2.12.3

2026-03-08 20:56:13 +08:00
parent 2bffafcd7a
commit be67c4ccc2
27 changed files with 3090 additions and 1722 deletions
@@ -1,5 +1,4 @@
-Imports System.Net.Http.Headers
-Imports System.Net.Sockets
+Imports System.Net.Sockets
 Imports System.Runtime.CompilerServices
 Imports System.Threading.Tasks

@@ -248,7 +247,7 @@ RequestFinished:
            SecretHeadersSign(Url, Request, SimulateBrowserHeaders)
            'DNS 解析
            CancelToken = New CancellationTokenSource(Timeout)
-            HostIp = DNSLookup(Request, CancelToken)
+            HostIp = DNSLookup(Request, CancelToken.Token)
            If HostIp IsNot Nothing AndAlso Not IPReliability.ContainsKey(HostIp) Then
                IPReliability(HostIp) = -0.01 '预先降低一点，这样快速的重复请求会使用不同的 IP 以提高成功率
            End If
@@ -263,11 +262,12 @@ RequestFinished:
                End If
            End SyncLock
            Response = RequestClient.SendAsync(Request, HttpCompletionOption.ResponseHeadersRead, CancelToken.Token).GetResultWithTimeout(CancelToken, Timeout)
-            Dim ResponseStream = Response.Content.ReadAsStreamAsync().GetAwaiter().GetResult()
            Dim ResponseBytes As Byte()
-            Using Stream As New MemoryStream
-                ResponseStream.CopyToAsync(Stream, 81920, CancelToken.Token).GetResultWithTimeout(CancelToken, Timeout)
-                ResponseBytes = Stream.ToArray()
+            Using ResponseStream = Response.Content.ReadAsStreamAsync().GetResultWithTimeout(CancelToken, Timeout)
+                Using Stream As New MemoryStream
+                    ResponseStream.CopyToAsync(Stream, 81920, CancelToken.Token).GetResultWithTimeout(CancelToken, Timeout)
+                    ResponseBytes = Stream.ToArray()
+                End Using
            End Using
            '输出
            If Response.IsSuccessStatusCode Then
@@ -304,10 +304,9 @@ RequestFinished:

