59 lines
2.2 KiB
Go
59 lines
2.2 KiB
Go
|
// 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
|
||
|
}
|