Takahiro Suzuki | 241c10e | 2020-12-17 20:17:57 +0900 | [diff] [blame] | 1 | // Copyright 2018 The etcd Authors |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | // you may not use this file except in compliance with the License. |
| 5 | // You may obtain a copy of the License at |
| 6 | // |
| 7 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | // See the License for the specific language governing permissions and |
| 13 | // limitations under the License. |
| 14 | |
| 15 | package picker |
| 16 | |
| 17 | import ( |
| 18 | "context" |
| 19 | "sync" |
| 20 | |
| 21 | "go.uber.org/zap" |
| 22 | "go.uber.org/zap/zapcore" |
| 23 | "google.golang.org/grpc/balancer" |
| 24 | "google.golang.org/grpc/resolver" |
| 25 | ) |
| 26 | |
| 27 | // newRoundrobinBalanced returns a new roundrobin balanced picker. |
| 28 | func newRoundrobinBalanced(cfg Config) Picker { |
| 29 | scs := make([]balancer.SubConn, 0, len(cfg.SubConnToResolverAddress)) |
| 30 | for sc := range cfg.SubConnToResolverAddress { |
| 31 | scs = append(scs, sc) |
| 32 | } |
| 33 | return &rrBalanced{ |
| 34 | p: RoundrobinBalanced, |
| 35 | lg: cfg.Logger, |
| 36 | scs: scs, |
| 37 | scToAddr: cfg.SubConnToResolverAddress, |
| 38 | } |
| 39 | } |
| 40 | |
| 41 | type rrBalanced struct { |
| 42 | p Policy |
| 43 | |
| 44 | lg *zap.Logger |
| 45 | |
| 46 | mu sync.RWMutex |
| 47 | next int |
| 48 | scs []balancer.SubConn |
| 49 | scToAddr map[balancer.SubConn]resolver.Address |
| 50 | } |
| 51 | |
| 52 | func (rb *rrBalanced) String() string { return rb.p.String() } |
| 53 | |
| 54 | // Pick is called for every client request. |
| 55 | func (rb *rrBalanced) Pick(ctx context.Context, opts balancer.PickOptions) (balancer.SubConn, func(balancer.DoneInfo), error) { |
| 56 | rb.mu.RLock() |
| 57 | n := len(rb.scs) |
| 58 | rb.mu.RUnlock() |
| 59 | if n == 0 { |
| 60 | return nil, nil, balancer.ErrNoSubConnAvailable |
| 61 | } |
| 62 | |
| 63 | rb.mu.Lock() |
| 64 | cur := rb.next |
| 65 | sc := rb.scs[cur] |
| 66 | picked := rb.scToAddr[sc].Addr |
| 67 | rb.next = (rb.next + 1) % len(rb.scs) |
| 68 | rb.mu.Unlock() |
| 69 | |
| 70 | rb.lg.Debug( |
| 71 | "picked", |
| 72 | zap.String("picker", rb.p.String()), |
| 73 | zap.String("address", picked), |
| 74 | zap.Int("subconn-index", cur), |
| 75 | zap.Int("subconn-size", n), |
| 76 | ) |
| 77 | |
| 78 | doneFunc := func(info balancer.DoneInfo) { |
| 79 | // TODO: error handling? |
| 80 | fss := []zapcore.Field{ |
| 81 | zap.Error(info.Err), |
| 82 | zap.String("picker", rb.p.String()), |
| 83 | zap.String("address", picked), |
| 84 | zap.Bool("success", info.Err == nil), |
| 85 | zap.Bool("bytes-sent", info.BytesSent), |
| 86 | zap.Bool("bytes-received", info.BytesReceived), |
| 87 | } |
| 88 | if info.Err == nil { |
| 89 | rb.lg.Debug("balancer done", fss...) |
| 90 | } else { |
| 91 | rb.lg.Warn("balancer failed", fss...) |
| 92 | } |
| 93 | } |
| 94 | return sc, doneFunc, nil |
| 95 | } |