istio

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/*
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Copyright 2019 The Kubernetes Authors.
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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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    http://www.apache.org/licenses/LICENSE-2.0
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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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package k8sresourcelock
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import (
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	"bytes"
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	"context"
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	"encoding/json"
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	kerrors "k8s.io/apimachinery/pkg/api/errors"
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)
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const (
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	UnknownLeader = "leaderelection.k8s.io/unknown"
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)
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// MultiLock is used for lock's migration
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type MultiLock struct {
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	Primary   Interface
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	Secondary Interface
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}
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// Get returns the older election record of the lock
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func (ml *MultiLock) Get(ctx context.Context) (*LeaderElectionRecord, []byte, error) {
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	primary, primaryRaw, err := ml.Primary.Get(ctx)
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	if err != nil {
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		return nil, nil, err
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	}
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	secondary, secondaryRaw, err := ml.Secondary.Get(ctx)
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	if err != nil {
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		// Lock is held by old client
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		if kerrors.IsNotFound(err) && primary.HolderIdentity != ml.Identity() {
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			return primary, primaryRaw, nil
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		}
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		return nil, nil, err
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	}
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	if primary.HolderIdentity != secondary.HolderIdentity {
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		primary.HolderIdentity = UnknownLeader
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		primaryRaw, err = json.Marshal(primary)
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		if err != nil {
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			return nil, nil, err
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		}
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	}
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	return primary, ConcatRawRecord(primaryRaw, secondaryRaw), nil
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}
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// Create attempts to create both primary lock and secondary lock
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func (ml *MultiLock) Create(ctx context.Context, ler LeaderElectionRecord) error {
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	err := ml.Primary.Create(ctx, ler)
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	if err != nil && !kerrors.IsAlreadyExists(err) {
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		return err
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	}
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	return ml.Secondary.Create(ctx, ler)
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}
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// Update will update and existing annotation on both two resources.
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func (ml *MultiLock) Update(ctx context.Context, ler LeaderElectionRecord) error {
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	err := ml.Primary.Update(ctx, ler)
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	if err != nil {
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		return err
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	}
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	_, _, err = ml.Secondary.Get(ctx)
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	if err != nil && kerrors.IsNotFound(err) {
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		return ml.Secondary.Create(ctx, ler)
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	}
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	return ml.Secondary.Update(ctx, ler)
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}
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// RecordEvent in leader election while adding meta-data
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func (ml *MultiLock) RecordEvent(s string) {
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	ml.Primary.RecordEvent(s)
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	ml.Secondary.RecordEvent(s)
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}
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// Describe is used to convert details on current resource lock
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// into a string
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func (ml *MultiLock) Describe() string {
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	return ml.Primary.Describe()
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}
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// Identity returns the Identity of the lock
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func (ml *MultiLock) Identity() string {
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	return ml.Primary.Identity()
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}
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// Key returns the Key of the lock
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func (ml *MultiLock) Key() string {
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	return ml.Primary.Key()
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}
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func ConcatRawRecord(primaryRaw, secondaryRaw []byte) []byte {
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	return bytes.Join([][]byte{primaryRaw, secondaryRaw}, []byte(","))
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}
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