TIdNotify.Notify() doesn't work when called from TIdTCPServer - delphi

Question

I have a Lazarus console app where I have a simple TIdTCPServer. To be a thread safe app, I added TLog.LogMsg() (which uses TIdNotify).
The problem is, when I call this function from the main thread, the message appears on the console, but when it is called from the OnExecute or OnConnect event of TIdTCPServer, the message is not displayed.
Can you help me with this problem?
program Srv;
{$I Synopse.inc}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes, SysUtils, CustApp, Generics.Collections, IdTCPServer, IdCustomTCPServer, IdContext, IdGlobal, Db, mORMot, mORMotSQLite3, IdSync, functions, SynCommons, SynSQLite3Static;
type
{ TMyApplication }
TMyApplication = class(TCustomApplication)
var IdTCPServer: TIdTCPServer;
protected
procedure DoRun; override;
procedure ServerOnConnect(AContext: TIdContext);
procedure ServerOnExecute(AContext: TIdContext);
public
constructor Create(TheOwner: TComponent); override;
destructor Destroy; override;
end;
type
TLog = class(TIdNotify)
protected
FMsg: string;
procedure DoNotify; override;
public
class procedure LogMsg(const AMsg: string);
end;
{ TMyApplication }
procedure TLog.DoNotify;
var i:integer;
begin
writeln(FMsg);
end;
class procedure TLog.LogMsg(const AMsg: string);
begin
with TLog.Create do
try
FMsg := AMsg;
Notify;
except
Free;
raise;
end;
end;
procedure TMyApplication.ServerOnExecute(AContext: TIdContext);
begin
TLog.LogMsg('test OnExecute'); // the message is not displayed
end;
procedure TMyApplication.ServerOnConnect(AContext: TIdContext);
begin
TLog.LogMsg('connect'); // the message is not displayed
end;
procedure TMyApplication.DoRun;
begin
TLog.LogMsg('test main 1'); //the message is displayed
IdTCPServer := TIdTCPServer.Create;
try
//Server.Name := 'Server';
IdTCPServer.ListenQueue := 15;
IdTCPServer.MaxConnections := 0;
IdTCPServer.TerminateWaitTime := 5000;
IdTCPServer.Bindings.Add.IP := '0.0.0.0';
IdTCPServer.Bindings.Add.Port := 80;
IdTCPServer.Bindings.Add.IPVersion:=Id_IPv4;
IdTCPServer.OnConnect := ServerOnConnect;
// IdTCPServer.OnDisconnect := ServerOnDiconnect;
//Server.OnException := IdTCPServer1Exception;
IdTCPServer.OnExecute := ServerOnExecute;
IdTCPServer.Active := True;
TLog.LogMsg('test main 2'); //the message is displayed
finally
// IdTCPServerCmd.Free;
end;
readln;
// stop program loop
Terminate;
end;
constructor TMyApplication.Create(TheOwner: TComponent);
begin
inherited Create(TheOwner);
StopOnException := True;
end;
destructor TMyApplication.Destroy;
begin
IdTCPServer.Free;
inherited Destroy;
end;
var
Application: TMyApplication;
begin
Application := TMyApplication.Create(nil);
Application.Title := 'My Application';
Application.Run;
Application.Free;
end.

Answer 1

Your main thread does not have a message loop to process TThread.Synchronize()/TThread.Queue() requests. It is blocked on Readln(). Since you are in a console app and not a GUI app, you need to manually call Classes.CheckSynchronize() periodically in the main thread.
On a side note, you are calling IdTCPServer.Bindings.Add() too many times. In your example, you need to call it only 1 time, creating 1 binding that has the 3 property values assigned to it. But instead, you are calling it 3 times, creating 3 separate bindings with 3 separate property settings. It should look more like this instead:
with IdTCPServer.Bindings.Add do
begin
IP := '0.0.0.0';
Port := 80;
IPVersion := Id_IPv4;
end;
Which can be simplified as 0.0.0.0 and Id_IPv4 are already the default values, so they can be omitted from your code. And TIdTCPServer has a DefaultPort property you can use instead. The TIdTCPServer.Active property setter will create its own default bindings if there are none defined explicitly.