| // Copyright 2015 The LUCI 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 retry |
| |
| import ( |
| "context" |
| "time" |
| ) |
| |
| // ExponentialBackoff is an Iterator implementation that implements exponential |
| // backoff retry. |
| type ExponentialBackoff struct { |
| Limited |
| |
| // Multiplier is the exponential growth multiplier. If < 1, a default of 2 |
| // will be used. |
| Multiplier float64 |
| // MaxDelay is the maximum duration. If <= zero, no maximum will be enforced. |
| MaxDelay time.Duration |
| } |
| |
| // Next implements Iterator. |
| func (b *ExponentialBackoff) Next(ctx context.Context, err error) time.Duration { |
| // Get Limited base delay. |
| delay := b.Limited.Next(ctx, err) |
| if delay == Stop { |
| return Stop |
| } |
| |
| // Bound our delay. |
| if b.MaxDelay > 0 && b.MaxDelay < delay { |
| delay = b.MaxDelay |
| } else { |
| // Calculate the next delay exponentially. |
| multiplier := b.Multiplier |
| if multiplier < 1 { |
| multiplier = 2 |
| } |
| b.Delay = time.Duration(float64(b.Delay) * multiplier) |
| } |
| return delay |
| } |