Introduce and enforce block time (#232)

* Recompile runtime.

* Introduce and enforce block time

Cargo.lock

@@ -2531,6 +2531,7 @@ name = "substrate-telemetry"
 version = "0.2.0"
 dependencies = [
  "lazy_static 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "log 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "slog 2.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "slog-async 2.3.0 (registry+https://github.com/rust-lang/crates.io-index)",

polkadot/api/src/full.rs

@@ -221,6 +221,7 @@ mod tests {
 			democracy: Some(Default::default()),
 			parachains: Some(Default::default()),
 			staking: Some(Default::default()),
+			timestamp: Some(Default::default()),
 		};
 
 		::client::new_in_mem(LocalDispatch::new(), genesis_config.build_storage()).unwrap()

polkadot/cli/src/preset_config.rs

@@ -136,6 +136,7 @@ impl PresetConfig {
 				voting_period: 7 * 120 * 24, // 7 day voting period for council members.
 			}),
 			parachains: Some(Default::default()),
+			timestamp: Some(Default::default()),
 		});
 		let boot_nodes = vec![
 			"enode://a93a29fa68d965452bf0ff8c1910f5992fe2273a72a1ee8d3a3482f68512a61974211ba32bb33f051ceb1530b8ba3527fc36224ba6b9910329025e6d9153cf50@104.211.54.233:30333".into(),
@@ -200,6 +201,7 @@ impl PresetConfig {
 				voting_period: 20,
 			}),
 			parachains: Some(Default::default()),
+			timestamp: Some(Default::default()),
 		});
 		let boot_nodes = Vec::new();
 		PresetConfig { genesis_config, boot_nodes }

polkadot/runtime/src/lib.rs

@@ -213,6 +213,7 @@ impl_outer_config! {
 		StakingConfig => staking,
 		DemocracyConfig => democracy,
 		CouncilConfig => council,
+		TimestampConfig => timestamp,
 		ParachainsConfig => parachains,
 	}
 }

substrate/runtime/timestamp/src/lib.rs

@@ -39,13 +39,13 @@ extern crate substrate_codec as codec;
 
 use runtime_support::{StorageValue, Parameter};
 use runtime_support::dispatch::Result;
-use runtime_primitives::traits::{HasPublicAux, Executable, MaybeEmpty};
+use runtime_primitives::traits::{HasPublicAux, Executable, MaybeEmpty, SimpleArithmetic};
 
 pub trait Trait: HasPublicAux + system::Trait {
 	// the position of the required timestamp-set extrinsic.
 	const SET_POSITION: u32;
 
-	type Value: Parameter + Default;
+	type Value: Parameter + Default + SimpleArithmetic;
 }
 
 decl_module! {
@@ -60,6 +60,8 @@ decl_module! {
 decl_storage! {
 	trait Store for Module<T: Trait>;
 	pub Now get(now): b"tim:val" => required T::Value;
+	// The minimum (and advised) period between blocks.
+	pub BlockPeriod get(block_period): b"tim:block_period" => required T::Value;
 
 	// Did the timestamp get updated in this block?
 	DidUpdate: b"tim:did" => default bool;
@@ -79,6 +81,10 @@ impl<T: Trait> Module<T> {
 			"Timestamp extrinsic must be at position {} in the block",
 			T::SET_POSITION
 		);
+		assert!(
+			now >= Self::get() + Self::block_period(),
+			"Timestamp but increment by at least <BlockPeriod> between sequential blocks"
+		);
 		<Self as Store>::Now::put(now);
 		<Self as Store>::DidUpdate::put(true);
 		Ok(())
@@ -92,9 +98,18 @@ impl<T: Trait> Executable for Module<T> {
 }
 
 #[cfg(any(feature = "std", test))]
-#[derive(Default)]
 pub struct GenesisConfig<T: Trait> {
 	pub now: T::Value,
+	pub period: T::Value,
+}
+
+impl<T: Trait> Default for GenesisConfig<T> {
+	fn default() -> Self {
+		GenesisConfig {
+			now: T::Value::default(),
+			period: T::Value::default(),
+		}
+	}
 }
 
 #[cfg(any(feature = "std", test))]
@@ -104,7 +119,8 @@ impl<T: Trait> runtime_primitives::BuildStorage for GenesisConfig<T>
 		use runtime_io::twox_128;
 		use codec::Slicable;
 		map![
-			twox_128(<Now<T>>::key()).to_vec() => self.now.encode()
+			twox_128(<Now<T>>::key()).to_vec() => self.now.encode(),
+			twox_128(<BlockPeriod<T>>::key()).to_vec() => self.period.encode()
 		]
 	}
 }
@@ -143,7 +159,7 @@ mod tests {
 	#[test]
 	fn timestamp_works() {
 		let mut t = system::GenesisConfig::<Test>::default().build_storage();
-		t.extend(GenesisConfig::<Test> { now: 42 }.build_storage());
+		t.extend(GenesisConfig::<Test> { now: 42, period: 0 }.build_storage());
 
 		with_externalities(&mut t, || {
 			assert_eq!(<Timestamp as Store>::Now::get(), 42);
@@ -151,4 +167,27 @@ mod tests {
 			assert_eq!(Timestamp::now(), 69);
 		});
 	}
+
+	#[test]
+	#[should_panic(expected = "Timestamp must be updated only once in the block")]
+	fn double_timestamp_should_fail() {
+		let mut t = system::GenesisConfig::<Test>::default().build_storage();
+		t.extend(GenesisConfig::<Test> { now: 42, period: 5 }.build_storage());
+
+		with_externalities(&mut t, || {
+			assert_ok!(Timestamp::aux_dispatch(Call::set(69), &0));
+			let _ = Timestamp::aux_dispatch(Call::set(70), &0);
+		});
+	}
+
+	#[test]
+	#[should_panic(expected = "Timestamp but increment by at least <BlockPeriod> between sequential blocks")]
+	fn block_period_is_enforced() {
+		let mut t = system::GenesisConfig::<Test>::default().build_storage();
+		t.extend(GenesisConfig::<Test> { now: 42, period: 5 }.build_storage());
+
+		with_externalities(&mut t, || {
+			let _ = Timestamp::aux_dispatch(Call::set(46), &0);
+		});
+	}
 }

substrate/telemetry/Cargo.toml

@@ -7,6 +7,7 @@ description = "Telemetry utils"
 [dependencies]
 parking_lot = "0.4"
 lazy_static = "1.0"
+log = "^0.3"
 slog = "^2"
 slog-json = "^2"
 slog-async = "^2"