[ROOT] Carrot cache

From: Dubois, Richard (richard@SLAC.stanford.edu)
Date: Thu Sep 05 2002 - 06:59:52 MEST 

 I am running into reproducability problems which I think is coming from not clearing the Carrot cache. Here is a sample simple  macro:

Bool_t gApacheExec=1;
//Bool_t gApacheNoCache=kTRUE;

void version_plot3()
{

  TApache ap;
  ap.SetNoCache();
  // Number of points stored in n 
  int n = 7;
  TCanvas* myCanvas = new TCanvas("myCanvas","A Simple Graph-Plotting Example",200,10,700,500); 

  
  myCanvas->SetFillColor(42);
  myCanvas->GetFrame()->SetFillColor(21);
  myCanvas->GetFrame()->SetBorderSize(12);
  myCanvas->GetFrame()->SetBorderMode(-1);
  
  // For the graph
  Double_t x[100], y[100];
  ap.Printf("n %i \n",n);

  for (Int_t i=0; i<n;i++) { 
      x[i] = i;
      y[i] = 2*i;     
  }
      

  gr = new TGraph(n, x, y);
  gr->SetTitle("Test CPU Time vs Version Number");
  gr->Draw("ACP");
  myCanvas->Update();
  myCanvas->GetFrame()->SetFillColor(21);
  myCanvas->GetFrame()->SetBorderSize(12);
  gr->GetHistogram()->SetXTitle("Version Number");
  gr->GetHistogram()->SetYTitle("CPU (secs)");

  myCanvas->Modified();

  ap.Put(myCanvas); 


}// end of version_plot3

and output in my browser window:

n 7 HTTP/1.1 200 OK Date: Thu, 05 Sep 2002 04:51:51 GMT Server: Apache/1.3.23 (Unix) Carrot-1.0.7 Last-Modified: Thu, 05 Sep 2002 04:51:51 GMT ETag: W/"58115-3b8-3d76e2e7" Cache-Control: no-cache,must-revalidate Pragma: no-cache Expires: -1 Keep-Alive: timeout=15, max=99 Connection: Keep-Alive, Keep-Alive Transfer-Encoding: chunked, chunked Content-Type: image/jpeg ÿØÿàJFIFHHÿÛC    -  $.' ",#( ---- plus lots more crap here!
 For some reason, the browser is not seeing the canvas/plot as a jpeg and is dumping the graphics to the screen. However in some cases, if I just keep refreshing the browser, the plot will come up. I tried this macro in straight Root with no TApache stuff and it worked fine. And I've had other macros which exhibit this weird refresh behaviour. Sometimes they will spontaneously work and sometimes not.

 I've tried setting SetNoCache, both via the gApache variable and my TApache ap. Only the latter puts something in the header about no cache. But neither seems to get the job done

 The other thing I don't understand from the how to avoid cache problems url is how to add (if I need to) the random query to a TApache::Put, specifically ap.Put(myCanvas).


Thanks!

Richard
--
Richard Dubois
Stanford Linear Accelerator Center
650-926-3824
650-926-8616 (FAX)
richard@slac.stanford.edu
http://www.slac.stanford.edu/~richard

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