open-vault/vendor/go.etcd.io/etcd/clientv3/balancer/connectivity.go

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// Copyright 2018 The etcd Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package balancer
import "google.golang.org/grpc/connectivity"
// connectivityStateEvaluator gets updated by addrConns when their
// states transition, based on which it evaluates the state of
// ClientConn.
type connectivityStateEvaluator struct {
numReady uint64 // Number of addrConns in ready state.
numConnecting uint64 // Number of addrConns in connecting state.
numTransientFailure uint64 // Number of addrConns in transientFailure.
}
// recordTransition records state change happening in every subConn and based on
// that it evaluates what aggregated state should be.
// It can only transition between Ready, Connecting and TransientFailure. Other states,
// Idle and Shutdown are transitioned into by ClientConn; in the beginning of the connection
// before any subConn is created ClientConn is in idle state. In the end when ClientConn
// closes it is in Shutdown state.
//
// recordTransition should only be called synchronously from the same goroutine.
func (cse *connectivityStateEvaluator) recordTransition(oldState, newState connectivity.State) connectivity.State {
// Update counters.
for idx, state := range []connectivity.State{oldState, newState} {
updateVal := 2*uint64(idx) - 1 // -1 for oldState and +1 for new.
switch state {
case connectivity.Ready:
cse.numReady += updateVal
case connectivity.Connecting:
cse.numConnecting += updateVal
case connectivity.TransientFailure:
cse.numTransientFailure += updateVal
}
}
// Evaluate.
if cse.numReady > 0 {
return connectivity.Ready
}
if cse.numConnecting > 0 {
return connectivity.Connecting
}
return connectivity.TransientFailure
}