fix: Panic with different composite-indexed child objects

internal/planner/multi.go

@@ -1,4 +1,4 @@
-// Copyright 2022 Democratized Data Foundation
+// Copyright 2024 Democratized Data Foundation
 //
 // Use of this software is governed by the Business Source License
 // included in the file licenses/BSL.txt.
@@ -214,22 +214,22 @@ func (s *selectNode) addSubPlan(fieldIndex int, newPlan planNode) error {
 		if err := s.planner.walkAndReplacePlan(s.source, origScan, multiscan); err != nil {
 			return err
 		}
-		// create multinode
-		multinode := &parallelNode{
+		// create parallelNode
+		parallelNode := &parallelNode{
 			p:         s.planner,
 			multiscan: multiscan,
 			docMapper: docMapper{s.source.DocumentMap()},
 		}
-		multinode.addChild(-1, s.source)
+		parallelNode.addChild(-1, s.source)
 		multiscan.addReader()
 		// replace our new node internal scanNode with our new multiscanner
 		if err := s.planner.walkAndReplacePlan(newPlan, origScan, multiscan); err != nil {
 			return err
 		}
 		// add our newly updated plan to the multinode
-		multinode.addChild(fieldIndex, newPlan)
+		parallelNode.addChild(fieldIndex, newPlan)
 		multiscan.addReader()
-		s.source = multinode
+		s.source = parallelNode
 
 	// we already have an existing parallelNode as our source
 	case *parallelNode:

internal/planner/scan.go

@@ -1,4 +1,4 @@
-// Copyright 2022 Democratized Data Foundation
+// Copyright 2024 Democratized Data Foundation
 //
 // Use of this software is governed by the Business Source License
 // included in the file licenses/BSL.txt.
@@ -325,35 +325,53 @@ func (p *Planner) Scan(
 type multiScanNode struct {
 	scanNode   *scanNode
 	numReaders int
-	numCalls   int
-
-	lastBool bool
-	lastErr  error
+	nextCount  int
+	initCount  int
+	startCount int
+	closeCount int
+
+	nextResult bool
+	nextErr    error
+	initErr    error
+	startErr   error
+	closeErr   error
 }
 
 func (n *multiScanNode) Init() error {
-	return n.scanNode.Init()
+	n.countAndCall(&n.initCount, func() {
+		n.initErr = n.scanNode.Init()
+	})
+	return n.initErr
 }
 
 func (n *multiScanNode) Start() error {
-	return n.scanNode.Start()
+	n.countAndCall(&n.startCount, func() {
+		n.startErr = n.scanNode.Start()
+	})
+	return n.startErr
 }
 
-// Next only calls Next() on the underlying
-// scanNode every numReaders.
-func (n *multiScanNode) Next() (bool, error) {
-	if n.numCalls == 0 {
-		n.lastBool, n.lastErr = n.scanNode.Next()
+func (n *multiScanNode) countAndCall(count *int, f func()) {
+	if *count == 0 {
+		f()
 	}
-	n.numCalls++
+	*count++
 
 	// if the number of calls equals the numbers of readers
-	// reset the counter, so our next call actually executes the Next()
-	if n.numCalls == n.numReaders {
-		n.numCalls = 0
+	// reset the counter, so our next call actually executes the function
+	if *count == n.numReaders {
+		*count = 0
 	}
+}
+
+// Next only calls Next() on the underlying
+// scanNode every numReaders.
+func (n *multiScanNode) Next() (bool, error) {
+	n.countAndCall(&n.nextCount, func() {
+		n.nextResult, n.nextErr = n.scanNode.Next()
+	})
 
-	return n.lastBool, n.lastErr
+	return n.nextResult, n.nextErr
 }
 
 func (n *multiScanNode) Value() core.Doc {
@@ -373,7 +391,10 @@ func (n *multiScanNode) Kind() string {
 }
 
 func (n *multiScanNode) Close() error {
-	return n.scanNode.Close()
+	n.countAndCall(&n.closeCount, func() {
+		n.closeErr = n.scanNode.Close()
+	})
+	return n.closeErr
 }
 
 func (n *multiScanNode) DocumentMap() *core.DocumentMapping {

tests/integration/index/query_with_composite_inxed_on_relation_test.go

@@ -0,0 +1,116 @@
+// Copyright 2024 Democratized Data Foundation
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+package index
+
+import (
+	"testing"
+
+	testUtils "github.com/sourcenetwork/defradb/tests/integration"
+)
+
+// This test was added during https://github.com/sourcenetwork/defradb/issues/2924
+// The issue was that [multiScanNode] that keeps track of how many calls to [Next()] should
+// be made, would call [Init()] and [Start()] every time without tracking, which would result
+// in child nodes being initialized and started multiple times, which in turn created
+// index iterators without closing them.
+func TestQueryWithCompositeIndexOnManyToOne_WithMultipleIndexedChildNodes_ShouldSucceed(t *testing.T) {
+	test := testUtils.TestCase{
+		Actions: []any{
+			testUtils.SchemaUpdate{
+				Schema: `
+					type User {
+						name: String 
+						devices: [Device]
+					}
+
+					type Device @index(fields: ["owner_id", "manufacturer_id"]) {
+						model: String
+						owner: User 
+						manufacturer: Manufacturer 
+					}
+
+					type Manufacturer {
+						name: String
+						devices: [Device]
+					}
+				`,
+			},
+			testUtils.CreateDoc{
+				DocMap: map[string]any{
+					"name": "John",
+				},
+			},
+			testUtils.CreateDoc{
+				CollectionID: 2,
+				DocMap: map[string]any{
+					"name": "Apple",
+				},
+			},
+			testUtils.CreateDoc{
+				CollectionID: 2,
+				DocMap: map[string]any{
+					"name": "Sony",
+				},
+			},
+			testUtils.CreateDoc{
+				CollectionID: 1,
+				DocMap: map[string]any{
+					"model":        "MacBook Pro",
+					"owner":        testUtils.NewDocIndex(0, 0),
+					"manufacturer": testUtils.NewDocIndex(2, 0),
+				},
+			},
+			testUtils.CreateDoc{
+				CollectionID: 1,
+				DocMap: map[string]any{
+					"model":        "PlayStation 5",
+					"owner":        testUtils.NewDocIndex(0, 0),
+					"manufacturer": testUtils.NewDocIndex(2, 1),
+				},
+			},
+			testUtils.Request{
+				Request: `query {
+					User {
+						devices {
+							model
+							owner {
+								name
+							}
+							manufacturer {
+								name
+							}
+						}
+					}
+				}`,
+				Results: map[string]any{
+					"User": []map[string]any{
+						{
+							"devices": []map[string]any{
+								{
+									"model":        "MacBook Pro",
+									"owner":        map[string]any{"name": "John"},
+									"manufacturer": map[string]any{"name": "Apple"},
+								},
+								{
+									"model":        "PlayStation 5",
+									"owner":        map[string]any{"name": "John"},
+									"manufacturer": map[string]any{"name": "Sony"},
+								},
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	testUtils.ExecuteTestCase(t, test)
+}