contracts: Expose rent parameter to contracts (#8231)

* contracts: Expose rent parameter to contracts

* cargo run --release --features=runtime-benchmarks --manifest-path=bin/node/cli/Cargo.toml -- benchmark --chain=dev --steps=50 --repeat=20 --pallet=pallet_contracts --extrinsic=* --execution=wasm --wasm-execution=compiled --heap-pages=4096 --output=./frame/contracts/src/weights.rs --template=./.maintain/frame-weight-template.hbs

* Fix typos

* Improve comments

* Add rent parameter weights

* Allow deploying a new schedule with the same version

* Add storage migration for new schedule

* Only decode the schedule version in storage migration

* Remove confusing docs

* Replace original_code_len() by aggregate_code_len()

Co-authored-by: Parity Benchmarking Bot <admin@parity.io>

substrate/frame/contracts/src/wasm/runtime.rs

@@ -215,6 +215,8 @@ pub enum RuntimeToken {
 	ChainExtension(u64),
 	/// Weight charged for copying data from the sandbox.
 	CopyIn(u32),
+	/// Weight of calling `seal_rent_params`.
+	RentParams,
 }
 
 impl<T: Config> Token<T> for RuntimeToken
@@ -283,6 +285,7 @@ where
 				.saturating_add(s.hash_blake2_128_per_byte.saturating_mul(len.into())),
 			ChainExtension(amount) => amount,
 			CopyIn(len) => s.return_per_byte.saturating_mul(len.into()),
+			RentParams => s.rent_params,
 		}
 	}
 }
@@ -1513,4 +1516,25 @@ define_env!(Env, <E: Ext>,
 			})),
 		}
 	},
+
+	// Stores the rent params into the supplied buffer.
+	//
+	// The value is stored to linear memory at the address pointed to by `out_ptr`.
+	// `out_len_ptr` must point to a u32 value that describes the available space at
+	// `out_ptr`. This call overwrites it with the size of the value. If the available
+	// space at `out_ptr` is less than the size of the value a trap is triggered.
+	//
+	// The data is encoded as [`crate::exec::RentParams`].
+	//
+	// # Note
+	//
+	// The returned information was collected and cached when the current contract call
+	// started execution. Any change to those values that happens due to actions of the
+	// current call or contracts that are called by this contract are not considered.
+	seal_rent_params(ctx, out_ptr: u32, out_len_ptr: u32) => {
+		ctx.charge_gas(RuntimeToken::RentParams)?;
+		Ok(ctx.write_sandbox_output(
+			out_ptr, out_len_ptr, &ctx.ext.rent_params().encode(), false, already_charged
+		)?)
+	},
 );