Offload vote cache lookup to a separate thread

nano/lib/stats_enums.hpp

@@ -48,6 +48,7 @@ enum class type
 	telemetry,
 	vote_generator,
 	vote_cache,
+	vote_cache_processor,
 	hinting,
 	blockprocessor,
 	blockprocessor_source,
@@ -112,6 +113,7 @@ enum class detail
 	cache,
 	rebroadcast,
 	queue_overflow,
+	triggered,
 
 	// processing queue
 	queue,

nano/lib/thread_roles.cpp

@@ -28,6 +28,9 @@ std::string nano::thread_role::get_string (nano::thread_role::name role)
 		case nano::thread_role::name::vote_processing:
 			thread_role_name_string = "Vote processing";
 			break;
+		case nano::thread_role::name::vote_cache_processing:
+			thread_role_name_string = "Vote cache proc";
+			break;
 		case nano::thread_role::name::block_processing:
 			thread_role_name_string = "Blck processing";
 			break;

nano/lib/thread_roles.hpp

@@ -14,6 +14,7 @@ enum class name
 	work,
 	message_processing,
 	vote_processing,
+	vote_cache_processing,
 	block_processing,
 	request_loop,
 	wallet_actions,

nano/node/active_elections.cpp

@@ -424,7 +424,7 @@ nano::election_insertion_result nano::active_elections::insert (std::shared_ptr<
 	{
 		debug_assert (result.election);
 
-		node.vote_router.trigger_vote_cache (hash);
+		node.vote_cache_processor.trigger (hash);
 		node.observers.active_started.notify (hash);
 		vacancy_update ();
 	}
@@ -507,7 +507,7 @@ bool nano::active_elections::publish (std::shared_ptr<nano::block> const & block
 			node.vote_router.connect (block_a->hash (), election);
 			lock.unlock ();
 
-			node.vote_router.trigger_vote_cache (block_a->hash ());
+			node.vote_cache_processor.trigger (block_a->hash ());
 
 			node.stats.inc (nano::stat::type::active, nano::stat::detail::election_block_conflict);
 		}

nano/node/fwd.hpp

@@ -11,10 +11,20 @@ class ledger;
 class local_vote_history;
 class logger;
 class network;
+class network_params;
 class node;
 class node_config;
+class node_flags;
+class node_observers;
+class online_reps;
+class rep_crawler;
+class rep_tiers;
 class stats;
+class vote_cache;
 class vote_generator;
+class vote_processor;
 class vote_router;
 class wallets;
+
+enum class vote_code;
 }

nano/node/node.cpp

@@ -200,6 +200,8 @@ nano::node::node (std::shared_ptr<boost::asio::io_context> io_ctx_a, std::filesy
 	vote_router{ *vote_router_impl },
 	vote_processor_impl{ std::make_unique<nano::vote_processor> (config.vote_processor, vote_router, observers, stats, flags, logger, online_reps, rep_crawler, ledger, network_params, rep_tiers) },
 	vote_processor{ *vote_processor_impl },
+	vote_cache_processor_impl{ std::make_unique<nano::vote_cache_processor> (config.vote_processor, vote_router, vote_cache, stats, logger) },
+	vote_cache_processor{ *vote_cache_processor_impl },
 	generator_impl{ std::make_unique<nano::vote_generator> (config, *this, ledger, wallets, vote_processor, history, network, stats, logger, /* non-final */ false) },
 	generator{ *generator_impl },
 	final_generator_impl{ std::make_unique<nano::vote_generator> (config, *this, ledger, wallets, vote_processor, history, network, stats, logger, /* final */ true) },
@@ -595,6 +597,7 @@ std::unique_ptr<nano::container_info_component> nano::collect_container_info (no
 	composite->add_component (collect_container_info (node.observers, "observers"));
 	composite->add_component (collect_container_info (node.wallets, "wallets"));
 	composite->add_component (node.vote_processor.collect_container_info ("vote_processor"));
+	composite->add_component (node.vote_cache_processor.collect_container_info ("vote_cache_processor"));
 	composite->add_component (node.rep_crawler.collect_container_info ("rep_crawler"));
 	composite->add_component (node.block_processor.collect_container_info ("block_processor"));
 	composite->add_component (collect_container_info (node.online_reps, "online_reps"));
@@ -713,6 +716,7 @@ void nano::node::start ()
 	wallets.start ();
 	rep_tiers.start ();
 	vote_processor.start ();
+	vote_cache_processor.start ();
 	block_processor.start ();
 	active.start ();
 	generator.start ();
@@ -757,6 +761,7 @@ void nano::node::stop ()
 	unchecked.stop ();
 	block_processor.stop ();
 	aggregator.stop ();
+	vote_cache_processor.stop ();
 	vote_processor.stop ();
 	rep_tiers.stop ();
 	scheduler.stop ();

nano/node/node.hpp

@@ -48,6 +48,7 @@ class confirming_set;
 class message_processor;
 class node;
 class vote_processor;
+class vote_cache_processor;
 class vote_router;
 class work_pool;
 class peer_history;
@@ -194,6 +195,8 @@ class node final : public std::enable_shared_from_this<node>
 	nano::vote_router & vote_router;
 	std::unique_ptr<nano::vote_processor> vote_processor_impl;
 	nano::vote_processor & vote_processor;
+	std::unique_ptr<nano::vote_cache_processor> vote_cache_processor_impl;
+	nano::vote_cache_processor & vote_cache_processor;
 	std::unique_ptr<nano::vote_generator> generator_impl;
 	nano::vote_generator & generator;
 	std::unique_ptr<nano::vote_generator> final_generator_impl;

nano/node/vote_processor.cpp

@@ -15,6 +15,10 @@
 
 using namespace std::chrono_literals;
 
