snapshot of https://github.com/grpc/grpc-go.git (master, 2026-09-15; blobs > 131072B omitted)

internal/xds/balancer/clustermanager/picker.go

@@ -0,0 +1,65 @@
+/*
+ *
+ * Copyright 2020 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package clustermanager
+
+import (
+	"context"
+
+	"google.golang.org/grpc/balancer"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+// pickerGroup contains a list of pickers. If the picker isn't ready, the pick
+// will be queued.
+type pickerGroup struct {
+	pickers map[string]balancer.Picker
+}
+
+func newPickerGroup(idToPickerState map[string]*subBalancerState) *pickerGroup {
+	pickers := make(map[string]balancer.Picker)
+	for id, st := range idToPickerState {
+		pickers[id] = st.state.Picker
+	}
+	return &pickerGroup{
+		pickers: pickers,
+	}
+}
+
+func (pg *pickerGroup) Pick(info balancer.PickInfo) (balancer.PickResult, error) {
+	cluster := PickedCluster(info.Ctx)
+	if p := pg.pickers[cluster]; p != nil {
+		return p.Pick(info)
+	}
+	return balancer.PickResult{}, status.Errorf(codes.Unavailable, "unknown cluster selected for RPC: %q", cluster)
+}
+
+type clusterKey struct{}
+
+// PickedCluster returns the cluster name stored in the context.
+func PickedCluster(ctx context.Context) string {
+	cluster, _ := ctx.Value(clusterKey{}).(string)
+	return cluster
+}
+
+// SetPickedCluster adds the selected cluster to the context for the
+// xds_cluster_manager LB policy to pick.
+func SetPickedCluster(ctx context.Context, cluster string) context.Context {
+	return context.WithValue(ctx, clusterKey{}, cluster)
+}