Source Code TCriticalSection Threrad Example Delphi

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TCriticalSection Threrad Example Delphi
Ivan Revelli - 15/May/2020

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Example on how to user a critical section in Delphi:

Delphi/Pascal

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TThreadedMsgEvent = class( TThread ) private FLock : TCriticalSection; FStr : TQueue<String>; FMemo : TMemo; function GetEvent : String; protected procedure Execute; override; public procedure AddEvent( aMsg : String ); constructor Create( AMemo: TMemo ); destructor Destroy; override; end; implementation { TThreadedMsgEvent } procedure TThreadedMsgEvent.AddEvent(aMsg: String); begin FLock.Acquire; FStr.Enqueue( FormatDateTime('DD/MM/YY HH:NN:SS.ZZZ',Now)+ ' : '+ aMsg ); FLock.Release; end; constructor TThreadedMsgEvent.Create(aMemo: TMemo); begin inherited Create(True); FreeOnTerminate := False; FOnMessage := ACallBack; FStr := TQueue<String>.Create(); FLock := TCriticalSection.Create; FMemo := aMemo; Resume; end; destructor TThreadedMsgEvent.Destroy; override; begin FreeAndNil( FStr ); FreeAndNil( FLock ); end; procedure TThreadedMsgEvent.Execute; begin while not Terminated do begin try if (FStr.Count > 0) then begin if Assigned( aMemo ) then begin TThread.synchronize( procedure begin FMemo.Lines.Add( GetEvent ); end; ); end; end; except end; TThread.Sleep(1); end; end; function TThreadedMsgEvent.GetEvent: String; begin FLock.Acquire; result := FStr.Dequeue; FLock.Release; end;

From post found at: https://stackoverflow.com/questions/17506615/how-to-handle-log-in-a-threaded-manner-in-delphi

In short:
How to handle Log in a Threaded manner in Delphi
Active 6 years, 10 months ago - Viewed 3k times

Delphi XE2
I have a form with a TMemo that I want to show what is going on in several services started by the application.
What I have running:

• idHTTPServer running with idContext responding to requests
• a Thread downloading updates from Dropbox
• idUDPServer responding to UDP requests
• another thread taking care of some database stuff.
• the main application thread also needed to add log

Basically, I need to know how to create a standard, unified, thread safe way to channel the log messages to my TMemo and keep the user updated of what is going on.
....


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[Eddie1331]

"Hey, I just threw together a simple example of a critical section in Delpi. Not sure if it's the most elegant solution, but it should give you an idea of how it works: https://pastebin.com/9rK4XvYd Let me know if you have any questions about it."

 

[andrjuha777]

"Hey OP, I just tried the example you posted and it works great for small threads. However, I did experience some performance issues with a high number of threads competing for the lock. Does anyone else have any experience optimizing TCriticalSection performance?"

 

[weektor]

"Hey OP, I've got some experience with threading in Delphi. Check out the Indy components, they have some great stuff for synchronizing threads. Specifically, the TCriticalSection component can help you achieve the functionality you're looking for."

 

[Verg]

Not an expert on Delphi, but I've used similar threading libraries on other platforms. Can you tell me more about what you're trying to achieve with a critical section in your thread implementation? Maybe we can brainstorm a solution or find an example online.