Singletone

Singletone (C++)

Добавил: pshenichny

Автор: pshenichny

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source

#include <stdio.h>
#include <windows.h>

class Simple
{
public:
	Simple ()
	{
		a = 5;
	}

~Simple ()
	{
		a = 0;
	}

int Get () const
	{
		return a;
	}

private:
	int a;
};

Simple simple;

// Небезопасный синглтон
__forceinline Simple & Instance ()
{
	static Simple one;
	return one;
}

CRITICAL_SECTION critical_section;

// Безопасный синглтон
__forceinline Simple & SafeInstance ()
{
    EnterCriticalSection ( & critical_section );
    static Simple one;
    LeaveCriticalSection ( & critical_section );

return one;
}

int main ()
{
	if ( SetPriorityClass ( GetCurrentProcess (), REALTIME_PRIORITY_CLASS ) == 0 )
	{
		printf ( "SetPriority failed.\n");
	}

InitializeCriticalSection ( & critical_section );
	
    const int LOOP_COUNT = 20000000;
    LARGE_INTEGER t1, t2, t3, t4, t_per_sec;
	volatile int k;

// обычный доступ
	QueryPerformanceCounter ( & t1 );
	for ( int i = 0; i < LOOP_COUNT; ++i )
	{
		k = simple.Get();
		k = simple.Get();
		k = simple.Get();
		k = simple.Get();
	}

// доступ через синглтон
	QueryPerformanceCounter ( & t2 );
	for ( int i = 0; i < LOOP_COUNT; ++i )
	{
		k = Instance().Get();
		k = Instance().Get();
		k = Instance().Get();
		k = Instance().Get();
	}

// доступ через безопасный синглтон
	QueryPerformanceCounter ( & t3 );
	for ( int i = 0; i < LOOP_COUNT; ++i )
	{
		k = SafeInstance().Get();
		k = SafeInstance().Get();
		k = SafeInstance().Get();
		k = SafeInstance().Get();
	}

QueryPerformanceCounter ( & t4 );
	QueryPerformanceFrequency ( & t_per_sec );

DeleteCriticalSection ( & critical_section );

printf ( "        simple.Get() = %I64u msec\n", 1000 * (t2.QuadPart - t1.QuadPart) / t_per_sec.QuadPart );
	printf ( "    Instance().Get() = %I64u msec\n", 1000 * (t3.QuadPart - t2.QuadPart) / t_per_sec.QuadPart );
	printf ( "SafeInstance().Get() = %I64u msec\n", 1000 * (t4.QuadPart - t3.QuadPart) / t_per_sec.QuadPart );

return 0;
}