Added heartbeat functionality to device update trigger

RGB.NET.Core/Devices/AbstractRGBDeviceProvider.cs

@@ -42,7 +42,7 @@ public abstract class AbstractRGBDeviceProvider : IRGBDeviceProvider
     #endregion
 
     #region Constructors
-        
+
     /// <summary>
     /// Initializes a new instance of the <see cref="AbstractRGBDeviceProvider" /> class.
     /// </summary>
@@ -157,7 +157,6 @@ public abstract class AbstractRGBDeviceProvider : IRGBDeviceProvider
     /// <returns>The newly created update trigger.</returns>
     protected virtual IDeviceUpdateTrigger CreateUpdateTrigger(int id, double updateRateHardLimit) => new DeviceUpdateTrigger(updateRateHardLimit);
 
-
     /// <summary>
     /// Resets the device provider and disposes all devices and update triggers.
     /// </summary>

RGB.NET.Core/Extensions/CustomUpdateDataExtension.cs

@@ -40,4 +40,16 @@ public static class CustomUpdateDataExtension
         customUpdateData[CustomUpdateDataIndex.UPDATE_DEVICES] = value;
         return customUpdateData;
     }
+
+    /// <summary>
+    /// Sets the <see cref="CustomUpdateDataIndex.HEARTBEAT"/>-Parameter to the given value.
+    /// </summary>
+    /// <param name="customUpdateData">The update-data to modify.</param>
+    /// <param name="value">The value to set.</param>
+    /// <returns>The modified update-data.</returns>
+    public static CustomUpdateData Heartbeat(this CustomUpdateData customUpdateData, bool value = true)
+    {
+        customUpdateData[CustomUpdateDataIndex.HEARTBEAT] = value;
+        return customUpdateData;
+    }
 }

RGB.NET.Core/Update/CustomUpdateData.cs

@@ -24,6 +24,11 @@ public static class CustomUpdateDataIndex
     /// default: true
     /// </summary>
     public const string UPDATE_DEVICES = "updateDevices";
+
+    /// <summary>
+    /// Used by <see cref="DeviceUpdateTrigger"/> to indicate heatbeat updates.
+    /// </summary>
+    public const string HEARTBEAT = "heartbeat";
 }
 
 /// <summary>

RGB.NET.Core/Update/Devices/DeviceUpdateTrigger.cs

@@ -1,5 +1,6 @@
 // ReSharper disable MemberCanBePrivate.Global
 
+using System.Diagnostics;
 using System.Threading;
 using System.Threading.Tasks;
 
@@ -52,9 +53,20 @@ public class DeviceUpdateTrigger : AbstractUpdateTrigger, IDeviceUpdateTrigger
         }
     }
 
+    /// <summary>
+    /// Gets or sets the time in ms after which a refresh-request is sent even if no changes are made in the meantime to prevent the target from timing out or similar problems.
+    /// To disable heartbeats leave it at 0.
+    /// </summary>
+    public int HeartbeatTimer { get; set; }
+
     /// <inheritdoc />
     public override double LastUpdateTime { get; protected set; }
 
+    /// <summary>
+    /// Gets or sets the timestamp of the last update.
+    /// </summary>
+    protected long LastUpdateTimestamp { get; set; }
+
     /// <summary>
     /// Gets or sets the event to trigger when new data is available (<see cref="TriggerHasData"/>).
     /// </summary>
@@ -145,6 +157,14 @@ public class DeviceUpdateTrigger : AbstractUpdateTrigger, IDeviceUpdateTrigger
             while (!UpdateToken.IsCancellationRequested)
                 if (HasDataEvent.WaitOne(Timeout))
                     LastUpdateTime = TimerHelper.Execute(() => OnUpdate(), UpdateFrequency * 1000);
+                else if ((HeartbeatTimer > 0) && (LastUpdateTimestamp > 0) && ((Stopwatch.GetTimestamp() - LastUpdateTimestamp) > HeartbeatTimer))
+                    OnUpdate(new CustomUpdateData().Heartbeat());
+    }
+
+    protected override void OnUpdate(CustomUpdateData? updateData = null)
+    {
+        base.OnUpdate(updateData);
+        LastUpdateTimestamp = Stopwatch.GetTimestamp();
     }
 
     /// <inheritdoc />