phuctm97

// Errors.
var (
	ErrUsernameIsTooShort            = errors.New("username must be at least 1-character length")
	ErrUsernameIsTooLong             = errors.New("username must be at most 32-character length")
	ErrUsernameContainsInvalidChar   = errors.New("username must contain only digits, underscores, dashes, dots and alphabetical letters")
	ErrUsernameBeginsWithInvalidChar = errors.New("username must begin with either underscore or an alphabetical letter")
	ErrEmailIsInvalid                = errors.New("email is invalid")
	ErrEmailIsTooLong                = errors.New("email must be at most 128-character length")
	ErrFullNameIsTooShort            = errors.New("full name must be at least 1-character length")
	ErrFullNameIsTooLong             = errors.New("full name must be at most 128-character length")

phuctm97

package users

// UserRepository abstracts accesses to users-related data.
type UserRepository interface {
	ExistsByUsername(string) (bool, error)
	ExistsByEmail(string) (bool, error)
}

phuctm97

package users

// ValidateUserUnique validates whether user's username or email is valid and returns errors or nil.
func ValidateUserUnique(userRepo UserRepository, user *User) error {
	errs := make([]error, 0)

	var exists bool
	var err error

	// Validate username.

phuctm97

package users

type mockUserRepository struct{}

func (r *mockUserRepository) ExistsByUsername(username string) (bool, error) {
	if username == "existed" {
		return true, nil
	}
	return false, nil
}

phuctm97

package readerswriters

import "sync"

var mutex = new(sync.RWMutex)

func writer(data []byte) {
    mutex.Lock()
    defer mutex.Unlock()
  

phuctm97

package syncval

import "sync"

// SyncValue is like a Go interface{} but is safe for concurrent use by multiple goroutines
// without additional locking or coordination.
type SyncValue struct {
	mutex *sync.RWMutex
	val   interface{}
}

phuctm97

package main

import (
	"context"
	"fmt"
	"os"
	"os/signal"
)

func taskA(ctx context.Context, index int) {

phuctm97

// Javascript.

const longRunningTask = async () => {
    // Simulate a workload.
    sleep(3000)
    return Math.floor(Math.random() * Math.floor(100))
}

const r = await longRunningTask()
console.log(r)

phuctm97

// Javascript.

const longRunningTask = async () => {
    // Simulate a workload.
    sleep(3000)
    return Math.floor(Math.random() * Math.floor(100))
}

const [a, b, c] = await Promise.all(longRunningTask(), longRunningTask(), longRunningTask())
console.log(a, b, c)

phuctm97

// Javascript.

const one = async () => {
    // Simulate a workload.
    sleep(Math.floor(Math.random() * Math.floor(2000)))
    return 1
}

const two = async () => {
    // Simulate a workload.