p2p: make stop signal idempotent

contrib/epee/include/net/abstract_tcp_server2.inl

@@ -1581,7 +1581,11 @@ namespace net_utils
   template<class t_protocol_handler>
   void boosted_tcp_server<t_protocol_handler>::send_stop_signal(std::function<void()> close_all_connections)
   {
-    m_stop_signal_sent = true;
+    if (m_stop_signal_sent.exchange(true))
+    {
+      MDEBUG("Stop signal already sent");
+      return;
+    }
     typename connection<t_protocol_handler>::shared_state *state = static_cast<typename connection<t_protocol_handler>::shared_state*>(m_state.get());
     state->stop_signal_sent = true;
     TRY_ENTRY();

src/p2p/net_node.h

@@ -449,6 +449,7 @@ namespace nodetool
     bool m_use_ipv6;
     bool m_require_ipv4;
     std::atomic<bool> is_closing;
+    std::atomic<bool> m_stop_signal_sent_once{false};
     std::unique_ptr<boost::thread> mPeersLoggerThread;
     //critical_section m_connections_lock;
     //connections_indexed_container m_connections;

src/p2p/net_node.inl

@@ -1107,6 +1107,11 @@ namespace nodetool
   template<class t_payload_net_handler>
   bool node_server<t_payload_net_handler>::send_stop_signal()
   {
+    if (m_stop_signal_sent_once.exchange(true))
+    {
+      MDEBUG("[node] Stop signal already sent");
+      return true;
+    }
     MDEBUG("[node] stopping server payload handler");
     m_payload_handler.stop();
     MDEBUG("[node] sending stop signal");