private void Thread_Failed(object sender, ThreadExitedArgs e)
{
bool isRaiseFailed = false;
lock (this._syncRoot)
{
if (e.WorkID != this._workID)
{
return; // 这次操作已经过期
}
if (this._status != DownloaderStatuses.Downloading)
{
return; // 只有Downloading状态才可能变为Failed状态
}
this.RefreshWorkID();
this._status = DownloaderStatuses.Failed;
this._progressTimer.Dispose();
this._progressTimer = null;
this.ClearThread();
this.CacheConfig();// 保存文件配置以便以后继续下载
this._sourceProvider = null;
this._writer.Dispose();
this._writer = null;
isRaiseFailed = true;
}// lock
if (isRaiseFailed)
{
this.OnFailed();
}
}
/// <summary>
/// 暂停，可以调用Start继续下载
/// </summary>
public void Pause()
{
lock (this._syncRoot)
{
if (this._status != DownloaderStatuses.Downloading)
{
return;
}
this._status = DownloaderStatuses.Paused;
// 刷新WorkID
this.RefreshWorkID();
this._progressTimer.Dispose();
this._progressTimer = null;
this.ClearThread();
// 缓存配置文件
this.CacheConfig();
// 清空SourceProvider
this._sourceProvider = null;
// 释放Writer
this._writer.Dispose();
this._writer = null;
}// lock
this.OnPaused();
}
public SegmentThread(int id, LocalFileWriter writer, SourceProvider sourceProvider, long workID)
{
this._id = id;
this._writer = writer;
this._sourceProvider = sourceProvider;
this._status = SegmentThreadStatuses.Idle;
this._workID = workID;
}
private void Thread_Completed(object sender, ThreadExitedArgs e)
{
bool isRaiseCompleted = false;
lock (this._syncRoot)
{
if (e.WorkID != this._workID)
{
return; // 这次操作已经过期
}
if (this._status != DownloaderStatuses.Downloading)
{
return; // 只有Downloading状态才可能变为Failed状态
}
if (!this._writer.IsCompleted())
{
return; // 文件下载还没有完成
}
this.RefreshWorkID();
this._status = DownloaderStatuses.Completed;
this._progressTimer.Dispose();
this._progressTimer = null;
this.ClearThread();
this._sourceProvider = null;
this._writer.Dispose();
this._writer = null;
if (File.Exists(this._savePath))
{
File.Delete(this._savePath);
}
File.Move(this._tmpPath, this._savePath);
if (File.Exists(this._configPath))
{
File.Delete(this._configPath);
}
isRaiseCompleted = true;
}// lock
if (isRaiseCompleted)
{
this.OnCompleted();
}
}
/// <summary>
/// 取消，会删除已经下载的文件
/// </summary>
public void Cancel()
{
lock (this._syncRoot)
{
if (this._status == DownloaderStatuses.Completed)
{
return; // 如果已经下载完成则Cancel无效
}
if (this._status == DownloaderStatuses.Cancelled)
{
return; // 如果已经取消了，则不能重复操作
}
if (this._status == DownloaderStatuses.Downloading)
{
// 刷新WorkID
this.RefreshWorkID();
this._progressTimer.Dispose();
this._progressTimer = null;
this.ClearThread();
// 清空SourceProvider
this._sourceProvider = null;
// 释放Writer
this._writer.Dispose();
this._writer = null;
}// if
this._status = DownloaderStatuses.Cancelled;
// 删除临时文件
if (File.Exists(this._tmpPath))
{
File.Delete(this._tmpPath);
}
// 删除配置文件
if (File.Exists(this._configPath))
{
File.Delete(this._configPath);
}
}// lock
this.OnCancelled();
}
/// <summary>
/// 开始下载
/// </summary>
public async void Start()
{
long workID;
SourceProvider sourceProvider;
lock (this._syncRoot)
{
if (this._status == DownloaderStatuses.Downloading)
{
throw new Exception("Downloader is working.");
}
if (this._status == DownloaderStatuses.Completed)
{
throw new Exception("Downloader is completed.");
}
this._status = DownloaderStatuses.Downloading; // 设置Downloader状态
// 生成新的workID
workID = this.RefreshWorkID();
// 重置SourceProvider
var protocalProvider = new HttpProtocalProvider();
var mirrorSelector = new SequentialMirrorSelector();
mirrorSelector.Initialize(this._config.MainSource, this._config.Mirrors);
sourceProvider = new SourceProvider(mirrorSelector, protocalProvider);
this._sourceProvider = sourceProvider;
}// lock
// 初始化SourceProvider
await sourceProvider.InitializeAsync(CancellationToken.None);
lock (this._syncRoot)
{
// 检测当前操作是否过期
if (workID != this._workID)
{
return;
}
var newRemoteFileInfo = this._sourceProvider.GetRemoteFileInfo();
// 对文件进行分片
List <LocalSegment> segments = new List <LocalSegment>();
if (this._config.HasSegment &&
this._config.RemoteInfo != null &&
RemoteFileInfo.IsSameFile(this._config.RemoteInfo, newRemoteFileInfo))
{
// 如果文件已经分片,服务器文件信息与缓存的文件信息一致则用缓存的文件分片
segments.AddRange(this._config.Segments);
}
// 如果没有分片或则缓存的文件已经过时了则重新分片
if (segments.Count == 0)
{
if (newRemoteFileInfo.IsAcceptRange)// 如果文件支持分段下载
{
var calculateSegments = this._segmentCalculator.GetSegments(this._maxThreadCount, newRemoteFileInfo);
foreach (var calculateSegment in calculateSegments)
{
segments.Add(new LocalSegment
{
StartPosition = calculateSegment.StartPosition,
EndPosition = calculateSegment.EndPosition
});
}
}
else// 如果文件不支持分段下载
{
if (newRemoteFileInfo.Size <= 0)
{
throw new Exception(string.Format("Remote file size invalid, size: {0}.", newRemoteFileInfo.Size));
}
// 整个文件只有一个片段
segments.Add(new LocalSegment
{
StartPosition = 0,
EndPosition = newRemoteFileInfo.Size - 1
});
// 设置最大线程数为1
this._maxThreadCount = 1;
} // else
} // if
// 创建LocalFileWriter
this._writer = new LocalFileWriter(this._tmpPath, segments, this._cacheLength);
this._writer.CreateFile();
// 缓存文件配置
this.CacheConfig();
// 创建下载线程
this._threads = new List <SegmentThread>();
for (int i = 0; i < this._maxThreadCount; i++)
{
var thread = new SegmentThread(i + 1, this._writer, this._sourceProvider, workID);
thread.Completed += Thread_Completed;
thread.Failed += Thread_Failed;
this._threads.Add(thread);
}
// 启动下载线程
foreach (var thread in this._threads)
{
thread.Start();
}
this._lastProgressChangeTime = DateTime.Now;
this._lastDownloadedSize = this._writer.GetDownloadedSize();
this._progressTimer = new Timer(ProgressTimer_Callback, workID, ProgressTimerInterval, Timeout.Infinite);
}// lock
this.OnStarted();
}