/*
Copyright 2017 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.
*/

package ipam

import (
	"time"
)

// Timeout manages the resync loop timing for a given node sync operation. The
// timeout changes depending on whether or not there was an error reported for
// the operation. Consecutive errors will result in exponential backoff to a
// maxBackoff timeout.
type Timeout struct {
	// Resync is the default timeout duration when there are no errors.
	Resync time.Duration
	// MaxBackoff is the maximum timeout when in a error backoff state.
	MaxBackoff time.Duration
	// InitialRetry is the initial retry interval when an error is reported.
	InitialRetry time.Duration

	// errs is the count of consecutive errors that have occurred.
	errs int
	// current is the current backoff timeout.
	current time.Duration
}

// Update the timeout with the current error state.
func (b *Timeout) Update(ok bool) {
	if ok {
		b.errs = 0
		b.current = b.Resync
		return
	}

	b.errs++
	if b.errs == 1 {
		b.current = b.InitialRetry
		return
	}

	b.current *= 2
	if b.current >= b.MaxBackoff {
		b.current = b.MaxBackoff
	}
}

// Next returns the next operation timeout given the disposition of err.
func (b *Timeout) Next() time.Duration {
	if b.errs == 0 {
		return b.Resync
	}
	return b.current
}