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// Copyright 2017 Google Inc. All Rights Reserved.
//
// 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 jsonclient
import (
"sync"
"time"
)
type backoff struct {
mu sync.RWMutex
multiplier uint
notBefore time.Time
}
const (
// maximum backoff is 2^(maxMultiplier-1) = 128 seconds
maxMultiplier = 8
)
func (b *backoff) set(override *time.Duration) time.Duration {
b.mu.Lock()
defer b.mu.Unlock()
if b.notBefore.After(time.Now()) {
if override != nil {
// If existing backoff is set but override would be longer than
// it then set it to that.
notBefore := time.Now().Add(*override)
if notBefore.After(b.notBefore) {
b.notBefore = notBefore
}
}
return time.Until(b.notBefore)
}
var wait time.Duration
if override != nil {
wait = *override
} else {
if b.multiplier < maxMultiplier {
b.multiplier++
}
wait = time.Second * time.Duration(1<<(b.multiplier-1))
}
b.notBefore = time.Now().Add(wait)
return wait
}
func (b *backoff) decreaseMultiplier() {
b.mu.Lock()
defer b.mu.Unlock()
if b.multiplier > 0 {
b.multiplier--
}
}
func (b *backoff) until() time.Time {
b.mu.RLock()
defer b.mu.RUnlock()
return b.notBefore
}
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