1 /* 2 * 3 * Copyright 2017 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 base defines a balancer base that can be used to build balancers with 20 // different picking algorithms. 21 // 22 // The base balancer creates a new SubConn for each resolved address. The 23 // provided picker will only be notified about READY SubConns. 24 // 25 // This package is the base of round_robin balancer, its purpose is to be used 26 // to build round_robin like balancers with complex picking algorithms. 27 // Balancers with more complicated logic should try to implement a balancer 28 // builder from scratch. 29 // 30 // All APIs in this package are experimental. 31 package base 32 33 import ( 34 "google.golang.org/grpc/balancer" 35 "google.golang.org/grpc/resolver" 36 ) 37 38 // PickerBuilder creates balancer.Picker. 39 type PickerBuilder interface { 40 // Build takes a slice of ready SubConns, and returns a picker that will be 41 // used by gRPC to pick a SubConn. 42 Build(readySCs map[resolver.Address]balancer.SubConn) balancer.Picker 43 } 44 45 // NewBalancerBuilder returns a balancer builder. The balancers 46 // built by this builder will use the picker builder to build pickers. 47 func NewBalancerBuilder(name string, pb PickerBuilder) balancer.Builder { 48 return &baseBuilder{ 49 name: name, 50 pickerBuilder: pb, 51 } 52 } 53
