1 files changed, 240 insertions, 0 deletions
diff --git a/engine/clockdriftmgr.cpp b/engine/clockdriftmgr.cpp
new file mode 100644
index 0000000..45d725c
--- /dev/null
+++ b/engine/clockdriftmgr.cpp
@@ -0,0 +1,240 @@
+//========= Copyright Valve Corporation, All rights reserved. ============//
+//
+// Purpose: 
+//
+//=============================================================================//
+
+#include "client.h"
+#include "clockdriftmgr.h"
+#include "demo.h"
+#include "server.h"
+#include "enginethreads.h"
+
+
+ConVar cl_clock_correction( "cl_clock_correction", "1", FCVAR_CHEAT, "Enable/disable clock correction on the client." );
+
+ConVar cl_clockdrift_max_ms( "cl_clockdrift_max_ms", "150", FCVAR_CHEAT, "Maximum number of milliseconds the clock is allowed to drift before the client snaps its clock to the server's." );
+ConVar cl_clockdrift_max_ms_threadmode( "cl_clockdrift_max_ms_threadmode", "0", FCVAR_CHEAT, "Maximum number of milliseconds the clock is allowed to drift before the client snaps its clock to the server's." );
+
+ConVar cl_clock_showdebuginfo( "cl_clock_showdebuginfo", "0", FCVAR_CHEAT, "Show debugging info about the clock drift. ");
+
+ConVar cl_clock_correction_force_server_tick( "cl_clock_correction_force_server_tick", "999", FCVAR_CHEAT, "Force clock correction to match the server tick + this offset (-999 disables it)."  );
+
+ConVar cl_clock_correction_adjustment_max_amount( "cl_clock_correction_adjustment_max_amount", "200", FCVAR_CHEAT, 
+	"Sets the maximum number of milliseconds per second it is allowed to correct the client clock. "
+	"It will only correct this amount if the difference between the client and server clock is equal to or larger than cl_clock_correction_adjustment_max_offset." );
+
+ConVar cl_clock_correction_adjustment_min_offset( "cl_clock_correction_adjustment_min_offset", "10", FCVAR_CHEAT, 
+	"If the clock offset is less than this amount (in milliseconds), then no clock correction is applied." );
+
+ConVar cl_clock_correction_adjustment_max_offset( "cl_clock_correction_adjustment_max_offset", "90", FCVAR_CHEAT, 
+	"As the clock offset goes from cl_clock_correction_adjustment_min_offset to this value (in milliseconds), "
+	"it moves towards applying cl_clock_correction_adjustment_max_amount of adjustment. That way, the response "
+	"is small when the offset is small." );
+
+
+
+// Given the offset (in milliseconds) of the client clock from the server clock,
+// returns how much correction we'd like to apply per second (in seconds).
+static float GetClockAdjustmentAmount( float flCurDiffInMS )
+{
+	flCurDiffInMS = clamp( flCurDiffInMS, cl_clock_correction_adjustment_min_offset.GetFloat(), cl_clock_correction_adjustment_max_offset.GetFloat() );
+
+	float flReturnValue = RemapVal( flCurDiffInMS,
+		cl_clock_correction_adjustment_min_offset.GetFloat(), cl_clock_correction_adjustment_max_offset.GetFloat(),
+		0, cl_clock_correction_adjustment_max_amount.GetFloat() / 1000.0f );
+
+	return flReturnValue;
+}
+	 
+
+// -------------------------------------------------------------------------------------------------- /
+// CClockDriftMgr implementation.
+// -------------------------------------------------------------------------------------------------- /
+
+CClockDriftMgr::CClockDriftMgr()
+{
+	Clear();
+}
+
+
+void CClockDriftMgr::Clear()
+{
+	m_nClientTick = 0;
+	m_nServerTick = 0;
+	m_iCurClockOffset = 0;
+	memset( m_ClockOffsets, 0, sizeof( m_ClockOffsets ) );
+}
+
+
+// when running in threaded host mode, the clock drifts by a predictable algorithm
+// because the client lags the server by one frame
+// so at each update from the network we have lastframeticks-1 pending ticks to execute
+// on the client.  If the clock has drifted by exactly that amount, allow it to drift temporarily
+// NOTE: When the server gets paused the tick count is still incorrect for a frame
+// NOTE: It should be possible to fix this by applying pause before the tick is incremented
+// NOTE: or decrementing the client tick after receiving pause
+// NOTE: This is due to the fact that currently pause is applied at frame start on the server
+// NOTE: and frame end on the client
+void CClockDriftMgr::SetServerTick( int nTick )
+{
+#if !defined( SWDS )
+	m_nServerTick = nTick;
+
+	int nMaxDriftTicks = IsEngineThreaded() ? 
+		TIME_TO_TICKS( (cl_clockdrift_max_ms_threadmode.GetFloat() / 1000.0) ) :
+		TIME_TO_TICKS( (cl_clockdrift_max_ms.GetFloat() / 1000.0) );
+
+	int clientTick = cl.GetClientTickCount() + g_ClientGlobalVariables.simTicksThisFrame - 1;
+	if ( cl_clock_correction_force_server_tick.GetInt() == 999 )
+	{
+		// If this is the first tick from the server, or if we get further than cl_clockdrift_max_ticks off, then 
+		// use the old behavior and slam the server's tick into the client tick.
+		if ( !IsClockCorrectionEnabled() ||
+			 clientTick == 0 || 
+			 abs(nTick - clientTick) > nMaxDriftTicks
+			)
+		{
+			cl.SetClientTickCount( nTick - (g_ClientGlobalVariables.simTicksThisFrame - 1) );
+			if ( cl.GetClientTickCount() < cl.oldtickcount )
+			{
+				cl.oldtickcount = cl.GetClientTickCount();
+			}
+			memset( m_ClockOffsets, 0, sizeof( m_ClockOffsets ) );
+		}
+	}
+	else
+	{
+		// Used for testing..
