Struct cumulus_primitives_storage_weight_reclaim::StorageWeightReclaimer

pub struct StorageWeightReclaimer { /* private fields */ }

StorageWeightReclaimer is a mechanism for manually reclaiming storage weight.

It internally keeps track of the proof size and storage weight at initialization time. At reclaim it computes the real consumed storage weight and refunds excess weight.

Example

let mut remaining_weight_meter = WeightMeter::with_limit(Weight::from_parts(10, 10));

let benched_weight = get_benched_weight();

// It is important to instantiate the `StorageWeightReclaimer` before we consume the weight
// for a piece of work from the weight meter.
let mut reclaim_helper = StorageWeightReclaimer::new(&remaining_weight_meter);

if remaining_weight_meter.try_consume(benched_weight).is_ok() {
	// Perform some work that takes has `benched_weight` storage weight.
	do_work();

	// Reclaimer will detect that we only consumed 2 bytes, so 3 bytes are reclaimed.
	let reclaimed = reclaim_helper.reclaim_with_meter(&mut remaining_weight_meter);

	// We reclaimed 3 bytes of storage size!
	assert_eq!(reclaimed, Some(Weight::from_parts(0, 3)));
	assert_eq!(get_storage_weight().total().proof_size(), 10);
	assert_eq!(remaining_weight_meter.remaining(), Weight::from_parts(10, 8));
}

Implementations

impl StorageWeightReclaimer

pub fn new(weight_meter: &WeightMeter) -> StorageWeightReclaimer

Creates a new StorageWeightReclaimer instance and initializes it with the storage size provided by weight_meter and reported proof size from the node.

pub fn reclaim_with_meter( &mut self, weight_meter: &mut WeightMeter, ) -> Option<Weight>

Check the consumed storage weight and add the reclaimed weight budget back to weight_meter.