From b3b8c926c1fd640cd1ac78f9d18a9db40d5c89e9 Mon Sep 17 00:00:00 2001
From: timur <12267899-timur.5@users.noreply.gitlab.com>
Date: Wed, 16 Nov 2022 07:32:17 -0400
Subject: [PATCH] SON connection pool.

---
 .../peerplays_sidechain_plugin.cpp            |  2 +-
 .../sidechain_net_handler_hive.cpp            | 56 ++++++++++++++++++-
 2 files changed, 55 insertions(+), 3 deletions(-)

diff --git a/libraries/plugins/peerplays_sidechain/peerplays_sidechain_plugin.cpp b/libraries/plugins/peerplays_sidechain/peerplays_sidechain_plugin.cpp
index 9e404315..bdb5ae57 100644
--- a/libraries/plugins/peerplays_sidechain/peerplays_sidechain_plugin.cpp
+++ b/libraries/plugins/peerplays_sidechain/peerplays_sidechain_plugin.cpp
@@ -857,7 +857,7 @@ void peerplays_sidechain_plugin_impl::on_applied_block(const signed_block &b) {
 
 void peerplays_sidechain_plugin_impl::schedule_rpc_client_selection() {
    fc::time_point now = fc::time_point::now();
-   static const int64_t time_to_next_rpc_selection = 5000000;
+   static const int64_t time_to_next_rpc_selection = 100000;//5000000;
    fc::time_point next_wakeup = now + fc::microseconds(time_to_next_rpc_selection);
    _rpc_client_selection_task = fc::schedule([this] {
       rpc_client_selection();
diff --git a/libraries/plugins/peerplays_sidechain/sidechain_net_handler_hive.cpp b/libraries/plugins/peerplays_sidechain/sidechain_net_handler_hive.cpp
index 8678298b..7f7026b0 100644
--- a/libraries/plugins/peerplays_sidechain/sidechain_net_handler_hive.cpp
+++ b/libraries/plugins/peerplays_sidechain/sidechain_net_handler_hive.cpp
@@ -970,10 +970,62 @@ hive_rpc_client *sidechain_net_handler_hive::get_active_rpc_client()
 
 void sidechain_net_handler_hive::select_active_rpc_client()
 {
+   //ilog("n_active_rpc_client=${n}", ("n", n_active_rpc_client));
    if (rpc_clients.size())
    {
-      n_active_rpc_client = (n_active_rpc_client + 1) % rpc_clients.size();
-      ilog("n_active_rpc_client=${n}", ("n", n_active_rpc_client));
+      int best_n = -1;
+      int best_quality = -1;
+
+      std::vector<uint64_t> head_block_numbers;
+      head_block_numbers.resize(rpc_clients.size());
+         
+      std::vector<int> qualities;
+      qualities.resize(rpc_clients.size());
+
+      for (size_t n=0; n < rpc_clients.size(); n++) {
+         hive_rpc_client *rpc_client = rpc_clients[n];
+         int quality = 0;
+         head_block_numbers[n] = std::numeric_limits<uint64_t>::max();
+
+         // make the ping
+         fc::time_point t_sent = fc::time_point::now();
+         const std::string reply = rpc_client->database_api_get_dynamic_global_properties();
+         fc::time_point t_received = fc::time_point::now();
+         if (!reply.empty()) {
+            std::stringstream ss(reply);
+            boost::property_tree::ptree json;
+            boost::property_tree::read_json(ss, json);
+            if (json.count("result")) {
+               uint64_t head_block_number = json.get<uint64_t>("result.head_block_number");
+               int t = (t_received - t_sent).count();
+               t += rand() % 10;
+               FC_ASSERT(t != -1);
+               head_block_numbers[n] = head_block_number;
+               FC_ASSERT(head_block_numbers[n] != std::numeric_limits<uint64_t>::max());
+               static const int t_limit = 10*1000000; // 10 sec
+               if (t < t_limit)
+                  quality = t_limit - t;  // the less time, the higher quality
+            }
+         }
+
+         //ilog("Hive RPC qual: ${n} -> ${q}", ("n", n)("q", quality));
+
+         // look for the best quality
+         if (quality > best_quality) {
+            best_n = n;
+            best_quality = quality;
+         }
+      }
+
+      FC_ASSERT(best_n != -1 && best_quality != -1);
+      if (best_n != n_active_rpc_client) {  // if the best client is not the current one, ...
+         uint64_t active_head_block_number = head_block_numbers[n_active_rpc_client];
+         if (active_head_block_number == std::numeric_limits<uint64_t>::max()  // ... and the current one has no known head block...
+            || head_block_numbers[best_n] >= active_head_block_number) {  // ...or the best client's head is more recent than the current, ...
+            n_active_rpc_client = best_n;   // ...then select new one
+            ilog("!!! Hive rpc_client reselected, now ${n}", ("n", n_active_rpc_client));
+         }
+      }
    }
 }