Merge pull request #5772 from onflow/leo/v0.33-check-events-hash-when…

…-block-has-no-events

Backport check events hash when block has no events

engine/execution/rpc/engine.go

@@ -269,12 +269,21 @@ func (h *handler) GetEventsForBlockIDs(
 			return nil, status.Errorf(codes.Internal, "state commitment for block ID %s could not be retrieved", bID)
 		}
 
-		// lookup events
-		blockEvents, err := h.events.ByBlockIDEventType(bID, flow.EventType(eType))
+		// lookup all events for the block
+		blockAllEvents, err := h.getEventsByBlockID(bID)
 		if err != nil {
 			return nil, status.Errorf(codes.Internal, "failed to get events for block: %v", err)
 		}
 
+		// filter events by type
+		eventType := flow.EventType(eType)
+		blockEvents := make([]flow.Event, 0, len(blockAllEvents))
+		for _, event := range blockAllEvents {
+			if event.Type == eventType {
+				blockEvents = append(blockEvents, event)
+			}
+		}
+
 		result, err := h.eventResult(bID, blockEvents)
 		if err != nil {
 			return nil, err
@@ -442,7 +451,7 @@ func (h *handler) GetTransactionResultsByBlockID(
 	}
 
 	// get all events for a block
-	blockEvents, err := h.events.ByBlockID(blockID)
+	blockEvents, err := h.getEventsByBlockID(blockID)
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, "failed to get events for block: %v", err)
 	}
@@ -792,3 +801,29 @@ func (h *handler) blockHeaderResponse(header *flow.Header) (*execution.BlockHead
 		Block: msg,
 	}, nil
 }
+
+// additional check that when there is no event in the block, double check if the execution
+// result has no events as well, otherwise return an error.
+// we check the execution result has no event by checking if each chunk's EventCollection is
+// the default hash for empty event collection.
+func (h *handler) getEventsByBlockID(blockID flow.Identifier) ([]flow.Event, error) {
+	blockEvents, err := h.events.ByBlockID(blockID)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "failed to get events for block: %v", err)
+	}
+
+	if len(blockEvents) == 0 {
+		executionResult, err := h.exeResults.ByBlockID(blockID)
+		if err != nil {
+			return nil, status.Errorf(codes.Internal, "failed to get execution result for block %v: %v", blockID, err)
+		}
+
+		for _, chunk := range executionResult.Chunks {
+			if chunk.EventCollection != flow.EmptyEventCollectionID {
+				return nil, status.Errorf(codes.Internal, "events not found for block %s, but chunk %d has events", blockID, chunk.Index)
+			}
+		}
+	}
+
+	return blockEvents, nil
+}

engine/execution/rpc/engine_test.go

@@ -140,7 +140,7 @@ func (suite *Suite) TestGetEventsForBlockIDs() {
 		suite.commits.On("ByBlockID", id).Return(nil, nil).Once()
 
 		// expect one call to lookup events for each block ID
-		suite.events.On("ByBlockIDEventType", id, flow.EventAccountCreated).Return(eventsForBlock, nil).Once()
+		suite.events.On("ByBlockID", id).Return(eventsForBlock, nil).Once()
 
 		// expect one call to lookup each block
 		suite.headers.On("ByBlockID", id).Return(block.Header, nil).Once()

model/flow/chunk.go

@@ -1,9 +1,23 @@
 package flow
 
 import (
+	"log"
+
 	"github.com/ipfs/go-cid"
 )
 
+var EmptyEventCollectionID Identifier
+
+func init() {
+	// Convert hexadecimal string to a byte slice.
+	var err error
+	emptyEventCollectionHex := "0e5751c026e543b2e8ab2eb06099daa1d1e5df47778f7787faab45cdf12fe3a8"
+	EmptyEventCollectionID, err = HexStringToIdentifier(emptyEventCollectionHex)
+	if err != nil {
+		log.Fatalf("Failed to decode hex: %v", err)
+	}
+}
+
 type ChunkBody struct {
 	CollectionIndex uint
 

model/flow/event_test.go

@@ -4,6 +4,7 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 
 	"github.com/onflow/flow-go/model/encoding/rlp"
 	"github.com/onflow/flow-go/model/fingerprint"
@@ -118,3 +119,12 @@ func TestEventsMerkleRootHash(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Equal(t, expectedRootHashHex, ABHash.String())
 }
+
+// TestEmptyEventsMerkleRootHash validates that the `EmptyEventCollectionID` constant
+// is equal to the hash of an empty events list. If this test fails, change the hex string constant
+// populating `EmptyEventCollectionID` accordingly.
+func TestEmptyEventsMerkleRootHash(t *testing.T) {
+	actualHash, err := flow.EventsMerkleRootHash([]flow.Event{})
+	require.NoError(t, err)
+	require.Equal(t, flow.EmptyEventCollectionID, actualHash)
+}