Add support for servers to periodically communicate with external services

Source/ACE.Common/GameConfiguration.cs

@@ -35,5 +35,7 @@ public class GameConfiguration
         public bool LandblockPreloading { get; set; }
 
         public List<PreloadedLandblocks> PreloadedLandblocks { get; set; }
+
+        public HeartbeatDefaults Heartbeat { get; set; }
     }
 }

Source/ACE.Common/HeartbeatDefaults.cs

@@ -0,0 +1,28 @@
+using Newtonsoft.Json;
+
+namespace ACE.Common
+{
+    public struct HeartbeatDefaults
+    {
+        /// <summary>
+        /// Whether hearbeats are enabled
+        /// </summary>
+        [System.ComponentModel.DefaultValue(true)]
+        [JsonProperty(DefaultValueHandling = DefaultValueHandling.Populate)]
+        public bool Enabled { get; set; }
+
+        /// <summary>
+        /// The heartbeat endpoint
+        /// </summary>
+        [System.ComponentModel.DefaultValue("https://heartbeat.treestats.net")]
+        [JsonProperty(DefaultValueHandling = DefaultValueHandling.Populate)]
+        public string Endpoint { get; set; }
+
+        /// <summary>
+        /// The heartbeat interval, in seconds
+        /// </summary>
+        [System.ComponentModel.DefaultValue(500)]
+        [JsonProperty(DefaultValueHandling = DefaultValueHandling.Populate)]
+        public int Interval { get; set; }
+    }
+}

Source/ACE.Server/Managers/HeartbeatManager.cs

@@ -0,0 +1,96 @@
+using System;
+
+using log4net;
+
+using ACE.Common.Performance;
+using System.Net.Http;
+using System.Text;
+using ACE.Common;
+using Newtonsoft.Json;
+
+namespace ACE.Server.Managers
+{
+    public static class HeartbeatManager
+    {
+        private static readonly ILog log = LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
+
+        /// <summary>
+        /// The rate at which HeartbeatManager.Tick() executes
+        /// </summary>
+        private static RateLimiter updateHeartbeatManagerRateLimiter;
+
+        /// <summary>
+        /// Endpoint to send heartbeats to
+        /// </summary>
+        private static Uri endpoint;
+
+        public static void Initialize()
+        {
+            //if (!ConfigManager.Config.Server.Heartbeat.Enabled)
+            //{
+            //    log.Debug("Not starting HeartbeatManager because it's disabled in config");
+
+            //    return;
+            //}
+
+            // endpoint = new Uri(ConfigManager.Config.Server.Heartbeat.Endpoint);
+            endpoint = new Uri("https://treestats-servers.herokuapp.com/");
+
+            // updateHeartbeatManagerRateLimiter = new RateLimiter(1, TimeSpan.FromSeconds(ConfigManager.Config.Server.Heartbeat.Interval));
+            updateHeartbeatManagerRateLimiter = new RateLimiter(1, TimeSpan.FromSeconds(10));
+        }
+
+        /// <summary>
+        /// One-off class to help serialize the heartbeat's JSON payload
+        /// </summary>
+        private class HeartbeatPayload
+        {
+            public string WorldName;
+            public int OnlineCount;
+        }
+
+        /// <summary>
+        /// Runs at intervals according to config
+        /// </summary>
+        public static void Tick()
+        {
+
+            if (updateHeartbeatManagerRateLimiter.GetSecondsToWaitBeforeNextEvent() > 0)
+                return;
+
+            log.Debug($"HeartbeatManager.Tick()");
+
+            updateHeartbeatManagerRateLimiter.RegisterEvent();
+            DoHeartbeat();
+        }
+
+        public static void DoHeartbeat()
+        {
+            using (var client = new HttpClient())
+            {
+                HttpResponseMessage response;
+
+                try
+                {
+                    HeartbeatPayload body = new HeartbeatPayload
+                    {
+                        OnlineCount = PlayerManager.GetOnlineCount(),
+                        WorldName = ConfigManager.Config.Server.WorldName
+                    };
+
+                    HttpContent content = new StringContent(JsonConvert.SerializeObject(body));
+                    response = client.PostAsync(endpoint, content).Result;
+
+                    if (!response.IsSuccessStatusCode)
+                    {
+                        log.Debug("Heartbeat Failed: " + response.Content);
+                    }
+                }
+                catch (Exception e)
+                {
+                    log.Debug("Exception while sending Heartbeat: " + e.Message);
+                }
+            }
+        }
+    }
+}

Source/ACE.Server/Managers/WorldManager.cs

@@ -375,6 +375,8 @@ private static void UpdateWorld()
                     Thread.Sleep(sessionCount == 0 ? 10 : 1); // Relax the CPU more if no sessions are connected
 
                 Timers.PortalYearTicks += worldTickTimer.Elapsed.TotalSeconds;
+
+                HeartbeatManager.Tick();
             }
 
             // World has finished operations and concedes the thread to garbage collection

Source/ACE.Server/Program.cs

@@ -196,6 +196,9 @@ public static void Main(string[] args)
             log.Info("Starting PropertyManager...");
             PropertyManager.Initialize();
 
+            log.Info("Starting HeartbeatManager...");
+            HeartbeatManager.Initialize();
+
             log.Info("Initializing GuidManager...");
             GuidManager.Initialize();