Pass topics along with events (#2563)

* Introduce an IndexedEvent

* Plumb topics through the Ext interface.

* Add topics to ext_deposit_event

* Charging for events.

* Check the number of topics.

* Check for duplicate topics.

* Bump API version.

* Move derive(*Eq) under test.

* Use sorting for finding duplicates.

Author: pepyakin

node/runtime/src/lib.rs

@@ -58,8 +58,8 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	spec_name: create_runtime_str!("node"),
 	impl_name: create_runtime_str!("substrate-node"),
 	authoring_version: 10,
-	spec_version: 78,
-	impl_version: 79,
+	spec_version: 80,
+	impl_version: 80,
 	apis: RUNTIME_API_VERSIONS,
 };
 

srml/contract/src/exec.rs

@@ -29,6 +29,9 @@ pub type CallOf<T> = <T as Trait>::Call;
 pub type MomentOf<T> = <T as timestamp::Trait>::Moment;
 pub type SeedOf<T> = <T as system::Trait>::Hash;
 
+/// A type that represents a topic of an event. At the moment a hash is used.
+pub type TopicOf<T> = <T as system::Trait>::Hash;
+
 #[cfg_attr(test, derive(Debug))]
 pub struct InstantiateReceipt<AccountId> {
 	pub address: AccountId,
@@ -106,8 +109,10 @@ pub trait Ext {
 	/// Returns a reference to the random seed for the current block
 	fn random_seed(&self) -> &SeedOf<Self::T>;
 
-	/// Deposit an event.
-	fn deposit_event(&mut self, data: Vec<u8>);
+	/// Deposit an event with the given topics.
+	///
+	/// There should not be any duplicates in `topics`.
+	fn deposit_event(&mut self, topics: Vec<TopicOf<Self::T>>, data: Vec<u8>);
 
 	/// Set rent allowance of the contract
 	fn set_rent_allowance(&mut self, rent_allowance: BalanceOf<Self::T>);
@@ -189,6 +194,15 @@ impl VmExecResult {
 	}
 }
 
+/// Struct that records a request to deposit an event with a list of topics.
+#[cfg_attr(any(feature = "std", test), derive(Debug, PartialEq, Eq))]
+pub struct IndexedEvent<T: Trait> {
+	/// A list of topics this event will be deposited with.
+	pub topics: Vec<T::Hash>,
+	/// The event to deposit.
+	pub event: Event<T>,
+}
+
 /// A trait that represent a virtual machine.
 ///
 /// You can view a virtual machine as something that takes code, an input data buffer,
@@ -238,7 +252,7 @@ pub struct ExecutionContext<'a, T: Trait + 'a, V, L> {
 	pub self_trie_id: Option<TrieId>,
 	pub overlay: OverlayAccountDb<'a, T>,
 	pub depth: usize,
-	pub events: Vec<Event<T>>,
+	pub events: Vec<IndexedEvent<T>>,
 	pub calls: Vec<(T::AccountId, T::Call)>,
 	pub config: &'a Config<T>,
 	pub vm: &'a V,
@@ -418,7 +432,10 @@ where
 				.into_result()?;
 
 			// Deposit an instantiation event.
-			nested.events.push(RawEvent::Instantiated(self.self_account.clone(), dest.clone()));
+			nested.events.push(IndexedEvent {
+				event: RawEvent::Instantiated(self.self_account.clone(), dest.clone()),
+				topics: Vec::new(),
+			});
 
 			(nested.overlay.into_change_set(), nested.events, nested.calls)
 		};
@@ -545,8 +562,10 @@ fn transfer<'a, T: Trait, V: Vm<T>, L: Loader<T>>(
 	if transactor != dest {
 		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));
+		ctx.events.push(IndexedEvent {
+			event: RawEvent::Transfer(transactor.clone(), dest.clone(), value),
+			topics: Vec::new(),
+		});
 	}
 
