Synapse : Stop download after X secondes
lazarus / 38-Networking and Web Programming

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Mukatai · 2014-03-04 09:09

Hello,

In my project i need to stop a download after X secondes. I use this
code for download the file in Memorystream :

Code: [Select]function DownloadFile(sURL,sLogin,sPass:string;var
OutStr:TMemoryStream) : boolean  ;
var
  HTTPclient: THTTPSend;
begin
  result := false ;
  HTTPclient := THTTPSend.Create ;
  HTTPclient.AddPortNumberToHost := true ;
  HTTPclient.UserName := sLogin ;
  HTTPclient.Password := sPass ;
  if HTTPclient.HTTPMethod('GET',sURL) then
    begin
      showmessage('Fonction start') ;
      if HTTPclient.ResultCode = 200 then
        begin
          HTTPclient.Document.SaveToStream(OutStr);
          result := true ;
        end;
    end ;
  HTTPclient.Free;
end;    

How can I stop the download after X seconds?

Thanks,
@+

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Leledumbo · 2014-03-04 09:45

Use TTimer, set the number of milliseconds in the Interval property.
Fill in OnTimer with the download stopper code. On the other hand, the
normal code can set Enabled to true upon starting download and to
false when it's done.

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Mukatai · 2014-03-04 10:34

thank you for your very fast reply !

I can't use a TTimer because it's an application console. I use this
fonction in web server (FCL) with Threaded:=True. When the client
calls a specific address i download a file from an other HTTP server
and send it. But the user can define the address of second http server
and if he enter an address of flux the download continuous until
memory is full. This is why I want to stop the download after X
seconds...

Do you see any other possibility ? Ideally not create another function
for stop the download...

Thanks

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Cyrax · 2014-03-04 13:08

You may try something like this:

Pseudocode:
Code: [Select]Loop.
   Read N bytes.
  Check if we have downloaded more than X seconds (GetTickCount etc.)
or we have dowloaded whole file.
  If we are, abort loop else continue loop.
  Write N bytes.
End loop.

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Mukatai · 2014-03-04 14:34

This is what I think but I do not know how?

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Leledumbo · 2014-03-04 15:08

QuoteI can't use a TTimer because it's an application
consolehttp://www.freepascal.org/docs-html/fcl/fptimer/index.html

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Fred vS · 2014-03-04 19:58

Quotehttp://www.freepascal.org/docs-html/fcl/fptimer/index.html

Oops, did not know 
@ Leledumbo : many thanks.

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Mukatai · 2014-03-04 20:40

Quote from: Leledumbo on March 04, 2014, 04:08:07 pmQuoteI can't use a
TTimer because it's an application
consolehttp://www.freepascal.org/docs-html/fcl/fptimer/index.html

I did not know this timer, thank you !

After much thought, I was inspired by examples with progress bar. I
created an obejct of HTTPsend with a time variable and a callback
procedure. In this callback i compare the download start date and
abort the HTTPsend procedure when time is up...

Code: [Select]THTTPDownload = class(THTTPSend)
  public
    ExpireTime : TDateTime ;
    constructor create ;
    procedure HTTPCallback(Sender: TObject; Reason: THookSocketReason;
const Value: string);
  end;

//CODE.....


procedure THTTPDownload.HTTPCallback(Sender: TObject; Reason:
THookSocketReason; const Value: string);
var
  DTnow : TDateTime ;
begin
  DTnow := Now ;
  if ExpireTime < DTnow then
    begin
      Abort;
      exit ;
    end;
end;

Constructor THTTPDownload.create ;
begin
  inherited Create ;
  ExpireTime := now + (1.0 / 1440) ;
end; 

function DownloadFile(sURL,sLogin,sPass:string;var
OutStr:TMemoryStream) : boolean  ;
var
  HTTPclient : THTTPDownload ;
begin
  result := false ;
  HTTPclient := THTTPDownload.Create ;
  HTTPclient.AddPortNumberToHost := true ;
  HTTPclient.UserName := sLogin ;
  HTTPclient.Password := sPass ;
  HTTPclient.Sock.OnStatus := @HTTPclient.HTTPCallback ;
  if HTTPclient.HTTPMethod('GET',sURL) then
    begin
        if HTTPclient.ResultCode = 200 then
        begin
          HTTPclient.Document.SaveToStream(OutStr);
          result := true ;
        end;
    end ;
  HTTPclient.Free;
end;  

I have not fully tested, but the few tests performed are good...

What do you think?

Thanks for the support of all member!

@+