75 lines
2.6 KiB
Go
75 lines
2.6 KiB
Go
/*
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*
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* Copyright 2022 gRPC authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*/
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package balancer
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import "google.golang.org/grpc/connectivity"
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// ConnectivityStateEvaluator takes the connectivity states of multiple SubConns
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// and returns one aggregated connectivity state.
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//
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// It's not thread safe.
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type ConnectivityStateEvaluator struct {
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numReady uint64 // Number of addrConns in ready state.
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numConnecting uint64 // Number of addrConns in connecting state.
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numTransientFailure uint64 // Number of addrConns in transient failure state.
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numIdle uint64 // Number of addrConns in idle state.
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}
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// RecordTransition records state change happening in subConn and based on that
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// it evaluates what aggregated state should be.
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//
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// - If at least one SubConn in Ready, the aggregated state is Ready;
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// - Else if at least one SubConn in Connecting, the aggregated state is Connecting;
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// - Else if at least one SubConn is Idle, the aggregated state is Idle;
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// - Else if at least one SubConn is TransientFailure (or there are no SubConns), the aggregated state is Transient Failure.
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//
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// Shutdown is not considered.
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func (cse *ConnectivityStateEvaluator) RecordTransition(oldState, newState connectivity.State) connectivity.State {
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// Update counters.
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for idx, state := range []connectivity.State{oldState, newState} {
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updateVal := 2*uint64(idx) - 1 // -1 for oldState and +1 for new.
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switch state {
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case connectivity.Ready:
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cse.numReady += updateVal
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case connectivity.Connecting:
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cse.numConnecting += updateVal
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case connectivity.TransientFailure:
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cse.numTransientFailure += updateVal
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case connectivity.Idle:
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cse.numIdle += updateVal
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}
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}
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return cse.CurrentState()
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}
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// CurrentState returns the current aggregate conn state by evaluating the counters
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func (cse *ConnectivityStateEvaluator) CurrentState() connectivity.State {
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// Evaluate.
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if cse.numReady > 0 {
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return connectivity.Ready
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}
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if cse.numConnecting > 0 {
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return connectivity.Connecting
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}
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if cse.numIdle > 0 {
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return connectivity.Idle
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}
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return connectivity.TransientFailure
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}
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