daemon: auto public nodes - cache and prioritize most stable nodes

src/rpc/bootstrap_node_selector.cpp

@@ -0,0 +1,117 @@
+// Copyright (c) 2020, The Monero Project
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+// 
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+// 
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+// 
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "bootstrap_node_selector.h"
+
+#include "crypto/crypto.h"
+
+namespace cryptonote
+{
+namespace bootstrap_node
+{
+
+  void selector_auto::node::handle_result(bool success)
+  {
+    if (!success)
+    {
+      fails = std::min(std::numeric_limits<size_t>::max() - 2, fails) + 2;
+    }
+    else
+    {
+      fails = std::max(std::numeric_limits<size_t>::min() + 2, fails) - 2;
+    }
+  }
+
+  void selector_auto::handle_result(const std::string &address, bool success)
+  {
+    auto &nodes_by_address = m_nodes.get<by_address>();
+    const auto it = nodes_by_address.find(address);
+    if (it != nodes_by_address.end())
+    {
+      nodes_by_address.modify(it, [success](node &entry) {
+        entry.handle_result(success);
+      });
+    }
+  }
+
+  boost::optional<node_info> selector_auto::next_node()
+  {
+    if (!has_at_least_one_good_node())
+    {
+      append_new_nodes();
+    }
+
+    if (m_nodes.empty())
+    {
+      return {};
+    }
+
+    auto node = m_nodes.get<by_fails>().begin();
+    const size_t count = std::distance(node, m_nodes.get<by_fails>().upper_bound(node->fails));
+    std::advance(node, crypto::rand_idx(count));
+
+    return {{node->address, {}}};
+  }
+
+  bool selector_auto::has_at_least_one_good_node() const
+  {
+    return !m_nodes.empty() && m_nodes.get<by_fails>().begin()->fails == 0;
+  }
+
+  void selector_auto::append_new_nodes()
+  {
+    bool updated = false;
+
+    for (const auto &node : m_get_nodes())
+    {
+      const auto &address = node.first;
+      const auto &white = node.second;
+      const size_t initial_score = white ? 0 : 1;
+      updated |= m_nodes.get<by_address>().insert({address, initial_score}).second;
+    }
+
+    if (updated)
+    {
+      truncate();
+    }
+  }
+
+  void selector_auto::truncate()
+  {
+    const size_t total = m_nodes.size();
+    if (total > m_max_nodes)
+    {
+      auto &nodes_by_fails = m_nodes.get<by_fails>();
+      auto from = nodes_by_fails.rbegin();
+      std::advance(from, total - m_max_nodes);
+      nodes_by_fails.erase(from.base(), nodes_by_fails.end());
+    }
+  }
+
+}
+}