Struct BudgetGuard 

pub struct BudgetGuard { /* private fields */ }

RAII guard that automatically releases a budget reservation on drop.

Wraps pre_flight_reserve and release_reservation into a scope-based guard so callers no longer need to track every exit path manually.

On the success path, call release for a clean async release. If release() is never called (early return, ? propagation, panic), the Drop impl spawns a background Tokio task to release the reservation — this is the safety net.

Once AsyncDrop stabilises on stable Rust, the explicit release() method can be removed and the async cleanup will happen transparently.

Example

use stygian_graph::adapters::graphql_throttle::{
    CostThrottleConfig, PluginBudget, BudgetGuard,
};

let budget = PluginBudget::new(CostThrottleConfig::default());
let guard = BudgetGuard::acquire(&budget).await;
// ... send request ...
guard.release().await; // explicit async release on success path

Implementations

impl BudgetGuard

pub async fn acquire(budget: &PluginBudget) -> Self

Acquire a reservation from budget, sleeping if the projected balance is too low.

Returns a guard that will release the reservation when dropped or when release is called.

Example

use stygian_graph::adapters::graphql_throttle::{
    CostThrottleConfig, PluginBudget, BudgetGuard,
};

let budget = PluginBudget::new(CostThrottleConfig::default());
let guard = BudgetGuard::acquire(&budget).await;
// reservation is now held
guard.release().await;

pub fn cost(&self) -> f64

The reserved cost held by this guard.

pub async fn release(self)

Explicitly release the reservation (async, preferred on success path).

After calling this, the guard’s Drop impl becomes a no-op.

Example

use stygian_graph::adapters::graphql_throttle::{
    CostThrottleConfig, PluginBudget, BudgetGuard,
};

let budget = PluginBudget::new(CostThrottleConfig::default());
let guard = BudgetGuard::acquire(&budget).await;
guard.release().await;

Trait Implementations

impl Drop for BudgetGuard

fn drop(&mut self)

Executes the destructor for this type.