Scott Baker | 8487c5d | 2019-10-18 12:49:46 -0700 | [diff] [blame^] | 1 | // Copyright 2019 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 connectivity implements client connectivity operations. |
| 16 | package connectivity |
| 17 | |
| 18 | import ( |
| 19 | "sync" |
| 20 | |
| 21 | "go.uber.org/zap" |
| 22 | "google.golang.org/grpc/connectivity" |
| 23 | ) |
| 24 | |
| 25 | // Recorder records gRPC connectivity. |
| 26 | type Recorder interface { |
| 27 | GetCurrentState() connectivity.State |
| 28 | RecordTransition(oldState, newState connectivity.State) |
| 29 | } |
| 30 | |
| 31 | // New returns a new Recorder. |
| 32 | func New(lg *zap.Logger) Recorder { |
| 33 | return &recorder{lg: lg} |
| 34 | } |
| 35 | |
| 36 | // recorder takes the connectivity states of multiple SubConns |
| 37 | // and returns one aggregated connectivity state. |
| 38 | // ref. https://github.com/grpc/grpc-go/blob/master/balancer/balancer.go |
| 39 | type recorder struct { |
| 40 | lg *zap.Logger |
| 41 | |
| 42 | mu sync.RWMutex |
| 43 | |
| 44 | cur connectivity.State |
| 45 | |
| 46 | numReady uint64 // Number of addrConns in ready state. |
| 47 | numConnecting uint64 // Number of addrConns in connecting state. |
| 48 | numTransientFailure uint64 // Number of addrConns in transientFailure. |
| 49 | } |
| 50 | |
| 51 | func (rc *recorder) GetCurrentState() (state connectivity.State) { |
| 52 | rc.mu.RLock() |
| 53 | defer rc.mu.RUnlock() |
| 54 | return rc.cur |
| 55 | } |
| 56 | |
| 57 | // RecordTransition records state change happening in subConn and based on that |
| 58 | // it evaluates what aggregated state should be. |
| 59 | // |
| 60 | // - If at least one SubConn in Ready, the aggregated state is Ready; |
| 61 | // - Else if at least one SubConn in Connecting, the aggregated state is Connecting; |
| 62 | // - Else the aggregated state is TransientFailure. |
| 63 | // |
| 64 | // Idle and Shutdown are not considered. |
| 65 | // |
| 66 | // ref. https://github.com/grpc/grpc-go/blob/master/balancer/balancer.go |
| 67 | func (rc *recorder) RecordTransition(oldState, newState connectivity.State) { |
| 68 | rc.mu.Lock() |
| 69 | defer rc.mu.Unlock() |
| 70 | |
| 71 | for idx, state := range []connectivity.State{oldState, newState} { |
| 72 | updateVal := 2*uint64(idx) - 1 // -1 for oldState and +1 for new. |
| 73 | switch state { |
| 74 | case connectivity.Ready: |
| 75 | rc.numReady += updateVal |
| 76 | case connectivity.Connecting: |
| 77 | rc.numConnecting += updateVal |
| 78 | case connectivity.TransientFailure: |
| 79 | rc.numTransientFailure += updateVal |
| 80 | default: |
| 81 | rc.lg.Warn("connectivity recorder received unknown state", zap.String("connectivity-state", state.String())) |
| 82 | } |
| 83 | } |
| 84 | |
| 85 | switch { // must be exclusive, no overlap |
| 86 | case rc.numReady > 0: |
| 87 | rc.cur = connectivity.Ready |
| 88 | case rc.numConnecting > 0: |
| 89 | rc.cur = connectivity.Connecting |
| 90 | default: |
| 91 | rc.cur = connectivity.TransientFailure |
| 92 | } |
| 93 | } |