CriticalSection

unit uNoCriticalSection;{ 能不能让它们别打架, 一个完了另一个再来? 这就要用到多线程的同步技术.　　前面说过, 最简单的同步手段就是 "临界区".　　先说这个 "同步"(Synchronize), 首先这个名字起的不好, 我们好像需要的是 "异步"; 其实异步也不准确...　　管它叫什么名字呢, 它的目的就是保证不冲突、有次序、都发生.　　"临界区"(CriticalSection): 当把一段代码放入一个临界区, 线程执行到临界区时就独占了, 让其他也要执行此代码的线程先等等; 这和前面用的 Lock 和 UnLock 差不多; 使用格式如下: var CS: TRTLCriticalSection;　 //声明一个 TRTLCriticalSection 结构类型变量; 它应该是全局的 InitializeCriticalSection(CS); //初始化 EnterCriticalSection(CS);　　　 //开始: 轮到我了其他线程走开 LeaveCriticalSection(CS);　　　//结束: 其他线程可以来了 DeleteCriticalSection(CS);　　//删除: 注意不能过早删除}interfaceuses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls;type TForm1 = class(TForm) ListBox1: TListBox; Button1: TButton; ListBox2: TListBox; Button2: TButton; Button3: TButton; Button4: TButton; procedure Button1Click(Sender: TObject); procedure Button3Click(Sender: TObject); procedure Button4Click(Sender: TObject); procedure Button2Click(Sender: TObject); private { Private declarations } public { Public declarations } end;var Form1: TForm1;implementation{$R *.dfm}var CS: TRTLCriticalSection; { no Critical Section }function MyThreadFun(p: Pointer): DWord; stdCall;var i: integer;begin for i := 0 to 10 do begin Form1.ListBox1.Items.Add(IntTostr(i)); end;end;procedure TForm1.Button1Click(Sender: TObject);var ID: DWORD;begin windows.CreateThread(nil, 0, @MyThreadFun, nil, 0, ID); windows.CreateThread(nil, 0, @MyThreadFun, nil, 0, ID); windows.CreateThread(nil, 0, @MyThreadFun, nil, 0, ID);end;{ with Critical Section }function MyThreadFun2(p: Pointer):DWord; stdcall;var i: integer;begin// if CS = NIL then// begin// showmessage("No INIT CS!");// Exit;// end; windows.EnterCriticalSection(CS); for i := 0 to 10 do begin Form1.ListBox2.Items.Add(IntTostr(i)); end; windows.LeaveCriticalSection(CS);end;procedure TForm1.Button2Click(Sender: TObject);var ID: DWORD;begin windows.CreateThread(nil, 0, @MyThreadFun2, nil, 0, ID); windows.CreateThread(nil, 0, @MyThreadFun2, nil, 0, ID); windows.CreateThread(nil, 0, @MyThreadFun2, nil, 0, ID);end;procedure TForm1.Button3Click(Sender: TObject);begin windows.InitializeCriticalSection(CS);end;procedure TForm1.Button4Click(Sender: TObject);begin windows.DeleteCriticalSection(CS);end;end.