+		cl.SetClientTickCount( nTick + cl_clock_correction_force_server_tick.GetInt() );
+	}
+
+	// adjust the clock offset by the clock with thread mode compensation
+	m_ClockOffsets[m_iCurClockOffset] = clientTick - m_nServerTick;
+	m_iCurClockOffset = (m_iCurClockOffset + 1) % NUM_CLOCKDRIFT_SAMPLES;
+#endif // SWDS
+}
+
+
+float CClockDriftMgr::AdjustFrameTime( float inputFrameTime )
+{
+	float flAdjustmentThisFrame = 0;
+	float flAdjustmentPerSec = 0;
+	if ( IsClockCorrectionEnabled() 
+#if !defined( _XBOX ) && !defined( SWDS )
+		 && !demoplayer->IsPlayingBack()
+#endif
+		)
+	{
+		// Get the clock difference in seconds.
+		float flCurDiffInSeconds = GetCurrentClockDifference() * host_state.interval_per_tick;
+		float flCurDiffInMS = flCurDiffInSeconds * 1000.0f;
+
+		// Is the server ahead or behind us?
+		if ( flCurDiffInMS > cl_clock_correction_adjustment_min_offset.GetFloat() )
+		{
+			flAdjustmentPerSec = -GetClockAdjustmentAmount( flCurDiffInMS );
+			flAdjustmentThisFrame = inputFrameTime * flAdjustmentPerSec;
+			flAdjustmentThisFrame = max( flAdjustmentThisFrame, -flCurDiffInSeconds );
+		}
+		else if ( flCurDiffInMS < -cl_clock_correction_adjustment_min_offset.GetFloat() )
+		{
+			flAdjustmentPerSec = GetClockAdjustmentAmount( -flCurDiffInMS );
+			flAdjustmentThisFrame = inputFrameTime * flAdjustmentPerSec;
+			flAdjustmentThisFrame = min( flAdjustmentThisFrame, -flCurDiffInSeconds );
+		}
+
+		if ( IsEngineThreaded() )
+		{
+			flAdjustmentThisFrame = -flCurDiffInSeconds;
+		}
+
+		AdjustAverageDifferenceBy( flAdjustmentThisFrame );
+	}
+
+	ShowDebugInfo( flAdjustmentPerSec );
+	return inputFrameTime + flAdjustmentThisFrame;
+}
+
+
+float CClockDriftMgr::GetCurrentClockDifference() const
+{
+	// Note: this could be optimized a little by updating it each time we add
+	// a sample (subtract the old value from the total and add the new one in).
+	float total = 0;
+	for ( int i=0; i < NUM_CLOCKDRIFT_SAMPLES; i++ )
+		total += m_ClockOffsets[i];
+
+	return total / NUM_CLOCKDRIFT_SAMPLES;
+}
+
+
+void CClockDriftMgr::ShowDebugInfo( float flAdjustment )
+{
+	if ( !cl_clock_showdebuginfo.GetInt() )
+		return;
+
+	if ( IsClockCorrectionEnabled() )
+	{
+		int high=-999, low=999;
+		int exactDiff = cl.GetClientTickCount() - m_nServerTick;
+		for ( int i=0; i < NUM_CLOCKDRIFT_SAMPLES; i++ )
+		{
+			high = max( (float)high, m_ClockOffsets[i] );
+			low = min( (float)low, m_ClockOffsets[i] );
+		}
+
+		Msg( "Clock drift: adjustment (per sec): %.2fms, avg: %.3f, lo: %d, hi: %d, ex: %d\n", flAdjustment*1000.0f, GetCurrentClockDifference(), low, high, exactDiff );
+	}
+	else
+	{
+		Msg( "Clock drift disabled.\n" );
+	}
+}
+
+
+void CClockDriftMgr::AdjustAverageDifferenceBy( float flAmountInSeconds )
+{
+	// Don't adjust the average if it's already tiny.
+	float c = GetCurrentClockDifference();
+	if ( c < 0.05f )
+		return;
+
+	float flAmountInTicks = flAmountInSeconds / host_state.interval_per_tick;
+	float factor = 1 + flAmountInTicks / c;
+
+	for ( int i=0; i < NUM_CLOCKDRIFT_SAMPLES; i++ )
+		m_ClockOffsets[i] *= factor;
+	
+	Assert( fabs( GetCurrentClockDifference() - (c + flAmountInTicks) ) < 0.001f );
+}
+
+extern float NET_GetFakeLag();
+extern ConVar net_usesocketsforloopback;
+
+bool CClockDriftMgr::IsClockCorrectionEnabled()
+{
+#ifdef SWDS
+	return false;
+#else
+
+	bool bIsMultiplayer = NET_IsMultiplayer();
+	// Assume we always want it in multiplayer
+	bool bWantsClockDriftMgr = bIsMultiplayer;
+	// If we're a multiplayer listen server, we can back off of that if we have zero latency (faked or due to sockets)
+	if ( bIsMultiplayer )
+	{
+		bool bIsListenServer = sv.IsActive();
+		bool bLocalConnectionHasZeroLatency = ( NET_GetFakeLag() <= 0.0f ) && !net_usesocketsforloopback.GetBool();
+
+		if ( bIsListenServer && bLocalConnectionHasZeroLatency )
+		{
+			bWantsClockDriftMgr = false;
+		}
+	}
+
+	// Only in multi-threaded client/server OR in multi player, but don't use it if we're the listen server w/ no fake lag
+	return cl_clock_correction.GetInt() && 
+		( IsEngineThreaded() ||	bWantsClockDriftMgr );		
+#endif
+}