Поток с использованием семафора

Автор: Xavier Pacheco

unit Main;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;

type
  TMainForm = class(TForm)
    Button1: TButton;
    ListBox1: TListBox;
    procedure Button1Click(Sender: TObject);
  private
    procedure ThreadsDone(Sender: TObject);
  end;

  TFooThread = class(TThread)
  protected
    procedure Execute; override;
  end;

var
  MainForm: TMainForm;

implementation

{$R *.DFM}

const
  MaxSize = 128;

var
  NextNumber: Integer = 0;
  DoneFlags: Integer = 0;
  GlobalArray: array[1..MaxSize] of Integer;
  hSem: THandle = 0;

function GetNextNumber: Integer;
begin
  Result := NextNumber; // return global var
  Inc(NextNumber); // inc global var
end;

procedure TFooThread.Execute;
var
  i: Integer;
  WaitReturn: DWORD;
begin
  OnTerminate := MainForm.ThreadsDone;
  WaitReturn := WaitForSingleObject(hSem, INFINITE);
  if WaitReturn = WAIT_OBJECT_0 then
  begin
    for i := 1 to MaxSize do
    begin
      GlobalArray[i] := GetNextNumber; // set array element
      Sleep(5); // let thread intertwine
    end;
  end;
  ReleaseSemaphore(hSem, 1, nil);
end;

procedure TMainForm.ThreadsDone(Sender: TObject);
var
  i: Integer;
begin
  Inc(DoneFlags);
  if DoneFlags = 2 then // make sure both threads finished
  begin
    for i := 1 to MaxSize do
      { fill listbox with array contents }
      Listbox1.Items.Add(IntToStr(GlobalArray[i]));
    CloseHandle(hSem);
  end;
end;

procedure TMainForm.Button1Click(Sender: TObject);
begin
  hSem := CreateSemaphore(nil, 1, 1, nil);
  TFooThread.Create(False); // create threads
  TFooThread.Create(False);
end;

end.