Contracts: Add transfer event (#801)

node/runtime/src/lib.rs

@@ -174,6 +174,7 @@ impl treasury::Trait for Runtime {
 impl contract::Trait for Runtime {
 	type Gas = u64;
 	type DetermineContractAddress = contract::SimpleAddressDeterminator<Runtime>;
+	type Event = Event;
 }
 
 impl DigestItem for Log {
@@ -208,7 +209,7 @@ construct_runtime!(
 		CouncilVoting: council_voting::{Module, Call, Storage, Event<T>},
 		CouncilMotions: council_motions::{Module, Call, Storage, Event<T>, Origin},
 		Treasury: treasury,
-		Contract: contract::{Module, Call, Config},
+		Contract: contract::{Module, Call, Config, Event<T>},
 	}
 );
 

srml/contract/Cargo.toml

@@ -7,7 +7,8 @@ authors = ["Parity Technologies <admin@parity.io>"]
 serde = { version = "1.0", default_features = false }
 serde_derive = { version = "1.0", optional = true }
 pwasm-utils = { version = "0.3", default_features = false }
-parity-codec = { version = "2.0", default_features = false }
+parity-codec = { version = "~2.0.1", default_features = false }
+parity-codec-derive = { version = "~2.0.1", default-features = false }
 parity-wasm = { version = "0.31", default_features = false }
 substrate-primitives = { path = "../../core/primitives", default_features = false }
 sr-primitives = { path = "../../core/sr-primitives", default_features = false }
@@ -28,6 +29,7 @@ std = [
 	"serde_derive",
 	"serde/std",
 	"parity-codec/std",
+	"parity-codec-derive/std",
 	"substrate-primitives/std",
 	"sr-primitives/std",
 	"sr-io/std",

srml/contract/src/exec.rs

@@ -14,7 +14,7 @@
 // You should have received a copy of the GNU General Public License
 // along with Substrate. If not, see <http://www.gnu.org/licenses/>.
 
-use super::{CodeOf, MaxDepth, ContractAddressFor, Module, Trait};
+use super::{CodeOf, MaxDepth, ContractAddressFor, Module, Trait, Event, RawEvent};
 use account_db::{AccountDb, OverlayAccountDb};
 use gas::GasMeter;
 use vm;
@@ -37,6 +37,7 @@ pub struct ExecutionContext<'a, T: Trait + 'a> {
 	pub self_account: T::AccountId,
 	pub overlay: OverlayAccountDb<'a, T>,
 	pub depth: usize,
+	pub events: Vec<Event<T>>,
 }
 
 impl<'a, T: Trait> ExecutionContext<'a, T> {
@@ -61,26 +62,27 @@ impl<'a, T: Trait> ExecutionContext<'a, T> {
 
 		let dest_code = <CodeOf<T>>::get(&dest);
 
-		let change_set = {
+		let (change_set, events) = {
 			let mut overlay = OverlayAccountDb::new(&self.overlay);
 
+			let mut nested = ExecutionContext {
+				overlay: overlay,
+				self_account: dest.clone(),
+				depth: self.depth + 1,
+				events: Vec::new(),
+			};
+
 			if value > T::Balance::zero() {
 				transfer(
 					gas_meter,
 					false,
 					&self.self_account,
 					&dest,
 					value,
-					&mut overlay,
+					&mut nested,
 				)?;
 			}
 
-			let mut nested = ExecutionContext {
-				overlay: overlay,
-				self_account: dest.clone(),
-				depth: self.depth + 1,
-			};
-
 			if !dest_code.is_empty() {
 				vm::execute(
 					&dest_code,
@@ -95,10 +97,11 @@ impl<'a, T: Trait> ExecutionContext<'a, T> {
 				).map_err(|_| "vm execute returned error while call")?;
 			}
 
-			nested.overlay.into_change_set()
+			(nested.overlay.into_change_set(), nested.events)
 		};
 
 		self.overlay.commit(change_set);
+		self.events.extend(events);
 
 		Ok(CallReceipt)
 	}
@@ -126,26 +129,27 @@ impl<'a, T: Trait> ExecutionContext<'a, T> {
 			return Err("contract already exists");
 		}
 
-		let change_set = {
+		let (change_set, events) = {
 			let mut overlay = OverlayAccountDb::new(&self.overlay);
 
+			let mut nested = ExecutionContext {
+				overlay: overlay,
+				self_account: dest.clone(),
+				depth: self.depth + 1,
+				events: Vec::new(),
+			};
+
 			if endowment > T::Balance::zero() {
 				transfer(
 					gas_meter,
 					true,
 					&self.self_account,
 					&dest,
 					endowment,
-					&mut overlay,
+					&mut nested,
 				)?;
 			}
 
-			let mut nested = ExecutionContext {
-				overlay: overlay,
-				self_account: dest.clone(),
-				depth: self.depth + 1,
-			};
-
 			let mut contract_code = Vec::new();
 			vm::execute(
 				init_code,
@@ -160,10 +164,11 @@ impl<'a, T: Trait> ExecutionContext<'a, T> {
 			).map_err(|_| "vm execute returned error while create")?;
 
 			nested.overlay.set_code(&dest, contract_code);
-			nested.overlay.into_change_set()
+			(nested.overlay.into_change_set(), nested.events)
 		};
 
 		self.overlay.commit(change_set);
+		self.events.extend(events);
 
