net.happybrackets.core

Class Synchronizer

java.lang.Object

net.happybrackets.core.Synchronizer

public class Synchronizer
extends java.lang.Object

A tool for each device to work out its current synch with respect to all other devices. We keep this independent of the audio system because the audio system start-time needs to be synched. Each synchronizer sends regular pulses every interval with the syntax: s MAC1 timeMS An s means send. Upon receiving an s, each synchronizer also responds with r MAC1 timeMS MAC2 timeMS This volley of broadcasts and responses allows each synchronizer to calculate network round-trips and average these over time. The device with the first MAC address, in alphanumeric order, is considered the master timer.

Method Summary

Modifier and Type	Method and Description
void	close() Shut down the Synchronizer.
long	correctedTimeNow() Returns the time corrected with short-term correction.
void	displayClock()
void	doAtTime(java.lang.Runnable r, long time) Cause an event to happen at the given time.
static Synchronizer	getInstance()
float	getStability() Return measure of the stability of the time correction.
static void	main(java.lang.String[] args)
long	stableTimeNow() Returns the time corrected with long-term correction.
static long	time() This returns the time in Linux format (ms since Jan 1st 1970) according to the synchronization.

Methods inherited from class java.lang.Object

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

Method Detail

getInstance

public static Synchronizer getInstance()

time

public static long time()

This returns the time in Linux format (ms since Jan 1st 1970) according to the synchronization. Note this is not guaranteed to be the right time, only the same time as the other devices on the network (also not guaranteed, but that's the aim).

Returns:

time in ms since Jan 1st 1970.

stableTimeNow

public long stableTimeNow()

Returns the time corrected with long-term correction. This should be accurate over longer periods of synch but not so sensitive to recent synch changes.

Returns:

time in ms since Jan 1st 1970.

correctedTimeNow

public long correctedTimeNow()

Returns the time corrected with short-term correction. This is more sensitive to recent synch changes but is not as reliable in the long-term as stableTimeNow().

Returns:

time in ms since Jan 1st 1970.

displayClock

public void displayClock()

doAtTime

public void doAtTime(java.lang.Runnable r,
                     long time)

Cause an event to happen at the given time.

Parameters:

r - the Runnable to run at the given time.

time - the synchronized time to enact the event, in ms since 1st Jan 1970.

close

public void close()

Shut down the Synchronizer. This is irreversible.

getStability

public float getStability()

Return measure of the stability of the time correction.

Returns:

near zero when very stable, higher values indicate less stability.

main

public static void main(java.lang.String[] args)