    ''' <summary>
    ''' 进行 DNS 解析。它仅在选择的 IP 与系统默认的不一致时才对 URL 中的 Host 进行替换。
-    ''' 返回请求时应使用的 IP；若为 IPv6，则加上了方括号。
-    ''' 若解析失败，则返回 Nothing。
+    ''' 返回请求时应使用的 IP。若解析失败，则返回 Nothing。
    ''' </summary>
-    Private Function DNSLookup(Request As HttpRequestMessage, CancelToken As CancellationTokenSource) As String
+    Private Function DNSLookup(Request As HttpRequestMessage, CancelToken As CancellationToken) As String
        '若一分钟内已失败过，则不再重复尝试解析，以减少断网时的 Exception 数量
        Dim Host = Request.RequestUri.Host
        SyncLock DNSFailureRecord.SyncRoot
@@ -320,43 +319,36 @@ RequestFinished:
            End If
        End SyncLock
        '初步 DNS 解析
-        Dim DnsTask As Task(Of IPAddress()) = Nothing
+        Dim Candidates As IPAddress()
        Try
-            DnsTask = Dns.GetHostAddressesAsync(Host)
-            DnsTask.Wait(CancelToken.Token)
+            Dim AsyncResult = Dns.BeginGetHostAddresses(Host, Nothing, Nothing)
+            If WaitHandle.WaitAny(New WaitHandle() {AsyncResult.AsyncWaitHandle, CancelToken.WaitHandle}) Then Throw New TimeoutException("DNS 解析超时")
+            Candidates = Dns.EndGetHostAddresses(AsyncResult).Distinct.ToArray
        Catch ex As Exception
            Log(ex, $"DNS 解析失败（{Host}）")
            DNSFailureRecord(Host) = Date.Now
            Return Nothing
        End Try
-        Dim Candidates As IPAddress() = DnsTask.Result.ToArray
        If Not Candidates.Any Then
            Log($"[Net] DNS 解析无结果（{Host}）")
            Return Nothing
        End If
        '若同时存在 IPv4 和 IPv6 地址，仅选择其中一类（因为 GFW 可能只屏蔽了 IPv4 或 IPv6）
-        Dim GetIPReliability = Function(Key) IPReliability.GetOrDefault(Key.ToString, 0)
+        Dim Reliabilities = Candidates.ToDictionary(Function(i) i, Function(i) IPReliability.GetOrDefault(i.ToString, 0))
        Dim IPv4Targets = Candidates.Where(Function(i) i.AddressFamily = AddressFamily.InterNetwork).ToArray
        Dim IPv6Targets = Candidates.Where(Function(i) i.AddressFamily = AddressFamily.InterNetworkV6).ToArray
        If IPv4Targets.Any AndAlso IPv6Targets.Any Then
-            Dim IPv4Reliability = IPv4Targets.Average(Function(i) GetIPReliability(i))
-            Dim IPv6Reliability = IPv6Targets.Average(Function(i) GetIPReliability(i))
+            Dim IPv4Reliability = IPv4Targets.Max(Function(i) Reliabilities(i))
+            Dim IPv6Reliability = IPv6Targets.Max(Function(i) Reliabilities(i))
            If Host = "api.modrinth.com" Then IPv6Reliability -= 0.1 '让 Modrinth 优先使用 IPv4 地址（#6887）
+            If ModeDebug Then Log($"[Net] DNS IPv4/IPv6 选择（{Host}），IPv4 {IPv4Reliability:0.000}，IPv6 {IPv6Reliability:0.000}")
            Candidates = If(IPv4Reliability >= IPv6Reliability, IPv4Targets, IPv6Targets)
        End If
        '选择可靠度最高的 IP
-        Dim MaxReliability As Double = Candidates.Max(Function(i) GetIPReliability(i))
-        Dim Target As IPAddress = Candidates.First(Function(i) GetIPReliability(i) = MaxReliability)
-        Dim TargetIp As String = If(Target.AddressFamily = AddressFamily.InterNetworkV6, $"[{Target}]", Target.ToString)
-        If Target IsNot Candidates.First Then
-            '优选结果与系统默认 IP 不一致，替换域名并设置 Host 头
-            If ModeDebug Then Log($"[Net] DNS 解析结果：{Host} → {Target}，所有可能的 IP 与可靠度：{DnsTask.Result.Select(Function(i) $"{i} → {GetIPReliability(i):0.000}").Join("；")}")
-            Request.Headers.Host = Host
-            Dim Builder As New UriBuilder(Request.RequestUri)
-            Builder.Host = TargetIp
-            Request.RequestUri = Builder.Uri
-        End If
-        Return TargetIp
+        Dim Target As IPAddress = Candidates.MaxBy(Function(i) Reliabilities(i))
+        Request.Headers.Host = Request.RequestUri.Authority
+        Request.RequestUri = (New UriBuilder(Request.RequestUri) With {.Host = If(Target.AddressFamily = AddressFamily.InterNetworkV6, $"[{Target}]", Target.ToString)}).Uri
+        Return Target.ToString
    End Function
    Private DNSFailureRecord As New SafeDictionary(Of String, Date)
    ''' <summary>
@@ -369,8 +361,10 @@ RequestFinished:
    ''' </summary>
    Private Sub RecordIPReliability(IP As String, Result As Double)
        If IP Is Nothing Then Return
-        If Not IPReliability.ContainsKey(IP) Then IPReliability(IP) = 0
-        IPReliability(IP) = (IPReliability(IP) + Result) / 2
+        SyncLock IPReliability.SyncRoot
+            If Not IPReliability.ContainsKey(IP) Then IPReliability(IP) = 0
+            IPReliability(IP) = (IPReliability(IP) + Result) / 2
+        End SyncLock
    End Sub

