DBMonitor & Dll issue - no log

[Louarn]

Hello all,

I have an issue with my dll and DB monitor since we upgrade our component to the 9.3.6 version.
Previously, we were in 8.3.11, and currently using delphi xe3.

Here is the pb: we have a application which call a DLL.
The application SQL is logged fine in DB Monitor, but not the SQL from de DLL.

In the dll, we have deactivated the SQL Monitor (removing the TOraSqlMonitor.create)

You will says: "hey dude, this is the fu*k !".

Well, in fact, yes and no.

When we have the "TOraSqlMonitor.create" in the dll, the loading of the dll hangs and never get back.
I am pretty sure that this is due to this line of code, in DBMonitorClient.pas:

Code: Select all

     constructor TEventSendThread.Create(DBMonitor: TDBMonitor);
     begin
       inherited Create(True);
     
       FConnectEvent := TEvent.Create(nil, True, False, '');
       FEndEvent := TEvent.Create(nil, True, False, '');
     {$IFDEF CLR}
       Handle.IsBackGround := True;
     {$ENDIF}
       FDBMonitor := DBMonitor;
     
       Resume;
       if IsLibrary then
--->     FConnectEvent.WaitFor(INFINITE);
     end;

I do not have the source code of the version 8.3.11 (or previous) of this file, but this line of code seems to be here at least since te revision 8.6.12.

Has anyone have the history of this file, or encounter this kind of issue ?

[AlexP]

Hello,

Try to reproduce the problem on the latest ODAC version 9.3.10. If the problem repeats, please send us a sample reproducing the problem to alexp*devart*com.

[Louarn]

Hello Alex,

I have send you a mail with the source code.
In fact, very simple: just try to load a dll with a sql monitor in it.
This hangs.

App. code:

Code: Select all

unit Unit2;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;

type
  TForm2 = class(TForm)
    Button1: TButton;
    Edit1: TEdit;
    Label1: TLabel;
    procedure Button1Click(Sender: TObject);
  private
    { Déclarations privées }
  public
    { Déclarations publiques }
  end;

var
  Form2       : TForm2;
  DllHandle   : THandle;
implementation

{$R *.dfm}

procedure TForm2.Button1Click(Sender: TObject);
begin
  try
    DllHandle := LoadLibrary (Pchar(Edit1.Text));
  except
   ShowMessage(SysErrorMessage(GetLastError));
  end;
end;

end.

Dll dpr code:

Code: Select all

library MyDll;
uses
  System.SysUtils,
  System.Classes,
  orasqlmonitor;

{$R *.res}
var  gorasqlmonitor : TOrasqlmonitor;

begin
  //gorasqlmonitor := TOraSqlMonitor.create(nil);
end.

If you uncomment the TOraSqlMonitor.create(nil), the application will hang when loading the dll.

Hope this can help you finding the issue !

[AlexP]

Thank you for the information. We have reproduced the problem and will investigate the reasons of such behavior.

[Louarn]

Ok, nice to see that I am not alone with this pb.

Please keep me in touch if you find a solution !

Thanks.

[AlexP]

We will inform you as soon as we have any results.

[Louarn]

Hello,

Is there any news on this issue ?
I mean, if a correction has been identified or planned ?

Thanks !

[AlexP]

We have investigated the problem more deeply and found out that, when dll is loading, the OS doesn't run other threads (and SQLMonitor uses threads), and we can't know whether the DLL was loaded or not.

[Louarn]

Hello Alex,

Do you mean that this issue will not meet a solution ?

[AlexP]

You should create ToraSQLMonitor in a separate method, and call this method after DLL is loaded.

Code: Select all

program MainProject;

{$APPTYPE CONSOLE}

uses
  SysUtils, Windows;
type
  TCreateOraSQLMonitor = procedure;stdcall;
var
   DllHandle: THandle;
   CreateOraSQLMonitor: TCreateOraSQLMonitor;
begin
  try
    DllHandle := LoadLibrary (Pchar('DllProject.dll'));
    CreateOraSQLMonitor := GetProcAddress(DllHandle, 'CreateOraSQLMonitor');
    CreateOraSQLMonitor;
  except
   Writeln(SysErrorMessage(GetLastError));
  end;
  readln;
end.

Code: Select all

library DllProject;

uses
  SysUtils,
  Classes,
  orasqlmonitor, DBMonitorClient, Ora;

{$R *.res}
var
  gorasqlmonitor : TOrasqlmonitor;

procedure CreateOraSQLMonitor;
begin
  gorasqlmonitor := TOrasqlmonitor.Create(nil);
end;

exports
  CreateOraSQLMonitor;

begin
end.

[Louarn]

Thanks AlexP, I will try and revert if it is Ko.

Don't be afraid, I will revert also if it is fine !

[Louarn]

Hello AlexP,

Seems to be fine with this way of doing.
Calling in the application a method of the dll in order to start the Sql Monitor is ok !

Thanks.

[AlexP]

Hello,

Glad to see that the issue was resolved. If you have any further questions, feel free to contact us.