text: /*
   *
   * Copyright 2017 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 base defines a balancer base that can be used to build balancers with
  // different picking algorithms.
  //
  // The base balancer creates a new SubConn for each resolved address. The
  // provided picker will only be notified about READY SubConns.
  //
  // This package is the base of round_robin balancer, its purpose is to be used
  // to build round_robin like balancers with complex picking algorithms.
  // Balancers with more complicated logic should try to implement a balancer
  // builder from scratch.
  //
  // All APIs in this package are experimental.
  package base
  
  import (
  	"google.golang.org/grpc/balancer"
  	"google.golang.org/grpc/resolver"
  )
  
  // PickerBuilder creates balancer.Picker.
  type PickerBuilder interface {
  	// Build takes a slice of ready SubConns, and returns a picker that will be
  	// used by gRPC to pick a SubConn.
  	Build(readySCs map[resolver.Address]balancer.SubConn) balancer.Picker
  }
  
  // NewBalancerBuilder returns a balancer builder. The balancers
  // built by this builder will use the picker builder to build pickers.
  func NewBalancerBuilder(name string, pb PickerBuilder) balancer.Builder {
  	return NewBalancerBuilderWithConfig(name, pb, Config{})
  }
  
  // Config contains the config info about the base balancer builder.
  type Config struct {
  	// HealthCheck indicates whether health checking should be enabled for this specific balancer.
  	HealthCheck bool
  }
  
  // NewBalancerBuilderWithConfig returns a base balancer builder configured by the provided config.
  func NewBalancerBuilderWithConfig(name string, pb PickerBuilder, config Config) balancer.Builder {
  	return &baseBuilder{
  		name:          name,
  		pickerBuilder: pb,
  		config:        config,
  	}
  }
  