    ''' <summary>
@@ -418,12 +412,10 @@ RequestFinished:
    ''' 基于限速，当前可以下载的剩余量。
    ''' </summary>
    Public NetTaskSpeedLimitLeft As Long = -1
-    Private ReadOnly NetTaskSpeedLimitLeftLock As New Object
    ''' <summary>
    ''' 正在运行中的线程数。
    ''' </summary>
    Public NetTaskThreadCount As Integer = 0
-    Private ReadOnly NetTaskThreadCountLock As New Object

    ''' <summary>
    ''' 下载源。
@@ -760,7 +752,6 @@ RequestFinished:
        ''' 文件的已下载大小。
        ''' </summary>
        Public DownloadDone As Long = 0
-        Private ReadOnly LockDone As New Object
        ''' <summary>
        ''' 文件的校验规则。
        ''' </summary>
@@ -840,14 +831,12 @@ RequestFinished:
        ''' </summary>
        Private ReadOnly Property ConnectAverage As Integer
            Get
-                SyncLock LockCount
-                    Return If(ConnectCount = 0, -1, ConnectTime / ConnectCount)
-                End SyncLock
+                Dim CurrentConnectCount As Integer = ConnectCount '防止竞态条件
+                Return If(CurrentConnectCount = 0, -1, ConnectTime / CurrentConnectCount)
            End Get
        End Property

        Private Const FilePieceLimit As Long = 256 * 1024
-        Public ReadOnly LockCount As New Object
        Public ReadOnly LockState As New Object
        Public ReadOnly LockChain As New Object
        Public ReadOnly LockSource As New Object
@@ -929,7 +918,7 @@ StartSingleThreadDownload:
                    If Source Is Nothing Then Return Nothing
                    Dim TargetUrl As String = Source.Url
                    If TargetUrl.Contains("pcl2-server") OrElse TargetUrl.Contains("bmclapi") OrElse TargetUrl.Contains("github.com") OrElse
-                       TargetUrl.Contains("optifine.net") OrElse TargetUrl.Contains("modrinth") OrElse TargetUrl.Contains("momot.rs") Then Return Nothing
+                       TargetUrl.Contains("optifine.net") OrElse TargetUrl.Contains("momot.rs") Then Return Nothing
                    '寻找最大碎片
                    'FUTURE: 下载引擎重做，计算下载源平均链接时间和线程下载速度，按最高时间节省来开启多线程
                    Dim FilePieceMax As NetThread = Threads
@@ -962,9 +951,7 @@ StartThread:

