cryptonote_protocol: kick idle synchronizing peers

In case they dropped off downloading for any reason, they'll get
sent to download again.

src/cryptonote_basic/connection_context.h

@@ -46,6 +46,7 @@ namespace cryptonote
     {
       state_befor_handshake = 0, //default state
       state_synchronizing,
+      state_standby,
       state_idle,
       state_normal
     };
@@ -69,6 +70,8 @@ namespace cryptonote
       return "state_befor_handshake";
     case cryptonote_connection_context::state_synchronizing:
       return "state_synchronizing";
+    case cryptonote_connection_context::state_standby:
+      return "state_standby";
     case cryptonote_connection_context::state_idle:
       return "state_idle";
     case cryptonote_connection_context::state_normal:

src/cryptonote_protocol/block_queue.cpp

@@ -334,6 +334,16 @@ crypto::hash block_queue::get_last_known_hash(const boost::uuids::uuid &connecti
   return hash;
 }
 
+bool block_queue::has_spans(const boost::uuids::uuid &connection_id) const
+{
+  for (const auto &span: blocks)
+  {
+    if (span.connection_id == connection_id)
+      return true;
+  }
+  return false;
+}
+
 float block_queue::get_speed(const boost::uuids::uuid &connection_id) const
 {
   boost::unique_lock<boost::recursive_mutex> lock(mutex);

src/cryptonote_protocol/block_queue.h

@@ -86,6 +86,7 @@ namespace cryptonote
     size_t get_num_filled_spans_prefix() const;
     size_t get_num_filled_spans() const;
     crypto::hash get_last_known_hash(const boost::uuids::uuid &connection_id) const;
+    bool has_spans(const boost::uuids::uuid &connection_id) const;
     float get_speed(const boost::uuids::uuid &connection_id) const;
     bool foreach(std::function<bool(const span&)> f, bool include_blockchain_placeholder = false) const;
     bool requested(const crypto::hash &hash) const;

src/cryptonote_protocol/cryptonote_protocol_handler.h

@@ -38,6 +38,7 @@
 #include <string>
 #include <ctime>
 
+#include "math_helper.h"
 #include "storages/levin_abstract_invoke2.h"
 #include "warnings.h"
 #include "cryptonote_protocol_defs.h"
@@ -131,6 +132,7 @@ namespace cryptonote
     bool on_connection_synchronized();
     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();
 
     t_core& m_core;
 
@@ -141,6 +143,7 @@ namespace cryptonote
     std::atomic<bool> m_stopping;
     boost::mutex m_sync_lock;
     block_queue m_block_queue;
+    epee::math_helper::once_a_time_seconds<30> m_idle_peer_kicker;
 
     boost::mutex m_buffer_mutex;
     double get_avg_block_size();

src/cryptonote_protocol/cryptonote_protocol_handler.inl

@@ -51,6 +51,7 @@
 #define BLOCK_QUEUE_NBLOCKS_THRESHOLD 10 // chunks of N blocks
 #define BLOCK_QUEUE_SIZE_THRESHOLD (100*1024*1024) // MB
 #define REQUEST_NEXT_SCHEDULED_SPAN_THRESHOLD (5 * 1000000) // microseconds
+#define IDLE_PEER_KICK_TIME (45 * 1000000) // microseconds
 
 namespace cryptonote
 {
@@ -1129,10 +1130,33 @@ skip:
   template<class t_core>
   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));
     return m_core.on_idle();
   }
   //------------------------------------------------------------------------------------------------------------------------
   template<class t_core>
+  bool t_cryptonote_protocol_handler<t_core>::kick_idle_peers()
+  {
+    MTRACE("Checking for idle 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_synchronizing)
+      {
+        const boost::posix_time::ptime now = boost::posix_time::microsec_clock::universal_time();
+        const boost::posix_time::time_duration dt = now - context.m_last_request_time;
+        if (dt.total_microseconds() > IDLE_PEER_KICK_TIME)
+        {
+          MINFO(context << " kicking idle peer");
+          ++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");
@@ -1243,6 +1267,7 @@ skip:
         {
           LOG_DEBUG_CC(context, "Block queue is " << nblocks << " and " << size << ", pausing");
           first = false;
+          context.m_state = cryptonote_connection_context::state_standby;
         }
         for (size_t n = 0; n < 50; ++n)
         {
@@ -1251,6 +1276,7 @@ skip:
           boost::this_thread::sleep_for(boost::chrono::milliseconds(100));
         }
       }
+      context.m_state = cryptonote_connection_context::state_synchronizing;
     }
 
     MDEBUG(context << " request_missing_objects: check " << check_having_blocks << ", force_next_span " << force_next_span << ", m_needed_objects " << context.m_needed_objects.size() << " lrh " << context.m_last_response_height << ", chain " << m_core.get_current_blockchain_height());
@@ -1402,6 +1428,7 @@ skip:
       //epee::net_utils::network_throttle_manager::get_global_throttle_inreq().logger_handle_net("log/dr-monero/net/req-all.data", sec, get_avg_block_size());
       //LOG_PRINT_CCONTEXT_L1("r = " << 200);
 
+      context.m_last_request_time = boost::posix_time::microsec_clock::universal_time();
       LOG_PRINT_CCONTEXT_L1("-->>NOTIFY_REQUEST_CHAIN: m_block_ids.size()=" << r.block_ids.size() << ", start_from_current_chain " << start_from_current_chain);
       post_notify<NOTIFY_REQUEST_CHAIN>(r, context);
     }else