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Adjust _startStamp by the amount of drift since the previous call to elapsed rather than adjusting the entire elapsed time.

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git-svn-id: svn+ssh://src.earth.threerings.net/nenya/trunk@429 ed5b42cb-e716-0410-a449-f6a68f950b19
This commit is contained in:
Charlie Groves
2008-02-27 19:15:08 +00:00
parent 5847ee1e99
commit 5a569a2fa3
1 changed files with 19 additions and 12 deletions
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src/java/com/threerings/media/timer/CalibratingTimer.java
+19 -12
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@@ -40,7 +40,7 @@ public abstract class CalibratingTimer
// documentation inherited from interface
public void reset ()
{
_startStamp = current();
_startStamp = _priorCurrent = current();
_driftMilliStamp = System.currentTimeMillis();
_driftTimerStamp = current();
_callsSinceCalibration = 0;
@@ -52,7 +52,13 @@ public abstract class CalibratingTimer
if (_callsSinceCalibration++ > 1000) {
calibrate();
}
return (long)(((current() - _startStamp)) / _driftFactor);
long current = current();
if (_driftRatio != 1.0) {
long elapsed = current - _priorCurrent;
_startStamp += (elapsed - (elapsed * _driftRatio));
_priorCurrent = current;
}
return current - _startStamp;
}
/** Calculates the drift factor from the time elapsed from the last calibrate call. */
@@ -60,27 +66,28 @@ public abstract class CalibratingTimer
{
long elapsedTimer = (current() - _driftTimerStamp);
double elapsedMillis = System.currentTimeMillis() - _driftMilliStamp;
double drift = (elapsedTimer / _milliDivider) / elapsedMillis;
double drift = elapsedMillis / (elapsedTimer / _milliDivider);
if (drift > 1.25 || drift < 0.75) {
if (_driftFactor == 1.0) {
Log.warning("Calibrating [drift=" + drift + "]");
}
_driftFactor = drift;
} else if (_driftFactor != 1.0) {
Log.warning("Calibrating [drift=" + drift + "]");
_driftRatio = drift;
} else if (_driftRatio != 1.0) {
// If we're within bounds now but we weren't before, reset _driftFactor and log it
_driftFactor = 1.0;
_driftRatio = 1.0;
Log.warning("Calibrating [drift=" + drift + "]");
}
_driftMilliStamp = System.currentTimeMillis();
_driftTimerStamp = current();
_callsSinceCalibration = 0;
}
/** Return the current value for this timer. */
public abstract long current ();
/** current() value when the timer was started. */
protected long _startStamp;
/** current() value when elapsed was called last. */
protected long _priorCurrent;
/** Amount by which current() should be divided to get milliseconds. */
protected long _milliDivider;
@@ -94,8 +101,8 @@ public abstract class CalibratingTimer
/** current() value from the last time we called calibrate. */
protected long _driftTimerStamp;
/** Factor by which the timer values are drifting from currentTimeMillis. */
protected double _driftFactor = 1.0;
/** Ratio of currentTimeMillis to timer millis. */
protected double _driftRatio = 1.0;
/** Number of calls to elapsed since we've called calibrate. */
protected int _callsSinceCalibration = 0;