目前我正在使用Delphi XE3客户机/服务器应用程序传输文件(使用Indy FTP组件)。客户端部分监视文件夹,获取文件列表,将其上传到服务器并删除原件。上传由一个单独的线程完成,该线程逐个处理文件。这些文件的范围可以从0到几千,它们的大小也会有很大的差异。多线程文件上传同步
这是一个为OSX和Windows编译的Firemonkey应用程序,所以我不得不使用TThread而不是OmniThreadLibrary,我首选。我的客户报告应用程序随机冻结。我不能复制它,但由于我对TThread没有太多的经验,我可能会在某处放置死锁状态。我阅读了很多例子,但我仍然不确定一些多线程细节。
的应用程序结构很简单:
在主线程计时器检查的文件夹,并得到有关每个文件到一个记录,这将进入一个通用信息的TList。此列表保留有关文件名称,大小,进度,文件是否已完全上传或必须重试的信息。所有显示在带有进度条的网格中等。此列表仅由主线程访问。 之后,通过调用AddFile方法(下面的代码)将列表中的项目发送到线程。线程将所有文件存储在如下所示的线程安全队列中http://delphihaven.wordpress.com/2011/05/06/using-tmonitor-2/
上传文件时,上传器线程会通过调用Synchronize来通知主线程。
主线程定期调用Uploader.GetProgress方法来检查当前文件的进度并显示它。这个函数实际上并不是线程安全的,但是会导致死锁,还是只返回错误的数据?
什么是安全有效的方法来进行进度检查?
那么这种方法好还是我错过了什么?你会如何做到这一点?
例如我虽然只是为了读取文件夹内容而创建一个新线程。这意味着我使用的TList必须是线程安全的,但必须始终访问TList以刷新GUI网格中显示的信息。不是所有的同步只会减慢GUI?
我已经发布了下面的简化代码以防万一有人想看它。如果没有,我会很乐意听到一些关于我应该使用的一般意见。主要目标是在OSX和Windows上工作;能够显示有关所有文件和当前进度的信息;并且无论文件的数量和大小如何都会有所反应。
这是上传器线程的代码。我已删除了部分的它更容易阅读:
type
TFileStatus = (fsToBeQueued, fsUploaded, fsQueued);
TFileInfo = record
ID: Integer;
Path: String;
Size: Int64;
UploadedSize: Int64;
Status: TFileStatus;
end;
TUploader = class(TThread)
private
FTP: TIdFTP;
fQueue: TThreadedQueue<TFileInfo>;
fCurrentFile: TFileInfo;
FUploading: Boolean;
procedure ConnectFTP;
function UploadFile(aFileInfo: TFileInfo): String;
procedure OnFTPWork(ASender: TObject; AWorkMode: TWorkMode; AWorkCount: Int64);
procedure SignalComplete;
procedure SignalError(aError: String);
protected
procedure Execute; override;
public
property Uploading: Boolean read FUploading;
constructor Create;
destructor Destroy; override;
procedure Terminate;
procedure AddFile(const aFileInfo: TFileInfo);
function GetProgress: TFileInfo;
end;
procedure TUploader.AddFile(const aFileInfo: TFileInfo);
begin
fQueue.Enqueue(aFileInfo);
end;
procedure TUploader.ConnectFTP;
begin
...
FTP.Connect;
end;
constructor TUploader.Create;
begin
inherited Create(false);
FreeOnTerminate := false;
fQueue := TThreadedQueue<TFileInfo>.Create;
// Create the TIdFTP and set ports and other params
...
end;
destructor TUploader.Destroy;
begin
fQueue.Close;
fQueue.Free;
FTP.Free;
inherited;
end;
// Process the whole queue and inform the main thread of the progress
procedure TUploader.Execute;
var
Temp: TFileInfo;
begin
try
ConnectFTP;
except
on E: Exception do
SignalError(E.Message);
end;
// Use Peek instead of Dequeue, because the item should not be removed from the queue if it fails
while fQueue.Peek(fCurrentFile) = wrSignaled do
try
if UploadFile(fCurrentFile) = '' then
begin
fQueue.Dequeue(Temp); // Delete the item from the queue if succesful
SignalComplete;
end;
except
on E: Exception do
SignalError(E.Message);
end;
end;
// Return the current file's info to the main thread. Used to update the progress indicators
function TUploader.GetProgress: TFileInfo;
begin
Result := fCurrentFile;
end;
// Update the uploaded size for the current file. This information is retrieved by a timer from the main thread to update the progress bar
procedure TUploader.OnFTPWork(ASender: TObject; AWorkMode: TWorkMode; AWorkCount: Int64);
begin
fCurrentFile.UploadedSize := AWorkCount;
end;
procedure TUploader.SignalComplete;
begin
Synchronize(
procedure
begin
frmClientMain.OnCompleteFile(fCurrentFile);
end);
end;
procedure TUploader.SignalError(aError: String);
begin
try
FTP.Disconnect;
except
end;
if fQueue.Closed then
Exit;
Synchronize(
procedure
begin
frmClientMain.OnUploadError(aError);
end);
end;
// Clear the queue and terminate the thread
procedure TUploader.Terminate;
begin
fQueue.Close;
inherited;
end;
function TUploader.UploadFile(aFileInfo: TFileInfo): String;
begin
Result := 'Error';
try
if not FTP.Connected then
ConnectFTP;
FUploading := true;
FTP.Put(aFileInfo.Path, ExtractFileName(aFileInfo.Path));
Result := '';
finally
FUploading := false;
end;
end;
和零件与上传交互的主线程:
......
