singleflight

README

go singleflight 泛型版

一、这是啥

Go官方扩展库singleflight的泛型实现：

https://cs.opensource.google/go/x/sync

二、Example

package main

import (
	"fmt"
	"github.com/golang-infrastructure/go-singleflight"
	"math/rand"
	"sync"
	"time"
)

func main() {

	var wg sync.WaitGroup
	g := singleflight.Group[int]{}

	begin := time.Now()
	for i := 0; i < 10; i++ {
		id := i
		wg.Add(1)
		go func() {
			defer wg.Done()
			v, err, shared := g.Do("test", func() (value int, err error) {
				fmt.Println(id, "开始执行了...")
				time.Sleep(time.Second * 3)
				return rand.Intn(100), nil
			})
			fmt.Println(id, v, err, shared)
		}()
	}
	wg.Wait()
	fmt.Println("cost: ", time.Now().Sub(begin).String())
	fmt.Println("All done")
}

三、TODO

• 写篇文章讨论一下singleflight，分析一下源码
• 跑下benchmark，看下泛型版对性能到底有多大的影响

Documentation

Overview

Package singleflight provides a duplicate function call suppression mechanism.

Index

• type Group
  • func (g *Group[T]) Do(key string, fn func() (T, error)) (v T, err error, shared bool)
  • func (g *Group[T]) DoChan(key string, fn func() (T, error)) <-chan Result[T]
  • func (g *Group[T]) Forget(key string)
• type Result

Types

type Group

type Group[T any] struct {
	// contains filtered or unexported fields
}

Group represents a class of work and forms a namespace in which units of work can be executed with duplicate suppression.

func (*Group[T]) Do

func (g *Group[T]) Do(key string, fn func() (T, error)) (v T, err error, shared bool)

Do executes and returns the results of the given function, making sure that only one execution is in-flight for a given key at a time. If a duplicate comes in, the duplicate caller waits for the original to complete and receives the same results. The return value shared indicates whether v was given to multiple callers.

func (*Group[T]) DoChan

func (g *Group[T]) DoChan(key string, fn func() (T, error)) <-chan Result[T]

DoChan is like Do but returns a channel that will receive the results when they are ready.

The returned channel will not be closed.

func (*Group[T]) Forget

func (g *Group[T]) Forget(key string)

Forget tells the singleflight to forget about a key. Future calls to Do for this key will call the function rather than waiting for an earlier call to complete.

type Result

type Result[T any] struct {
	Val    T
	Err    error
	Shared bool
}

Result holds the results of Do, so they can be passed on a channel.