Source: backoff.go in package google.golang.org/grpc/internal/backoff

Source File
	backoff.go

Belonging Package
	google.golang.org/grpc/internal/backoff

* * 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.

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.

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)


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