3 * Copyright 2017 gRPC authors.
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
9 * http://www.apache.org/licenses/LICENSE-2.0
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.
19 // Package base defines a balancer base that can be used to build balancers with
20 // different picking algorithms.
22 // The base balancer creates a new SubConn for each resolved address. The
23 // provided picker will only be notified about READY SubConns.
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.
30 // All APIs in this package are experimental.
34 "google.golang.org/grpc/balancer"
35 "google.golang.org/grpc/resolver"
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
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 NewBalancerBuilderWithConfig(name, pb, Config{})
51 // Config contains the config info about the base balancer builder.
53 // HealthCheck indicates whether health checking should be enabled for this specific balancer.
57 // NewBalancerBuilderWithConfig returns a base balancer builder configured by the provided config.
58 func NewBalancerBuilderWithConfig(name string, pb PickerBuilder, config Config) balancer.Builder {