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. 16package connectivity 17 18import ( 19 "sync" 20 21 "go.uber.org/zap" 22 "google.golang.org/grpc/connectivity" 23) 24 25// Recorder records gRPC connectivity. 26type Recorder interface { 27 GetCurrentState() connectivity.State 28 RecordTransition(oldState, newState connectivity.State) 29} 30 31// New returns a new Recorder. 32func 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 39type 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 51func (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 67func (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} 94