Add test to illustrate updating tenantQuerierAssignments outside of tree

pkg/scheduler/queue/tree_queue_sketch.go

@@ -89,12 +89,12 @@ func (t *Tree) newNode(name string, depth int) TreeNodeIFace {
 		}
 	case shuffleShard:
 		return &ShuffleShardNode{
-			name:            name,
-			localQueue:      list.New(),
-			queueOrder:      make([]string, 0),
-			queueMap:        make(map[string]TreeNodeIFace, 1),
-			depth:           depth,
-			stateUpdateInfo: t.ShuffleShardState,
+			name:              name,
+			localQueue:        list.New(),
+			queueOrder:        make([]string, 0),
+			queueMap:          make(map[string]TreeNodeIFace, 1),
+			depth:             depth,
+			ShuffleShardState: t.ShuffleShardState,
 		}
 	default:
 		panic("no defined node type at provided depth")
@@ -218,13 +218,13 @@ func (rrn *RoundRobinNode) IsEmpty() bool {
 }
 
 type ShuffleShardNode struct {
-	name            string
-	localQueue      *list.List // should never be populated
-	queuePosition   int
-	queueOrder      []string // will be a slice of tenants (+ self?)
-	queueMap        map[string]TreeNodeIFace
-	depth           int
-	stateUpdateInfo *ShuffleShardState
+	name          string
+	localQueue    *list.List // should never be populated
+	queuePosition int
+	queueOrder    []string // will be a slice of tenants (+ self?)
+	queueMap      map[string]TreeNodeIFace
+	depth         int
+	*ShuffleShardState
 }
 
 func (ssn *ShuffleShardNode) Name() string {
@@ -242,6 +242,11 @@ func (ssn *ShuffleShardNode) dequeue() (path QueuePath, v any) {
 		return path, nil
 	}
 
+	// can't get a tenant if no querier set
+	if ssn.currentQuerier == nil {
+		return path, nil
+	}
+
 	// no children, but has a non-zero length local queue -- should probably never happen?
 	if len(ssn.queueOrder) == 0 {
 		if elt := ssn.localQueue.Front(); elt != nil {
@@ -274,8 +279,8 @@ func (ssn *ShuffleShardNode) dequeueGetNode() (string, TreeNodeIFace) {
 			checkIndex = 0
 		}
 		tenantName := ssn.queueOrder[checkIndex]
-		if tenantQuerierSet, ok := ssn.stateUpdateInfo.tenantQuerierMap[TenantID(tenantName)]; ok {
-			if _, ok := tenantQuerierSet[*ssn.stateUpdateInfo.currentQuerier]; ok {
+		if tenantQuerierSet, ok := ssn.tenantQuerierMap[TenantID(tenantName)]; ok {
+			if _, ok := tenantQuerierSet[*ssn.currentQuerier]; ok {
 				return tenantName, ssn.queueMap[tenantName]
 			}
 		}

pkg/scheduler/queue/tree_queue_sketch_test.go

@@ -1,7 +1,6 @@
 package queue
 
 import (
-	"fmt"
 	"github.com/stretchr/testify/require"
 	"testing"
 )
@@ -207,7 +206,6 @@ func Test_RoundRobinDequeue(t *testing.T) {
 			var finalValue any
 			for i := 0; i < tt.numDequeuesToExpected; i++ {
 				_, finalValue = tree.Dequeue()
-				fmt.Println("v: ", finalValue)
 			}
 			v, ok := finalValue.(string)
 			require.True(t, ok)
@@ -324,3 +322,44 @@ func Test_ShuffleShardDequeue(t *testing.T) {
 	}
 
 }
+
+// This test is a little messy; I can clean it up, but it's meant to illustrate that we can update a state
+// in tenantQuerierAssignments, and the tree dequeue behavior will adjust accordingly.
+func Test_ChangeShuffleShardState(t *testing.T) {
+	tqa := tenantQuerierAssignments{
+		tenantQuerierIDs: map[TenantID]map[QuerierID]struct{}{"tenant-1": {"querier-1": {}}, "tenant-2": {"querier-2": {}}},
+	}
+
+	state := &ShuffleShardState{
+		tenantQuerierMap: tqa.tenantQuerierIDs,
+		currentQuerier:   nil,
+	}
+
+	tree, err := NewTree([]NodeType{shuffleShard, roundRobin, roundRobin}, state)
+	require.NoError(t, err)
+	err = tree.EnqueueBackByPath(QueuePath{"tenant-1", "query-component-1"}, "query-1")
+	err = tree.EnqueueBackByPath(QueuePath{"tenant-2", "query-component-1"}, "query-2")
+	err = tree.EnqueueBackByPath(QueuePath{"tenant-2", "query-component-1"}, "query-3")
+	require.NoError(t, err)
+
+	querier1 := QuerierID("querier-1")
+	querier2 := QuerierID("querier-2")
+	querier3 := QuerierID("querier-3")
+
+	// set state to querier-2 should dequeue query-2
+	state.currentQuerier = &querier2
+	_, v := tree.Dequeue()
+	require.Equal(t, "query-2", v)
+
+	// set state to querier-1 should dequeue query-1
+	state.currentQuerier = &querier1
+	_, v = tree.Dequeue()
+	require.Equal(t, "query-1", v)
+
+	// update tqa map to assign querier-3 to tenant-2, then set state to querier-3 should dequeue query-3
+	tqa.tenantQuerierIDs["tenant-2"]["querier-3"] = struct{}{}
+	state.currentQuerier = &querier3
+	_, v = tree.Dequeue()
+	require.Equal(t, "query-3", v)
+
+}