+/*
+ * vote_processor
+ */
+
 nano::vote_processor::vote_processor (vote_processor_config const & config_a, nano::vote_router & vote_router, nano::node_observers & observers_a, nano::stats & stats_a, nano::node_flags & flags_a, nano::logger & logger_a, nano::online_reps & online_reps_a, nano::rep_crawler & rep_crawler_a, nano::ledger & ledger_a, nano::network_params & network_params_a, nano::rep_tiers & rep_tiers_a) :
 	config{ config_a },
 	vote_router{ vote_router },
@@ -218,6 +222,129 @@ std::unique_ptr<nano::container_info_component> nano::vote_processor::collect_co
 	return composite;
 }
 
+/*
+ * vote_cache_processor
+ */
+
+nano::vote_cache_processor::vote_cache_processor (vote_processor_config const & config_a, nano::vote_router & vote_router_a, nano::vote_cache & vote_cache_a, nano::stats & stats_a, nano::logger & logger_a) :
+	config{ config_a },
+	vote_router{ vote_router_a },
+	vote_cache{ vote_cache_a },
+	stats{ stats_a },
+	logger{ logger_a }
+{
+}
+
+nano::vote_cache_processor::~vote_cache_processor ()
+{
+	debug_assert (!thread.joinable ());
+}
+
+void nano::vote_cache_processor::start ()
+{
+	debug_assert (!thread.joinable ());
+
+	thread = std::thread ([this] () {
+		nano::thread_role::set (nano::thread_role::name::vote_cache_processing);
+		run ();
+	});
+}
+
+void nano::vote_cache_processor::stop ()
+{
+	{
+		nano::lock_guard<nano::mutex> guard{ mutex };
+		stopped = true;
+	}
+	condition.notify_all ();
+	if (thread.joinable ())
+	{
+		thread.join ();
+	}
+}
+
+void nano::vote_cache_processor::trigger (nano::block_hash const & hash)
+{
+	{
+		nano::lock_guard<nano::mutex> guard{ mutex };
+		if (triggered.size () >= config.max_triggered)
+		{
+			triggered.pop_front ();
+			stats.inc (nano::stat::type::vote_cache_processor, nano::stat::detail::overfill);
+		}
+		triggered.push_back (hash);
+	}
+	condition.notify_all ();
+	stats.inc (nano::stat::type::vote_cache_processor, nano::stat::detail::triggered);
+}
+
+void nano::vote_cache_processor::run ()
+{
+	nano::unique_lock<nano::mutex> lock{ mutex };
+	while (!stopped)
+	{
+		stats.inc (nano::stat::type::vote_cache_processor, nano::stat::detail::loop);
+
+		if (!triggered.empty ())
+		{
+			run_batch (lock);
+			debug_assert (!lock.owns_lock ());
+			lock.lock ();
+		}
+		else
+		{
+			condition.wait (lock, [&] { return stopped || !triggered.empty (); });
+		}
+	}
+}
+
+void nano::vote_cache_processor::run_batch (nano::unique_lock<nano::mutex> & lock)
+{
+	debug_assert (lock.owns_lock ());
+	debug_assert (!mutex.try_lock ());
+	debug_assert (!triggered.empty ());
+
+	// Swap and deduplicate
+	decltype (triggered) triggered_l;
+	swap (triggered_l, triggered);
+
+	lock.unlock ();
+
+	std::unordered_set<nano::block_hash> hashes;
+	hashes.reserve (triggered_l.size ());
+	hashes.insert (triggered_l.begin (), triggered_l.end ());
+
+	stats.add (nano::stat::type::vote_cache_processor, nano::stat::detail::processed, hashes.size ());
+
+	for (auto const & hash : hashes)
+	{
+		auto cached = vote_cache.find (hash);
+		for (auto const & cached_vote : cached)
+		{
+			vote_router.vote (cached_vote, nano::vote_source::cache, hash);
+		}
+	}
+}
+
+std::size_t nano::vote_cache_processor::size () const
+{
+	nano::lock_guard<nano::mutex> guard{ mutex };
+	return triggered.size ();
+}
+
+bool nano::vote_cache_processor::empty () const
+{
+	return size () == 0;
+}
+
+std::unique_ptr<nano::container_info_component> nano::vote_cache_processor::collect_container_info (std::string const & name) const
+{
+	nano::lock_guard<nano::mutex> guard{ mutex };
+	auto composite = std::make_unique<container_info_composite> (name);
+	composite->add_component (std::make_unique<container_info_leaf> (container_info{ "triggered", triggered.size (), sizeof (decltype (triggered)::value_type) }));
+	return composite;
+}
+
 /*
  * vote_processor_config
  */
@@ -242,4 +369,4 @@ nano::error nano::vote_processor_config::deserialize (nano::tomlconfig & toml)
 	toml.get ("batch_size", batch_size);
 
