74 lines
2.3 KiB
Go
74 lines
2.3 KiB
Go
/*
|
|
*
|
|
* Copyright 2017 gRPC 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 backoff implement the backoff strategy for gRPC.
|
|
//
|
|
// This is kept in internal until the gRPC project decides whether or not to
|
|
// allow alternative backoff strategies.
|
|
package backoff
|
|
|
|
import (
|
|
"time"
|
|
|
|
grpcbackoff "google.golang.org/grpc/backoff"
|
|
"google.golang.org/grpc/internal/grpcrand"
|
|
)
|
|
|
|
// Strategy defines the methodology for backing off after a grpc connection
|
|
// failure.
|
|
type Strategy interface {
|
|
// Backoff returns the amount of time to wait before the next retry given
|
|
// the number of consecutive failures.
|
|
Backoff(retries int) time.Duration
|
|
}
|
|
|
|
// DefaultExponential is an exponential backoff implementation using the
|
|
// default values for all the configurable knobs defined in
|
|
// https://github.com/grpc/grpc/blob/master/doc/connection-backoff.md.
|
|
var DefaultExponential = Exponential{Config: grpcbackoff.DefaultConfig}
|
|
|
|
// Exponential implements exponential backoff algorithm as defined in
|
|
// https://github.com/grpc/grpc/blob/master/doc/connection-backoff.md.
|
|
type Exponential struct {
|
|
// Config contains all options to configure the backoff algorithm.
|
|
Config grpcbackoff.Config
|
|
}
|
|
|
|
// Backoff returns the amount of time to wait before the next retry given the
|
|
// number of retries.
|
|
func (bc Exponential) Backoff(retries int) time.Duration {
|
|
if retries == 0 {
|
|
return bc.Config.BaseDelay
|
|
}
|
|
backoff, max := float64(bc.Config.BaseDelay), float64(bc.Config.MaxDelay)
|
|
for backoff < max && retries > 0 {
|
|
backoff *= bc.Config.Multiplier
|
|
retries--
|
|
}
|
|
if backoff > max {
|
|
backoff = max
|
|
}
|
|
// Randomize backoff delays so that if a cluster of requests start at
|
|
// the same time, they won't operate in lockstep.
|
|
backoff *= 1 + bc.Config.Jitter*(grpcrand.Float64()*2-1)
|
|
if backoff < 0 {
|
|
return 0
|
|
}
|
|
return time.Duration(backoff)
|
|
}
|