// Main form
fUniqueID: Integer; // This is a unique number given to each file, because there might be several with the same names(after one is uploaded and deleted)
fUploader: TUploader; // The uploader thread
fFiles: TList<TFileInfo>;
fCurrentFileName: String; // Used to display the progress
function IndexOfFile(aID: Integer): Integer; //Return the index of the record inside the fFiles given the file ID
public
procedure OnCompleteFile(aFileInfo: TFileInfo);
procedure OnUploadError(aError: String);
end;
// This is called by the uploader with Synchronize
procedure TfrmClientMain.OnUploadError(aError: String);
begin
// show and log the error
end;
// This is called by the uploader with Synchronize
procedure TfrmClientMain.OnCompleteFile(aFileInfo: TFileInfo);
var
I: Integer;
begin
I := IndexOfFile(aFileInfo.ID);
if (I >= 0) and (I < fFiles.Count) then
begin
aFileInfo.Status := fsUploaded;
aFileInfo.UploadedSize := aFileInfo.Size;
FFiles.Items[I] := aFileInfo;
Inc(FFilesUploaded);
TFile.Delete(aFileInfo.Path);
colProgressImg.UpdateCell(I);
end;
end;
procedure TfrmClientMain.ProcessFolder;
var
NewFiles: TStringDynArray;
I, J: Integer;
FileInfo: TFileInfo;
begin
// Remove completed files from the list if it contains more than XX files
while FFiles.Count > 1000 do
if FFiles[0].Status = fsUploaded then
begin
Dec(FFilesUploaded);
FFiles.Delete(0);
end else
Break;
NewFiles := TDirectory.GetFiles(WatchFolder, '*.*',TSearchOption.soAllDirectories);
for I := 0 to Length(NewFiles) - 1 do
begin
FileInfo.ID := FUniqueID;
Inc(FUniqueID);
FileInfo.Path := NewFiles[I];
FileInfo.Size := GetFileSizeByName(NewFiles[I]);
FileInfo.UploadedSize := 0;
FileInfo.Status := fsToBeQueued;
FFiles.Add(FileInfo);
if (I mod 100) = 0 then
begin
UpdateStatusLabel;
grFiles.RowCount := FFiles.Count;
Application.ProcessMessages;
if fUploader = nil then
break;
end;
end;
// Send the new files and resend failed to the uploader thread
for I := 0 to FFiles.Count - 1 do
if (FFiles[I].Status = fsToBeQueued) then
begin
if fUploader = nil then
Break;
FileInfo := FFiles[I];
FileInfo.Status := fsQueued;
FFiles[I] := FileInfo;
SaveDebug(1, 'Add: ' + ExtractFileName(FFiles[I].Path));
FUploader.AddFile(FFiles[I]);
end;
end;
procedure TfrmClientMain.tmrGUITimer(Sender: TObject);
var
FileInfo: TFileInfo;
I: Integer;
begin
if (fUploader = nil) or not fUploader.Uploading then
Exit;
FileInfo := fUploader.GetProgress;
I := IndexOfFile(FileInfo.ID);
if (I >= 0) and (I < fFiles.Count) then
begin
fFiles.Items[I] := FileInfo;
fCurrentFileName := ExtractFileName(FileInfo.Path);
colProgressImg.UpdateCell(I);
end;
end;
function TfrmClientMain.IndexOfFile(aID: Integer): Integer;
var
I: Integer;
begin
Result := -1;
for I := 0 to FFiles.Count - 1 do
if FFiles[I].ID = aID then
Exit(I);
end;
我不确定,但没有测试..但你尝试添加TIdAntiFreeze,并检查行为是否相同? (FMX.IdAntiFreeze) – Whiler
TIdAntiFreeze设计用于防止在主线程中使用Indy组件(例如,放在表单上)时冻结GUI。我在一个单独的线程中使用它,所以我不明白它会有什么帮助。至少据我所知... – VGeorgiev
第一次看,你的错误处理看起来不对我。例如,在Execute方法中,如果ConnectFTP调用失败,则会异常(在通知有关错误之后),并且仍然发出对UploadFile的调用。恕我直言,你必须清理它,并让线程在FatalException中死掉,或者正确处理Execute方法中的异常,例如重试连接多次,这可能取决于错误的类型。另一方面,如果你在主线程中有一个列表,我看不出为什么你需要在单个线程中有一个队列。 – jachguate