config.go

Documentation: google.golang.org/grpc/xds/internal/balancer/priority

     1  /*
     2   *
     3   * Copyright 2020 gRPC authors.
     4   *
     5   * Licensed under the Apache License, Version 2.0 (the "License");
     6   * you may not use this file except in compliance with the License.
     7   * You may obtain a copy of the License at
     8   *
     9   *     http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   *
    17   */
    18  
    19  package priority
    20  
    21  import (
    22  	"encoding/json"
    23  	"fmt"
    24  
    25  	internalserviceconfig "google.golang.org/grpc/internal/serviceconfig"
    26  	"google.golang.org/grpc/serviceconfig"
    27  )
    28  
    29  // Child is a child of priority balancer.
    30  type Child struct {
    31  	Config                     *internalserviceconfig.BalancerConfig `json:"config,omitempty"`
    32  	IgnoreReresolutionRequests bool                                  `json:"ignoreReresolutionRequests,omitempty"`
    33  }
    34  
    35  // LBConfig represents priority balancer's config.
    36  type LBConfig struct {
    37  	serviceconfig.LoadBalancingConfig `json:"-"`
    38  
    39  	// Children is a map from the child balancer names to their configs. Child
    40  	// names can be found in field Priorities.
    41  	Children map[string]*Child `json:"children,omitempty"`
    42  	// Priorities is a list of child balancer names. They are sorted from
    43  	// highest priority to low. The type/config for each child can be found in
    44  	// field Children, with the balancer name as the key.
    45  	Priorities []string `json:"priorities,omitempty"`
    46  }
    47  
    48  func parseConfig(c json.RawMessage) (*LBConfig, error) {
    49  	var cfg LBConfig
    50  	if err := json.Unmarshal(c, &cfg); err != nil {
    51  		return nil, err
    52  	}
    53  
    54  	prioritiesSet := make(map[string]bool)
    55  	for _, name := range cfg.Priorities {
    56  		if _, ok := cfg.Children[name]; !ok {
    57  			return nil, fmt.Errorf("LB policy name %q found in Priorities field (%v) is not found in Children field (%+v)", name, cfg.Priorities, cfg.Children)
    58  		}
    59  		prioritiesSet[name] = true
    60  	}
    61  	for name := range cfg.Children {
    62  		if _, ok := prioritiesSet[name]; !ok {
    63  			return nil, fmt.Errorf("LB policy name %q found in Children field (%v) is not found in Priorities field (%+v)", name, cfg.Children, cfg.Priorities)
    64  		}
    65  	}
    66  	return &cfg, nil
    67  }
    68
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