refactor: download limiter

src/Starward/Pages/Setting/DownloadSettingPage.xaml

@@ -85,6 +85,7 @@
                         Spacing="12">
                 <NumberBox MinWidth="100"
                            Minimum="0"
+                           Maximum="2097151"
                            Value="{x:Bind SpeedLimit, Mode=TwoWay}" />
                 <TextBlock VerticalAlignment="Center" Text="KB/s" />
             </StackPanel>

src/Starward/Pages/Setting/DownloadSettingPage.xaml.cs

@@ -5,6 +5,7 @@
 using Starward.Services.Download;
 using System;
 using System.IO;
+using System.Threading.RateLimiting;
 using System.Threading.Tasks;
 using Windows.Storage;
 using Windows.System;
@@ -69,7 +70,15 @@ partial void OnDefaultInstallPathChanged(string? value)
     private int speedLimit = AppConfig.SpeedLimitKBPerSecond;
     partial void OnSpeedLimitChanged(int value)
     {
-        InstallGameManager.SpeedLimitBytesPerSecond = value == 0 ? long.MaxValue : value * 1024;
+        InstallGameManager.SpeedLimitBytesPerSecond = value <= 0 ? int.MaxValue : value * 1024;
+        InstallGameManager.rateLimiter = new TokenBucketRateLimiter(new TokenBucketRateLimiterOptions
+        {
+            TokensPerPeriod = InstallGameManager.SpeedLimitBytesPerPeriod,
+            ReplenishmentPeriod = InstallGameManager.SpeedLimitReplenishmentPeriod,
+            TokenLimit = InstallGameManager.SpeedLimitBytesPerPeriod,
+            QueueProcessingOrder = QueueProcessingOrder.OldestFirst,
+            AutoReplenishment = true
+        });
         AppConfig.SpeedLimitKBPerSecond = value;
     }
 

src/Starward/Services/Download/InstallGameManager.cs

@@ -6,7 +6,7 @@
 using System.Collections.Concurrent;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
-using System.Threading;
+using System.Threading.RateLimiting;
 
 namespace Starward.Services.Download;
 
@@ -20,8 +20,15 @@ internal class InstallGameManager
     private InstallGameManager()
     {
         _services = new();
-        long speed = AppConfig.SpeedLimitKBPerSecond * 1024;
-        SpeedLimitBytesPerSecond = speed == 0 ? long.MaxValue : speed;
+        int speed = AppConfig.SpeedLimitKBPerSecond * 1024;
+        rateLimiter = new TokenBucketRateLimiter(new TokenBucketRateLimiterOptions
+        {
+            TokensPerPeriod = SpeedLimitBytesPerPeriod,
+            ReplenishmentPeriod = SpeedLimitReplenishmentPeriod,
+            TokenLimit = SpeedLimitBytesPerPeriod,
+            QueueProcessingOrder = QueueProcessingOrder.OldestFirst,
+            AutoReplenishment = true
+        });
     }
 
 
@@ -33,10 +40,18 @@ private InstallGameManager()
     public static long DownloadBytesInSecond;
 
 
-    public static long SpeedLimitBytesPerSecond { get; set; }
+    public static int SpeedLimitBytesPerSecond { get; set; }
+
+
+    public static int SpeedLimitBytesPerPeriod => Math.Max((int)Math.Floor((double)SpeedLimitBytesPerSecond / 40), 1 << 14);
+
+
+    // 25: 将每秒切割为上面的40份，间隔越小速度越精准。
+    // 因为buffer较小，间隔极小的话请求令牌的速度将大于补充令牌逻辑运行的时间，导致无论限速多少实际速度只会在1MB/s左右。
+    public static TimeSpan SpeedLimitReplenishmentPeriod => SpeedLimitBytesPerPeriod == 1 << 14 ? TimeSpan.FromSeconds((1 << 14) / (double)SpeedLimitBytesPerSecond) : TimeSpan.FromMilliseconds(25);
 
 
-    public static bool IsExceedSpeedLimit => Interlocked.Read(ref DownloadBytesInSecond) >= SpeedLimitBytesPerSecond;
+    public static TokenBucketRateLimiter rateLimiter;
 
 
     private long _lastTimeStamp;

src/Starward/Services/Download/InstallGameService.cs

@@ -21,6 +21,7 @@
 using System.Text;
 using System.Text.Json.Nodes;
 using System.Threading;
+using System.Threading.RateLimiting;
 using System.Threading.Tasks;
 using Vanara.PInvoke;
 
@@ -1203,14 +1204,16 @@ protected async Task DownloadItemAsync(InstallGameItem item, CancellationToken c
                 int length;
                 while ((length = await hs.ReadAsync(buffer, cancellationToken).ConfigureAwait(false)) != 0)
                 {
+                    RateLimitLease lease;
+                    if (InstallGameManager.SpeedLimitBytesPerSecond != int.MaxValue)
+                        do
+                        {
+                            lease = await InstallGameManager.rateLimiter.AcquireAsync(length, cancellationToken).ConfigureAwait(false);
+                            if (!lease.IsAcquired)
+                                await Task.Delay(1, cancellationToken).ConfigureAwait(false);
+                        } while (!lease.IsAcquired);
                     await fs.WriteAsync(buffer.AsMemory(0, length), cancellationToken).ConfigureAwait(false);
                     Interlocked.Add(ref _finishBytes, length);
-                    Interlocked.Add(ref InstallGameManager.DownloadBytesInSecond, length);
-                    if (InstallGameManager.IsExceedSpeedLimit)
-                    {
-                        long t = Stopwatch.GetTimestamp() / (Stopwatch.Frequency / 1000) % 1000;
-                        await Task.Delay((int)(1000 - t), cancellationToken);
-                    }
                 }
             }
         }

src/Starward/Starward.csproj

@@ -43,6 +43,7 @@
 		<PackageReference Include="Serilog.Sinks.File" Version="6.0.0" />
 		<PackageReference Include="Starward.Assets" Version="0.4.13" />
 		<PackageReference Include="Starward.NativeLib" Version="0.2.1" />
+		<PackageReference Include="System.Threading.RateLimiting" Version="8.0.0" />
 		<PackageReference Include="Vanara.PInvoke.ComCtl32" Version="4.0.2" />
 		<PackageReference Include="Vanara.PInvoke.DwmApi" Version="4.0.2" />
 		<PackageReference Include="Vanara.PInvoke.Ole" Version="4.0.2" />