Don't allow bids for a ParaId where there is an overlapping lease period (#3361)

* add already leased

Co-Authored-By: parity-processbot <>

* add unit test

Co-Authored-By: parity-processbot <>

* add integration test and fix

Co-Authored-By: parity-processbot <>

* better doc

Co-Authored-By: parity-processbot <>

* Update runtime/common/src/slots.rs

* Update runtime/common/src/slots.rs

* Apply suggestions from code review

Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>
Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* Update runtime/common/src/integration_tests.rs

* Update runtime/common/src/integration_tests.rs

* cargo run --release --features=runtime-benchmarks -- benchmark --chain=kusama-dev --steps=50 --repeat=20 --pallet=runtime_common::auctions --extrinsic=* --execution=wasm --wasm-execution=compiled --heap-pages=4096 --header=./file_header.txt --output=./runtime/kusama/src/weights/runtime_common_auctions.rs

* cargo run --release --features=runtime-benchmarks -- benchmark --chain=kusama-dev --steps=50 --repeat=20 --pallet=runtime_common::auctions --extrinsic=* --execution=wasm --wasm-execution=compiled --heap-pages=4096 --header=./file_header.txt --output=./runtime/kusama/src/weights/runtime_common_auctions.rs

* cargo run --release --features=runtime-benchmarks -- benchmark --chain=kusama-dev --steps=50 --repeat=20 --pallet=runtime_common::crowdloan --extrinsic=* --execution=wasm --wasm-execution=compiled --heap-pages=4096 --header=./file_header.txt --output=./runtime/kusama/src/weights/runtime_common_crowdloan.rs

* cargo run --release --features=runtime-benchmarks -- benchmark --chain=westend-dev --steps=50 --repeat=20 --pallet=runtime_common::auctions --extrinsic=* --execution=wasm --wasm-execution=compiled --heap-pages=4096 --header=./file_header.txt --output=./runtime/westend/src/weights/runtime_common_auctions.rs

* cargo run --release --features=runtime-benchmarks -- benchmark --chain=westend-dev --steps=50 --repeat=20 --pallet=runtime_common::crowdloan --extrinsic=* --execution=wasm --wasm-execution=compiled --heap-pages=4096 --header=./file_header.txt --output=./runtime/westend/src/weights/runtime_common_crowdloan.rs

* cargo run --release --features=runtime-benchmarks -- benchmark --chain=kusama-dev --steps=50 --repeat=20 --pallet=runtime_common::slots --extrinsic=* --execution=wasm --wasm-execution=compiled --heap-pages=4096 --header=./file_header.txt --output=./runtime/kusama/src/weights/runtime_common_slots.rs

* cargo run --release --features=runtime-benchmarks -- benchmark --chain=westend-dev --steps=50 --repeat=20 --pallet=runtime_common::slots --extrinsic=* --execution=wasm --wasm-execution=compiled --heap-pages=4096 --header=./file_header.txt --output=./runtime/westend/src/weights/runtime_common_slots.rs

Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>
Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>
Co-authored-by: Parity Bot <admin@parity.io>

polkadot/runtime/common/src/slots.rs

@@ -22,7 +22,7 @@
 //! must handled by a separately, through the trait interface that this pallet provides or the root dispatchables.
 
 use sp_std::prelude::*;
-use sp_runtime::traits::{CheckedSub, Zero, CheckedConversion};
+use sp_runtime::traits::{CheckedSub, Zero, CheckedConversion, Saturating};
 use frame_support::{
 	decl_module, decl_storage, decl_event, decl_error, dispatch::DispatchResult,
 	traits::{Currency, ReservableCurrency, Get}, weights::Weight,
@@ -421,6 +421,41 @@ impl<T: Config> Leaser for Module<T> {
 	fn lease_period_index() -> Self::LeasePeriod {
 		<frame_system::Pallet<T>>::block_number() / T::LeasePeriod::get()
 	}
+
+	fn already_leased(
+		para_id: ParaId,
+		first_period: Self::LeasePeriod,
+		last_period: Self::LeasePeriod,
+	) -> bool {
+		let current_lease_period = Self::lease_period_index();
+
+		// Can't look in the past, so we pick whichever is the biggest.
+		let start_period = first_period.max(current_lease_period);
+		// Find the offset to look into the lease period list.
+		// Subtraction is safe because of max above.
+		let offset = match (start_period - current_lease_period).checked_into::<usize>() {
+			Some(offset) => offset,
+			None => return true,
+		};
+
+		// This calculates how deep we should look in the vec for a potential lease.
+		let period_count = match last_period.saturating_sub(start_period).checked_into::<usize>() {
+			Some(period_count) => period_count,
+			None => return true,
+		};
+
+		// Get the leases, and check each item in the vec which is part of the range we are checking.
+		let leases = Leases::<T>::get(para_id);
+		for slot in offset ..= offset + period_count {
+			if let Some(Some(_)) = leases.get(slot) {
+				// If there exists any lease period, we exit early and return true.
+				return true
+			}
+		}
+
+		// If we got here, then we did not find any overlapping leases.
+		false
+	}
 }