use golang context

custome_context_select.go

package main

import (
	"context"
	"errors"
	"fmt"
	"time"
)

func main() {
	ctx, cancel := context.WithTimeout(context.Background(), time.Millisecond*1500)
	defer cancel()
	for i := 1; i <= 10; i++ {
		response := ctxFetch(ctx, i)
		fmt.Printf("%+v is ctx.cancel: %v\n", response, errors.Is(response.Err, context.DeadlineExceeded))
	}
	time.Sleep(time.Second * 5)
}

type Response struct {
	Data any
	Code int
	Err  error
}

func ctxFetch(ctx context.Context, id any) Response {
	res := make(chan Response)
	go func() {
		defer close(res)
		res <- fetch(id)
	}()
	select {
	case <-ctx.Done():
		return Response{Data: id, Code: 415, Err: fmt.Errorf("cancel: %w", ctx.Err())}
	case response := <-res:
		return response
	}
}

func fetch(id any) Response {
	time.Sleep(time.Millisecond * 500)
	return Response{
		Data: id,
		Code: 200,
		Err:  nil,
	}
}