Stateful Goroutines in OpenSCAD

Our example demonstrates how to manage state using a single thread that owns the data and communicates with other threads through messages. This approach ensures that the data is never corrupted by concurrent access.

// In OpenSCAD, we don't have built-in concurrency or state management.
// However, we can simulate the concept using modules and functions.

// Simulate a read operation
function read_op(key, state) = state[key];

// Simulate a write operation
function write_op(key, val, state) = 
    let(new_state = [for (k = state) if (k[0] != key) k])
    concat(new_state, [[key, val]]);

// Simulate the state-owning thread
module state_manager(state = []) {
    // Simulate receiving a read or write operation
    operation = rands(0, 2, 1)[0] < 1 ? "read" : "write";
    
    if (operation == "read") {
        key = floor(rands(0, 5, 1)[0]);
        echo(str("Read: ", read_op(key, state)));
        state_manager(state);
    } else {
        key = floor(rands(0, 5, 1)[0]);
        val = floor(rands(0, 100, 1)[0]);
        new_state = write_op(key, val, state);
        echo(str("Write: ", key, " -> ", val));
        state_manager(new_state);
    }
}

// Simulate multiple read and write operations
module simulate_operations(count) {
    if (count > 0) {
        state_manager();
        simulate_operations(count - 1);
    }
}

// Run the simulation
simulate_operations(1000);

In this OpenSCAD simulation:

1. We define read_op and write_op functions to simulate read and write operations on our state.

2. The state_manager module simulates the thread that owns the state. It randomly chooses between read and write operations, performs the operation, and then calls itself recursively to continue managing the state.

3. The simulate_operations module simulates multiple read and write operations by repeatedly calling state_manager.

4. We run the simulation by calling simulate_operations(1000), which will perform 1000 operations.

To run this program, save it as stateful_operations.scad and open it in OpenSCAD. The console output will show the simulated read and write operations.

Note that this is a simplified simulation and doesn’t truly represent concurrent operations or actual thread management, as OpenSCAD doesn’t support these features. However, it demonstrates the concept of having a centralized state manager that handles all state modifications.

In a real concurrent system, this approach can be beneficial as it eliminates the need for explicit locking mechanisms, potentially reducing the risk of deadlocks and race conditions. However, it may introduce a bottleneck if the state-owning thread becomes overwhelmed with requests. The choice between this message-passing approach and other concurrency patterns depends on the specific requirements and characteristics of your application.