How thread safe are delegates?
I’m running some TCP connection code in different thread.
When a certain message is received i would like to call a delegate, but how thread safe are these?
The delegate handlers will spawn actors, remove actors, change actor properties … depending on the received message.
EDIT:
Or would it be better to have a lockable queue on the game instance which process the messages in the tick method?
I don’t know about delegates themselves, but yeah if you’re doing anything involving actors/world, you flat out need to be doing it on the game thread only. You won’t be able to directly invoke a delegate doing anything like that from an external thread.
Pretty sure your edit is the way to go. TQueue is thread-safe and lock free.
Thats great, just checked the information on the TQueue, exactly what i need 
Din’t know there were thread safe / lock-less collection templates available.
Or you could just push it onto the TaskGraph and mention in the Task that it’s only supposed to run on the game thread.
See [FONT=Courier New]TaskGraphInterfaces.h and the comment on line 498-ish:
/**
The user defined task type can take arguments to a constructor. These arguments (unfortunately) must not be references.
The API required of TTask:
class FGenericTask
{
TSomeType SomeArgument;
public:
FGenericTask(TSomeType InSomeArgument) // CAUTION!: Must not use references in the constructor args; use pointers instead if you need by reference
: SomeArgument(InSomeArgument)
{
// Usually the constructor doesn't do anything except save the arguments for use in DoWork or GetDesiredThread.
}
~FGenericTask()
{
// you will be destroyed immediately after you execute. Might as well do cleanup in DoWork, but you could also use a destructor.
}
FORCEINLINE TStatId GetStatId() const
{
RETURN_QUICK_DECLARE_CYCLE_STAT(FGenericTask, STATGROUP_TaskGraphTasks);
}
[static] ENamedThreads::Type GetDesiredThread()
{
return ENamedThreads::[named thread or AnyThread];
}
void DoTask(ENamedThreads::Type CurrentThread, const FGraphEventRef& MyCompletionGraphEvent)
{
// The arguments are useful for setting up other tasks.
// Do work here, probably using SomeArgument.
MyCompletionGraphEvent->DontCompleteUntil(TGraphTask<FSomeChildTask>::CreateTask(NULL,CurrentThread).ConstructAndDispatchWhenReady());
}
};
**/
As mentioned bad things happen if you create actors on any other thread