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public/tier1/reliabletimer.h

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+//========= Copyright Valve Corporation, All rights reserved. ============//
+//
+// Purpose: 
+//
+//=============================================================================
+
+#ifndef RELIABLETIMER_H
+#define RELIABLETIMER_H
+
+#include "tier0/dbg.h"
+//#include "constants.h"
+#include "tier0/fasttimer.h"
+#include "tier1/tier1.h"
+#include "tier1/strtools.h"
+
+#define DbgAssert Assert
+#define kMILLION (1000000)
+#define kTHOUSAND (1000)
+
+// Timer class that uses QueryPerformanceCounter.  This is heavier-weight than CFastTimer which uses rdtsc,
+// but this is reliable on multi-core systems whereas CFastTimer is not.
+
+class CReliableTimer
+{
+public:
+	CReliableTimer();
+	void Start();
+	void End();
+	int64 GetMicroseconds();
+	int64 GetMilliseconds();
+	void SetLimit( uint64 m_cMicroSecDuration );
+	bool BLimitReached();
+	int64 CMicroSecOverage();
+	int64 CMicroSecLeft(); 
+	int64 CMilliSecLeft();
+private:
+	int64 GetPerformanceCountNow();
+
+	int64 m_nPerformanceCounterStart;
+	int64 m_nPerformanceCounterEnd;
+	int64 m_nPerformanceCounterLimit;
+
+	static int64 sm_nPerformanceFrequency;
+	static bool sm_bUseQPC;
+};
+
+
+//-----------------------------------------------------------------------------
+// Purpose: Records timer start time
+//-----------------------------------------------------------------------------
+inline void CReliableTimer::Start()
+{
+	m_nPerformanceCounterStart = GetPerformanceCountNow();
+}
+
+//-----------------------------------------------------------------------------
+// Purpose: Records timer end time
+//-----------------------------------------------------------------------------
+inline void CReliableTimer::End()
+{
+	m_nPerformanceCounterEnd = GetPerformanceCountNow();
+
+	// enforce that we've advanced at least one cycle
+	if ( m_nPerformanceCounterEnd < m_nPerformanceCounterStart )
+	{
+#ifdef _SERVER
+		if ( m_nPerformanceCounterEnd+10000 < m_nPerformanceCounterStart )
+			AssertMsgOnce( false, CDbgFmtMsg( "CReliableTimer went backwards - start:%lld end:%lld", m_nPerformanceCounterStart, m_nPerformanceCounterEnd ).ToString() );
+#endif
+		m_nPerformanceCounterEnd = m_nPerformanceCounterStart + 1;
+	}
+}
+
+
+//-----------------------------------------------------------------------------
+// Purpose: Gets microseconds elapsed between start and end
+//-----------------------------------------------------------------------------
+inline int64 CReliableTimer::GetMicroseconds()
+{
+	DbgAssert( m_nPerformanceCounterStart );		// timer must have been started
+	DbgAssert( m_nPerformanceCounterEnd );			// timer must have been ended
+	DbgAssert( 0 != sm_nPerformanceFrequency );	// must have calc'd performance counter frequency
+	return ( ( m_nPerformanceCounterEnd - m_nPerformanceCounterStart ) * kMILLION / sm_nPerformanceFrequency );
+}
+
+
+//-----------------------------------------------------------------------------
+// Purpose: Gets microseconds elapsed between start and end
+//-----------------------------------------------------------------------------
+inline int64 CReliableTimer::GetMilliseconds()
+{
+	DbgAssert( m_nPerformanceCounterStart );		// timer must have been started
+	DbgAssert( m_nPerformanceCounterEnd );			// timer must have been ended
+	DbgAssert( 0 != sm_nPerformanceFrequency );	// must have calc'd performance counter frequency
+	return ( ( m_nPerformanceCounterEnd - m_nPerformanceCounterStart ) * kTHOUSAND / sm_nPerformanceFrequency );
+}
+
+
+//-----------------------------------------------------------------------------
+// Purpose: Sets a limit on this timer that can subsequently be checked against
+//-----------------------------------------------------------------------------
+inline void CReliableTimer::SetLimit( uint64 cMicroSecDuration )
+{