 	Ok(())
@@ -631,8 +650,11 @@ where
 		&self.timestamp
 	}
 
-	fn deposit_event(&mut self, data: Vec<u8>) {
-		self.ctx.events.push(RawEvent::Contract(self.ctx.self_account.clone(), data));
+	fn deposit_event(&mut self, topics: Vec<T::Hash>, data: Vec<u8>) {
+		self.ctx.events.push(IndexedEvent {
+			topics,
+			event: RawEvent::Contract(self.ctx.self_account.clone(), data),
+		});
 	}
 
 	fn set_rent_allowance(&mut self, rent_allowance: BalanceOf<T>) {
@@ -659,7 +681,7 @@ where
 mod tests {
 	use super::{
 		BalanceOf, ExecFeeToken, ExecutionContext, Ext, Loader, EmptyOutputBuf, TransferFeeKind, TransferFeeToken,
-		Vm, VmExecResult, InstantiateReceipt, RawEvent,
+		Vm, VmExecResult, InstantiateReceipt, RawEvent, IndexedEvent,
 	};
 	use crate::account_db::AccountDb;
 	use crate::gas::GasMeter;
@@ -1262,8 +1284,14 @@ mod tests {
 				// there are instantiation event.
 				assert_eq!(ctx.overlay.get_code_hash(&created_contract_address).unwrap(), dummy_ch);
 				assert_eq!(&ctx.events, &[
-					RawEvent::Transfer(ALICE, created_contract_address, 100),
-					RawEvent::Instantiated(ALICE, created_contract_address),
+					IndexedEvent {
+						event: RawEvent::Transfer(ALICE, created_contract_address, 100),
+						topics: Vec::new(),
+					},
+					IndexedEvent {
+						event: RawEvent::Instantiated(ALICE, created_contract_address),
+						topics: Vec::new(),
+					}
 				]);
 			}
 		);
@@ -1314,9 +1342,18 @@ mod tests {
 				// there are instantiation event.
 				assert_eq!(ctx.overlay.get_code_hash(&created_contract_address).unwrap(), dummy_ch);
 				assert_eq!(&ctx.events, &[
-					RawEvent::Transfer(ALICE, BOB, 20),
-					RawEvent::Transfer(BOB, created_contract_address, 15),
-					RawEvent::Instantiated(BOB, created_contract_address),
+					IndexedEvent {
+						event: RawEvent::Transfer(ALICE, BOB, 20),
+						topics: Vec::new(),
+					},
+					IndexedEvent {
+						event: RawEvent::Transfer(BOB, created_contract_address, 15),
+						topics: Vec::new(),
+					},
+					IndexedEvent {
+						event: RawEvent::Instantiated(BOB, created_contract_address),
+						topics: Vec::new(),
+					},
 				]);
 			}
 		);
@@ -1362,7 +1399,10 @@ mod tests {
 				// The contract wasn't created so we don't expect to see an instantiation
 				// event here.
 				assert_eq!(&ctx.events, &[
-					RawEvent::Transfer(ALICE, BOB, 20),
+					IndexedEvent {
+						event: RawEvent::Transfer(ALICE, BOB, 20),
+						topics: Vec::new(),
+					},
 				]);
 			}
 		);

srml/contract/src/lib.rs

@@ -393,7 +393,12 @@ decl_module! {
 				DirectAccountDb.commit(ctx.overlay.into_change_set());
 
 				// Then deposit all events produced.
-				ctx.events.into_iter().for_each(Self::deposit_event);
+				ctx.events.into_iter().for_each(|indexed_event| {
+					<system::Module<T>>::deposit_event_indexed(
+						&*indexed_event.topics,
+						<T as Trait>::Event::from(indexed_event.event).into(),
+					);
+				});
 			}
 
 			// Refund cost of the unused gas.
@@ -447,7 +452,12 @@ decl_module! {
 				DirectAccountDb.commit(ctx.overlay.into_change_set());
 