                End SyncLock
                '开始线程
-                SyncLock NetTaskThreadCountLock
-                    NetTaskThreadCount += 1
-                End SyncLock
+                Interlocked.Increment(NetTaskThreadCount)
                SyncLock LockSource
                    If Not HasAvailableSource(False) Then SourcesOnce.First.SingleThread = ThreadInfo
                End SyncLock
@@ -986,7 +973,7 @@ StartThread:
                CancelToken As CancellationTokenSource = Nothing, HostIp As String = Nothing
            '部分下载源真的特别慢，并且只需要一个请求，例如 Ping 为 20s，如果增长太慢，就会造成类似 2.5s 5s 7.5s 10s 12.5s... 的极大延迟
            '延迟过长会导致某些特别慢的链接迟迟不被掐死
-            Dim Timeout As Integer = Math.Min(Math.Max(ConnectAverage, 10000) * (1 + Th.Source.FailCount), 30000)
+            Dim Timeout As Integer = Math.Min(Math.Max(ConnectAverage, 15000) * (1 + Th.Source.FailCount), 30000)
            Th.State = NetState.Connecting
            Try
                Dim HttpDataCount As Integer = 0
@@ -994,8 +981,8 @@ StartThread:
                HttpRequest = New HttpRequestMessage(HttpMethod.Get, Th.Source.Url)
                SecretHeadersSign(Th.Source.Url, HttpRequest, SimulateBrowserHeaders)
                CancelToken = New CancellationTokenSource(Timeout)
-                HostIp = DNSLookup(HttpRequest, CancelToken) 'DNS 预解析
-                If Not Th.IsFirstThread Then HttpRequest.Headers.Range = New RangeHeaderValue(Th.DownloadStart, Nothing)
+                HostIp = DNSLookup(HttpRequest, CancelToken.Token) 'DNS 预解析
+                If Not Th.IsFirstThread Then HttpRequest.Headers.Range = New Headers.RangeHeaderValue(Th.DownloadStart, Nothing)
                Dim ContentLength As Long = 0
                Response = ThreadClient.SendAsync(HttpRequest, HttpCompletionOption.ResponseHeadersRead, CancelToken.Token).GetResultWithTimeout(CancelToken, Timeout)
                If Not Response.IsSuccessStatusCode Then Throw New Exception($"错误码 {Response.StatusCode} ({CInt(Response.StatusCode)})，{Th.Source.Url}") '状态码检查
@@ -1032,7 +1019,7 @@ StartThread:
                            Dim DriveName As String = Drive.Name.First.ToString
                            Dim RequiredSpace = If(PathTemp.StartsWithF(DriveName), ContentLength * 1.1, 0) +
                                                If(LocalPath.StartsWithF(DriveName), ContentLength + 5 * 1024 * 1024, 0)
-                            If Drive.TotalFreeSpace < RequiredSpace Then
+                            If RequiredSpace > 0 AndAlso Drive.TotalFreeSpace < RequiredSpace Then
                                Throw New Exception(DriveName & " 盘空间不足，无法进行下载。" & vbCrLf & "需要至少 " & GetString(RequiredSpace) & " 空间，但当前仅剩余 " & GetString(Drive.TotalFreeSpace) & "。" &
                                                    If(PathTemp.StartsWithF(DriveName), vbCrLf & vbCrLf & "下载时需要与文件同等大小的空间存放缓存，你可以在设置中调整缓存文件夹的位置。", ""))
                            End If
@@ -1040,7 +1027,7 @@ StartThread:
                    End If
                ElseIf FileSize < 0 Then
                    Throw New Exception("非首线程运行时，尚未获取文件大小")
-                ElseIf Th.DownloadStart > 0 AndAlso ContentLength = FileSize Then
+                ElseIf Th.DownloadStart > 0 AndAlso ContentLength >= FileSize Then
 NotSupportRange:
                    SyncLock LockSource
                        If SourcesOnce.Contains(Th.Source) Then GoTo SourceBreak
@@ -1076,11 +1063,9 @@ NotSupportRange:
                        Threading.Thread.Sleep(16)
                    End While
                    Dim RealDataCount As Integer = If(IsUnknownSize, HttpDataCount, Math.Min(HttpDataCount, Th.DownloadUndone))
-                    SyncLock NetTaskSpeedLimitLeftLock
-                        If NetTaskSpeedLimitHigh > 0 Then NetTaskSpeedLimitLeft -= RealDataCount
-                    End SyncLock
+                    If NetTaskSpeedLimitHigh > 0 Then Interlocked.Add(NetTaskSpeedLimitLeft, -RealDataCount)
                    Dim DeltaTime = GetTimeMs() - Th.LastReceiveTime
-                    If DeltaTime > 1000000 Then DeltaTime = 1 '避免时间刻反转导致出现极大值
