TUN-8407: Upgrade go to version 1.22.2

vendor/google.golang.org/grpc/internal/balancer/gracefulswitch/config.go

@@ -0,0 +1,83 @@
+/*
+ *
+ * Copyright 2024 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 gracefulswitch
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"google.golang.org/grpc/balancer"
+	"google.golang.org/grpc/serviceconfig"
+)
+
+type lbConfig struct {
+	serviceconfig.LoadBalancingConfig
+
+	childBuilder balancer.Builder
+	childConfig  serviceconfig.LoadBalancingConfig
+}
+
+func ChildName(l serviceconfig.LoadBalancingConfig) string {
+	return l.(*lbConfig).childBuilder.Name()
+}
+
+// ParseConfig parses a child config list and returns a LB config for the
+// gracefulswitch Balancer.
+//
+// cfg is expected to be a json.RawMessage containing a JSON array of LB policy
+// names + configs as the format of the "loadBalancingConfig" field in
+// ServiceConfig.  It returns a type that should be passed to
+// UpdateClientConnState in the BalancerConfig field.
+func ParseConfig(cfg json.RawMessage) (serviceconfig.LoadBalancingConfig, error) {
+	var lbCfg []map[string]json.RawMessage
+	if err := json.Unmarshal(cfg, &lbCfg); err != nil {
+		return nil, err
+	}
+	for i, e := range lbCfg {
+		if len(e) != 1 {
+			return nil, fmt.Errorf("expected a JSON struct with one entry; received entry %v at index %d", e, i)
+		}
+
+		var name string
+		var jsonCfg json.RawMessage
+		for name, jsonCfg = range e {
+		}
+
+		builder := balancer.Get(name)
+		if builder == nil {
+			// Skip unregistered balancer names.
+			continue
+		}
+
+		parser, ok := builder.(balancer.ConfigParser)
+		if !ok {
+			// This is a valid child with no config.
+			return &lbConfig{childBuilder: builder}, nil
+		}
+
+		cfg, err := parser.ParseConfig(jsonCfg)
+		if err != nil {
+			return nil, fmt.Errorf("error parsing config for policy %q: %v", name, err)
+		}
+
+		return &lbConfig{childBuilder: builder, childConfig: cfg}, nil
+	}
+
+	return nil, fmt.Errorf("no supported policies found in config: %v", string(cfg))
+}