interface.go

/*
Copyright 2016 The Kubernetes 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.
*/

// Modified by Swisscom (Schweiz) AG.
// Copyright 2024 Swisscom (Schweiz) AG

package leaselocker

import (
	"context"

	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/client-go/tools/record"
)

// LockRecord is the record that is stored in the lease.
// This information should be used for observational purposes only and could be replaced
// with a random string (e.g. UUID) with only slight modification of this code.
type LockRecord struct {
	Identity string
	// HolderIdentity is the ID that owns the lease. If empty, no one owns this lease and
	// all callers may acquire. Versions of this library prior to Kubernetes 1.14 will not
	// attempt to acquire leases with empty identities and will wait for the full lease
	// interval to expire before attempting to reacquire. This value is set to empty when
	// a client voluntarily steps down.
	HolderIdentity       string      `json:"holderIdentity"`
	LeaseDurationSeconds int         `json:"leaseDurationSeconds"`
	AcquireTime          metav1.Time `json:"acquireTime"`
	RenewTime            metav1.Time `json:"renewTime"`
	LeaseTransitions     int         `json:"leaseTransitions"`
}

// ResourceLockConfig common data that exists across different
// resource locks
type ResourceLockConfig struct {
	// Identity is the unique string identifying a lock holder across
	// all participants.
	Identity string
	// EventRecorder is optional.
	EventRecorder record.EventRecorder
}

// Interface offers a common interface for locking on arbitrary
// resources used in locking. The Interface is used
// to hide the details on specific implementations in order to allow
// them to change over time.  This interface is strictly for use
// by the leaselocker code.
type Interface interface {
	// Get returns the LockRecord
	Get(ctx context.Context) (*LockRecord, []byte, error)

	// Create attempts to create a LockRecord
	Create(ctx context.Context, lr LockRecord) error

	// Update will update and existing LockRecord
	Update(ctx context.Context, lr LockRecord) error

	// RecordEvent is used to record events
	RecordEvent(string)

	// Identity will return the locks Identity
	Identity() string

	// Describe is used to convert details on current resource lock
	// into a string
	Describe() string
}