Lazarus Pascal

Clear the FTP Directory Listing Cache

Demonstrates the Chilkat Ftp2.ClearDirCache method, which clears the cached listing for the current remote directory. It takes no arguments; the next indexed-listing call fetches a fresh listing from the server.

Background: The index-based directory API caches the listing the first time you read it, so repeated accessor calls avoid extra round trips. The trade-off is staleness: if the directory changes — files added or removed, whether by your own operations or another process — the cache still reflects the old state. ClearDirCache discards it so the next GetDirCount queries the server again.

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Lazarus Pascal

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.Ftp2;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  ftp: TFtp2;
  n: Integer;

begin
  success := False;

  //  Demonstrates the Ftp2.ClearDirCache method, which clears the cached listing for the current
  //  remote directory.  It takes no arguments and is a void method.

  ftp := TFtp2.Create;

  ftp.Hostname := 'ftp.example.com';
  ftp.Username := 'myFtpLogin';

  //  Normally you would not hard-code the password in source.  You should instead obtain it
  //  from an interactive prompt, environment variable, or a secrets vault.
  ftp.Password := 'myPassword';

  success := ftp.Connect();
  if (success = False) then
    begin
      WriteLn(ftp.LastErrorText);
      Exit;
    end;

  success := ftp.ChangeRemoteDir('public_html');
  if (success = False) then
    begin
      WriteLn(ftp.LastErrorText);
      Exit;
    end;

  //  The first GetDirCount caches the listing.
  n := ftp.GetDirCount();
  WriteLn('Entries: ' + n);

  //  ... the remote directory changes (files added or removed by another process) ...

  //  Discard the cache so the next listing call fetches fresh data from the server.
  ftp.ClearDirCache();

  n := ftp.GetDirCount();
  WriteLn('Entries after refresh: ' + n);

  success := ftp.Disconnect();
  if (success = False) then
    begin
      WriteLn(ftp.LastErrorText);
      Exit;
    end;


  ftp.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.