Allow duplicate topics in smart contract events (#13065)

* Removed `has_duplicates` check form the `deposit_event`.
Removed the usage of `Error::DuplicateTopics`.

* ".git/.scripts/commands/bench/bench.sh" pallet dev pallet_contracts

Co-authored-by: command-bot <>

substrate/frame/contracts/src/lib.rs

@@ -816,8 +816,6 @@ pub mod pallet {
 		RandomSubjectTooLong,
 		/// The amount of topics passed to `seal_deposit_events` exceeds the limit.
 		TooManyTopics,
-		/// The topics passed to `seal_deposit_events` contains at least one duplicate.
-		DuplicateTopics,
 		/// The chain does not provide a chain extension. Calling the chain extension results
 		/// in this error. Note that this usually  shouldn't happen as deploying such contracts
 		/// is rejected.

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

@@ -1988,6 +1988,52 @@ mod tests {
 		assert!(mock_ext.gas_meter.gas_left().ref_time() > 0);
 	}
 
+	const CODE_DEPOSIT_EVENT_DUPLICATES: &str = r#"
+(module
+	(import "seal0" "seal_deposit_event" (func $seal_deposit_event (param i32 i32 i32 i32)))
+	(import "env" "memory" (memory 1 1))
+
+	(func (export "call")
+		(call $seal_deposit_event
+			(i32.const 32) ;; Pointer to the start of topics buffer
+			(i32.const 129) ;; The length of the topics buffer.
+			(i32.const 8) ;; Pointer to the start of the data buffer
+			(i32.const 13) ;; Length of the buffer
+		)
+	)
+	(func (export "deploy"))
+
+	(data (i32.const 8) "\00\01\2A\00\00\00\00\00\00\00\E5\14\00")
+
+	;; Encoded Vec<TopicOf<T>>, the buffer has length of 129 bytes.
+	(data (i32.const 32) "\10"
+"\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01"
+"\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02"
+"\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01"
+"\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04")
+)
+"#;
+
+	/// Checks that the runtime allows duplicate topics.
+	#[test]
+	fn deposit_event_duplicates_allowed() {
+		let mut mock_ext = MockExt::default();
+		assert_ok!(execute(CODE_DEPOSIT_EVENT_DUPLICATES, vec![], &mut mock_ext,));
+
+		assert_eq!(
+			mock_ext.events,
+			vec![(
+				vec![
+					H256::repeat_byte(0x01),
+					H256::repeat_byte(0x02),
+					H256::repeat_byte(0x01),
+					H256::repeat_byte(0x04)
+				],
+				vec![0x00, 0x01, 0x2a, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xe5, 0x14, 0x00]
+			)]
+		);
+	}
+
 	const CODE_DEPOSIT_EVENT_MAX_TOPICS: &str = r#"
 (module
 	(import "seal0" "seal_deposit_event" (func $seal_deposit_event (param i32 i32 i32 i32)))
@@ -2027,44 +2073,6 @@ mod tests {
 		);
 	}
 
-	const CODE_DEPOSIT_EVENT_DUPLICATES: &str = r#"
-(module
-	(import "seal0" "seal_deposit_event" (func $seal_deposit_event (param i32 i32 i32 i32)))
-	(import "env" "memory" (memory 1 1))
-
-	(func (export "call")
-		(call $seal_deposit_event
-			(i32.const 32) ;; Pointer to the start of topics buffer
-			(i32.const 129) ;; The length of the topics buffer.
-			(i32.const 8) ;; Pointer to the start of the data buffer
-			(i32.const 13) ;; Length of the buffer
-		)
-	)
-	(func (export "deploy"))
-
-	(data (i32.const 8) "\00\01\2A\00\00\00\00\00\00\00\E5\14\00")
-
-	;; Encoded Vec<TopicOf<T>>, the buffer has length of 129 bytes.
-	(data (i32.const 32) "\10"
-"\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01"
-"\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02"
-"\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01"
-"\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04\04")
-)
-"#;
-
-	/// Checks that the runtime traps if there are duplicates.
-	#[test]
-	fn deposit_event_duplicates() {
-		assert_eq!(
-			execute(CODE_DEPOSIT_EVENT_DUPLICATES, vec![], MockExt::default(),),
-			Err(ExecError {
-				error: Error::<Test>::DuplicateTopics.into(),
-				origin: ErrorOrigin::Caller,
-			})
-		);
-	}
-
 	/// calls `seal_block_number` compares the result with the constant 121.
 	const CODE_BLOCK_NUMBER: &str = r#"
 (module

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

@@ -2085,15 +2085,6 @@ pub mod env {
 		data_ptr: u32,
 		data_len: u32,
 	) -> Result<(), TrapReason> {
-		fn has_duplicates<T: Ord>(items: &mut Vec<T>) -> bool {
-			items.sort();
-			// Find any two consecutive equal elements.
-			items.windows(2).any(|w| match &w {
-				&[a, b] => a == b,
-				_ => false,
-			})
-		}
-
 		let num_topic = topics_len
 			.checked_div(sp_std::mem::size_of::<TopicOf<E::T>>() as u32)
 			.ok_or("Zero sized topics are not allowed")?;
@@ -2102,7 +2093,7 @@ pub mod env {
 			return Err(Error::<E::T>::ValueTooLarge.into())
 		}
 
-		let mut topics: Vec<TopicOf<<E as Ext>::T>> = match topics_len {
+		let topics: Vec<TopicOf<<E as Ext>::T>> = match topics_len {
 			0 => Vec::new(),
 			_ => ctx.read_sandbox_memory_as_unbounded(memory, topics_ptr, topics_len)?,
 		};
@@ -2112,13 +2103,6 @@ pub mod env {
 			return Err(Error::<E::T>::TooManyTopics.into())
 		}
 
-		// Check for duplicate topics. If there are any, then trap.
-		// Complexity O(n * log(n)) and no additional allocations.
-		// This also sorts the topics.
-		if has_duplicates(&mut topics) {
-			return Err(Error::<E::T>::DuplicateTopics.into())
-		}
-
 		let event_data = ctx.read_sandbox_memory(memory, data_ptr, data_len)?;
 
 		ctx.ext.deposit_event(topics, event_data);