+                    If DeltaTime > 100000000 Then DeltaTime = 1 '避免时间刻反转导致出现极大值
                    If RealDataCount > 0 Then
                        '有数据
                        If Th.DownloadDone = 0 Then
@@ -1089,27 +1074,21 @@ NotSupportRange:
                            SyncLock LockState
                                If State < NetState.Downloading Then State = NetState.Downloading
                            End SyncLock
-                            SyncLock LockCount
-                                ConnectCount += 1
-                                ConnectTime += GetTimeMs() - Th.InitTime
-                            End SyncLock
+                            Interlocked.Increment(ConnectCount)
+                            Interlocked.Add(ConnectTime, GetTimeMs() - Th.InitTime)
                        End If
-                        SyncLock LockCount
-                            Th.Source.FailCount = 0
-                            For Each Task In Tasks
-                                Task.FailCount = 0
-                            Next
-                        End SyncLock
-                        NetManager.DownloadDone += RealDataCount
-                        SyncLock LockDone
-                            DownloadDone += RealDataCount
-                        End SyncLock
+                        Th.Source.FailCount = 0
+                        For Each Task In Tasks
+                            Task.FailCount = 0
+                        Next
+                        Interlocked.Add(NetManager.DownloadDone, RealDataCount)
+                        Interlocked.Add(DownloadDone, RealDataCount)
                        Th.DownloadDone += RealDataCount
                        ResultStream.Write(ResponseBytes, 0, RealDataCount)
                        '已完成
                        If Th.DownloadUndone = 0 AndAlso Not IsUnknownSize Then Exit While
                        '检查速度是否过慢
-                        If DeltaTime > 5000 AndAlso DeltaTime > RealDataCount AndAlso '数据包间隔大于 5s，且速度小于 1K/s
+                        If Th.LastReceiveTime > 0 AndAlso DeltaTime > 5000 AndAlso DeltaTime > RealDataCount AndAlso '数据包间隔大于 5s，且速度小于 1K/s
                                    Th.Source.SingleThread Is Nothing Then '且并非单线程下载
                            Throw New TimeoutException("由于速度过慢断开链接，下载 " & RealDataCount & " B，消耗 " & DeltaTime & " ms。")
                        End If
@@ -1147,9 +1126,7 @@ SourceBreak:
                CancelToken?.Dispose()
                If Not IsNoSplit Then ResultStream?.Dispose()
                '改变计数
-                SyncLock NetTaskThreadCountLock
-                    NetTaskThreadCount -= 1
-                End SyncLock
+                Interlocked.Decrement(NetTaskThreadCount)
                '合并
                If ((FileSize >= 0 AndAlso DownloadDone >= FileSize) OrElse (FileSize = -1 AndAlso DownloadDone > 0)) AndAlso
                    State < NetState.Merging AndAlso Th.State <> NetState.Interrupted Then Merge(Th)
@@ -1157,12 +1134,10 @@ SourceBreak:
        End Sub
        Private Sub SourceFail(Th As NetThread, ex As Exception, IsMergeFailure As Boolean)
            '状态变更
-            SyncLock LockCount
-                Th.Source.FailCount += 1
-                For Each Task In Tasks
-                    Task.FailCount += 1
-                Next
-            End SyncLock
+            Interlocked.Increment(Th.Source.FailCount)
+            For Each Task In Tasks
+                Interlocked.Increment(Task.FailCount)
+            Next
            Th.State = NetState.Interrupted
            Th.Source.Ex = ex
            '根据情况判断，是否在多线程下禁用下载源（连续错误过多，或不支持断点续传）
@@ -1241,10 +1216,8 @@ SourceBreak:
            SyncLock LockChain
                Threads = Nothing
            End SyncLock
-            NetManager.DownloadDone -= DownloadDone
-            SyncLock LockDone
-                DownloadDone = 0
-            End SyncLock
+            Interlocked.Add(NetManager.DownloadDone, -DownloadDone)
+            DownloadDone = 0
            SpeedLastDone = 0
        End Sub