 	return toml.get_error ();
-}
+}

nano/node/vote_processor.hpp

@@ -4,6 +4,7 @@
 #include <nano/lib/threading.hpp>
 #include <nano/lib/utility.hpp>
 #include <nano/node/fair_queue.hpp>
+#include <nano/node/fwd.hpp>
 #include <nano/node/rep_tiers.hpp>
 #include <nano/node/vote_router.hpp>
 #include <nano/secure/common.hpp>
@@ -13,32 +14,6 @@
 #include <thread>
 #include <unordered_set>
 
-namespace nano
-{
-namespace store
-{
-	class component;
-}
-class node_observers;
-class stats;
-class node_config;
-class logger;
-class online_reps;
-class rep_crawler;
-class ledger;
-class network_params;
-class node_flags;
-class stats;
-class rep_tiers;
-enum class vote_code;
-class vote_router;
-
-namespace transport
-{
-	class channel;
-}
-}
-
 namespace nano
 {
 class vote_processor_config final
@@ -53,21 +28,25 @@ class vote_processor_config final
 	size_t pr_priority{ 3 };
 	size_t threads{ std::clamp (nano::hardware_concurrency () / 2, 1u, 4u) };
 	size_t batch_size{ 1024 };
+	size_t max_triggered{ 16384 };
 };
 
 class vote_processor final
 {
 public:
-	vote_processor (vote_processor_config const &, nano::vote_router & vote_router, nano::node_observers &, nano::stats &, nano::node_flags &, nano::logger &, nano::online_reps &, nano::rep_crawler &, nano::ledger &, nano::network_params &, nano::rep_tiers &);
+	vote_processor (vote_processor_config const &, nano::vote_router &, nano::node_observers &, nano::stats &, nano::node_flags &, nano::logger &, nano::online_reps &, nano::rep_crawler &, nano::ledger &, nano::network_params &, nano::rep_tiers &);
 	~vote_processor ();
 
 	void start ();
 	void stop ();
 
-	/** @returns true if the vote was queued for processing */
+	/** Queue vote for processing. @returns true if the vote was queued */
 	bool vote (std::shared_ptr<nano::vote> const &, std::shared_ptr<nano::transport::channel> const &, nano::vote_source = nano::vote_source::live);
 	nano::vote_code vote_blocking (std::shared_ptr<nano::vote> const &, std::shared_ptr<nano::transport::channel> const &, nano::vote_source = nano::vote_source::live);
 
+	/** Queue hash for vote cache lookup and processing. */
+	void trigger (nano::block_hash const & hash);
+
 	std::size_t size () const;
 	bool empty () const;
 
@@ -101,4 +80,41 @@ class vote_processor final
 	mutable nano::mutex mutex{ mutex_identifier (mutexes::vote_processor) };
 	std::vector<std::thread> threads;
 };
+
+class vote_cache_processor final
+{
+public:
+	vote_cache_processor (vote_processor_config const &, nano::vote_router &, nano::vote_cache &, nano::stats &, nano::logger &);
+	~vote_cache_processor ();
+
+	void start ();
+	void stop ();
+
+	/** Queue hash for vote cache lookup and processing. */
+	void trigger (nano::block_hash const & hash);
+
+	std::size_t size () const;
+	bool empty () const;
+
+	std::unique_ptr<container_info_component> collect_container_info (std::string const & name) const;
+
+private:
+	void run ();
+	void run_batch (nano::unique_lock<nano::mutex> &);
+
+private: // Dependencies
+	vote_processor_config const & config;
+	nano::vote_router & vote_router;
+	nano::vote_cache & vote_cache;
+	nano::stats & stats;
+	nano::logger & logger;
+
+private:
+	std::deque<nano::block_hash> triggered;
+
+	bool stopped{ false };
+	nano::condition_variable condition;
+	mutable nano::mutex mutex;
+	std::thread thread;
+};
 }

nano/node/vote_router.cpp

@@ -123,16 +123,6 @@ std::unordered_map<nano::block_hash, nano::vote_code> nano::vote_router::vote (s
 	return results;
 }
 
-bool nano::vote_router::trigger_vote_cache (nano::block_hash const & hash)
-{
-	auto cached = cache.find (hash);
-	for (auto const & cached_vote : cached)
-	{
-		vote (cached_vote, nano::vote_source::cache, hash);
-	}
-	return !cached.empty ();
-}
-
 bool nano::vote_router::active (nano::block_hash const & hash) const
 {
 	std::shared_lock lock{ mutex };