TSpinWait (C++)

Description

The following example illustrates the usage of a TSpinWait record. This is a console application, where the main thread waits in a spin-loop until a global variable is set by a secondary thread.

Code

#include <vcl.h>
#pragma hdrstop

#include <tchar.h>
#include <Classes.hpp>
#include <iostream>
using namespace std;

#pragma argsused

// ---------------------------------------------------------------------------
static bool flag;

// ---------------------------------------------------------------------------
class TThreadCause : public TThread {
private:
	void __fastcall Execute() {
		Sleep(100); // 100 milliseconds
		flag = true;
}

public:
	TThreadCause(bool createSuspended) : TThread(createSuspended) {
	}
};

// ---------------------------------------------------------------------------
int _tmain(int argc, _TCHAR* argv[]) {
	flag = false;
	TThread *cause = new TThreadCause(true);
	cause->Start();

	TSpinWait spinner;
	spinner.Reset();

	while (flag == false) {
	   cout << spinner.Count << endl;
	   spinner.SpinCycle();
	}
	cout << spinner.Count << endl;
	cout << "flag is " << flag << endl; // displays "flag is 1"

	return 0;
}

Uses

• SysUtils.TSpinWait ( fr | de | ja )
• SysUtils.TSpinWait.SpinCycle ( fr | de | ja )