Stateful Goroutines in UnrealScript

In this example, we'll explore how to manage state using a dedicated actor in UnrealScript. This approach aligns with UnrealScript's object-oriented nature and event-driven programming model.

```unrealscript
class StatefulActor extends Actor;

var private Map_Int_To_Int State;
var private int ReadOps;
var private int WriteOps;

event PostBeginPlay()
{
    super.PostBeginPlay();
    State = new class'Map_Int_To_Int';
    SetTimer(1.0, false, 'ReportOperations');
}

function ReadState(int Key, out int Value)
{
    Value = State.Get(Key);
    ReadOps++;
}

function WriteState(int Key, int Value)
{
    State.Set(Key, Value);
    WriteOps++;
}

function ReportOperations()
{
    `Log("ReadOps:" @ ReadOps);
    `Log("WriteOps:" @ WriteOps);
}

In this UnrealScript example, we create a StatefulActor class that manages the state. The state is stored in a private Map_Int_To_Int variable, which is similar to a map in other languages.

We use two functions, ReadState and WriteState, to access and modify the state. These functions also increment counters for read and write operations.

To simulate concurrent access, we can create multiple instances of another actor class that repeatedly calls these functions:

class StateAccessor extends Actor;

var StatefulActor StateManager;

event PostBeginPlay()
{
    super.PostBeginPlay();
    SetTimer(0.001, true, 'PerformOperations');
}

function PerformOperations()
{
    local int Key, Value;

    Key = Rand(5);
    
    if (FRand() < 0.9) // 90% chance of read
    {
        StateManager.ReadState(Key, Value);
    }
    else // 10% chance of write
    {
        Value = Rand(100);
        StateManager.WriteState(Key, Value);
    }
}

In the level blueprint or in another script, you would spawn one StatefulActor and multiple StateAccessor actors:

var StatefulActor StateManager;
var array<StateAccessor> Accessors;

function SpawnActors()
{
    local int i;
    local StateAccessor Accessor;

    StateManager = Spawn(class'StatefulActor');

    for (i = 0; i < 100; i++)
    {
        Accessor = Spawn(class'StateAccessor');
        Accessor.StateManager = StateManager;
        Accessors.AddItem(Accessor);
    }
}

This setup allows multiple StateAccessor instances to concurrently access the state managed by a single StatefulActor. The StatefulActor reports the number of read and write operations after one second.

While this approach doesn’t use explicit locks or channels as in the original example, it achieves a similar result by centralizing state management in a single actor and allowing other actors to interact with it. This aligns with UnrealScript’s event-driven nature and provides a thread-safe way to manage shared state in the context of Unreal Engine’s single-threaded gameplay logic.

Remember that actual concurrency in UnrealScript is limited, as the engine runs game logic in a single thread. However, this pattern can be useful for managing shared state among multiple actors in a clean and centralized manner.