contracts: Add seal_rent_status

bin/node/runtime/Cargo.toml

@@ -237,3 +237,8 @@ try-runtime = [
 	"pallet-vesting/try-runtime",
 	"pallet-gilt/try-runtime",
 ]
+# Make contract callable functions marked as __unstable__ available. Do not enable
+# on live chains as those are subject to change.
+contracts-unstable-interface = [
+	"pallet-contracts/unstable-interface"
+]

frame/contracts/Cargo.toml

@@ -74,3 +74,6 @@ runtime-benchmarks = [
 	"rand_pcg",
 ]
 try-runtime = ["frame-support/try-runtime"]
+# Make contract callable functions marked as __unstable__ available. Do not enable
+# on live chains as those are subject to change.
+unstable-interface = []

frame/contracts/README.md

@@ -69,7 +69,8 @@ It is up the the individual client if and how those messages are presented to th
 This buffer is also printed as a debug message. In order to see these messages on the node
 console the log level for the `runtime::contracts` target needs to be raised to at least
 the `debug` level. However, those messages are easy to overlook because of the noise generated
-by block production. A good starting point for observing them on the console is:
+by block production. A good starting point for observing them on the console is using this
+command line in the root directory of the substrate repository:
 
 ```bash
 cargo run --release -- --dev --tmp -lerror,runtime::contracts=debug
@@ -81,4 +82,27 @@ to `error` in order to prevent them from spamming the console.
 `--dev`: Use a dev chain spec
 `--tmp`: Use temporary storage for chain data (the chain state is deleted on exit)
 
+## Unstable Interfaces
+
+Driven by the desire to have an iterative approach in developing new contract interfaces
+this pallet contains the concept of an unstable interface. Akin to the rust nightly compiler
+it allows us to add new interfaces but mark them as unstable so that contract languages can
+experiment with them and give feedback before we stabilize those.
+
+In order to access interfaces marked as `__unstable__` in `runtime.rs` one need to compile
+this crate with the `unstable-interface` feature enabled. It should be obvious that any
+live runtime should never be compiled with this feature: In addition to be subject to
+change or removal those interfaces do not have proper weights associated with them and
+are therefore considered unsafe.
+
+The substrate runtime exposes this feature as `contracts-unstable-interface`. Example
+commandline for running the substrate node with unstable contracts interfaces:
+
+```bash
+cargo run --release --features contracts-unstable-interface -- --dev
+```
+
+New interfaces are generally added as unstable and might go through several iterations
+before they are promoted to a stable interface.
+
 License: Apache-2.0

frame/contracts/src/benchmarking/mod.rs

@@ -527,14 +527,6 @@ benchmarks! {
 		let origin = RawOrigin::Signed(instance.caller.clone());
 	}: call(origin, instance.addr, 0u32.into(), Weight::max_value(), vec![])
 
-	seal_rent_params {
-		let r in 0 .. API_BENCHMARK_BATCHES;
-		let instance = Contract::<T>::new(WasmModule::getter(
-			"seal_rent_params", r * API_BENCHMARK_BATCH_SIZE
-		), vec![], Endow::Max)?;
-		let origin = RawOrigin::Signed(instance.caller.clone());
-	}: call(origin, instance.addr, 0u32.into(), Weight::max_value(), vec![])
-
 	seal_weight_to_fee {
 		let r in 0 .. API_BENCHMARK_BATCHES;
 		let pages = code::max_pages::<T>();

frame/contracts/src/exec.rs

@@ -17,7 +17,7 @@
 
 use crate::{
 	CodeHash, Event, Config, Pallet as Contracts,
-	BalanceOf, ContractInfo, gas::GasMeter, rent::Rent, storage::Storage,
+	BalanceOf, ContractInfo, gas::GasMeter, rent::{Rent, RentStatus}, storage::Storage,
 	Error, ContractInfoOf, Schedule, AliveContractInfo, AccountCounter,
 };
 use sp_core::crypto::UncheckedFrom;
@@ -313,6 +313,9 @@ pub trait Ext: sealing::Sealed {
 	/// Information needed for rent calculations.
 	fn rent_params(&self) -> &RentParams<Self::T>;
 
+	/// Information about the required deposit and resulting rent.
+	fn rent_status(&mut self, at_refcount: u32) -> RentStatus<Self::T>;
+
 	/// Get a mutable reference to the nested gas meter.
 	fn gas_meter(&mut self) -> &mut GasMeter<Self::T>;
 
@@ -1240,6 +1243,20 @@ where
 		&self.top_frame().rent_params
 	}
 
+	fn rent_status(&mut self, at_refcount: u32) -> RentStatus<Self::T> {
+		let frame = self.top_frame_mut();
+		let balance = T::Currency::free_balance(&frame.account_id);
+		let code_size = frame.rent_params.code_size;
+		let refcount = frame.rent_params.code_refcount;
+		<Rent<T, E>>::rent_status(
+			&balance,
+			&frame.contract_info(),
+			code_size,
+			refcount,
+			at_refcount,
+		)
+	}
+
 	fn gas_meter(&mut self) -> &mut GasMeter<Self::T> {
 		&mut self.top_frame_mut().nested_meter
 	}
@@ -2194,6 +2211,48 @@ mod tests {
 		});
 	}
 
+	#[test]
+	fn rent_status_works() {
+		let code_hash = MockLoader::insert(Call, |ctx, _| {
+			assert_eq!(ctx.ext.rent_status(0), RentStatus {
+				max_deposit: 80000,
+				current_deposit: 80000,
+				custom_refcount_deposit: None,
+				max_rent: 32,
+				current_rent: 32,
+				custom_refcount_rent: None,
+				_reserved: None,
+			});
+			assert_eq!(ctx.ext.rent_status(1), RentStatus {
+				max_deposit: 80000,
+				current_deposit: 80000,
+				custom_refcount_deposit: Some(80000),
+				max_rent: 32,
+				current_rent: 32,
+				custom_refcount_rent: Some(32),
+				_reserved: None,
+			});
+			exec_success()
+		});
+
+		ExtBuilder::default().build().execute_with(|| {
+			let subsistence = Contracts::<Test>::subsistence_threshold();
+			let schedule = <Test as Config>::Schedule::get();
+			let mut gas_meter = GasMeter::<Test>::new(GAS_LIMIT);
+			set_balance(&ALICE, subsistence * 10);
+			place_contract(&BOB, code_hash);
+			MockStack::run_call(
+				ALICE,
+				BOB,
+				&mut gas_meter,
+				&schedule,
+				0,
+				vec![],
+				None,
+			).unwrap();
+		});
+	}
+
 	#[test]
 	fn in_memory_changes_not_discarded() {
 		// Call stack: BOB -> CHARLIE (trap) -> BOB' (success)