fix: events emitted in hooks are duplicated

CHANGELOG.md

@@ -29,6 +29,7 @@
 - [\#790](https://github.com/cosmos/evm/pull/790) fix panic in historical query due to missing EvmCoinInfo.
 - [\#800](https://github.com/cosmos/evm/pull/800) Fix denom exponent validation in virtual fee deduct in vm module.
 - [\#817](https://github.com/cosmos/evm/pull/817) Align GetCoinbaseAddress to handle empty proposer address in contexts like CheckTx where proposer doesn't exist.
+- [\#814](https://github.com/cosmos/evm/pull/814) Fix duplicated events in post tx processor.
 - [\#816](https://github.com/cosmos/evm/pull/816) Avoid nil pointer when RPC requests execute before evmCoinInfo initialization in PreBlock with defaultEvmCoinInfo fallback.
 
 ## v0.5.0

tests/integration/x/vm/test_state_transition.go

@@ -38,6 +38,8 @@ import (
 	govtypes "github.com/cosmos/cosmos-sdk/x/gov/types"
 )
 
+const TestPostProcessingEventType = "test_post_processing_event"
+
 func (s *KeeperTestSuite) TestContextSetConsensusParams() {
 	// set new value of max gas in consensus params
 	maxGas := int64(123456789)
@@ -675,6 +677,7 @@ func (s *KeeperTestSuite) TestApplyTransactionWithTxPostProcessing() {
 					keeper.NewMultiEvmHooks(
 						&testHooks{
 							postProcessing: func(ctx sdk.Context, sender common.Address, msg core.Message, receipt *gethtypes.Receipt) error {
+								ctx.EventManager().EmitEvent(sdk.NewEvent(TestPostProcessingEventType))
 								return nil
 							},
 						},
@@ -706,7 +709,17 @@ func (s *KeeperTestSuite) TestApplyTransactionWithTxPostProcessing() {
 				s.Require().Equal(senderBefore.Sub(sdkmath.NewIntFromBigInt(transferAmt)), senderAfter)
 				s.Require().Equal(recipientBefore.Add(sdkmath.NewIntFromBigInt(transferAmt)), recipientAfter)
 			},
-			func(s *KeeperTestSuite) {},
+			func(s *KeeperTestSuite) {
+				// check if the event emitted exactly once
+				events := s.Network.GetContext().EventManager().Events()
+				var postProcessingEvents []sdk.Event
+				for _, event := range events {
+					if event.Type == TestPostProcessingEventType {
+						postProcessingEvents = append(postProcessingEvents, event)
+					}
+				}
+				s.Require().Len(postProcessingEvents, 1)
+			},
 		},
 		{
 			"pass - evm tx succeeds, post processing is called but fails, the balance is unchanged",

x/vm/keeper/state_transition.go

@@ -262,8 +262,6 @@ func (k *Keeper) ApplyTransaction(ctx sdk.Context, tx *ethtypes.Transaction) (*t
 		return nil, errorsmod.Wrap(err, "failed to extract sender address from ethereum transaction")
 	}
 
-	eventsLen := len(tmpCtx.EventManager().Events())
-
 	// Only call PostTxProcessing if there are hooks set, to avoid calling commitFn unnecessarily
 	if !k.HasHooks() {
 		// If there are no hooks, we can commit the state immediately if the tx is successful
@@ -297,11 +295,6 @@ func (k *Keeper) ApplyTransaction(ctx sdk.Context, tx *ethtypes.Transaction) (*t
 			} else {
 				res.Logs = types.NewLogsFromEth(receipt.Logs)
 			}
-
-			events := tmpCtx.EventManager().Events()
-			if len(events) > eventsLen {
-				ctx.EventManager().EmitEvents(events[eventsLen:])
-			}
 		}
 	}