From 709a2c7b7c27ebda7f606dc4314cf92ec1ef69f3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=A9bastien=20Blin?=
 <sebastien.blin@savoirfairelinux.com>
Date: Tue, 29 May 2018 15:21:17 -0400
Subject: [PATCH] dht_proxy_server: avoid mutex when getting /

The dht_proxy_server should be always up, so getNodesStats will
be pretty always up-to-date. We can add it into a job and avoid
to wait for this method to finish (and this method use an
internal lock) to have a quick answer about the status of the proxy.

Note: the update is forced during the initialization of the proxy
---
 include/opendht/dht_proxy_server.h | 10 +++++++---
 src/dht_proxy_server.cpp           | 27 +++++++++++++++++++++++++--
 2 files changed, 32 insertions(+), 5 deletions(-)

diff --git a/include/opendht/dht_proxy_server.h b/include/opendht/dht_proxy_server.h
index b5216ad4..ecf8fbb4 100644
--- a/include/opendht/dht_proxy_server.h
+++ b/include/opendht/dht_proxy_server.h
@@ -21,12 +21,13 @@
 
 #pragma once
 
+#include "callbacks.h"
 #include "def.h"
-#include "sockaddr.h"
 #include "infohash.h"
-#include "scheduler.h"
-#include "value.h"
 #include "proxy.h"
+#include "scheduler.h"
+#include "sockaddr.h"
+#include "value.h"
 
 #include <thread>
 #include <memory>
@@ -237,6 +238,9 @@ private:
     std::thread schedulerThread_;
 
     Sp<Scheduler::Job> printStatsJob_;
+    mutable std::mutex statsMutex_;
+    mutable NodeStats ipv4Stats_ {};
+    mutable NodeStats ipv6Stats_ {};
 
     // Handle client quit for listen.
     // NOTE: can be simplified when we will supports restbed 5.0
diff --git a/src/dht_proxy_server.cpp b/src/dht_proxy_server.cpp
index d92c03b6..86eb6ab7 100644
--- a/src/dht_proxy_server.cpp
+++ b/src/dht_proxy_server.cpp
@@ -30,6 +30,8 @@
 #include <functional>
 #include <limits>
 
+#include <iostream>
+
 using namespace std::placeholders;
 
 namespace dht {
@@ -128,6 +130,16 @@ DhtProxyServer::DhtProxyServer(std::shared_ptr<DhtRunner> dht, in_port_t port ,
                 std::cout << getStats().toString() << std::endl;
                 scheduler_.edit(printStatsJob_, scheduler_.time() + PRINT_STATS_PERIOD);
             }
+            if (not stopListeners) {
+                // Refresh stats cache
+                auto newIpv4Stats = dht_->getNodesStats(AF_INET);
+                auto newIpv6Stats = dht_->getNodesStats(AF_INET6);
+                {
+                    std::lock_guard<std::mutex> lck(statsMutex_);
+                    ipv4Stats_ = std::move(newIpv4Stats);
+                    ipv6Stats_ = std::move(newIpv6Stats);
+                }
+            }
         });
         while (service_->is_up()  and not stopListeners) {
             std::unique_lock<std::mutex> lock(schedulerLock_);
@@ -205,8 +217,19 @@ DhtProxyServer::getNodeInfo(const std::shared_ptr<restbed::Session>& session) co
                     if (id)
                         result["id"] = id.toString();
                     result["node_id"] = dht_->getNodeId().toString();
-                    result["ipv4"] = dht_->getNodesStats(AF_INET).toJson();
-                    result["ipv6"] = dht_->getNodesStats(AF_INET6).toJson();
+                    {
+                        std::lock_guard<std::mutex> lck(statsMutex_);
+                        if (ipv4Stats_.good_nodes == 0 && ipv6Stats_.good_nodes == 0) {
+                            // NOTE: we want to avoid the disconnected state as much as possible
+                            // So, if the node is disconnected, we should force the update of the cache
+                            // and reconnect as soon as possible
+                            // This should not happen much
+                            ipv4Stats_ = dht_->getNodesStats(AF_INET);
+                            ipv6Stats_ = dht_->getNodesStats(AF_INET);
+                        }
+                        result["ipv4"] = ipv4Stats_.toJson();
+                        result["ipv6"] = ipv6Stats_.toJson();
+                    }
                     result["public_ip"] = s->get_origin(); // [ipv6:ipv4]:port or ipv4:port
                     Json::StreamWriterBuilder wbuilder;
                     wbuilder["commentStyle"] = "None";