rhailib/docs/TRUE_NON_BLOCKING_IMPLEMENTATION.md

# True Non-Blocking Implementation (No rt.block_on)

## Problem with Previous Approach

The issue was using `rt.block_on()` which blocks the spawned thread:

```rust
// THIS BLOCKS THE THREAD:
thread::spawn(move || {
    let rt = Runtime::new().expect("Failed to create runtime");
    rt.block_on(async {  // <-- This blocks!
        // async code here
    });
});
```

## Solution: Use tokio::spawn Instead

Use `tokio::spawn` to run async code without blocking:

```rust
// THIS DOESN'T BLOCK:
tokio::spawn(async move {
    // async code runs in tokio's thread pool
    let client = Client::new();
    match make_stripe_request(&client, &stripe_secret, "payment_intents", &form_data).await {
        Ok(response) => {
            dispatch_response_script(&worker_id, &context_id, "new_create_payment_intent_response", &response).await;
        }
        Err(error) => {
            dispatch_error_script(&worker_id, &context_id, "new_create_payment_intent_error", &error).await;
        }
    }
});
```

## Complete Corrected Implementation

### Payment Intent Function (Corrected)

```rust
#[rhai_fn(name = "create_async", return_raw)]
pub fn create_payment_intent_async(
    intent: &mut RhaiPaymentIntent,
    worker_id: String,
    context_id: String,
    stripe_secret: String
) -> Result<String, Box<EvalAltResult>> {
    let form_data = prepare_payment_intent_data(intent);
    
    // Use tokio::spawn instead of thread::spawn + rt.block_on
    tokio::spawn(async move {
        let client = Client::new();
        match make_stripe_request(&client, &stripe_secret, "payment_intents", &form_data).await {
            Ok(response) => {
                dispatch_response_script(
                    &worker_id, 
                    &context_id, 
                    "new_create_payment_intent_response", 
                    &response
                ).await;
            }
            Err(error) => {
                dispatch_error_script(
                    &worker_id, 
                    &context_id, 
                    "new_create_payment_intent_error", 
                    &error
                ).await;
            }
        }
    });
    
    // Returns immediately - no blocking!
    Ok("payment_intent_request_dispatched".to_string())
}
```

### Product Function (Corrected)

```rust
#[rhai_fn(name = "create_async", return_raw)]
pub fn create_product_async(
    product: &mut RhaiProduct,
    worker_id: String,
    context_id: String,
    stripe_secret: String
) -> Result<String, Box<EvalAltResult>> {
    let form_data = prepare_product_data(product);
    
    tokio::spawn(async move {
        let client = Client::new();
        match make_stripe_request(&client, &stripe_secret, "products", &form_data).await {
            Ok(response) => {
                dispatch_response_script(
                    &worker_id, 
                    &context_id, 
                    "new_create_product_response", 
                    &response
                ).await;
            }
            Err(error) => {
                dispatch_error_script(
                    &worker_id, 
                    &context_id, 
                    "new_create_product_error", 
                    &error
                ).await;
            }
        }
    });
    
    Ok("product_request_dispatched".to_string())
}
```

### Price Function (Corrected)

```rust
#[rhai_fn(name = "create_async", return_raw)]
pub fn create_price_async(
    price: &mut RhaiPrice,
    worker_id: String,
    context_id: String,
    stripe_secret: String
) -> Result<String, Box<EvalAltResult>> {
    let form_data = prepare_price_data(price);
    
    tokio::spawn(async move {
        let client = Client::new();
        match make_stripe_request(&client, &stripe_secret, "prices", &form_data).await {
            Ok(response) => {
                dispatch_response_script(
                    &worker_id, 
                    &context_id, 
                    "new_create_price_response", 
                    &response
                ).await;
            }
            Err(error) => {
                dispatch_error_script(
                    &worker_id, 
                    &context_id, 
                    "new_create_price_error", 
                    &error
                ).await;
            }
        }
    });
    
    Ok("price_request_dispatched".to_string())
}
```

### Subscription Function (Corrected)

```rust
#[rhai_fn(name = "create_async", return_raw)]
pub fn create_subscription_async(
    subscription: &mut RhaiSubscription,
    worker_id: String,
    context_id: String,
    stripe_secret: String
) -> Result<String, Box<EvalAltResult>> {
    let form_data = prepare_subscription_data(subscription);
    
    tokio::spawn(async move {
        let client = Client::new();
        match make_stripe_request(&client, &stripe_secret, "subscriptions", &form_data).await {
            Ok(response) => {
                dispatch_response_script(
                    &worker_id, 
                    &context_id, 
                    "new_create_subscription_response", 
                    &response
                ).await;
            }
            Err(error) => {
                dispatch_error_script(
                    &worker_id, 
                    &context_id, 
                    "new_create_subscription_error", 
                    &error
                ).await;
            }
        }
    });
    
    Ok("subscription_request_dispatched".to_string())
}
```

