Lock before stopping when it is necessary to notify other threads (#2608)

This prevents having all threads waiting and the system freezing. Mostly important for tests, especially with sanitizers, but could happen on stopping the node normally.

Portmapping requires an atomic bool, and the database queue doesn't after this change.

Other small related bootstrap changes included in this PR per Serg's suggestion.

nano/node/bootstrap/bootstrap_attempt.cpp

@@ -202,9 +202,11 @@ bool nano::bootstrap_attempt_legacy::consume_future (std::future<bool> & future_
 
 void nano::bootstrap_attempt_legacy::stop ()
 {
-	stopped = true;
-	condition.notify_all ();
 	nano::unique_lock<std::mutex> lock (mutex);
+	stopped = true;
+	lock.unlock ();
+	condition.notify_all ();
+	lock.lock ();
 	if (auto i = frontiers.lock ())
 	{
 		try
@@ -478,7 +480,7 @@ bool nano::bootstrap_attempt_legacy::request_frontier (nano::unique_lock<std::mu
 	lock_a.unlock ();
 	auto connection_l (node->bootstrap_initiator.connections->connection (shared_from_this (), first_attempt));
 	lock_a.lock ();
-	if (connection_l)
+	if (connection_l && !stopped)
 	{
 		endpoint_frontier_request = connection_l->channel->get_tcp_endpoint ();
 		std::future<bool> future;

nano/node/bootstrap/bootstrap_connections.cpp

@@ -76,7 +76,8 @@ std::shared_ptr<nano::bootstrap_client> nano::bootstrap_connections::connection
 	if (result == nullptr && connections_count == 0 && new_connections_empty && attempt_a != nullptr)
 	{
 		node.logger.try_log (boost::str (boost::format ("Bootstrap attempt stopped because there are no peers")));
-		attempt_a->stopped = true;
+		lock.unlock ();
+		attempt_a->stop ();
 	}
 	return result;
 }
@@ -440,19 +441,22 @@ void nano::bootstrap_connections::requeue_pull (nano::pull_info const & pull_a,
 
 void nano::bootstrap_connections::clear_pulls (uint64_t bootstrap_id_a)
 {
-	nano::lock_guard<std::mutex> lock (mutex);
-	auto i (pulls.begin ());
-	while (i != pulls.end ())
 	{
-		if (i->bootstrap_id == bootstrap_id_a)
+		nano::lock_guard<std::mutex> lock (mutex);
+		auto i (pulls.begin ());
+		while (i != pulls.end ())
 		{
-			i = pulls.erase (i);
-		}
-		else
-		{
-			++i;
+			if (i->bootstrap_id == bootstrap_id_a)
+			{
+				i = pulls.erase (i);
+			}
+			else
+			{
+				++i;
+			}
 		}
 	}
+	condition.notify_all ();
 }
 
 void nano::bootstrap_connections::run ()
@@ -477,9 +481,11 @@ void nano::bootstrap_connections::run ()
 
 void nano::bootstrap_connections::stop ()
 {
+	nano::unique_lock<std::mutex> lock (mutex);
 	stopped = true;
+	lock.unlock ();
 	condition.notify_all ();
-	nano::lock_guard<std::mutex> lock (mutex);
+	lock.lock ();
 	for (auto i : clients)
 	{
 		if (auto client = i.lock ())

nano/node/bootstrap/bootstrap_lazy.cpp

@@ -519,7 +519,7 @@ void nano::bootstrap_attempt_wallet::request_pending (nano::unique_lock<std::mut
 	lock_a.unlock ();
 	auto connection_l (node->bootstrap_initiator.connections->connection (shared_from_this ()));
 	lock_a.lock ();
-	if (connection_l)
+	if (connection_l && !stopped)
 	{
 		auto account (wallet_accounts.front ());
 		wallet_accounts.pop_front ();

nano/node/confirmation_height_processor.cpp

@@ -34,7 +34,10 @@ nano::confirmation_height_processor::~confirmation_height_processor ()
 
 void nano::confirmation_height_processor::stop ()
 {
-	stopped = true;
+	{
+		nano::lock_guard<std::mutex> guard (mutex);
+		stopped = true;
+	}
 	condition.notify_one ();
 	if (thread.joinable ())
 	{

nano/node/portmapping.hpp

@@ -59,7 +59,7 @@ private:
 	boost::asio::ip::address_v4 address;
 	std::array<mapping_protocol, 2> protocols;
 	uint64_t check_count{ 0 };
-	bool on{ false };
+	std::atomic<bool> on{ false };
 	std::mutex mutex;
 };
 }

nano/node/write_database_queue.cpp

@@ -77,6 +77,9 @@ nano::write_guard nano::write_database_queue::pop ()
 
 void nano::write_database_queue::stop ()
 {
-	stopped = true;
+	{
+		nano::lock_guard<std::mutex> guard (mutex);
+		stopped = true;
+	}
 	cv.notify_all ();
 }

nano/node/write_database_queue.hpp

@@ -2,7 +2,6 @@
 
 #include <nano/lib/locks.hpp>
 
-#include <atomic>
 #include <condition_variable>
 #include <deque>
 #include <functional>
@@ -53,6 +52,6 @@ private:
 	std::mutex mutex;
 	nano::condition_variable cv;
 	std::function<void()> guard_finish_callback;
-	std::atomic<bool> stopped{ false };
+	bool stopped{ false };
 };
 }