protocol: change standby mode to not wait sleeping

src/cryptonote_protocol/cryptonote_protocol_handler.h

@@ -131,6 +131,7 @@ namespace cryptonote
     bool should_download_next_span(cryptonote_connection_context& context) const;
     void drop_connection(cryptonote_connection_context &context, bool add_fail, bool flush_all_spans);
     bool kick_idle_peers();
+    bool check_standby_peers();
     int try_add_next_blocks(cryptonote_connection_context &context);
 
     t_core& m_core;
@@ -143,6 +144,7 @@ namespace cryptonote
     boost::mutex m_sync_lock;
     block_queue m_block_queue;
     epee::math_helper::once_a_time_seconds<30> m_idle_peer_kicker;
+    epee::math_helper::once_a_time_milliseconds<100> m_standby_checker;
 
     boost::mutex m_buffer_mutex;
     double get_avg_block_size();

src/cryptonote_protocol/cryptonote_protocol_handler.inl

@@ -1210,6 +1210,7 @@ skip:
   bool t_cryptonote_protocol_handler<t_core>::on_idle()
   {
     m_idle_peer_kicker.do_call(boost::bind(&t_cryptonote_protocol_handler<t_core>::kick_idle_peers, this));
+    m_standby_checker.do_call(boost::bind(&t_cryptonote_protocol_handler<t_core>::check_standby_peers, this));
     return m_core.on_idle();
   }
   //------------------------------------------------------------------------------------------------------------------------
@@ -1245,6 +1246,22 @@ skip:
   }
   //------------------------------------------------------------------------------------------------------------------------
   template<class t_core>
+  bool t_cryptonote_protocol_handler<t_core>::check_standby_peers()
+  {
+    m_p2p->for_each_connection([&](cryptonote_connection_context& context, nodetool::peerid_type peer_id, uint32_t support_flags)->bool
+    {
+      if (context.m_state == cryptonote_connection_context::state_standby)
+      {
+        LOG_PRINT_CCONTEXT_L2("requesting callback");
+        ++context.m_callback_request_count;
+        m_p2p->request_callback(context);
+      }
+      return true;
+    });
+    return true;
+  }
+  //------------------------------------------------------------------------------------------------------------------------
+  template<class t_core>
   int t_cryptonote_protocol_handler<t_core>::handle_request_chain(int command, NOTIFY_REQUEST_CHAIN::request& arg, cryptonote_connection_context& context)
   {
     MLOG_P2P_MESSAGE("Received NOTIFY_REQUEST_CHAIN (" << arg.block_ids.size() << " blocks");
@@ -1338,14 +1355,13 @@ skip:
     bool start_from_current_chain = false;
     if (!force_next_span)
     {
-      bool first = true;
-      while (1)
+      do
       {
         size_t nblocks = m_block_queue.get_num_filled_spans();
         size_t size = m_block_queue.get_data_size();
         if (nblocks < BLOCK_QUEUE_NBLOCKS_THRESHOLD || size < BLOCK_QUEUE_SIZE_THRESHOLD)
         {
-          if (!first)
+          if (context.m_state != cryptonote_connection_context::state_standby)
           {
             LOG_DEBUG_CC(context, "Block queue is " << nblocks << " and " << size << ", resuming");
           }
@@ -1368,10 +1384,9 @@ skip:
           break;
         }
 
-        if (first)
+        if (context.m_state != cryptonote_connection_context::state_standby)
         {
           LOG_DEBUG_CC(context, "Block queue is " << nblocks << " and " << size << ", pausing");
-          first = false;
           context.m_state = cryptonote_connection_context::state_standby;
         }
 
@@ -1385,13 +1400,8 @@ skip:
           return true;
         }
 
-        for (size_t n = 0; n < 50; ++n)
-        {
-          if (m_stopping)
-            return true;
-          boost::this_thread::sleep_for(boost::chrono::milliseconds(100));
-        }
-      }
+        return true;
+      } while(0);
       context.m_state = cryptonote_connection_context::state_synchronizing;
     }