Use start/stop pattern in block_processor (#4462)

nano/node/blockprocessor.cpp

@@ -46,9 +46,21 @@ nano::block_processor::block_processor (nano::node & node_a, nano::write_databas
 			block_processed.notify (result, context);
 		}
 	});
-	processing_thread = std::thread ([this] () {
+}
+
+nano::block_processor::~block_processor ()
+{
+	// Thread must be stopped before destruction
+	debug_assert (!thread.joinable ());
+}
+
+void nano::block_processor::start ()
+{
+	debug_assert (!thread.joinable ());
+
+	thread = std::thread ([this] () {
 		nano::thread_role::set (nano::thread_role::name::block_processing);
-		this->process_blocks ();
+		run ();
 	});
 }
 
@@ -59,7 +71,10 @@ void nano::block_processor::stop ()
 		stopped = true;
 	}
 	condition.notify_all ();
-	nano::join_or_pass (processing_thread);
+	if (thread.joinable ())
+	{
+		thread.join ();
+	}
 }
 
 std::size_t nano::block_processor::size ()
@@ -172,14 +187,13 @@ void nano::block_processor::rollback_competitor (store::write_transaction const
 	}
 }
 
-void nano::block_processor::process_blocks ()
+void nano::block_processor::run ()
 {
 	nano::unique_lock<nano::mutex> lock{ mutex };
 	while (!stopped)
 	{
 		if (have_blocks_ready ())
 		{
-			active = true;
 			lock.unlock ();
 
 			auto processed = process_batch (lock);
@@ -194,7 +208,6 @@ void nano::block_processor::process_blocks ()
 			batch_processed.notify (processed);
 
 			lock.lock ();
-			active = false;
 		}
 		else
 		{

nano/node/blockprocessor.hpp

@@ -67,8 +67,11 @@ public: // Context
 
 public:
 	block_processor (nano::node &, nano::write_database_queue &);
+	~block_processor ();
 
+	void start ();
 	void stop ();
+
 	std::size_t size ();
 	bool full ();
 	bool half_full ();
@@ -78,7 +81,7 @@ public:
 	bool should_log ();
 	bool have_blocks_ready ();
 	bool have_blocks ();
-	void process_blocks ();
+
 	std::unique_ptr<container_info_component> collect_container_info (std::string const & name);
 
 	std::atomic<bool> flushing{ false };
@@ -93,6 +96,7 @@ public: // Events
 	nano::observer_set<std::shared_ptr<nano::block> const &> rolled_back;
 
 private:
+	void run ();
 	// Roll back block in the ledger that conflicts with 'block'
 	void rollback_competitor (store::write_transaction const &, nano::block const & block);
 	nano::block_status process_one (store::write_transaction const &, context const &, bool forced = false);
@@ -106,15 +110,14 @@ private: // Dependencies
 	nano::write_database_queue & write_database_queue;
 
 private:
-	bool stopped{ false };
-	bool active{ false };
-
 	std::deque<context> blocks;
 	std::deque<context> forced;
 
 	std::chrono::steady_clock::time_point next_log;
+
+	bool stopped{ false };
 	nano::condition_variable condition;
 	nano::mutex mutex{ mutex_identifier (mutexes::block_processor) };
-	std::thread processing_thread;
+	std::thread thread;
 };
 }

nano/node/node.cpp

@@ -635,6 +635,7 @@ void nano::node::start ()
 	}
 	wallets.start ();
 	vote_processor.start ();
+	block_processor.start ();
 	active.start ();
 	generator.start ();
 	final_generator.start ();