com.threerings.media.timer
Class CalibratingTimer

java.lang.Object
  com.threerings.media.timer.CalibratingTimer

All Implemented Interfaces:

MediaTimer

Direct Known Subclasses:

NanoTimer, PerfTimer

public abstract class CalibratingTimer
extends Object
implements MediaTimer

Calibrates timing values from a subclass' implementation of current against those returned by System.currentTimeMillis. If the subclass timer is moving 1.25 times faster or .75 times slower than currentTimeMillis, hold it to the values from currentTimeMillis.

Field Summary

protected Interval	_calibrateInterval Interval that fires every five seconds to run the calibration.
protected static RuntimeAdjust.BooleanAdjust	_debugCalibrate A debug hook that toggles dumping of calibration values.
protected long	_driftMilliStamp currentTimeMillis() value from the last time we called calibrate.
protected float	_driftRatio Ratio of currentTimeMillis to timer millis.
protected long	_driftTimerStamp current() value from the last time we called calibrate.
protected float	_maxDriftRatio The largest drift we've had to adjust for.
protected long	_microDivider Amount by which current() should be divided to get microseconds.
protected long	_milliDivider Amount by which current() should be divided to get milliseconds.
protected long	_priorCurrent current() value when elapsed was called last.
protected long	_startStamp current() value when the timer was started.
protected static int	CALIBRATE_INTERVAL Milliseconds between calibrate calls.
protected Logger	log Used to log things.
protected static float	MAX_ALLOWED_DRIFT_RATIO The largest drift ratio we'll allow without correcting.
protected static float	MIN_ALLOWED_DRIFT_RATIO The smallest drift ratio we'll allow without correcting.

Constructor Summary

CalibratingTimer()

Method Summary

protected void	calibrate() Calculates the drift factor from the time elapsed from the last calibrate call.
void	clearMaxDriftRatio() Clears out our remembered max drift.
abstract long	current() Return the current value for this timer.
protected long	elapsed() Returns the difference between _startStamp and current()
long	getElapsedMicros() Returns the number of microseconds that have elapsed since the timer was created or last MediaTimer.reset().
long	getElapsedMillis() Returns the number of milliseconds that have elapsed since the timer was created or last MediaTimer.reset().
float	getMaxDriftRatio() Returns the greatest drift ratio we've had to compensate for.
protected void	init(long milliDivider, long microDivider) Initializes this timer.
void	reset() Resets the timer's monotonically increasing value.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

_startStamp

protected long _startStamp

current() value when the timer was started.

_priorCurrent

protected long _priorCurrent

current() value when elapsed was called last.

_milliDivider

protected long _milliDivider

Amount by which current() should be divided to get milliseconds.

_microDivider

protected long _microDivider

Amount by which current() should be divided to get microseconds.

_driftMilliStamp

protected long _driftMilliStamp

currentTimeMillis() value from the last time we called calibrate.

_driftTimerStamp

protected long _driftTimerStamp

current() value from the last time we called calibrate.

_driftRatio

protected float _driftRatio

Ratio of currentTimeMillis to timer millis.

_maxDriftRatio

protected float _maxDriftRatio

The largest drift we've had to adjust for.

_calibrateInterval

protected Interval _calibrateInterval

Interval that fires every five seconds to run the calibration.

log

protected final Logger log

Used to log things.

MAX_ALLOWED_DRIFT_RATIO

protected static final float MAX_ALLOWED_DRIFT_RATIO

The largest drift ratio we'll allow without correcting.

See Also:

Constant Field Values

MIN_ALLOWED_DRIFT_RATIO

protected static final float MIN_ALLOWED_DRIFT_RATIO

The smallest drift ratio we'll allow without correcting.

See Also:

Constant Field Values

CALIBRATE_INTERVAL

protected static final int CALIBRATE_INTERVAL

Milliseconds between calibrate calls.

See Also:

Constant Field Values

_debugCalibrate

protected static RuntimeAdjust.BooleanAdjust _debugCalibrate

A debug hook that toggles dumping of calibration values.

Constructor Detail

CalibratingTimer

public CalibratingTimer()

Method Detail

init

protected void init(long milliDivider,
                    long microDivider)

Initializes this timer. Must be called before the timer is used.

Parameters:

milliDivider - - value by which current() must be divided to get milliseconds

microDivider - - value by which current() must be divided to get microseconds

getElapsedMicros

public long getElapsedMicros()

Description copied from interface: MediaTimer

Returns the number of microseconds that have elapsed since the timer was created or last MediaTimer.reset(). Note: the accuracy of this method is highly dependent on the timer implementation used.

Specified by:

getElapsedMicros in interface MediaTimer

getElapsedMillis

public long getElapsedMillis()

Description copied from interface: MediaTimer

Returns the number of milliseconds that have elapsed since the timer was created or last MediaTimer.reset(). Note: the accuracy of this method is highly dependent on the timer implementation used.

Specified by:

getElapsedMillis in interface MediaTimer

reset

public void reset()

Description copied from interface: MediaTimer

Resets the timer's monotonically increasing value.

Specified by:

reset in interface MediaTimer

current

public abstract long current()

Return the current value for this timer.

getMaxDriftRatio

public float getMaxDriftRatio()

Returns the greatest drift ratio we've had to compensate for.

clearMaxDriftRatio

public void clearMaxDriftRatio()

Clears out our remembered max drift.

elapsed

protected long elapsed()

Returns the difference between _startStamp and current()

calibrate

protected void calibrate()

Calculates the drift factor from the time elapsed from the last calibrate call.