Indy TIdHTTPServer and safe multithread behavior

[hrayon]

I want to increment the value of a global variable securely, but the increment routine is within the OnCommandGet method of the object of type TIdHTTPServer. The correct way would be to use the TCriticalSection variable?
See the pseudo-code:

Code: Pascal  [Select][+][-]

1. ...
2. g_TCriticalSection_Flag: TCriticalSection;
3. g_integer_counter: Integer;
4. ...
5. On Start Daemon
6.    g_TCriticalSection_Flag: = TCriticalSection.Create;
7.    g_integer_counter: = 0;
8. End On Start Daemon
9.  
10. OnCommandGet
11.    Try
12.       g_TCriticalSection_Flag.Enter;
13.       g_integer_counter: = g_integer_counter + 1;
14.    Finally
15.       g_TCriticalSection_Flag.Leave;
16.    End
17. End OnCommandGet
18.  
19. On Stop Daemon
20.     g_TCriticalSection_Flag.Free;
21. End On Stop Daemon
22.  

[Remy Lebeau]

I want to increment the value of a global variable securely, but the increment routine is within the OnCommandGet method of the object of type TIdHTTPServer. The correct way would be to use the TCriticalSection variable?

That is one way to do it.  And Indy even have a TIdThreadSafeInteger class for that very purpose:

Code: Pascal  [Select][+][-]

1. uses
2.   ..., IdThreadSafe;
3.  
4. g_integer_counter: TIdThreadSafeInteger;
5.  
6. On Start Daemon
7.    g_integer_counter := TIdThreadSafeInteger.Create;
8. End On Start Daemon
9.  
10. OnCommandGet
11.   g_integer_counter.Increment;
12. End OnCommandGet
13.  
14. On Stop Daemon
15.   g_integer_counter.Free;
16. End On Stop Daemon
17.  

On the other hand, if you don't want the overhead of a critical section, you can use atomic APIs instead, like System.InterlockedIncrement():

Code: Pascal  [Select][+][-]

1. g_integer_counter: Longint;
2.  
3. On Start Daemon
4.    g_integer_counter := 0;
5. End On Start Daemon
6.  
7. OnCommandGet
8.   InterLockedIncrement(g_integer_counter);
9. End OnCommandGet
10.