay;
 };
 
 /** Port-mapping related constants whose value depends on the active network */