Merge pull request #4764 from peppy/fix-unlimited-update-handling

Add better documentation and handling of update rate extremities

osu.Framework/Graphics/Performance/FrameTimeDisplay.cs

···
             elapsedSinceLastUpdate = 0;
 
             counter.Text = $"{displayFps:0}fps ({rollingElapsed:0.00}ms)"
-                           + (clock.Throttling ? $"{(clock.MaximumUpdateHz < 10000 ? clock.MaximumUpdateHz.ToString("0") : "∞").PadLeft(4)}hz" : string.Empty);
+                           + (clock.Throttling ? $"{(clock.MaximumUpdateHz > 0 && clock.MaximumUpdateHz < 10000 ? clock.MaximumUpdateHz.ToString("0") : "∞").PadLeft(4)}hz" : string.Empty);
         }
 
         private class CounterText : SpriteText

osu.Framework/Platform/GameHost.cs

···
 
         private double maximumUpdateHz;
 
+        /// <summary>
+        /// The target number of update frames per second when the game window is active.
+        /// </summary>
+        /// <remarks>
+        /// A value of 0 is treated the same as "unlimited" or <see cref="double.MaxValue"/>.
+        /// </remarks>
         public double MaximumUpdateHz
         {
             get => maximumUpdateHz;
···
 
         private double maximumDrawHz;
 
+        /// <summary>
+        /// The target number of draw frames per second when the game window is active.
+        /// </summary>
+        /// <remarks>
+        /// A value of 0 is treated the same as "unlimited" or <see cref="double.MaxValue"/>.
+        /// </remarks>
         public double MaximumDrawHz
         {
             get => maximumDrawHz;
             set => DrawThread.ActiveHz = maximumDrawHz = value;
         }
 
+        /// <summary>
+        /// The target number of updates per second when the game window is inactive.
+        /// This is applied to all threads.
+        /// </summary>
+        /// <remarks>
+        /// A value of 0 is treated the same as "unlimited" or <see cref="double.MaxValue"/>.
+        /// </remarks>
         public double MaximumInactiveHz
         {
             get => DrawThread.InactiveHz;

osu.Framework/Statistics/PerformanceMonitor.cs

···
 
         private Thread thread;
 
-        public double FrameAimTime => 1000.0 / (Clock?.MaximumUpdateHz ?? double.MaxValue);
+        public double FrameAimTime => 1000.0 / (Clock?.MaximumUpdateHz > 0 ? Clock.MaximumUpdateHz : double.MaxValue);
 
         internal PerformanceMonitor(GameThread thread, IEnumerable<StatisticsCounterType> counters)
         {

osu.Framework/Threading/GameThread.cs

···
         private CultureInfo culture;
 
         /// <summary>
-        /// The refresh rate this thread should run at when active. Only applies when the underlying clock is throttling.
+        /// The target number of updates per second when the game window is active.
         /// </summary>
+        /// <remarks>
+        /// A value of 0 is treated the same as "unlimited" or <see cref="double.MaxValue"/>.
+        /// </remarks>
         public double ActiveHz
         {
             get => activeHz;
···
         private double activeHz = DEFAULT_ACTIVE_HZ;
 
         /// <summary>
-        /// The refresh rate this thread should run at when inactive. Only applies when the underlying clock is throttling.
+        /// The target number of updates per second when the game window is inactive.
         /// </summary>
+        /// <remarks>
+        /// A value of 0 is treated the same as "unlimited" or <see cref="double.MaxValue"/>.
+        /// </remarks>
         public double InactiveHz
         {
             get => inactiveHz;

osu.Framework/Timing/ThrottledFrameClock.cs

···
     public class ThrottledFrameClock : FramedClock
     {
         /// <summary>
-        /// The number of updated per second which is permitted.
+        /// The target number of updates per second. Only used when <see cref="Throttling"/> is <c>true</c>.
         /// </summary>
+        /// <remarks>
+        /// A value of 0 is treated the same as "unlimited" or <see cref="double.MaxValue"/>.
+        /// </remarks>
         public double MaximumUpdateHz = 1000.0;
 
         /// <summary>
-        /// Whether throttling should be enabled. Defaults to true.
+        /// Whether throttling should be enabled. Defaults to <c>true</c>.
         /// </summary>
         public bool Throttling = true;
 
···
 
             if (Throttling)
             {
-                if (MaximumUpdateHz > 0)
+                if (MaximumUpdateHz > 0 && MaximumUpdateHz < double.MaxValue)
                 {
                     throttle();
                 }