 				// Then deposit all events produced.
-				ctx.events.into_iter().for_each(Self::deposit_event);
+				ctx.events.into_iter().for_each(|indexed_event| {
+					<system::Module<T>>::deposit_event_indexed(
+						&*indexed_event.topics,
+						<T as Trait>::Event::from(indexed_event.event).into(),
+					);
+				});
 			}
 
 			// Refund cost of the unused gas.
@@ -653,15 +663,21 @@ pub struct Schedule<Gas> {
 	/// Gas cost to deposit an event; the per-byte portion.
 	pub event_data_per_byte_cost: Gas,
 
+	/// Gas cost to deposit an event; the cost per topic.
+	pub event_per_topic_cost: Gas,
+
 	/// Gas cost to deposit an event; the base.
-	pub event_data_base_cost: Gas,
+	pub event_base_cost: Gas,
 
 	/// Gas cost per one byte read from the sandbox memory.
 	pub sandbox_data_read_cost: Gas,
 
 	/// Gas cost per one byte written to the sandbox memory.
 	pub sandbox_data_write_cost: Gas,
 
+	/// The maximum number of topics supported by an event.
+	pub max_event_topics: u32,
+
 	/// Maximum allowed stack height.
 	///
 	/// See https://wiki.parity.io/WebAssembly-StackHeight to find out
@@ -685,9 +701,11 @@ impl<Gas: As<u64>> Default for Schedule<Gas> {
 			regular_op_cost: Gas::sa(1),
 			return_data_per_byte_cost: Gas::sa(1),
 			event_data_per_byte_cost: Gas::sa(1),
-			event_data_base_cost: Gas::sa(1),
+			event_per_topic_cost: Gas::sa(1),
+			event_base_cost: Gas::sa(1),
 			sandbox_data_read_cost: Gas::sa(1),
 			sandbox_data_write_cost: Gas::sa(1),
+			max_event_topics: 4,
 			max_stack_height: 64 * 1024,
 			max_memory_pages: 16,
 			enable_println: false,

srml/contract/src/tests.rs

@@ -64,7 +64,7 @@ impl_outer_dispatch! {
 	}
 }
 
-#[derive(Clone, Eq, PartialEq)]
+#[derive(Clone, Eq, PartialEq, Debug)]
 pub struct Test;
 impl system::Trait for Test {
 	type Origin = Origin;
@@ -313,14 +313,16 @@ fn account_removal_removes_storage() {
 const CODE_RETURN_FROM_START_FN: &str = r#"
 (module
 	(import "env" "ext_return" (func $ext_return (param i32 i32)))
-	(import "env" "ext_deposit_event" (func $ext_deposit_event (param i32 i32)))
+	(import "env" "ext_deposit_event" (func $ext_deposit_event (param i32 i32 i32 i32)))
 	(import "env" "memory" (memory 1 1))
 
 	(start $start)
 	(func $start
 		(call $ext_deposit_event
-			(i32.const 8)
-			(i32.const 4)
+			(i32.const 0) ;; The topics buffer
+			(i32.const 0) ;; The topics buffer's length
+			(i32.const 8) ;; The data buffer
+			(i32.const 4) ;; The data buffer's length
 		)
 		(call $ext_return
 			(i32.const 8)
@@ -337,7 +339,7 @@ const CODE_RETURN_FROM_START_FN: &str = r#"
 	(data (i32.const 8) "\01\02\03\04")
 )
 "#;
-const HASH_RETURN_FROM_START_FN: [u8; 32] = hex!("abb4194bdea47b2904fe90b4fd674bd40d96f423956627df8c39d2b1a791ab9d");
+const HASH_RETURN_FROM_START_FN: [u8; 32] = hex!("66c45bd7c473a1746e1d241176166ef53b1f207f56c5e87d1b6650140704181b");
 
 #[test]
 fn instantiate_and_call_and_deposit_event() {