@@ -1271,7 +1244,7 @@ Retry:
                SyncLock LockChain
                    '合并文件
                    If IsNoSplit Then
-                        '仅有一个线程，从缓存中输出
+                        '仅有一个线程，从内存中输出
                        If ModeDebug Then Log($"[Download] {LocalName}：下载结束，从内存输出文件")
                        Cache.Position = 0
                        WriteFile(LocalPath, Cache)
@@ -1321,6 +1294,7 @@ Retry:
                End SyncLock
            Catch ex As Exception
                RetryCount += 1
+                If State > NetState.Merging Then Return '通常是因为在合并时被中断了
                Log(ex, $"合并文件出错，第 {RetryCount} 次尝试（{LocalName}）")
                '重新尝试合并
                If RetryCount < 3 Then
@@ -1372,9 +1346,7 @@ Retry:
        Private Sub AbortInternal()
            On Error Resume Next
            Reset()
-            SyncLock NetManager.LockRemain
-                NetManager.FileRemain -= 1
-            End SyncLock
+            Interlocked.Decrement(NetManager.FileRemain)
        End Sub

        '状态改变接口
@@ -1386,9 +1358,7 @@ Retry:
                If State >= NetState.Finished Then Return
                State = NetState.Finished
            End SyncLock
-            SyncLock NetManager.LockRemain
-                NetManager.FileRemain -= 1
-            End SyncLock
+            Interlocked.Decrement(NetManager.FileRemain)
            If PrintLog Then Log($"[Download] {LocalName}：已完成")
            For Each Task In Tasks
                Task.OnFileFinish(Me)
@@ -1522,8 +1492,8 @@ FinishExCatch:
                        If File.LocalPath.EndsWithF("\") Then Throw New ArgumentException("请输入含文件名的完整文件路径：" & File.LocalPath)
                        Directory.CreateDirectory(GetPathFromFullPath(File.LocalPath)) '创建目标文件夹
                    Next
-                    '接入下载管理器
-                    NetManager.Start(Me)
+                    '接入下载管理器，获取新开始下载的文件列表
+                    Dim NewFiles = NetManager.Start(Me)

                    '====================================
                    ' 已存在文件查找
@@ -1531,9 +1501,8 @@ FinishExCatch:

                    '整理允许进行查找的文件
                    Dim FilesToCheck As New List(Of NetFile)
-                    Dim DisabledCopy As Boolean = Setup.Get("SystemDebugSkipCopy") '在设置中禁用了复制
-                    For Each File In Files
-                        If Not DisabledCopy AndAlso File.Check?.CanUseExistsFile Then
+                    For Each File In NewFiles
+                        If File.Check?.CanUseExistsFile Then
                            FilesToCheck.Add(File)
                        Else '不允许，直接开始下载
                            SyncLock LockState
@@ -1570,7 +1539,7 @@ FinishExCatch:
        End Sub
        Private Sub CheckExistingFiles(Files As List(Of NetFile), FolderList As List(Of String))
            Try
-                If ModeDebug Then Log($"[Download] 文件检查线程已启动，分配的文件数：{Files.Count}")
+                If ModeDebug Then Log($"[Download] 文件检查开始，本线程负责的文件数：{Files.Count}")
                '列出 MC 文件夹中的各个版本文件夹
                Dim VersionFolders As New List(Of String)
                For Each McFolder In FolderList
@@ -1584,7 +1553,7 @@ FinishExCatch:
                '处理每个文件
                For Each File As NetFile In Files
                    Dim Target As String = CheckExistingFile(FolderList, VersionFolders, File)
-                    If File.State >= NetState.WaitingToDownload Then Return '中断
+                    If File.State >= NetState.WaitingToDownload Then Continue For '中断
                    '已找到相同文件
                    If Target IsNot Nothing Then
                        File.IsCopy = True
@@ -1594,6 +1563,8 @@ Retry:
                            If Target <> File.LocalPath Then
                                Log($"[Download] 复制已存在的文件：{Target} → {File.LocalPath}")
                                CopyFile(Target, File.LocalPath)
+                            Else
+                                If ModeDebug Then Log($"[Download] 需要下载的文件已存在，并通过校验：{Target}")
                            End If
                            File.Finish(False)
                            Continue For
@@ -1619,6 +1590,8 @@ Retry:
        Private Function CheckExistingFile(FolderList As List(Of String), VersionFolders As List(Of String), File As NetFile) As String
            '目标文件已存在
            If File.Check.Check(File.LocalPath) Is Nothing Then Return File.LocalPath
+            '在设置中禁用了复制
+            If Setup.Get("SystemDebugSkipCopy") Then Return Nothing
            '没有可用的检查规则，只能开始下载
            If File.Check.Hash Is Nothing AndAlso File.Check.ActualSize < 0 Then Return Nothing
            '大致判断文件类别
@@ -1633,7 +1606,7 @@ Retry:
                    Return Nothing
                End If
            End If
-            Dim Type = TypeIndexes.MaxOf(Function(kv) kv.Item2).FolderName.TrimStart("\"c)
+            Dim Type = TypeIndexes.MaxBy(Function(kv) kv.Item2).FolderName.TrimStart("\"c)
            '根据类别进行查找
            Static Sizes As New SafeDictionary(Of String, Long)
            Select Case Type
@@ -1757,8 +1730,7 @@ Retry:
        ''' <summary>
        ''' 需要下载的文件。为“本地地址 - 文件对象”键值对。
        ''' </summary>
-        Public Files As New Dictionary(Of String, NetFile)
-        Public ReadOnly LockFiles As New Object
+        Public AllFiles As New SafeDictionary(Of String, NetFile)

        ''' <summary>
        ''' 当前的所有下载任务。
@@ -1768,25 +1740,12 @@ Retry:
        ''' <summary>
        ''' 已下载完成的大小。
        ''' </summary>
-        Public Property DownloadDone As Long
-            Get
-                Return _DownloadDone
-            End Get
-            Set(value As Long)
-                SyncLock LockDone
-                    _DownloadDone = value
-                End SyncLock
-            End Set
-        End Property
-        Private _DownloadDone As Long = 0
-        Private ReadOnly LockDone As New Object
-
+        Public DownloadDone As Long = 0

        ''' <summary>
        ''' 尚未完成下载的文件数。
        ''' </summary>
        Public FileRemain As Integer = 0
-        Public ReadOnly LockRemain As New Object

