c# winform backgroundworker 스레드 중단/재개하기 코드

c# winform background worker에서 중요한 점은

background worker에서 do_work는 별도의 background 스레드에서 동작하기 때문에 UI를 손볼 수 없다.

ui의 변경은 ProgressChangedEventHandler나 RunWorkCompletedEventHandler에서 조정한다.

또한 background worker의 중단/재개 방법을 코드로 적는다.

버튼으로 중단/재개를 할 수 있으며, P(중단) R(재개) 키를 누름으로서 프로그램의 중단/재개를 할 수 있다.

 

======= 코드 =======

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Diagnostics;
using System.Threading;
 
namespace WinFormsApp5
{
    public partial class Form1 : Form
    {
        private BackgroundWorker worker;
        private ManualResetEvent _pauseEvent = new ManualResetEvent(true);
        public Form1()
        {
            InitializeComponent();
        }
 
        private void Pause()
        {
            _pauseEvent.Reset();
        }
 
        private void Resume()
        {
            _pauseEvent.Set();
        }
 
        protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
        {
            switch (keyData)
            {
                case Keys.P:
                    Debug.WriteLine("Pause(P) key button is pressed");
                    Pause();
                    break;
                case Keys.R:
                    Debug.WriteLine("Resume(R) key button is pressed");
                    Resume();
                    break;
            }
            return base.ProcessCmdKey(ref msg, keyData);
       }
        
 
        private void button1_Click(object sender, EventArgs e)
        {
            worker = new BackgroundWorker();
            worker.WorkerReportsProgress = true;
            worker.WorkerSupportsCancellation = true;
            // worker_DoWork가 별도의 백그라운드 스레드임
            // worker_ProgressChanged와 worker_RunWorkerCompleted는 UI 스레드에서 돌아감
            worker.DoWork += new DoWorkEventHandler(worker_DoWork);
            worker.ProgressChanged += new ProgressChangedEventHandler(worker_ProgressChanged);
            worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted);
 
            worker.RunWorkerAsync();
            button1.Enabled = false;            
        }
        
        private void worker_DoWork(object sender,
            DoWorkEventArgs e)
        {
            int N = 100;
            for (int i=1; i <= N; i++)
            {
                if (worker.CancellationPending)
                {
                    e.Cancel = true;
                    return;
                }
                // P 버튼을 누르면 Stop
                // R 버튼을 누르면 Resume
                _pauseEvent.WaitOne();
                string filename = "Data_" + i + ".txt";
                Upload(filename);
                worker.ReportProgress(i, filename);
            }
        }
 
        void Upload(string filename)
        {
            Debug.WriteLine("Uploading " + filename);
            Thread.Sleep(1000);
        }
 
        void worker_ProgressChanged(object sender,
            ProgressChangedEventArgs e)
        {
            if (_pauseEvent.WaitOne(0))
            { label1.Text = string.Format("Progress : {0} %", e.ProgressPercentage); }
        }
 
        void worker_RunWorkerCompleted(object sender,
            RunWorkerCompletedEventArgs e)
        {
            if (e.Cancelled)
            {
                label1.Text = "작업 취소됨";
            }
            else if (e.Error != null)
            {
                throw e.Error;
            }
            else
            {
                label1.Text = string.Format("{0} files updated", e.Result);
            }
        }
 
        private void CancelButton_Click(object sender, EventArgs e)
        {
            worker.CancelAsync();
        }
 
        private void StopButton_Click(object sender, EventArgs e)
        {
            if (_pauseEvent.WaitOne(0))
            {
                Pause();
                label1.Text = "업데이트가 잠시 중단되었습니다.";
            }
        }
 
        private void ResumeButton_Click(object sender, EventArgs e)            
        {
            label1.Text = "업데이트가 재개되었습니다.";
            Resume();
        }
    }
}