 		Ok(CreateReceipt {
 			address: dest,
@@ -183,15 +188,15 @@ impl<'a, T: Trait> ExecutionContext<'a, T> {
 /// Note, that the fee is denominated in `T::Balance` units, but
 /// charged in `T::Gas` from the provided `gas_meter`. This means
 /// that the actual amount charged might differ.
-fn transfer<T: Trait>(
+fn transfer<'a, T: Trait>(
 	gas_meter: &mut GasMeter<T>,
 	contract_create: bool,
 	transactor: &T::AccountId,
 	dest: &T::AccountId,
 	value: T::Balance,
-	overlay: &mut OverlayAccountDb<T>,
+	ctx: &mut ExecutionContext<'a, T>,
 ) -> Result<(), &'static str> {
-	let would_create = overlay.get_balance(dest).is_zero();
+	let would_create = ctx.overlay.get_balance(dest).is_zero();
 
 	let fee: T::Balance = if contract_create {
 		<Module<T>>::contract_fee()
@@ -207,7 +212,7 @@ fn transfer<T: Trait>(
 		return Err("not enough gas to pay transfer fee");
 	}
 
-	let from_balance = overlay.get_balance(transactor);
+	let from_balance = ctx.overlay.get_balance(transactor);
 	let new_from_balance = match from_balance.checked_sub(&value) {
 		Some(b) => b,
 		None => return Err("balance too low to send value"),
@@ -217,15 +222,16 @@ fn transfer<T: Trait>(
 	}
 	<T as balances::Trait>::EnsureAccountLiquid::ensure_account_liquid(transactor)?;
 
-	let to_balance = overlay.get_balance(dest);
+	let to_balance = ctx.overlay.get_balance(dest);
 	let new_to_balance = match to_balance.checked_add(&value) {
 		Some(b) => b,
 		None => return Err("destination balance too high to receive value"),
 	};
 
 	if transactor != dest {
-		overlay.set_balance(transactor, new_from_balance);
-		overlay.set_balance(dest, new_to_balance);
+		ctx.overlay.set_balance(transactor, new_from_balance);
+		ctx.overlay.set_balance(dest, new_to_balance);
+		ctx.events.push(RawEvent::Transfer(transactor.clone(), dest.clone(), value));
 	}
 
 	Ok(())

srml/contract/src/lib.rs

@@ -59,6 +59,9 @@ extern crate serde_derive;
 #[cfg(feature = "std")]
 extern crate serde;
 
+#[macro_use]
+extern crate parity_codec_derive;
+
 extern crate parity_wasm;
 extern crate pwasm_utils;
 
@@ -116,6 +119,9 @@ pub trait Trait: balances::Trait {
 
 	// As<u32> is needed for wasm-utils
 	type Gas: Parameter + Default + Codec + SimpleArithmetic + Copy + As<Self::Balance> + As<u64> + As<u32>;
+
+	/// The overarching event type.
+	type Event: From<Event<Self>> + Into<<Self as system::Trait>::Event>;
 }
 
 pub trait ContractAddressFor<AccountId: Sized> {
@@ -169,6 +175,17 @@ decl_module! {
 	}
 }
 
+decl_event! {
+	pub enum Event<T>
+	where
+		<T as balances::Trait>::Balance,
+		<T as system::Trait>::AccountId
+	{
+		/// Transfer happened `from` -> `to` with given `value` as part of a `message-call` or `create`.
+		Transfer(AccountId, AccountId, Balance),
+	}
+}
+
 decl_storage! {
 	trait Store for Module<T: Trait> as Contract {
 		/// The fee required to create a contract. At least as big as staking's ReclaimRebate.
@@ -206,6 +223,11 @@ impl<T: Trait> double_map::StorageDoubleMap for StorageOf<T> {
 }
 
 impl<T: Trait> Module<T> {
+	/// Deposit one of this module's events.
+	fn deposit_event(event: Event<T>) {
+		<system::Module<T>>::deposit_event(<T as Trait>::Event::from(event).into());
+	}
+
 	/// Make a call to a specified account, optionally transferring some balance.
 	fn call(
 		origin: <T as system::Trait>::Origin,
@@ -226,6 +248,7 @@ impl<T: Trait> Module<T> {
 			self_account: origin.clone(),
 			depth: 0,
 			overlay: OverlayAccountDb::<T>::new(&account_db::DirectAccountDb),
+			events: Vec::new(),
 		};
 
 		let mut output_data = Vec::new();
@@ -234,6 +257,9 @@ impl<T: Trait> Module<T> {
 		if let Ok(_) = result {
 			// Commit all changes that made it thus far into the persistant storage.
 			account_db::DirectAccountDb.commit(ctx.overlay.into_change_set());
+
+			// Then deposit all events produced.
+			ctx.events.into_iter().for_each(Self::deposit_event);
 		}
 
 		// Refund cost of the unused gas.
@@ -273,12 +299,16 @@ impl<T: Trait> Module<T> {
 			self_account: origin.clone(),
 			depth: 0,
 			overlay: OverlayAccountDb::<T>::new(&account_db::DirectAccountDb),
+			events: Vec::new(),
 		};
 		let result = ctx.create(origin.clone(), endowment, &mut gas_meter, &ctor_code, &data);
 
 		if let Ok(_) = result {
 			// Commit all changes that made it thus far into the persistant storage.
 			account_db::DirectAccountDb.commit(ctx.overlay.into_change_set());
+
+			// Then deposit all events produced.
+			ctx.events.into_iter().for_each(Self::deposit_event);
 		}
 
 		// Refund cost of the unused gas.