+	DbgAssert( 0 != sm_nPerformanceFrequency );	// must have calc'd performance counter frequency
+	m_nPerformanceCounterStart = GetPerformanceCountNow();
+	m_nPerformanceCounterLimit = m_nPerformanceCounterStart + ( ( cMicroSecDuration * sm_nPerformanceFrequency  ) / kMILLION );
+}
+
+
+//-----------------------------------------------------------------------------
+// Purpose: Returns if previously set limit has been reached
+//-----------------------------------------------------------------------------
+inline bool CReliableTimer::BLimitReached()
+{
+	DbgAssert( m_nPerformanceCounterStart );	// SetLimit must have been called
+	DbgAssert( m_nPerformanceCounterLimit );	// SetLimit must have been called
+	int64 nPerformanceCountNow = GetPerformanceCountNow();
+
+	// make sure time advances
+	if ( nPerformanceCountNow < m_nPerformanceCounterStart )
+	{
+#ifdef _SERVER
+		if ( nPerformanceCountNow+10000 < m_nPerformanceCounterStart )
+			AssertMsgOnce( false, CDbgFmtMsg( "CReliableTimer went backwards - start:%lld end:%lld", m_nPerformanceCounterStart, m_nPerformanceCounterEnd ).ToString() );
+#endif
+		// reset the limit to be lower, to match our new clock
+		m_nPerformanceCounterLimit = nPerformanceCountNow + (m_nPerformanceCounterLimit - m_nPerformanceCounterStart);
+	}
+
+	return ( nPerformanceCountNow >= m_nPerformanceCounterLimit );
+}
+
+
+//-----------------------------------------------------------------------------
+// Purpose: Returns microseconds current time is past limit, or 0 if not past limit
+//-----------------------------------------------------------------------------
+inline int64 CReliableTimer::CMicroSecOverage()
+{
+	DbgAssert( m_nPerformanceCounterStart );	// SetLimit must have been called
+	DbgAssert( m_nPerformanceCounterLimit );	// SetLimit must have been called
+	int64 nPerformanceCountNow = GetPerformanceCountNow();
+#ifdef _SERVER
+	if ( nPerformanceCountNow+10000 < m_nPerformanceCounterStart )
+		AssertMsgOnce( nPerformanceCountNow >= m_nPerformanceCounterStart, CDbgFmtMsg( "CReliableTimer went backwards - start:%lld end:%lld", m_nPerformanceCounterStart, m_nPerformanceCounterEnd ).ToString() );
+#endif
+	int64 nPerformanceCountOver = ( nPerformanceCountNow > m_nPerformanceCounterLimit ? 
+		nPerformanceCountNow - m_nPerformanceCounterLimit : 0 );
+
+	Assert( 0 != sm_nPerformanceFrequency );	// must have calc'd performance counter frequency
+	return ( nPerformanceCountOver * kMILLION / sm_nPerformanceFrequency );
+}
+
+
+//-----------------------------------------------------------------------------
+// Purpose: Returns microseconds remaining until limit
+//-----------------------------------------------------------------------------
+inline int64 CReliableTimer::CMicroSecLeft()
+{
+	DbgAssert( m_nPerformanceCounterStart );	// SetLimit must have been called
+	DbgAssert( m_nPerformanceCounterLimit );	// SetLimit must have been called
+	int64 nPerformanceCountNow = GetPerformanceCountNow();
+#ifdef _SERVER
+	if ( nPerformanceCountNow+10000 < m_nPerformanceCounterStart )
+		AssertMsgOnce( nPerformanceCountNow >= m_nPerformanceCounterStart, CDbgFmtMsg( "CReliableTimer went backwards - start:%lld end:%lld", m_nPerformanceCounterStart, m_nPerformanceCounterEnd ).ToString() );
+#endif
+	int64 nPerformanceCountLeft = ( nPerformanceCountNow < m_nPerformanceCounterLimit ? 
+		m_nPerformanceCounterLimit - nPerformanceCountNow : 0 );
+
+	DbgAssert( 0 != sm_nPerformanceFrequency );	// must have calc'd performance counter frequency
+	return ( nPerformanceCountLeft * kMILLION / sm_nPerformanceFrequency );
+}
+
+
+//-----------------------------------------------------------------------------
+// Purpose: Returns milliseconds remaining until limit
+//-----------------------------------------------------------------------------
+inline int64 CReliableTimer::CMilliSecLeft()
+{
+	return CMicroSecLeft() / 1000;
+}
+
+
+#endif // TICKLIMITTIMER_H