### Coupon Function (Corrected)

```rust
#[rhai_fn(name = "create_async", return_raw)]
pub fn create_coupon_async(
    coupon: &mut RhaiCoupon,
    worker_id: String,
    context_id: String,
    stripe_secret: String
) -> Result<String, Box<EvalAltResult>> {
    let form_data = prepare_coupon_data(coupon);
    
    tokio::spawn(async move {
        let client = Client::new();
        match make_stripe_request(&client, &stripe_secret, "coupons", &form_data).await {
            Ok(response) => {
                dispatch_response_script(
                    &worker_id, 
                    &context_id, 
                    "new_create_coupon_response", 
                    &response
                ).await;
            }
            Err(error) => {
                dispatch_error_script(
                    &worker_id, 
                    &context_id, 
                    "new_create_coupon_error", 
                    &error
                ).await;
            }
        }
    });
    
    Ok("coupon_request_dispatched".to_string())
}
```

## Helper Functions (Same as Before)

```rust
async fn make_stripe_request(
    client: &Client,
    secret_key: &str,
    endpoint: &str,
    form_data: &HashMap<String, String>
) -> Result<String, String> {
    let url = format!("https://api.stripe.com/v1/{}", endpoint);
    
    let response = client
        .post(&url)
        .basic_auth(secret_key, None::<&str>)
        .form(form_data)
        .send()
        .await
        .map_err(|e| format!("HTTP request failed: {}", e))?;
    
    let response_text = response.text().await
        .map_err(|e| format!("Failed to read response: {}", e))?;
    
    Ok(response_text)
}

async fn dispatch_response_script(
    worker_id: &str,
    context_id: &str,
    script_name: &str,
    response_data: &str
) {
    let script_content = format!(
        r#"
        let response_json = `{}`;
        let parsed_data = parse_json(response_json);
        eval_file("flows/{}.rhai");
        "#,
        response_data.replace('`', r#"\`"#),
        script_name
    );
    
    if let Ok(dispatcher) = RhaiDispatcherBuilder::new()
        .caller_id("stripe")
        .worker_id(worker_id)
        .context_id(context_id)
        .redis_url("redis://127.0.0.1/")
        .build()
    {
        let _ = dispatcher
            .new_play_request()
            .script(&script_content)
            .submit()
            .await;
    }
}

async fn dispatch_error_script(
    worker_id: &str,
    context_id: &str,
    script_name: &str,
    error_data: &str
) {
    let script_content = format!(
        r#"
        let error_json = `{}`;
        let parsed_error = parse_json(error_json);
        eval_file("flows/{}.rhai");
        "#,
        error_data.replace('`', r#"\`"#),
        script_name
    );
    
    if let Ok(dispatcher) = RhaiDispatcherBuilder::new()
        .caller_id("stripe")
        .worker_id(worker_id)
        .context_id(context_id)
        .redis_url("redis://127.0.0.1/")
        .build()
    {
        let _ = dispatcher
            .new_play_request()
            .script(&script_content)
            .submit()
            .await;
    }
}
```

## Key Differences

### Before (Blocking):
```rust
thread::spawn(move || {
    let rt = Runtime::new().expect("Failed to create runtime");
    rt.block_on(async {  // <-- BLOCKS THE THREAD
        // async code
    });
});
```

### After (Non-Blocking):
```rust
tokio::spawn(async move {  // <-- DOESN'T BLOCK
    // async code runs in tokio's thread pool
});
```

## Benefits of tokio::spawn

1. **No Blocking** - Uses tokio's async runtime, doesn't block
2. **Efficient** - Reuses existing tokio thread pool
3. **Lightweight** - No need to create new runtime per request
4. **Scalable** - Can handle many concurrent requests
5. **Simple** - Less code, cleaner implementation

## Usage (Same as Before)

```rhai
let payment_intent = new_payment_intent()
    .amount(2000)
    .currency("usd")
    .customer("cus_customer123");

// This returns immediately, HTTP happens asynchronously
let result = payment_intent.create_async(
    "worker-1",
    "context-123", 
    "sk_test_..."
);

print(`Request dispatched: ${result}`);
// Script ends, but HTTP continues in background
```

## Requirements

Make sure your application is running in a tokio runtime context. If not, you might need to ensure the Rhai engine is running within a tokio runtime.

This implementation provides true non-blocking behavior - the Rhai function returns immediately while the HTTP request and script dispatch happen asynchronously in the background.