        '这些属性由 RefreshStat 刷新
        ''' <summary>
@@ -1855,9 +1814,9 @@ Retry:
                        Thread.Sleep(20)
                        '获取文件列表
                        Dim AllFiles As List(Of NetFile)
-                        SyncLock LockFiles
-                            If Id = 0 AndAlso FileRemain = 0 AndAlso Files.Any() Then Files.Clear() '若已完成，则清空
-                            AllFiles = Files.Values.ToList()
+                        SyncLock Me.AllFiles.SyncRoot
+                            If Id = 0 AndAlso FileRemain = 0 AndAlso Me.AllFiles.Any() Then Me.AllFiles.Clear() '若已完成，则清空
+                            AllFiles = Me.AllFiles.Values.ToList()
                        End SyncLock
                        Dim WaitingFiles As New List(Of NetFile)
                        Dim OngoingFiles As New List(Of NetFile)
@@ -1865,7 +1824,7 @@ Retry:
                            If File.Uuid Mod 2 = Id Then Continue For
                            If File.State = NetState.WaitingToDownload Then
                                WaitingFiles.Add(File)
-                            ElseIf File.State < NetState.Merging Then
+                            ElseIf File.State < NetState.Merging AndAlso File.State >= NetState.WaitingToDownload Then
                                OngoingFiles.Add(File)
                            End If
                        Next
@@ -1908,7 +1867,7 @@ Retry:
                    Dim NextTick As Long = GetTimeMs()
                    While True
                        '增加限速余量
-                        If NetTaskSpeedLimitHigh > 0 Then NetTaskSpeedLimitLeft = NetTaskSpeedLimitHigh / 10
+                        If NetTaskSpeedLimitHigh > 0 Then Interlocked.Add(NetTaskSpeedLimitLeft, CLng(NetTaskSpeedLimitHigh / 10))
                        '刷新公开属性
                        RefreshStat()
                        '等待 100 ms
@@ -1931,7 +1890,7 @@ Retry:
        ''' <summary>
        ''' 开始一个下载任务。
        ''' </summary>
-        Public Sub Start(Task As LoaderDownload)
+        Public Function Start(Task As LoaderDownload) As List(Of NetFile)
            StartManager()
            '清理缓存
            SyncLock DownloadCacheLock '防止同时开启多个下载任务时重复清理
@@ -1943,45 +1902,30 @@ Retry:
                    Catch ex As Exception
                        Log(ex, "清理下载缓存失败")
                    End Try
+                    IsDownloadCacheCleared = True
                End If
-                IsDownloadCacheCleared = True
-            End SyncLock
-            '文件处理
-            SyncLock LockFiles
-                '添加每个文件
-                For i = 0 To Task.Files.Count - 1
-                    Dim File = Task.Files(i)
-                    If Files.ContainsKey(File.LocalPath) Then
-                        '已有该文件
-                        If Files(File.LocalPath).State >= NetState.Finished Then
-                            '该文件已经下载过一次，且下载完成
-                            '将已下载的文件替换成当前文件，重新下载
-                            File.Tasks.Add(Task)
-                            Files(File.LocalPath) = File
-                            SyncLock LockRemain
-                                FileRemain += 1
-                            End SyncLock
-                            If ModeDebug Then Log($"[Download] {File.LocalName}：重新加入下载列表，目标 {File.LocalPath}")
-                        Else
-                            '该文件正在下载中
-                            '将当前文件替换成下载中的文件，即两个任务指向同一个文件
-                            File = Files(File.LocalPath)
-                            File.Tasks.Add(Task)
-                        End If
-                    Else
-                        '没有该文件
-                        File.Tasks.Add(Task)
-                        Files.Add(File.LocalPath, File)
-                        SyncLock LockRemain
-                            FileRemain += 1
-                        End SyncLock
-                        If ModeDebug Then Log($"[Download] {File.LocalName}：已加入下载列表，目标 {File.LocalPath}")
-                    End If
-                    Task.Files(i) = File '回设
-                Next
            End SyncLock
+            '添加每个文件
+            Dim NewFiles As New List(Of NetFile)
+            For i = 0 To Task.Files.Count - 1
+                Dim File As NetFile = Task.Files(i)
+                If AllFiles.ContainsKey(File.LocalPath) AndAlso AllFiles(File.LocalPath).State < NetState.Finished Then
+                    '该文件正在被另一个任务下载
+                    If ModeDebug Then Log($"[Download] {File.LocalName}：无需开始，该文件已在下载中，目标 {File.LocalPath}")
+                    File = AllFiles(File.LocalPath) '将列表中的文件替换成下载中的文件，即两个任务指向同一个文件；抛弃现在的 File 对象
+                    Task.Files(i) = File
+                Else
+                    '常规情况（该文件可能已在其他任务中下载完成，但这并不影响）
+                    If ModeDebug Then Log($"[Download] {File.LocalName}：开始，目标 {File.LocalPath}")
+                    AllFiles(File.LocalPath) = File
+                    NewFiles.Add(File)
+                    Interlocked.Increment(FileRemain)
+                End If
+                File.Tasks.Add(Task)
+            Next
            Tasks.Add(Task)
-        End Sub
+            Return NewFiles
+        End Function

    End Class