map 的并发读写

parallelMap

package tests

import (
	"sync"
	"testing"
)

func TestMap(t *testing.T) {
	ids := []int64{1, 2, 3, 1, 2, 3}
	parallelIndexMap(ids)
	parallelMap(ids)
}

func parallelIndexMap(ids []int64) {
	type info struct {
		id int64
	}
	var maps = make(map[int64]int, len(ids))
	var array = make([]*info, len(ids))
	for i, id := range ids {
		maps[id] = i
	}
	var wg = &sync.WaitGroup{}

	for _, id := range ids {
		wg.Add(1)
		go func(id int64) {
			defer wg.Done()
			index := maps[id]
			array[index] = &info{id: id}
		}(id)
	}
	wg.Wait()
}

func parallelMap(ids []int64) {
	type info struct {
		id int64
	}
	var maps = make(map[int64]*info, len(ids))
	var wg = &sync.WaitGroup{}

	for _, id := range ids {
		wg.Add(1)
		go func(id int64) {
			defer wg.Done()
			maps[id] = &info{
				id: id,
			}
		}(id)
	}
	wg.Wait()
}