Account for items weight in pallet parameters

prdoc/pr_6477.prdoc

@@ -0,0 +1,16 @@
+# Schema: Polkadot SDK PRDoc Schema (prdoc) v1.0.0
+# See doc at https://raw.githubusercontent.com/paritytech/polkadot-sdk/master/prdoc/schema_user.json
+
+title: Account for parameters weight
+
+doc:
+  - audience: Runtime Dev
+    description: |
+      This PR addresses potential discrepancies in weight measurement by accounting for all parameters at block initialization.
+      It introduces a mechanism to account for the weight (both `ref_time` and `proof_size`) of all parameters at the start of each block.
+      This is necessary to account for parameters that might be accessed in scenarios not covered by benchmarking.
+      An example could be the parameter usage within the `OnChargeTransaction` of the `pallet_transaction_payment`.
+
+crates:
+- name: pallet-parameters
+  bump: minor

substrate/frame/parameters/Cargo.toml

@@ -18,6 +18,7 @@ frame-support = { features = ["experimental"], workspace = true }
 frame-system = { workspace = true }
 sp-core = { workspace = true }
 sp-runtime = { workspace = true }
+cumulus-primitives-storage-weight-reclaim = { workspace = true, default-features = false}
 frame-benchmarking = { optional = true, workspace = true }
 
 [dev-dependencies]
@@ -37,6 +38,7 @@ std = [
 	"serde",
 	"sp-core/std",
 	"sp-runtime/std",
+	"cumulus-primitives-storage-weight-reclaim/std",
 ]
 runtime-benchmarks = [
 	"frame-benchmarking/runtime-benchmarks",

substrate/frame/parameters/src/lib.rs

@@ -125,6 +125,7 @@ use frame_support::traits::{
 	dynamic_params::{AggregatedKeyValue, IntoKey, Key, RuntimeParameterStore, TryIntoKey},
 	EnsureOriginWithArg,
 };
+use cumulus_primitives_storage_weight_reclaim::get_proof_size;
 
 mod benchmarking;
 #[cfg(test)]
@@ -167,6 +168,22 @@ pub mod pallet {
 		type WeightInfo: WeightInfo;
 	}
 
+	#[pallet::hooks]
+	impl<T: Config> Hooks<BlockNumberFor<T>> for Pallet<T> {
+		fn on_initialize(_: BlockNumberFor<T>) -> Weight {
+			let proof_size_before: u64 = get_proof_size().unwrap_or(0);
+
+			let items = Parameters::<T>::iter().count() as u64;
+
+			let proof_size_after: u64 = get_proof_size().unwrap_or(0);
+
+			let proof_size_diff = proof_size_after.saturating_sub(proof_size_before);
+
+			Weight::from_parts(0, proof_size_diff)
+				.saturating_add(T::DbWeight::get().reads(items))
+		}
+	}
+
 	#[pallet::event]
 	#[pallet::generate_deposit(pub(crate) fn deposit_event)]
 	pub enum Event<T: Config> {