mirror of
https://github.com/etcd-io/etcd.git
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113 lines
4.0 KiB
Go
113 lines
4.0 KiB
Go
// Copyright 2022 The etcd 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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package model
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import (
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"encoding/json"
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"fmt"
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"reflect"
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"github.com/anishathalye/porcupine"
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)
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// NonDeterministicModel extends DeterministicModel to allow for clients with imperfect knowledge of request destiny.
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// Unknown/error response doesn't inform whether request was persisted or not, so model
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// considers both cases. This is represented as multiple equally possible deterministic states.
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// Failed requests fork the possible states, while successful requests merge and filter them.
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var NonDeterministicModel = porcupine.Model{
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Init: func() interface{} {
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var states nonDeterministicState
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data, err := json.Marshal(states)
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if err != nil {
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panic(err)
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}
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return string(data)
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},
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Step: func(st interface{}, in interface{}, out interface{}) (bool, interface{}) {
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var states nonDeterministicState
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err := json.Unmarshal([]byte(st.(string)), &states)
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if err != nil {
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panic(err)
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}
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ok, states := states.Step(in.(EtcdRequest), out.(MaybeEtcdResponse))
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data, err := json.Marshal(states)
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if err != nil {
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panic(err)
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}
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return ok, string(data)
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},
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DescribeOperation: func(in, out interface{}) string {
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return fmt.Sprintf("%s -> %s", describeEtcdRequest(in.(EtcdRequest)), describeEtcdResponse(in.(EtcdRequest), out.(MaybeEtcdResponse)))
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},
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}
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type nonDeterministicState []etcdState
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func (states nonDeterministicState) Step(request EtcdRequest, response MaybeEtcdResponse) (bool, nonDeterministicState) {
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if len(states) == 0 {
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if response.Err == nil && !response.PartialResponse {
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return true, nonDeterministicState{initState(request, response.EtcdResponse)}
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}
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states = nonDeterministicState{emptyState()}
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}
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var newStates nonDeterministicState
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switch {
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case response.Err != nil:
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newStates = states.stepFailedRequest(request)
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case response.PartialResponse:
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newStates = states.stepPartialRequest(request, response.EtcdResponse.Revision)
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default:
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newStates = states.stepSuccessfulRequest(request, response.EtcdResponse)
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}
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return len(newStates) > 0, newStates
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}
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// stepFailedRequest duplicates number of states by considering request persisted and lost.
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func (states nonDeterministicState) stepFailedRequest(request EtcdRequest) nonDeterministicState {
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newStates := make(nonDeterministicState, 0, len(states)*2)
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for _, s := range states {
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newStates = append(newStates, s)
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newState, _ := s.step(request)
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if !reflect.DeepEqual(newState, s) {
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newStates = append(newStates, newState)
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}
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}
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return newStates
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}
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// stepPartialRequest filters possible states by leaving ony states that would return proper revision.
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func (states nonDeterministicState) stepPartialRequest(request EtcdRequest, responseRevision int64) nonDeterministicState {
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newStates := make(nonDeterministicState, 0, len(states))
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for _, s := range states {
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newState, modelResponse := s.step(request)
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if modelResponse.Revision == responseRevision {
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newStates = append(newStates, newState)
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}
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}
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return newStates
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}
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// stepSuccessfulRequest filters possible states by leaving ony states that would respond correctly.
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func (states nonDeterministicState) stepSuccessfulRequest(request EtcdRequest, response EtcdResponse) nonDeterministicState {
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newStates := make(nonDeterministicState, 0, len(states))
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for _, s := range states {
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newState, modelResponse := s.step(request)
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if Match(modelResponse, MaybeEtcdResponse{EtcdResponse: response}) {
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newStates = append(newStates, newState)
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}
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}
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return newStates
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}
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