Merge pull request #4556 from clemahieu/vote_generator_write_queue

nano/node/vote_generator.cpp

@@ -94,6 +94,7 @@ void nano::vote_generator::process_batch (std::deque<queue_entry_t> & batch)
 {
 	std::deque<candidate_t> candidates_new;
 	{
+		auto guard = ledger.store.write_queue.wait (is_final ? nano::store::writer::voting_final : nano::store::writer::voting);
 		auto transaction = ledger.store.tx_begin_write ({ tables::final_votes });
 
 		for (auto & [root, hash] : batch)

nano/store/write_queue.cpp

@@ -73,18 +73,14 @@ nano::store::write_guard nano::store::write_queue::wait (writer writer)
 	}
 
 	nano::unique_lock<nano::mutex> lk (mutex);
+	debug_assert (std::none_of (queue.cbegin (), queue.cend (), [writer] (auto const & item) { return item == writer; }));
 	// Add writer to the end of the queue if it's not already waiting
 	auto exists = std::find (queue.cbegin (), queue.cend (), writer) != queue.cend ();
 	if (!exists)
 	{
 		queue.push_back (writer);
 	}
-
+	cv.wait (lk, [&] () { return queue.front () == writer; });
-	while (queue.front () != writer)
-	{
-		cv.wait (lk);
-	}
-
 	return write_guard (guard_finish_callback);
 }
 

nano/store/write_queue.hpp

@@ -14,6 +14,8 @@ enum class writer
 	confirmation_height,
 	process_batch,
 	pruning,
+	voting,
+	voting_final,
 	testing // Used in tests to emulate a write lock
 };