retry simulation

0.md

Retry simulation

Retry simulation for https://github.com/wal-g/wal-g/blob/feb60cc7d25056c443b310f99639c6effe32c01c/pkg/storages/s3/folder.go#L51

How to run

Copy and paste to https://go.dev/play/

or

place code in file retry_simulation.go and run go run retry_simulation.go

retry_simulation.go

package main

import (
	"errors"
	"log"
	"math"
	"math/rand"
	"time"
)

var (
	RangeMaxRetriesDefault  = 10
	RangeQueryMinRetryDelay = 30 * time.Millisecond
	RangeQueryMaxRetryDelay = 300 * time.Second
	MaxRetriesDefault       = 15
)

func getReaderSettings() (rangeEnabled bool, retriesCount int, minRetryDelay, maxRetryDelay time.Duration) {
	rangeEnabled = true

	retriesCount = RangeMaxRetriesDefault

	if minRetryDelay == 0 {
		minRetryDelay = RangeQueryMinRetryDelay
	}
	if maxRetryDelay == 0 {
		maxRetryDelay = RangeQueryMaxRetryDelay
	}

	return rangeEnabled, retriesCount, minRetryDelay, maxRetryDelay
}

func simulateRangeQuery() error {
	return errors.New("simulated range query error")
}

func getJitterDelay(duration time.Duration) time.Duration {
	return time.Duration(rand.Int63n(int64(duration)) + int64(duration))
}

func getIncrSleep(retryCount int, minDelay time.Duration, maxDelay time.Duration) time.Duration {
	var delay time.Duration

	actualRetryCount := int(math.Log2(float64(minDelay))) + 1
	if actualRetryCount < 63-retryCount {
		delay = time.Duration(1<<uint64(retryCount)) * getJitterDelay(minDelay)
		if delay > maxDelay {
			delay = getJitterDelay(maxDelay / 2)
		}
	} else {
		delay = getJitterDelay(maxDelay / 2)
	}
	return delay
}

func main() {
	rangeEnabled, retriesCount, minRetryDelay, maxRetryDelay := getReaderSettings()

	log.Printf("rangeEnabled: %v, retriesCount: %v, minRetryDelay: %v, maxRetryDelay: %v", rangeEnabled, retriesCount, minRetryDelay, maxRetryDelay)

	for i := 1; i <= retriesCount; i++ {
		log.Printf("Retry #%d for range query", i)

		err := simulateRangeQuery()
		if err == nil {
			log.Println("Range query successful!")
			break
		}

		if i == retriesCount {
			log.Println("Max retries reached, giving up.")
			break
		}

		// Calculate the retry delay
		retryDelay := getIncrSleep(i, minRetryDelay, maxRetryDelay)

		log.Printf("Range query failed. Retrying in %v...", retryDelay)
		//time.Sleep(retryDelay)
	}

	log.Println("Simulation finished.")
}